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Human Physiology (Biology 4)
Lecture Notes

Updated July 2017
Instructor: Rebecca Bailey

1

Chapter 1

•

Anatomy
-

•

Homeostasis

the study of body structure

Physiology
- the study of body function
1
...
explain how events occur
b
...
g
...
teleological approach
a
...
e
...
, you shiver because you need to keep warm
3
...
atoms and molecules

- Cells
1
...
humans are multicellular
3
...
obtain nutrients and O2
b
...
eliminate wastes
d
...
respond to environmental changes
f
...
transport molecules
h
...
in multicellular organisms, cells specialize

- Tissues
1
...
plus extracellular material

2

2
...
muscle
(1) specialized for contraction and force generation
(2) skeletal - movement of body or body parts
(3) cardiac - pump blood
(4) smooth - movement of organs
b
...
g
...
g
...
nervous
(1) specialized for initiating and transmitting electrical impulses
(2) brain, spinal cord, nerves
d
...
group of two or more tissues designed to perform specific functions

- Body System (organ system)
1
...
group of organ systems

•

Homeostasis
- a dynamic equilibrium where body conditions are maintained within narrow limits
1
...
each cell contributes
3
...
outside cells, inside body

3

b
...
concentration of nutrient molecules
a
...
concentration of O2 and CO2
a
...
CO2 made must be removed
3
...
become toxic at high levels
4
...
acidity affects enzyme reactions and nerve cell impulses
5
...
maintaining cell volume
b
...
temperature
a
...
volume and pressure
a
...
sensor
a
...
responds to changes (stimuli) by sending input to
...
integrator
a
...
compares set point to input
c
...

3
...
responds to changes

4

- most control systems operate using negative feedback
1
...
resists change
- positive feedback
1
...
uterine contractions during childbirth
3
...
plasma membrane (cell membrane)
a
...
intracellular fluid (ICF) - inside cell
c
...
selectively permeable - controls movement of molecules between ICF and ECF
2
...
usually near cell center
b
...
contains DNA, "genetic blueprint," directs protein synthesis, control center of cell
3
...
area between nucleus and plasma membrane
b
...
cytosol is semiliquid, site of chemical reactions

•

Organelles (see table Summary of Cytoplasm Components)
- endoplasmic reticulum (ER)
1
...
two types
a
...
rough - interconnected flattened sacs
(1) has ribosomes which help in protein synthesis (cell also has "free" ribosomes)
3
...
synthesizes proteins and lipids, releases them to ER lumen
(1) some will be secreted from the cell (hormones, enzymes), some will become
new membrane for the cell or its organelles, or other protein parts of organelles
(2) once in the lumen the protein can be modified (pieces removed, sugars
added)

6

4
...
in most cells it packages and transports products of rough ER (sections pinch off and
become transport vesicles, move to Golgi complex)
b
...
layers of flattened membranous sacs (cisternae)
2
...
sorts and sends products to appropriate place
a
...
secretory vesicles transport products out of specialized cells, fuses with plasma
membrane (secretion, exocytosis)

- lysosomes
1
...
digest cellular debris and other substances (old organelles, bacteria)
a
...
cell can use digested material

- peroxisomes
1
...
use oxygen to remove hydrogen from molecules (detoxify wastes and other chemicals
like alcohol)

- mitochondria
1
...
inner membrane has folds called cristae (folds increase surface area)
b
...
play a role in apoptosis (programmed cell death)

7

3
...
energy in chemical bonds of food molecules can't be used directly
b
...
three major steps in forming ATP (called cellular respiration)
a
...
citric acid cycle (also called Krebs cycle or tricarboxylic acid cycle)
(1) pyruvic acid is transported to mitochondrial matrix
(2) pyruvic acid ➝ acetyl CoA
(3) acetyl CoA enters citric acid cycle, which is a series of reactions
(4) CO2 is produced
(5) hydrogen atoms are attached to carrier molecules (NAD+, nicotinamide
adenine dinucleotide; FAD, flavine adenine dinucleotide; become NADH and
FADH2)
(6) 2 more ATP/original glucose
c
...
not all the energy in glucose is used to make ATP (no energy transfer is 100% efficient)
6
...
ATP is used for all the cell's energy needs (making and transporting substances, mechanical
work like muscle contraction)

- vaults
1
...
probably used to transport molecules from nucleus to other cell locations (mRNA, ribosomes)
3
...
enzymatic regulation of intermediary metabolism
a
...
g
...
provides raw material for structure and function
2
...
free ribosomes make enzymes for use in cytosol
3
...
inclusions - masses of stored nutrients
b
...
supports and organizes parts of cell
2
...
microtubules
a
...
maintain shape of cell
(1) early in cell development
(2) in asymmetrical cells
c
...
g
...
movement of cilia and flagella
(1) project from surface of cell
(2) cilia are shorter, hairlike, many on a single cell; move substances across
surface of cell (respiratory tract, oviduct)
(3) flagella are long, one per human cell; move whole cell (sperm)
(4) both have same basic structure of grouped microtubules; movement is
produced when a motor protein (dynein) displaces tubules relative to one another
e
...
microfilaments
a
...
cellular contractile systems
(1) muscle cells
(2) contractile ring that divides a cell - pinches cell together and separates halves
(3) amoeboid movement - some cells can alternately form and break down actin
filaments in order to move the whole cell (e
...
, white blood cells)
c
...
intermediate filaments
a
...
strengthen and stabilize cells
c
...
elements of cytoskeleton are interconnected
a
...
organizes groups of enzymes
c
...
may transfer mechanical forces for communication, may influence gene regulation

11

Chapter 3

•

Plasma Membrane & Membrane Potential

Basics
- selectively permeable - controls what gets in and out of cell
- Membrane Structure
1
...
hydrophilic (water loving) heads are polar, face outward toward water
b
...
responsible for membrane fluidity

2
...
between phospholipids
b
...
proteins
a
...
g
...
some on one side of membrane
(1) receptors - bind with molecules on outer surface and initiate changes in cell
(chemicals in blood only influence cells with the right receptors)
(2) membrane bound enzymes – chemical reactions at inner or outer membrane
surface
(3) filamentous meshwork on inner side bind with cytoskeleton to maintain cell
shape and for movement
(4) cell adhesion molecules (CAMs) - stick out from outer surface and secure cell
to other cells (caherins “zip” cells together in tissues/organs), also cell
communication (growth, defense responses), integrins span the membrane and
link cytoskeleton to external environment and relay regulatory signals
(5) some allow cells to recognize "self" and interact with one another (often
glycoproteins)

12

4
...
on outer surface, bound to membrane proteins and lipids (glycoproteins, glycolipids)
b
...
involved in tissue growth (cells won't overgrow)

-

•

structure known as fluid mosaic model

Cell to cell adhesions
- carbohydrates on membrane surface help arrange cells into groups, which are held together in
various ways
1
...
extracellular matrix (connective tissues)
a
...
g
...
g
...
substances diffuse through, going between blood and tissues
c
...
specialized junctions
a
...
g
...
tight junctions - impermeable barrier, common in epithelial sheets where they prevent
leakage
c
...
g
...
small, uncharged or nonpolar molecules move through lipid bilayer (e
...
, O2 CO2, fatty acids)
2
...
substances too big or without a special protein transporter need special mechanisms to get
through the membrane

13

- Passive Transport (no ATP used)
1
...
simple diffusion - substance moves through lipid bilayer or protein channels (e
...
, O2,
CO2, some ions)
b
...
facilitated diffusion uses a carrier protein that binds to the molecule to be transported
and brings it to the other side of the membrane (e
...
, glucose)
2
...
g
...
carrier proteins transport substance against its concentration gradient (needs ATP to change
conformation)
a
...
g
...
secondary active transport - driven by gradients set up by primary active transport
(1) in the digestive tract glucose and amino acids are "dragged along" with Na+
diffusing into cell (Na+ gradient set up by Na+-K+ pump)

