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Chapter 19 (Differential gene expression in development):
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Determination sets the developmental fate of a cell even before any characteristics
of the cell type are observed
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Morphogenesis is the
organization and distribution of differentiated cells into organs and the body
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Pluripotent cells have the potential to develop into most other cell types, but they
cannot form new embryos- they occur in the later stages of the embryo
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Example:
(multipotent blood stem cells can become RBC, WBC, or platelets)
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They include specific proteins, small regulatory RNAs, and mRNAs
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The diffuse from
one cell to surrounding cells, setting up a concentration gradient
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5
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Gap
genes organize broad areas along the anterior-posterior axis, mutations in these
genes result in gaps in the body plan (omission of larval segments)
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Mutations in pair rule
genes results in embryos missing every other segment
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Mutations in segment polarity genes result in segments in which
posterior structures are replaced by mirror image anterior structures
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What is parthenogenesis?
Parthenogenesis is a phenomenon (asexual reproduction) in which offspring
develop from unfertilized eggs
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Species that reproduce parthenogenetically
also engage in sexual production or at least sexual behavior at other times
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2
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Spermatogenesis: The male germ cell (2n) undergoes mitosis in adulthood and
produces a spermatogonium
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The genetic material in the primary spermatocyte has replicated, but the number
of chromosomes remains the same (2n)
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The second meiotic division produces spermatids (n) each of
which is different genetically and eventually differentiates into individual sperm
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This all occurs in the embryo
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The second meiotic division produces
another polar body and a haploid egg (ootid)
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What is ovulation? What is the follicle? What is the
corpus luteum?
Primary oocytes (2n) begin to mature, about once a month the primary oocyte and
its surrounding cells make the follicle
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After 1 week, only one primary oocycte
continues to develop
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At ovulation, the follicle ruptures, releasing an oocyte
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If pregnancy does not occur, the corpus luteum degenerates
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Learn the uterine cycle
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The endometrium starts to thicken in preparation for a blastocyst 5
days into the ovarian cycle
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The endometrium breaks down (if
no blastocyst arrives in that time) and tissue with blood flows from the body
through the vagina in a process called menstruation
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Estrus (state of sexual receptivity) is “heat” around the time
of ovulation in other mammalian species
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Estrogen and progesterone stimulate the development of the endometrium in
preparation for pregnancy
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Know the parts and functions of a neuron: dendrites, cell body, axon, and axon
terminals
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The cell body contains the
nucleus and most cell organelles
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The axon terminals synapse with a target cell
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What is a motor end plate?
The postsynaptic membrane of the neuromuscular junction
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3
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Neurotransmitters bind to ionotropic
receptors and cause a direct change in ion movement across the plasma membrane
of the postsynaptic cell (faster and shorter lived)
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What is the Vomeronasal Organ? Where is it found? How do snakes and
mammals use it?
The vomeronasal organ is a small tubular structure embedded in the nasal
epithelium of amphibians, reptiles, and many mammals (not humans)
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Information from these
chemoreceptors goes into an olfactory bulb in the brain and to other regions
involved in sexual and instinctive behaviors in the brain
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The snake uses its tongue to smell its

environment, not to taste it
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3
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Merkel’s discs: tactile receptors, found in hairy and nonhairy skin; provide
information about anything touching the skin, adapt slowly
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Ruffini endings: deeper in the skin, adapt slowly and are good at providing
information about vibrating stimuli of low frequencies
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4
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Muscle spindles are mechanoreceptors in skeletal muscle
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When a muscle is stretched, the
muscle spindles are also stretched and transmit AP to the CNS
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Golgi tendon organs are a type of mechanoreceptor, found
in tendons and ligaments and provides information about the force generated by a
contracting muscle
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Chapter 48: Musculoskeletal Systems
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Slow twitch fibers are better adapted for sustained aerobic activity
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Fast twitch fibers can generate maximum
tension quickly, but they also fatigue quickly
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2
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As a result, fewer cross bridges
can form and less force can be produced
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Titin
molecules create enough elastic recoil to pull the actin and myosin fibrils back
into an overlapping arrangement
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Because they have no place to go, additional shortening is
difficult
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What are the three major systems by which ATP is supplied to muscles?
The immediate system that uses preformed ATP and creatine phosphate
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And the
oxidative system that metabolizes carbohydrates or fats all the way to H2O and
CO2
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What is the difference between membranous and cartilage bone?
Membranous bone forms on a scaffold of connective tissue membrane
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5
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Cancellous bone has numerous internal cavities
that make it appear spongy (although it is rigid)
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Describe Fick’s Law of Diffusion
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Equation:

2
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O2 diffuses about 8k times more rapidly in air than in water
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3
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Reduced PO2 at
higher altitudes constrains O2 uptake
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How does temperature affect oxygen availability in water?
Warm water holds less dissolved gas than cold water does (less O2)
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What is the difference between ventilation and perfusion?
Ventilation is actively moving the external medium over the gas exchange
surfaces (breathing)- exposes surfaces to maximum O2 and minimum CO2
concentrations
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There is constant one way flow of oxygenated water
over the gills, which maximizes the PO2 on the external gill surfaces
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The
air flows through the lungs unidirectionally rather than bidirectionally
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Birds also have air sacs, which receive inhaled
air, but are not gas exchange surfaces- they are involved in the flow of air through
the lungs
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Air flows through the parabronchi and diffuses into
the air capillaries which are gas exchange surfaces
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How does 2,3-Biphosphoglyceric Acid (BPG) affect the affinity of hemoglobin
for O2?
During times of low PO2, red blood cells increase their rate of glycolysis and
produce more BPG
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As a result, at any PO2, hemoglobin releases more of its bound
O2 than it otherwise would
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How is most CO2 transported in the blood? How else is it transported?
CO2 is transported in the blood in the form of bicarbonate ions- CO2 is converted
to bicarbonate, transported to the lungs, and then converted back to CO2
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10
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Bicarbonate ions then enter the
plasma in exchange for chloride ions
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The CO2
diffuses out of the RBCs to the blood plasma and to the air in the alveoli and is
exhaled
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Describe the cardiac cycle
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The systole phase is
when the ventricles contract, the diastole phase is when the ventricles relax
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Describe the simplified steps of the process of blood clotting
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Platelets release substances that cause the
vessel to contract, the sticky platelets form a plug and initiate the formation of a
fibrin clot
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The end result of this cascade is to
convert an inactive circulating enzyme (prothrombin) to its active form
(thrombin)
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4
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Atherosclerosis: hardening of the arteries – leads to heart attack or stroke
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Thrombus is a blood clot caused by blood platelets sticking to the plaquethey block arteries
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A myocardial infarction is a heart attack causes by total blockage of
the blood vessel
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When the
embolus travels and becomes lodged in a small vessel and block its flow, it
becomes an embolism
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