2
...
endocytosis (pino/phagocytosis)
(1) fuse with lysosomes which break down substance and release products to
cell (e
...
, bacteria)
(2) vesicle travels to opposite side of cell and releases contents (cells lining
capillaries)
b
...
gap junctions
a
...
important in spread of electrical signals (cardiac and smooth muscle, very rarely
neurons)
2
...
phagocytes (body defense cells) recognize and kill invading cells
3
...
a specific chemical is made by special cells
(1) acts on target cells, which then respond appropriately
b
...
g
...
specialized protein receptors on plasma membrane bind with a particular messenger
a
...
many possible responses
c
...
channel regulation
a
...
receptor binding site is part of the channel, messenger binds ➝ channel opens
c
...
, neurotransmitters trigger movement of Na+, K+, or both across the membrane,
which changes the electrical activity of cell (muscle and nerve cells)
3
...
messenger binds and activates a receptor-enzyme (usually a protein kinase that
phosphorylates another protein)
b
...
eg
...
second messenger systems (most common pathway)
a
...
cAMP pathway (cyclic adenosine monophosphate, most common)
(1) messenger binds to receptor
(2) activates G protein which activates adenylyl cyclase (on cytoplasmic side of
membrane)
(3) ATP ➝ cAMP, which diffuses through cell
(4) cAMP-dependent protein kinase activated, then phosphorylates a particular
intracellular protein (this changes the protein's shape/function, bringing about the
appropriate response)
(5) can switch cellular processes on or off, eg
...
Ca

2+

pathway
(1) messenger binds to receptor
(2) activates G protein which activates phospholipase C (on cytoplasmic side of
membrane)
(3) PIP2 ➝ DAG + IP3
(phosphatidylinositol bisphosphate, diacylglycerol, inositoltriphosphate)
2+

2+

(4) IP3 increases Ca in cytosol (from stores in ER), Ca diffuses through cell
and binds to the protein calmodulin, which in turn activates another protein,
bringing about the appropriate response
(5) pathway important in cell movement such as smooth muscle contraction
d
...
very low concentrations of first messengers trigger large responses - one messenger
molecule can result in millions of product molecules
f
...
an interesting example of a signal transduction pathway

16

2
...
development
b
...
immune system (infected cells and worn-out phagocytes)
d
...
cell detaches from neighboring cells and shrinks, killed from the inside by caspases, which
take apart DNA, cytoskeleton, etc
...
cells normally receive signals for survival, which block the pathway causing apoptosis
(1) absence of growth factors or detachment from extracellular matrix act as
triggers
b
...
problems in pathways likely involved in Alzheimer's, Parkinson's and AIDS
d
...
mitochondria play a role (release cytochrome c which activates caspases)
4
...
separated charges have the potential to do work - electrical force of attraction can be
harnessed
2
...
all plasma membranes have potential
4
...
Na+
2
...
A- (large anionic intracellular proteins)
- Na+-K+ pump
1
...
directly generates about 20% of potential
a
...
indirectly generates other 80% of membrane potential
a
...
K+ will passively flow out, increasing membrane potential
(1) K+ flows out until concentration gradient is balance by electrical gradient
(negative charges inside attract K+)
c
...
leads to resting membrane potential of -70mV in a typical nerve cell (sign means more
negative inside)

- other effects
1
...
contributes to negative charges that balance leakage of K+ out of cell
2
...
high outside
b
...
altering membrane potential results in nerve impulses and muscle contraction
a
...
significance in other cells not understood

18

Chapter 4

•

Neuronal Physiology

Terms
- excitable tissues: capable of producing electrical signals (transient, rapid changes in membrane
potential), nerve & muscle
- resting membrane potential: the membrane potential that exists when no net changes in potential
are occurring
- graded potentials: local changes in membrane potential that vary in magnitude (flow of ions)
- action potentials: brief, rapid reversals in membrane potential, which can spread throughout the
membrane (flow of ions)
- voltage-gated channels: membrane channels that open or close in response to changes in
potential
- polarization: a membrane that has potential is polarized
- depolarization: a decrease in membrane potential (inside becomes more positive)
- triggering event: event that initiates a depolarization (stimulus like light or touch, chemical
messenger)
- hyperpolarization: an increase in membrane potential (inside becomes more negative)
- repolarization: return to resting potential after a depolarization

•

Graded Potentials
- magnitude of graded potential related to magnitude of triggering event
1
...
when a graded potential occurs, a piece of the membrane (called the active area) has a
different potential than the rest of the membrane (which is at resting potential, called the inactive
area)
a
...
previously inactive areas become active and more current flow occurs
2
...
decreases as it moves along the membrane
b
...
function as signals over short distances
3
...
important for nerve and muscle cells (e
...
, postsynaptic potentials)

19

•

Action Potentials (AP)
- can be transmitted over long distances without losing strength
- Depolarization
1
...
once threshold is reached, membrane quickly depolarizes to +30 mV
(1) when triggering event begins depolarization, some of the voltage-gated Na+
channels open, Na+ flows into cell (proteins that make up the channel have
charged portions, shape change occurs as those charges interact with charges
surrounding the membrane)
(2) this further depolarizes the membrane, causing even more Na+ channels to
open
(3) at threshold all the Na+ channels are open and there is an explosive increase
in Na+ permeability (P Na+)
(4) at peak depolarization, the Na+ channels close (the channel is constructed so
that the same depolarization that opens them also closes them)

- Repolarization begins
1
...
this restores internal negativity
3
...

a
...
newly opened K+ channels close
(1) hyperpolarization occurs before channels close (membrane even more
negative than at resting potential)
(2) resting potential restored

- AP lasts about 1 millisecond

- ion gradient restored
1
...
important for long term maintenance of gradient
b
...
cell body
a
...
receives signals from other cells (contains receptors for chemical messengers)
2
...
projections from cell body
b
...
axon (nerve fiber)
a
...
conducts APs away from cell body
c
...
axon hillock (part of cell body and first part of axon) is area where APs generated in
most neurons
e
...
may be less than a mm or more than a m

•

Propagation of an AP
- Conduction by local current flow (contiguous conduction)
1
...
local current flow between this active area and adjacent inactive area causes new AP
b
...
occurs in myelinated fibers
a
...
nodes of Ranvier
(1) bare spaces between myelin
(2) contain Na+ channels
2
...
much faster
b
...
larger fiber diameter ➝ faster conduction
2
...
g
...
smaller unmyelinated fibers found in areas where speed not critical to function (e
...
fibers
innervating digestive tract)

- Refractory period
1
...
membrane that just had AP not very sensitive to further stimulation
a
...
relative refractory period
(1) needs stronger than usual stimulation to produce another AP
(2) only some Na+ gates ready to open, some K+ gates still open
3
...
a membrane responds with a maximal AP or it doesn't respond at all
a
...
nervous system differentiates between relatively weak or strong stimuli by frequency of APs
a
...

1
...
gland
3
...
junction between axon terminal of one neuron and dendrites or cell body of next neuron
2
...
anatomy of a synapse
a
...
postsynaptic neuron
(1) conducts APs away from synapse
(2) portion at synapse called subsynaptic membrane
c
...
generally operates in one direction (changes in membrane potential in presynaptic neuron
bring changes in membrane potential of postsynaptic neuron)
5
...
AP reaches presynaptic neuron axon terminal
b
...
Ca

2+

2+

channels in synaptic knob open

influx induces release of neurotransmitter from synaptic vesicles by exocytosis

d
...
triggers opening of specific ion channels in subsynaptic membrane (chemically-gated
channels)

- Two types of synapses
1
...
Na+ and K+ channels open
b
...
results in small depolarization called an EPSP (excitatory postsynaptic potential), a
kind of graded potential
d
...
inhibitory synapse
a
...
K+ ➝ out, or Cl-➝ in
c
...
each IPSP moves membrane further away from threshold
3
...
the same neurotransmitter is generally released at a given synapse
(1) some nts are always excitatory
(2) some nts are always inhibitory
(3) some nts produce an IPSP at one synapse and an EPSP at another synapse

23

- Synaptic delay
1
...
5 - 1 msec)
2
...
as long as the nt is bound to receptor, IPSP or EPSP continues
2
...
diffuses away from synaptic cleft
b
...
actively transported back to presynaptic neuron

- Neurotransmitters and second messenger systems
1
...
some use second messenger systems (cAMP), which work in short term and long term
changes like memory

- Grand postsynaptic potentials (GPSP)
1
...
temporal summation
a
...
spatial summation
a
...
classical neurotransmitters
a
...
made in axon terminal
c
...
neuropeptides
a
...
made in cell body, stored in dense-core vesicles in the axon terminal
(1) one or more may be released along with a classical nt
c
...
most are neuromodulators

24

(1) don't cause EPSPs/IPSPs
(2) cause long term changes in synapse
(3) often use second messenger systems

- Presynaptic inhibition and facilitation
1
...
probably involves Ca

2+

b
...
in convergence a single neuron is influenced by many other neurons synapsing on it
2
...
brain and spinal cord
- peripheral nervous system (PNS)
1
...
afferent (sensory) division
a
...
efferent (motor) division
a
...
somatic nervous system
(1) motor neurons supplying muscles
c
...
in afferent division of PNS
2
...
generates APs in response to a stimulus
3
...
synapses with other neurons in spinal cord
- efferent
1
...
cell body in CNS
3
...
in CNS, between afferent and efferent neurons
2
...
astrocytes
a
...
repair of injury and scar formation
c
...
take up and break down some nts (glutamate, GABA)
e
...
enhance synapse formation and modify function, physical and chemical influences
g
...
oligodendrocytes
a
...
ependymal cells
a
...
help form cerebrospinal fluid (CSF)
c
...
microglia
a
...
secrete nerve cell growth factor

- blood-brain barrier
1
...
only substances that can pass through cells can be exchanged (lipid soluble
substances, e
...
, O2, CO2, alcohol, steroid hormones; substances with specific carriers,
e
...
, glucose, amino acids, ions)
2
...
keeps out circulating hormones that act like nts

- CSF
1
...
cushions CNS
3
...
directly contacts CNS cells and exchanges take place
4
...
dura mater - outer layer
a
...
arachnoid mater - middle layer
a
...
arachnoid villi reabsorb CSF (return to blood in sinuses)
3
...
well vascularized
b
...
cranium (skull) - brain
2
...
connected by corpus callosum
2
...
some degree of specialization
a
...
right - nonlanguage skills like spatial perception and art/music
4
...
occipital, temporal, parietal, frontal
2
...
motor areas - control voluntary motor functions
2
...
association areas - integrate diverse information

28

- selected functional areas
1
...
receives visual information
b
...
primary auditory cortex
a
...
surrounding higher-order auditory cortex interprets
3
...
receives sensory input (somesthetic sensations from skin like touch, temp
...
)
(1) localizes source of input, perceives intensity of stimulus, capable of spatial
discrimination
(2) sensory homunculus - a particular region of the brain receives information
from a certain part of the body
4
...
integrates somatosensory and visual input
b
...
primary motor cortex
a
...
supplementary motor area
a
...
premotor cortex
a
...
interacts with posterior parietal cortex
8
...
Broca's area
(1) important in ability to speak - interacts with motor areas for speech
b
...
Broca's and Wernicke's usually in left hemisphere only, right side has affective
language areas, which express and comprehend emotion in speech

29

9
...
plans for voluntary activities
b
...
personality
d
...
parietal-temporal-occipital association cortex
a
...
limbic association cortex
a
...
many areas can change based on need, e
...
:
a
...
use of a particular body part can result in more cortical space being devoted to it

- areas constantly interact

•

Subcortical structures
- basal nuclei (basal ganglia)
1
...
functional aggregations of cell bodies
a
...
maintaining purposeful motor activity and suppressing unnecessary movement
c
...
complex aspects of motor control
e
...
receives input from all cortical areas
4
...
preliminary processing of sensory input
a
...
crude awareness of sensation
3
...
some degree of consciousness
5
...
contains many nuclei, each with a functional specialty

- hypothalamus
1
...
integrating center for homeostasis, links ANS and endocrine system
a
...
regulates water balance (urine output) and thirst (contains osmoreceptors - test
concentration of body fluids)
c
...
controls endocrine functioning (produces hormones, regulates pituitary)
e
...
controls autonomic centers in brain and spinal cord (e
...
, activity of smooth and
cardiac muscle, exocrine glands)
g
...
parts of cortex, basal nuclei, thalamus, hypothalamus
2
...
) and physical expressions of
emotion (attacking when angered, laughing, crying, etc
...
contains "reward" and "punishment" centers
4
...
norepinephrine, dopamine and serotonin important neurotransmitters (precise role
unclear, more of these nts associated with pleasure, less with depression)

•

Learning and Memory
- learning: acquisition of knowledge or skills as a consequence of experience, instruction, or both
- memory: storage of knowledge for later recall
- remembering: process of retrieving information from storage
- forgetting: inability to retrieve information
- memory trace: neural change responsible for storage of information
1
...
particular areas appear to be important in certain kinds of memories
a
...
cerebellum - procedural memories (a
...
a
...
g
...
short-term
a
...
limited capacity
c
...
forgetting is permanent (unless consolidated)
e
...
long-term
a
...
large storage capacity
c
...
quite stable, forgetting usually transient
e
...
emotional state - transfer better when more alert and motivated
2
...
association of new information with old information

•

cerebellum
- different portions specialize in particular functions (mostly ipsilateral)
1
...
enhances muscle tone
4
...
input from cortical motor areas and peripheral receptors (indirect)
b
...
plans and initiates voluntary movement
a
...
procedural memories

32

•

brain stem
- all incoming and outgoing fibers pass through, most synapse here for processing
- functions
1
...
contains nuclei for control of autonomic activities
a
...
respiratory centers (rate and depth of breathing)
c
...
modulates pain
4
...
contains reticular formation
a
...
controls cortical alertness (reticular activating system - RAS)
c
...
contains sleep centers

•

Sleep
- an active process in which an individual is not consciously aware of surroundings but can be
aroused by external stimuli
- types of sleep
1
...
from light sleep to deep sleep and back
b
...
paradoxical (REM) sleep
a
...
characterized by lack of movement (except eyes), irregular heart and respiratory
rate and blood pressure, dreaming
- probably controlled by 3 centers that interact to produce the stages of sleep (arousal system, slow
wave center, REM center)
- functions
1
...
accomplish changes for learning and memory

33

•

Spinal Cord
-

extends from brain stem

- has paired spinal nerves
1
...
both afferent (sensory) and efferent (motor and ANS) fibers

- gray matter
1
...
dorsal horns
a
...
afferent neurons terminate
3
...
efferent ANS cell bodies
4
...
efferent motor neuron cell bodies

- white matter
1
...
ascending: cord ➝ brain
b
...
response that occurs without conscious effort
a
...
g
...
acquired (conditioned): learned through practice (e
...
, typing , playing sports)
2
...
receptor responds to stimulus by generating an AP
b
...

c
...
efferent pathway transmits information to
...
effector (muscle or gland)
3
...
spinal cord is integrating center (no brain involvement needed)
b
...
brain can modify spinal reflex
(1) consciously override by sending inhibitory signals to muscle group that
would move, excitatory signals to antagonistic muscle group

35

Chapter 6

•

PNS: Afferent Division

Basics
- information carried toward CNS
1
...
from surface areas
a
...
special senses - vision, hearing, taste, smell
- perception: our conscious interpretation of the world created by the brain from a pattern of nerve
impulses from sensory receptors

•

Receptor Physiology
- peripheral ends of afferent neurons have receptors that detect stimuli (changes in internal or
external environment)
1
...
each kind of receptor is specialized to respond to one kind of stimulus (the adequate
stimulus)
a
...
receptor may be a special cell associated with the peripheral ending of a neuron

- types of receptors (based on what they respond to)
1
...
mechanoreceptors - mechanical stimuli
3
...
osmoreceptors - concentration of body fluids
5
...
nociceptors (pain receptors) - tissue damage or distortion (intense stimulation of any
receptor perceived as pain)

- graded receptor potentials
1
...
opens ion channels - main effect is Na+ flowing in (depolarization), if summation of
depolarizations reaches threshold, AP generated (called a generator potential)

36

b
...
stronger stimuli ➝ greater frequency of APs (frequency code)
d
...
continued stimulation does not result in APs
2
...
important when continuous information is useful (posture and balance sensed by
proprioceptors, nociceptors)
3
...
useful when more information not necessary (touch)
b
...
mechanisms not well known, may be inactivation of Na+ channels

- somatosensory pathways
1
...

2
...

3
...
process of sending information through a particular pathway is projection, results in
knowledge of type, location and intensity of stimulus

- acuity (discriminative ability)
1
...
greater density of receptors results in greater acuity

3
...
areas nearest stimulus stimulated to a greater extent, areas farther away stimulated
less
b
...
mechanical
2
...
polymodal

- sensitized by prostaglandins (fatty acid derivatives from lipid bilayer, act locally)
- fast pain pathway
1
...
localized, sharp sensation

- slow pain pathway
1
...
dull, aching, poorly localized sensation
3
...
g
...
first-order afferent fibers synapse in spinal cord and release substance P (nt unique to pain
fibers)
2
...
signals passed to hypothalamus and limbic system, emotional and behavioral
responses occur
3
...
neural mechanisms can suppress transmission in pain pathways at the spinal cord
(presynaptic inhibition of release of substance P)
a
...
uses opiate receptors on afferent pain fiber terminal
a
...
endogenous opiates (e
...
, endorphins, enkephalins, dynorphin)
3
...
pain modulators include exercise, acupuncture, hypnosis and some types of stress

38

Chapter 7

•

PNS: Efferent Division

Basics
- autonomic nervous system
1
...
innervates cardiac and smooth muscle, glands
- somatic nervous system
1
...
innervates skeletal muscle
- two neurotransmitters
1
...
norepinephrine (NE)

•

ANS
- pathways typically have a 2 neuron chain extending from CNS to the innervated organ
1
...
sympathetic
a
...
preganglionic fibers are short, synapse in a sympathetic chain ganglion along the
spinal cord (release ACh)
(1) some pass through the ganglion and synapse later in collateral
ganglion nearer to the innervated organ
c
...
parasympathetic
a
...
preganglionic fibers are long, synapse in terminal ganglia in or near effector organs
(release ACh)
c
...
most visceral organs innervated by both sympathetic and parasympathetic fibers
2
...
either can be excitatory or inhibitory depending on which organ

39

4
...
called sympathetic or parasympathetic tone, or tonic activity
5
...
sympathetic dominance results in increase of oxygen/nutrient rich
blood flow to skeletal muscles (vessels dilate), heart beats faster and more forcefully,
blood pressure increases, respiratory airways dilate, glycogen and fat stores broken
down, digestive and urinary activities inhibited, pupils dilate, sweating
b
...
allows precise control over body functions
7
...

a
...
most sweat glands have only sympathetic fibers, and postganglionic fibers release
ACh
c
...
an endocrine gland with cortex and medulla
2
...
NE and epinephrine released (reinforce sympathetic activity)

- receptor proteins
1
...
binding of nt induces response via second messenger

2
...
nicotinic - on postganglionic cell bodies in all autonomic ganglia and on cells of
adrenal medulla (in sympathetic and parasympathetic)
(1) always excitatory response
b
...
adrenergic receptors on effector organs (sympathetic)
a
...
beta (β) receptors
(1) β binds with NE and E, found mostly in heart, excitatory response
1

(increased rate/force of contraction)
(2) β bind mostly with E, response inhibitory (e
...
, dilation of arterioles and
2

bronchioles)
- ANS regulated by
...
medulla in brain stem
2
...
prefrontal association cortex

•

Somatic Nervous System
- cell bodies of motor neurons in ventral horn of spinal cord, terminates on skeletal muscle cell
(releases ACh)
1
...
inhibition due to presynaptic inhibition
3
...
subject to conscious and subconscious control (posture, balance, stereotypical movements)

- neuromuscular junction
1
...
each terminal is enlarged into a terminal button (or axon terminal), which fits into a
groove in the muscle fiber (motor end plate)
b
...
electrochemical events
a
...
voltage-gated Ca

2+

channels open (Ca

2+

diffuses into terminal button)

c
...
ACh diffuses across cleft and binds with receptors on motor end plate
e
...
a large enough EPP triggers AP in muscle fiber membrane surrounding motor end
plate (typically one EPP enough)
(1) spreads by local current flow throughout muscle fiber, resulting in muscle
contraction
g
...
skeletal (striated, voluntary, multinucleate)
a
...
cardiac (striated, involuntary, one nucleus)
a
...
smooth (unstriated, involuntary, one nucleus)
a
...
whole muscle
a
...
connective tissue extends to form tendons attaching muscle to bone
2
...
contains myofibrils (specialized organelles) which are made up of protein
filaments (myofilaments)
b
...
thin filaments
(1) made mostly of actin molecules, each of which has a myosin binding
site (cross bridge binding site)
(2) tropomyosin blocks binding sites when cell at rest
(3) troponin holds tropomyosin in place, has Ca

2+

binding site

d
...
plasma membrane also called sarcolemma
(1) forms T tubules, which project into cell (continuous with surface
membrane, allowing electrical activity at cell surface to be transmitted
throughout cell)
f
...
k
...
lateral sacs, stores Ca )

43

- Contraction (excitation-contraction coupling and the sliding filament mechanism)
1
...
spreads throughout cell surface and T tubules by local current flow
2
...
Ca

2+

2+

from terminal cisternae

binds to troponin, changing its shape so that it moves tropomyosin out of the way of the

binding sites
4
...
power stroke - myosin had uses energy of ATP to pivot and pull thin filaments toward the
center of sarcomere
6
...
"cocking" of the myosin head - ATP ➝ ADP + Pi by ATPase, myosin head returns to original
position (high energy conformation)
8
...
once AP is over (1-2 msec) Ca
b
...
troponin and tropomyosin again cover binding sites
d
...
other important points
a
...
latent period is time between AP and contraction
c
...
contraction of an individual cell is an all-or-none response

•

Skeletal muscle mechanics
- gradation of whole muscle tension
1
...
recruiting more motor units ➝ more tension (more force, stronger contraction)
a
...
smaller motor units in muscles needing precise control (eyes, fingers), larger motor
units in muscles designed for power (legs)
c
...
g
...
influencing tension in each fiber
a
...
length-tension relationship (optimal length ➝ increased tension)
(1) maximal force possible at optimal length - myosin cross bridges have
maximal access to actin binding sites
c
...
thicker fibers ➝ increased tension
(1) more myofilaments in cell

- types of contraction
1
...
tension constant, muscle changes length
(1) concentric contraction - muscle shortens (lifting a load)
(2) eccentric contraction - muscle lengthens (lowering load)
2
...
tension develops, length stays the same (trying to lift too heavy a load, pushing
against a wall)

- muscles accomplish work (force x distance), but most of the energy muscles use (about 75%)
converted to heat

- lever systems
1
...
depending on construction of system, allows a given effort to move a heavier load, or to move
it farther and faster

•

Skeletal muscle metabolism
- muscle cells have enough ATP reserves to last 4-6 seconds of strenuous activity
- 3 ways to form ATP
1
...
contains high energy phosphate group
CP + ADP ➝ creatine + ATP (with enzyme creatine kinase)

45

b
...
enough stores to last 15-20 sec
2
...
in mitochondria, needs O2
(1) fueled by fatty acids (during rest or light exercise, slow) or glucose (during
more intense exercise, from blood and glycogen stores)
b
...
constant supply of O2 facilitated by myoglobin (stores O2, increases O2 transfer from
blood)
d
...
anaerobic glycolysis
a
...
good for short term (high intensity)

- fatigue
1
...
increase in Pi from the breakdown of ATP is primary cause (interferes w/power stroke,
2+

2+

decreases sensitivity of regulatory proteins to Ca , decrease amount of Ca released)
2+

b
...
depleted glycogen reserves
2
...
ACh synthesis too slow to keep up with high intensity exercise
3
...
CNS does not activate motor neurons due to pain or tiredness

- oxygen debt
1
...
breaks down lactic acid, replenishes stores of creatine phosphate and glycogen
b
...
slow-oxidative
a
...
use oxidative phosphorylation (lots of mitochondria, myoglobin, capillaries)

46

c
...
fast-glycolytic
a
...
use anaerobic glycolysis (few mitochondria, little myoglobin, lots of glycogen &
glycolytic enzymes)
c
...
fast-oxidative
a
...
mostly oxidative phosphorylation, some anaerobic glycolysis (characteristics of
slow-ox and fast-gly)
c
...
endurance exercise converts fast-glycolytic to fast-oxidative, weight lifting does the
opposite
a
...

2
...
depends on nerve supply

•

Control of skeletal muscle
- 3 levels of input
1
...
corticospinal (pyramidal) motor system
a
...
activity planned by premotor and supplementary motor areas, and cerebellum
c
...
multineuronal (extrapyramidal) motor system
a
...
mainly regulation of posture and large muscle groups (subconscious)

- afferent signals
1
...
muscle proprioceptors sense changes in length and tension
a
...
local spinal reflexes

47

3
...
in middle of muscle, monitors muscle length and speed of stretching
b
...
when whole muscle contracts, gamma motor neurons signal ends of intrafusal fibers
to contract (takes up slack so receptors maintain sensitivity to stretch)
4
...
in tendons, monitor tension
b
...
can inhibit alpha motor neurons of that muscle to prevent damage

•

Smooth muscle
- functional anatomy
1
...
thick and thin filaments
a
...
tropomyosin does not block binding sites
3
...
Ca

2+

enters mostly from ECF (voltage-gated Ca

2+

channels), then some from sarcoplasmic

reticulum
2
...
cross bridge cycling occurs until Ca

2+

no longer available (actively pumped back to ECF and

SR)

- multiunit smooth muscle
1
...
innervated by ANS, which initiates contractions
3
...
cells electrically linked (gap junctions)
2
...
no resting potential - cells gradually depolarize with automatic changes in channel
permeability
b
...
a single contraction can be 3 sec long (cross bridge cycling and Ca

2+

removal slow)

2
...
ATP use slow
b
...
can develop tension even when stretched to about 2
...
heart is the pump
a
...
blood vessels are passageways
3
...
pulmonary circuit
a
...
right side is pump
2
...
heart ➝ body tissues and back (at tissues, picks up CO2, releases O2)
b
...
AV valves attached by chordae tendinae to papillary muscles so that they open in one
direction only
2
...
provides attachment for valves and muscle
2
...
endocardium (epithelial lining)
2
...
epicardium (thin fibrous connective tissue layer)

- pericardial sac
1
...
anchors heart
b
...
specialized cells that initiate and conduct APs
2
...
decreased flow of K+ out and increased inward flow of Na+ through “funny” channels
results in slow depolarization
b
...
at threshold voltage-gated long-lasting Ca

2+

channels open, more Ca

2+

flows in (this

is the AP)
d
...
locations
a
...
AV node (atrioventricular)
(1) electrical connection between atria and ventricles
(2) signal slightly delayed (
...
AV bundle (bundle of His)
(1) branch into ventricles
d
...
APs spread from cell to cell
a
...
cardiac muscle APs
a
...
voltage-gated Na+ channels open, Na+ ➝ in, cell depolarized to +30 mV
c
...
at the end of the plateau, Ca channels close, voltage-gated K+ channels open
2+

(K+ ➝ out, repolarization)
3
...
AP travels down T tubules, voltage-gated Ca channels open,
2+

Ca ➝ in from ECF
2+

2+

b
...
Ca binds with troponin-tropomyosin complex, cross bridge cycling occurs
2+

d
...
extent of cross bridge cycling depends on amount of Ca that enters cytosol (unlike in
2+

skeletal muscle, where enough Ca for maximum contraction is always released)
2+

4
...
long refractory period
a
...
tetanus does not occur (no summation)
c
...
diastole
a
...
blood fills ventricles (amount at end of diastole is called end-diastolic volume, EDV is
about 135 ml)
c
...
systole
a
...
semilunar valves open
c
...
typically about 5 liters/min at rest (entire blood volume)
2
...
difference between CO at rest and maximum CO is cardiac reserve

- factors influencing heart rate (HR)
1
...
primarily supplies atria (SA and AV nodes)
b
...
also increases PK+ at AV node, lengthening delay
d
...
little effect on strength of ventricular contraction
2
...
acts on SA node
(1) decreases PK+ by speeding up inactivation of K+ channels, resulting in
"hypopolarization", threshold reached more quickly
b
...
speeds spread of AP throughout nodal system by enhancing Ca influx

- factors influencing stroke volume (SV)
1
...
resting cardiac muscle is at less than optimal length - stretching fibers by increasing
EDV (increasing venous return) results in a more forceful contraction (increases SV)
b
...
increasing contractility (increasing SV)
2+

a
...
most blood flow occurs during diastole
2
...
uses mostly free fatty acids, but can use glucose
3
...
adenosine (formed from breaking down ATP) released from muscle cells
(1) during O2 deficit
(2) during increased activity (using more ATP)
(3) induces dilation of vessels (smooth muscle relaxes)

•

Homeostatic imbalances
- heart failure (heart can't keep up with demands of body)
1
...
damage from heart attack or impaired circulation to cardiac muscle
b
...
contractility of heart is decreased
a
...
body compensates with increased sympathetic activity and retaining salt and water to
expand blood volume and increase EDV
c
...
complications of disease are leading cause of death in US
2
...
vascular spasm - decreased O2 triggers platelet activating factor (PAF) release from
vessels, causing spastic constriction, further decreasing O2 to heart
b
...
thromboembolism - plaque breaks through lining of blood vessels and platelets form
abnormal clots (thrombus) if clot breaks free (embolus) it can block small vessels
(complete blockage causes myocardial infarction - heart attack)
3
...
usually during physical or emotional stress
b
...
risk factors - genetics, obesity, old age, smoking, high blood pressure, diabetes, lack of
exercise, nervous tension, high blood cholesterol levels
5
...
high blood levels of homocysteine (promotes smooth muscle growth and causes
oxidation)
b
...
cholesterol
a
...
low density lipoproteins (LDL) transport to cells ("bad cholesterol")
c
...
cholesterol needed for cell membranes, hormones, bile salts - but high levels of LDL
associated with atherosclerosis

55

Chapter 10

•

Blood Vessels and Blood Pressure

Basics
- exchanges between blood and tissue cells take place through the interstitial fluid

- all organs receive fresh blood
1
...
reconditioning organs receive a high proportion of cardiac output (digestive system, kidneys)

- organization "vascular tree"
1
...
arterioles (adjusts blood flow to tissues)
3
...
venules (carries blood to veins)
5
...
directly proportional to pressure gradient
2
...
vessel radius - smaller vessels ➝ more resistance
b
...
length of vessel - longer vessel ➝ more resistance

•

Arteries
- fast transport
1
...
walls contain endothelial lining surrounded by smooth muscle and connective tissue fibers
(collagen and elastin), which allow walls to stretch to contain pumped blood
2
...
blood pressure is the force exerted by blood on vessel walls
a
...
systolic pressure is the maximum pressure during systole (should be <120 mmHg)
c
...
systolic - diastolic = pulse pressure (the pressure felt in arteries near the body
surface)
2
...
vasoconstriction and vasodilation (narrowing and enlarging)
2
...
myogenic activity
b
...
chemical influences
a
...
local metabolic factors probably act by causing release of chemical mediators from
endothelial cells (called vasoactive mediators), e
...
,
(1) endothelial-derived relaxing factor (EDRF), also known as nitric oxide (NO)
inhibits Ca

2+

influx in smooth muscle - vasodilator

(2) endothelin – vasoconstrictor

57

2
...
application of heat (vasodilation) or cold (vasoconstriction)
b
...
sympathetic activity produces generalized vasoconstriction, increasing resistance and BP
(don't vasoconstrict brain)
MAP = CO x total peripheral resistance
a
...
E at β receptors causes vasodilation (heart, skeletal muscles)
2

2
...
vasopressin - important in fluid balance, vasoconstrictor
b
...
local control mechanisms can override

•

Capillaries
- responsible for exchanges between plasma and interstitial fluid (solute exchange mainly by
diffusion)
1
...
highly branched
3
...
lipid soluble substances pass through cells (O2, CO2)
5
...
some vesicular transport (hormones)
7
...
rings of smooth muscle can block flow through capillaries in less active tissues
a
...
important in distribution of fluids between plasma and interstitial fluid
a
...
fluid reabsorbed at venular end
(1) capillary BP lower than plasma-colloid osmotic pressure
2
...
fluid shifts occur as needed
a
...
excess fluid in blood, shifts to interstitial fluid
c
...
large valvelike openings allow in fluid and any leaked proteins (lymph)
2
...
skeletal muscles help squeeze lymph through
4
...
low plasma proteins
a
...
kidney or liver disease, diet deficient in protein, burns
2
...
loss of proteins
b
...
increased venous pressure
a
...
congestive heart failure, pregnancy
4
...
lymph node removal, parasite

59

•

Veins
- transport back to heart
- blood reservoir
1
...
venous storage decreases effective circulating volume
a
...
sympathetic activity
a
...
still low resistance vessels (large radius)
2
...
acts as pump
3
...
one-way valves every few centimeters allow flow toward heart only
4
...
acts as pump due to decreased pressure in thoracic cavity
5
...
blood "sucked in" as ventricles relax

•

Blood Pressure
- MAP is main driving force
1
...
not too high or extra work for heart, increased risk of vascular damage

- short term regulation (seconds)
1
...
pressure sensors in carotid sinus and aortic arch sense changes in MAP and pulse
pressure
(1) rate of firing increases with increasing pressure, decreases with decreasing
pressure
b
...
adjustments in total blood volume via salt/water balance - urinary system and thirst
(volume receptors in left atrium, osmoreceptors in hypothalamus)

60

- other contributing factors
1
...
sense low O2 and high acid
(1) increase respiratory activity but also increase BP (signals CV center)
2
...
exercise
a
...
hypothalamic temperature regulation
a
...
vasoactive substances from endothelial cells
6
...
BP above 140/90 (high-normal is 135/85)
2
...
include atherosclerosis, endocrine disorders, nervous system defects
3
...

a
...
excessive salt intake
c
...
defects in Na+-K+ pumps
e
...
excess vasopressin
4
...
stresses heart and blood vessels
a
...
rupture of vessels - stroke, heart attack
c
...
kidney failure due to damaged vessels
e
...
BP below 100/60
2
...
standing up - gravity decreases venous return
b
...
when blood flow to tissues inadequate its called circulatory shock
a
...
may become irreversible

62

Chapter 11

•

Blood

Basics
- 8% of body weight, 5-5
...
formed elements
a
...
leukocytes (WBCs)
c
...
matrix is plasma

•

Plasma
- 90% water
- contains proteins, ions, buffers, respiratory gases, nutrients, wastes, hormones
- proteins are functionally important
1
...
3 types
a
...
globulins - bind substances for transport, blood clotting, inactive precursors,
antibodies
c
...
carries most of O2 (4 O2/molecule)
2
...
helps buffer blood

- no nucleus or organelles

- contains glycolytic enzymes for making ATP
-

- contain carbonic anhydrase, which converts CO2 to its transported form (HCO3 , bicarbonate)

63

- erythropoiesis (production of RBCs)
1
...
occurs in red bone marrow (in adults - sternum, vertebrae, ends of long bones, ribs, base of
skull)
a
...
controlled by hormone erythropoietin
(1) released by kidneys in response to decreased O2
(2) restoring normal O2 levels is negative feedback
c
...
process takes days to weeks depending on how many cells needed

•

Leukocytes (WBCs)
- body defense
- originally made in red marrow in response to stimulating factors
1
...
live about 10 days
2
...
can be stored in spleen (as are RBCs)
4
...
vascular spasm
a
...
formation of platelet plug seals break
a
...
actin-myosin complex in platelets contracts and strengthens plug
c
...
blood clotting needed to plug larger holes
a
...
clot retraction
(1) platelets contract and squeeze serum from clot
4
...
as healing occurs plasmin dissolves clot

65

Chapter 12

•

Body Defenses

External Defenses (first line of defense)
- Skin (integument)
1
...
keratinocytes form barrier, also influence immune cells
2
...
contain specialized immune cells
3
...
secretions of sweat and oil (sebaceous) glands are toxic to bacteria

- Mucous membranes and associated structures (line cavities open to outside of body)
1
...
salivary enzymes kill bacteria
b
...
secretions contain antibodies
d
...
gut-associated lymphoid tissue (GALT) a
...
a
...
appendix contains immune cells
2
...
acidic urine
b
...
sticky mucus in genitourinary tract traps pathogens & has antibodies
(1) swept out as organ empties
(2) engulfed by phagocytes
3
...
large particles filtered by hairs in nasal passages
b
...
sticky mucus traps pathogens in airways
(1) cilia sweeps mucus upward (swallowed, or coughing, sneezing or
expectorating removes it from body)
(2) antibodies secreted in mucus
d
...
neutrophils: highly mobile phagocytes
2
...
basophils: release histamine and heparin (inflammatory response) involved in allergic
reactions
4
...
B lymphocytes: secrete antibodies
(1) probably mature in bone marrow
b
...
monocytes: become macrophages - large phagocytes in tissues

- most in tissues, some circulate in blood
1
...
store, produce or process lymphocytes
b
...
located to catch invaders and decrease their spread

•

Nonspecific defenses (general defenses or innate immunity)
- responses that defend against any invader or abnormal material
- triggered by general molecular patterns associated with pathogens or other dangers
- Inflammation (Inflammatory Response)
1
...
destroy/inactivate invaders
b
...
prepare for healing
d
...
resident macrophages begin phagocytosis
3
...

a
...
increased capillary permeability ➝ plasma proteins flow out, ➝ edema (swelling,
pain)
4
...
neutrophils and monocytes migrate to area

67

a
...
move to tissues by diapedesis
c
...
phagocytosis occurs to recognized substances
(1) rough surfaces of damaged cells
(2) opsonins - chemical placed on non-self cell by immune system, links it to
phagocyte (antibodies, complement)
e
...
released by virus-infected cells, triggers production of virus-blocking enzymes in nearby
cells
2
...
similar to a type of lymphocyte, lyse virus-infected cells and cancer cells

- Complement system
1
...
lyses non-self cells
(1) membrane attack complex (MAC) inserts into bacterial membrane and pokes
holes
b
...
promote vasodilation and histamine release
d
...
B lymphocytes specialize in recognizing free-existing invaders like bacteria, bacterial
toxins, some viruses (antibody-mediated or humoral immunity)
2
...
during maturation each B and T cell becomes capable of responding to a particular invader
(only one specific kind of invader for each individual cell)
a
...
recognize antigens - large, complex molecule that the immune system can respond to
a
...
may be on cell surface or individual molecules secreted by the pathogen
5
...
major histocompatibility complex (MHC) is a group of genes that determines which
MHC glycoproteins an individual has
b
...
B cells display antibodies on their surfaces and secrete them
a
...
each antibody molecule has 2 binding sites for a specific antigen
2
...

a
...
some become memory cells, which launch a more powerful attack if the body is
exposed to that antigen again (secondary response)
3
...
neutralization - bind to free floating antigens and stop them from causing harm
b
...
act as opsonins, enhancing phagocytosis
d
...
stimulate killer cells to lyse bacteria (similar to natural killer cells but require
antibodies)
4
...
infections, vaccines
5
...
breast milk, snake bite/rabies/tetanus shots

69

•

Cell-mediated immunity
- macrophages "present antigen" to T cells (often to B cells also)
1
...
appropriate type of T cell binds and is activated to reproduce and differentiate

- T cells require both non-self and self antigen to bind and destroy a cell

- types of T cells
1
...
destroy virus-infected, cancer or transplanted cells
(1) direct killing by releasing perforin to poke holes and lyse cell
(2) indirect by signaling for apoptosis (programmed cell death)
2
...
secrete cytokines that regulate nearly all aspects of immune response, including
...
suppressor T cells
a
...
limit responses of other immune cells
c
...
innate lymphoid cells (ILCs) similar duties as T cells but faster and less powerful
2
...
route for water and heat loss
2
...
acid-base balance (CO2)
4
...
defense against inhaled invaders
6
...
alters blood composition

•

Functional anatomy
- airways
1
...
thin walled and surrounded by capillaries
a
...
type I cells - simple squamous epithelium
c
...
macrophages fight invaders

- pleural sacs
1
...
intrapleural fluid lubricates surfaces and helps lungs stick to thoracic wall

71

•

Respiratory mechanics
- in ventilation air flows down a pressure gradient
1
...
atmospheric pressure (760 mmHg at sea level)
b
...
k
...
intrapulmonary pressure (varies)
c
...
k
...
intrathoracic pressure is within the pleural sac (756
mmHg at rest)
2
...
intrapleural fluid (sticky)
b
...
inspiration
a
...
volume of thoracic cavity and lungs increases
c
...
air flows in
4
...
inspiratory muscles relax (quiet breathing)
b
...
intra-alveolar pressure increases
d
...
forced expiration
a
...
adjusted to meet the body's needs
a
...
sympathetic stimulation/epinephrine ➝ bronchodilation ➝ decreased resistance ➝
increased airflow
- matching airflow to blood flow (ventilation-perfusion coupling)
1
...
bronchioles
a
...
decreased CO2 ➝ bronchoconstriction ➝ decreased airflow

72

3
...
decreased O2 ➝ vasoconstriction ➝ decreased blood flow
b
...
simultaneous adjustments mean air and blood not wasted
a
...
healthy lungs recoil after stretching and are compliant (easy to inflate)
2
...
elastin fibers in lung connective tissue
b
...
in healthy lungs breathing requires little energy
a
...
5% during exercise
c
...
alveolar PO2 is lower than atmospheric PO2 and alveolar PCO2 is higher than atmospheric
PCO2
a
...
newly inspired air mixes with old air (15% new air with inspiration)
2
...
at lungs
a
...
PCO2 always higher in blood, CO2 ➝ alveoli

73

4
...
PO2 always higher in blood, O2 ➝ tissues
b
...
during exercise
...
more pulmonary capillaries open, increasing surface area for exchanges
b
...
disease thickens membrane and increases distance for diffusion (pulmonary edema,
pulmonary fibrosis, pneumonia

•

Gas transport
- O2
1
...
5% dissolved in blood
2
...
5% on hemoglobin (Hb)
Hb

+

O2

HbO2

↔

(reduced Hb)

(oxyhemoglobin)

3
...
primary influence is PO2
(1) pulmonary capillaries - increased PO2 leads to formation of HbO2 at lungs
(2) systemic capillaries - decreased PO2 leads to O2 dissociation from HbO2 at
tissues
b
...
curve shifts to the right in active tissues (more O2 is released at active tissues at a
given PO2)
(1) Bohr effect - increased PCO2
(2) increased acid (from increased CO2 and lactic acid)
(3) increased temperature
(4) increased 2,3-bisphosphoglycerate (BPG), produced inside RBCs in
increasing amounts when HbO2 levels below normal

74

- CO2
1
...
30% as HbCO2 (carbaminohemoglobin)
a
...
60% as HCO3 (bicarbonate, more soluble than CO2)
a
...
can occur in plasma, but more efficient in RBCs because of enzyme carbonic
anhydrase
c
...
most of the accumulated H+ binds to Hb (helps buffer the blood)

•

Control of Respiration
- medullary respiratory center
1
...
dorsal respiratory group (DRG) responsible for quiet breathing
a
...
quiet expiration begins when neurons stop firing
3
...
not active in quiet breathing
b
...
pneumotaxic and apneustic centers "fine tune" medullary centers to produce smooth
inspirations and expirations

- Hering-Breuer reflex
1
...
inhibit inspiratory neurons

75

- Influencing factors
1
...
central chemoreceptors in medulla sense increased PCO2 (via increased H+ in CSF)
and signal respiratory centers to increase ventilation
b
...
PO2 important only at very low O2 levels
a
...
precise triggers to increase ventilation unknown (ventilation increases before significant
changes in PCO2 and PO2)
2
...

a
...
increase in body temperature
c
...
input from cerebral cortex

- other factors
1
...
pain
3
...
swallowing

76

Chapter 14

•

Urinary System

The Kidney is the major functional organ, other organs carry urine out of the body
- basic functions
1
...
electrolyte (ion) balance
3
...
acid/base balance
5
...
secrete erythropoietin
7
...
converts vitamin D to its active form

- nephron is the functional unit of the kidney
1
...
glomerulus
a
...
renal artery branches to form afferent and efferent arteriole for each nephron
(1) efferent arteriole divides to form peritubular capillaries (supply renal
tissue with blood)
3
...
glomerular capsule surrounds glomerulus and collects filtrate
b
...
loop
d
...
collecting duct/tubule - drains fluid from several nephrons to renal pelvis
4
...
regulates kidney function
b
...
granular cells (juxtaglomerular cells or JG cells) are specialized smooth muscle
cells of arterioles
5
...
cortical - lie mainly in cortex (80%)
b
...
glomerular filtration
a
...
entire plasma volume filtered 65 times/day
c
...
tubular reabsorption
a
...
tubular secretion
a
...
glomerular capillaries are 100x more permeable than other capillaries
2
...
inner layer of glomerular capsule
a
...
higher than in other capillaries
a
...
glomerular filtration rate (GFR)
a
...
autoregulation
(1) allows GFR to remain constant despite changes in BP
(vasoconstriction/dilation of afferent arteriole)
(2) myogenic mechanism - arteriolar smooth muscle constricts when stretched,
relaxes with decreased pressure
(3) tubuloglomerular feedback mechanism - macula densa detects changes in
rate of filtrate flow or osmotic changes and signals granular cells to release
vasoactive substances
increased flow ➝ vasoconstriction ➝ decreased GFR
decreased flow ➝ vasodilation ➝ increased GFR

78

(4) sufficient in MAP 80-180 mmHg range
c
...
5% of the salt that is filtered
- different portions of tubule specialize in particular substances
- most substances pass through tubule cells (transepithelial transport)
- can be active or passive
1
...
occurs via Na+-K+ ATPase in the basolateral membrane
a
...
tied to reabsorption of other substances (glucose, amino acids, water, Cl-, urea)
c
...
DCT and collecting tubule - hormonal control, reabsorption according to need
2
...
in response to decreased NaCl/dec
...
BP, macula densa signals
granular cells to release renin (an enzyme)
b
...
angiotensin I ➝ angiotensin II in lungs
(1) vasoconstriction of arterioles
(2) stimulates thirst
(3) stimulates vasopressin release (H2O reabsorption)
(4) adrenal cortex releases aldosterone - promotes insertion of more Na+
channels and Na+-K+ pumps into cells of DCT and collecting tubule (Cl- and H2O
follow Na+)

79

3
...
released from atria in response to increased stretch from inc ECF/inc BP
b
...
cotransport systems driven by Na+-K+ pumps in PCT

- Water reabsorption
1
...
80% osmotically follows solute reabsorption (water flows through channels into cells or
through leaky tight junctions)
3
...
only waste product reabsorbed
2
...
important in acid/base balance
2
...
can be coupled to Na+ reabsorption instead of K+ (basolateral pump in distal nephron)
- K+ secretion
1
...
controlled secretion of K+ in DCT and collecting tubule
a
...
inc plasma K+ ➝ inc aldosterone ➝ inc K+ secretion
dec plasma K+ ➝ dec aldosterone ➝ dec K+ secretion
c
...
special carriers for each in PCT
2
...
other substances like drugs or pollutants
a
...
long loops of juxtamedullary nephrons establish a vertical osmotic gradient in interstitial
fluid of medulla
2
...
water can be reabsorbed from collecting tubules as it flows through gradient (under control
of vasopressin)

- establishing the gradient (countercurrent multiplication) - by loop
1
...
ascending limb pumps out Na+ but is impermeable to H2O
3
...
leads to gradient of 300-1200 mosm/L in medulla
b
...
filtrate in DCT very dilute
2
...
H2O not reabsorbed, urine dilute
3
...
cAMP second messenger system - results in insertion of H2O channels in tubule
b
...
medullary gradient does not dissipate because of the construction of the blood supply
2
...
internal urethral sphincter made of smooth muscle (involuntary)
2
...
occurs at 250-400 ml urine
2
...
we become conscious of having to urinate, but we can temporarily override reflex
until it's convenient

82

Chapter 16

•

Digestive System

Basics
- function: transfer nutrients, H2O and electrolytes from food to body
1
...
motility
a
...
secretion
a
...
digestion
a
...
absorption
a
...
network of nerves in digestive tract wall (enteric nervous system)
2
...
mainly coordinate activities
3
...
influences motility and secretion
a
...
act directly on glands and smooth muscle

- receptors and reflexes
1
...
chemoreceptors
b
...
osmoreceptors

83

2
...
short reflexes - entirely within intrinsic nerves
b
...
produced in mucosa, released to blood in response to local chemical changes or nerve
stimulation

•

Mouth
- mastication (chewing)
1
...
begins digestion of carbohydrate with salivary amylase
2
...
lysozyme lyses bacteria
4
...
store food and release to duodenum at the appropriate rate
2
...
mix food with gastric secretions to make chyme

- 4 aspects of motility
1
...
plasticity - stomach can stretch without increasing tension
b
...
gastric storage
a
...
gastric mixing
a
...
peristaltic contractions
4
...
peristaltic waves push some chyme into duodenum
b
...
influencing factors (duodenum)
(1) stimuli such as fat, acid, increased osmolarity and distention in duodenum
trigger slowing of gastric emptying via neural and hormonal responses
(2) neural response - short and long reflexes (enterogastric reflex)
(3) hormonal response - enterogastrones released to blood act on stomach
(secretin, cholecystokinin or CCK, gastric inhibitory peptide or GIP)

- gastric secretions come from gastric pits/gastric glands
1
...
surface epithelial cells secrete thick alkaline mucus that protects stomach from acid
and digestive enzymes
b
...
parietal cells secrete HCl and intrinsic factor
(1) HCl activates digestive enzymes and produces optimal pH for protein
digestion; breaks down connective tissue and muscle; kills bacteria
(2) intrinsic factor allows absorption of vitamin B12
d
...
pyloric gland area (antrum)
a
...
G cells secrete hormone gastrin
(1) stimulates parietal and chief cells
(2) stimulates growth of mucosa in stomach and small intestine
3
...
cephalic phase
(1) thinking about food and eating increases gastric secretion via
parasympathetic stimulation

85

b
...
intestinal phase
(1) protein stimulates release of intestinal gastrin (excitatory component)
*(2) enterogastric reflex and enterogastrones suppress secretory activity
(inhibitory component)

•

Small Intestine
-

major organ of digestion and absorption

- motility: segmentation
1
...
slowly moves chyme forward
3
...
ileum segments in response to gastrin when chyme is in the stomach (gastroileal reflex)

- pancreas secretes digestive enzymes and protective alkaline fluid (NaHCO3) into duodenum
1
...
cephalic phase - parasympathetic stimulation
b
...
intestinal phase - secretin ➝ NaHCO3, CCK ➝ enzymes
2
...
secreted in inactive forms
b
...
trypsin digests protein and converts other enzymes to active forms
chymotrypsinogen ➝ chymotrypsin
procarboxypeptidase ➝ carboxypeptidase
d
...
pancreatic amylase (secreted in active form)
a
...
pancreatic lipase (active)
a
...
bile salts, cholesterol and lecithin are produced by hepatocytes (other fluids come from bile
duct cells)
a
...
form micelles that carry non-water soluble products of fat digestion to absorption
sites on mucosa
c
...
other liver functions
a
...

b
...
activates vitamin D
d
...
excretes cholesterol
f
...
secretes mucus, but digestive enzymes are in epithelial cell membranes (brush border)
2
...
Na+
a
...
Na+-K+ pump at basolateral side establishes gradients for passive movement
c
...
also involved in secondary active transport of sugars and amino acids
4
...
bacteria also synthesize vitamin K, which we absorb (important in clotting)
2
...
haustral contraction (similar to segmentation but slower)
a
...
mass movements (gastrocolic reflex)
a
...
insoluble helps food move faster and generate satiety signal sooner
2
...
chemical secreted into the blood that acts on target cells elsewhere in the body
a
...
function at very low concentrations
3
...
includes neurohormones
5
...
regulate metabolism
2
...
coping with stress
4
...
reproduction
6
...
digestion/absorption

- 3 categories of hormones
- most hormone systems operate with negative feedback
- diurnal (circadian) rhythms
1
...
set point changed by CNS
2
...
external cues like light/dark or activity/inactivity

- endocrine disorders
1
...
hypersecretion (tumors)
3
...
action of hormone depends on number of receptors
a
...
other hormones influence receptors of a different hormone (number of receptors or
affinity)
(1) permissiveness - enhances response of another hormone
(2) synergism - both hormones enhance each others response
(3) antagonism - inhibits response of another hormone

•

Pineal Gland
- melatonin
1
...
cued by light/dark sensed by eyes
2
...

a
...
inhibit sex hormones
c
...
slow aging (antioxidant)

•

Hypothalamus and Posterior Pituitary (neurohypophysis)
- Hypothalamus produces hormones that are stored in posterior pituitary
1
...
conserves H2O (when osmolarity increased)
2
...
uterine contractions during childbirth
a
...
triggered by neuroendocrine reflexes (baby's head pushing against cervix)
2
...
triggered by baby nursing

90

•

Hypothalamus and Anterior Pituitary (adenohypophysis)
- Anterior pituitary produces hormones and releases them in response to hormones from
hypothalamus
1
...
anterior pituitary tropic hormones act on other endocrine glands
a
...
adrenocorticotropic hormone (ACTH, adrenocorticotropin)
(1) growth and secretion of adrenal cortex (cortisol)
(2) corticotropin releasing hormone (CRH)
c
...
growth hormone (GH, somatotropin)
(1) regulates growth and metabolism
(2) growth hormone releasing hormone (GHRH) and growth hormone inhibiting
hormone (GHIH)
3
...
prolactin (PRL)
(1) breast development and milk production in typical female
(2) prolactin releasing factor (PRF) and prolactin inhibiting hormone (PIH)

- Growth Hormone
1
...
growth of cells in size/number
(1) stimulates protein synthesis and cellular uptake of amino acids
(2) inhibits protein breakdown
b
...
conserves glucose (for brain) and use fat stores
a
...
triggered by exercise, stress, changes in blood nutrient levels such as increase in
amino acids, decrease in fatty acids
c
...
mix of T3 and T4
2
...
increases overall metabolic rate
4
...
critical for normal nervous system activity
6
...
disorders among most common in endocrine system
a
...
hyperthyroidism - increased MR, perspiration, loss of weight, weakness, palpitations,
irritability, bulging eyes

- Calcitonin
1
...
inhibits breakdown of bone
b
...
influence mineral balance (e
...
, aldosterone)

- sex hormones
1
...
cortisol (stress response; makes energy and building blocks available)
a
...
increases blood aa and fatty acids
(1) stimulates breakdown of protein and fat
c
...
important in adaptation to stress
e
...
anti-inflammatory

92

•

Adrenal Medulla
- secretes both NE and E (E more important)

- Epinephrine
1
...
inc HR and CO, vasoconstrictor ➝ inc BP (α and β )
1

b
...
bronchodilation (β )
2

d
...
metabolic effects (stress response makes energy and building blocks available)
a
...
increases blood fatty acids
(1) breakdown of fats
c
...
stores energy as body absorbs nutrients (absorptive state)
a
...
decreases blood fatty acids
(1) glucose ➝ adipose tissue to form fatty acids and glycerol
(2) fatty acids ➝ cells
(3) inhibits lipolysis
c
...
diabetes most common endocrine disorder

93

- Glucagon
1
...
increases blood glucose
(1) decreases glycogenesis
(2) increases glycogenolysis and gluconeogenesis
b
...
involved in Ca

2+

balance (opposite of calcitonin)

a
...
also involved in PO4 balance
a
...
major functions
a
...
secrete sex hormones (androgens & estrogens)
(1) mainly testosterone (male)
(2) mainly estrogen & progesterone (female)
(3) important in the development of secondary sex characteristics (hair
distribution, body shape, voice change) as well as major reproductive functions
and development

- essential reproductive functions in the typical male
1
...
delivery of sperm to female

- essential reproductive functions in the typical female
1
...
receive sperm and transport for fertilization
3
...
parturition and nourishment of infant

- sex differentiation

•

Spermatogenesis
- begins at puberty

- parts of sperm
1
...
acrosome has enzymes to penetrate egg
2
...
tail is for movement

95

- control of spermatogenesis
1
...
probably due to a decrease in melatonin
2
...
luteinizing hormone (LH a
...
a
...
follicle stimulating hormone (FSH) ➝ spermiogenesis (sperm remodeling)

•

Semen
- produced by different glands
1
...
fructose for energy
b
...
fibrinogen for clotting
2
...
alkaline fluid neutralizes acidic female reproductive tract
b
...
enzymes break down clot (fibrinolysin)
3
...
neutralize acidic male urethra

•

Oogenesis
- begins during fetal development
1
...
will not complete meiosis unless fertilized
3
...
due to decrease in melatonin and increase in % body fat
- follicular phase
1
...
FSH ➝ granulosa cells make estrogen from androgen
3
...
LH surge triggers release of ovum
a
...
high LH level triggers development of corpus luteum
a
...
LH declines ➝ corpus luteum degenerates ➝ progesterone decreases
2
...
estrogen stimulates growth of endometrium and synthesis of progesterone receptors in
endometrium

- secretory phase
1
...
endometrium breaks down from lack of estrogen and progesterone (due to neg feedback
effects of progesterone on LH)

97



---