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Nervous System
Stimulus – any change in the environment that causes an organism to respond
Receptors - special structures in an organism’s design that detects stimuli i
...
ears, eyes,
taste buds, pressure sensors, heat sensors
...
g
...
They may be simple or complex
...
They depend on the organism that is
involved
...

Central Nervous System – the division of the nervous system that includes the brain and
spinal cord which are involved in decision making processes
Autonomic Nervous System –a division of the peripheral nervous system consisting of motor
fibers from the brain and spinal cord that serve the internal organs of the body; not under
voluntary control
Neuron - the basic unit of a nervous system
...

Sensory neuron – transmit impulses from receptors to the brain
Motor neuron - transmit the impulses to effectors from the brain
Interneurons- make up the brain and the spinal cord
...

Threshold stimulus – the stimulus must be sufficient strength before the impulse can be
initiated in the neuron
All or nothing response – a neuron cannot partially conduct an impulse
...

Resting state – when a neuron is not carrying an impulse it is prepared to do so
...

Nerve pathway - route taken by an impulse
...


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How nerve impulses are transmitted

-chemical shifts in the membrane based of 4 types of ions

-Na+

-K+

-Cl-

-negative protein molecules

-ions are not evenly distributed between the inside and outside of the cell
Resting State - the outer membrane is charged while the inner membrane is negative
...


-The Na+ ions rush in and stimulate the adjacent portion of the nerve membrane and the
impulse is carried to the end brush
...


The impulse is made up of charged particles not current electricity
...
They are separated by a
microscopic space called a synapse
...

Neurohumors –transmitter hormones
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It is slower than a reflex
...
A complex pathway is so frequently used it becomes almost like a reflex, a
habit
...
They generally conduct
impulses toward the cell body
...

Axon –usually a long, thin fiber that extends from the cell body
...

Endbrush - an abundant, tuftlike branching at the axon ending of certain nerve cells
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Shwann cells - A glial cell that wraps around the nerve fiber in the peripheral nervous
system, and forms the myelin sheaths of peripheral axons
...

Myelin sheath - fat-containing cells that insulate the axon from electrical activity
...
A gap exists between each
myelin sheath cell along the axon
...

Nodes of Ranvier - The gaps (approximately 1 micrometer wide) formed between myelin
sheath cells long the axons
Soma - cell body of a neuron contains the nucleus and other structures common to living
cells
...


Multiple sclerosis is characterized by patches of demyelination (destruction or loss of the
myelin sheath) in the central nervous system
...

Disruption of muscle control, speech and visual disturbances are common
...
The fluid acts as a
shock absorber to protect the brain
Pia mater – lies next to the brain and contains blood vessels to feed the cerebrum
Concussion – a blow strong enough to cause bruising and bleeding in the pia mater
Spinal Meningitis – a dangerous inflammation of the meninges and cerebral spinal fluid
Corpus callosum – nerve fibers that make a bridge like connection between the hemispheres
Cerebral cortex – the outermost layer of the cerebrum or gray matter
...
It has three major functions,
sensory, motor and associative
...

Cerebrum – the largest part of the human brain
...
This groove separates the cerebrum into the right and left cerebral
hemispheres
Cerebrum lobes
Frontal lobe – the centre of thought
...
It is the home of personality
...
It is the part of the
brain that
must learn to walk and talk
...
It is
involved in the phantom limb effect
Temporal lobe – is the centre of memory
...

Occipital lobe - specializes in the analysis of sight

!

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Cerebellum – a fist sized structure that helps you carry out coordinated movements
...

Reptile brain – the ancient inner part of the temporal love that contains the limbic system
...
It receives all types if sensory
input: vision, touch, hearing, taste and smell
...
It is
the destination of the rabies virus which explains the emotional response of victims
...


-All sensory information except smell must pass from the cerebrum through it
to the
amygdala

- It is home of the reticular system
...


- It is the part of your brain that is extremely focused and capable of blocking
intense
pain
...


- They receive the information about identity of people and objects (face of an
acquaintance, mother, friend, enemy) and discerns the emotional
relationship
appropriate (love, anger, disappointment)

- information is sent to the rest of the limbic system to produce an emotional
arousal
...
That controls body temperature, blood
pressure and
emotions
...


- a command centre for
the autonomic nervous system
...


-It will prepare you for proper emotional responses to a particular face
(real
smiles come from the hypothalamus)
3 outputs

-hormones and neural impulses to the pituitary gland

-neural commands to autonomic nervous system (it makes tears, sweat, controls blood
pressure,
heart rate, body temperature, respiration, bladder function and defecation)

-controls actual behaviour – feeding, fighting, fleeing and sexual behavio

!
Pons –a bulge in the brainstem that sends fibers to the cerebellum
...

Brain stem –the pons, the medulla oblongata, and the midbrain
Hippocampi- two tiny seashores shaped objects on either side of the brain which are involved
in making new long term memories
Midbrain – the only optic love that connects the eyes to the brain

Medulla oblongata – connects the spinal cord to the brain and controls functions like heart
rate, blood pressure and breathing rates
Has 2 main parts
Somatic nervous system – controls voluntary muscles
Autonomic nervous system – controls involuntary actions of vital body organs like
heart, lungs, digestive system, and glands
...

for fight

opposes
activity


Sympathetic nerves - produce hormone noradrenalin which readies the body
or flight
...
Located in the thalamus
Pinae – a flap of skin supported by cartilage
...

Auditory canal –the passage leading from the outer ear to the middle ear that has special
glands that secrete a waxy material which prevents foreign objects from entering the ear
Eustachian tube – a tube going from the middle of the ear to the throat to make the pressure
in the middle ear equal to the pressure of the atmosphere outside the body
Tympanic membrane (eardrum) – a delicate membrane stretched across the inner end of the
auditory canal
...
Made of coiled, liquid-filled tubes that are separated from
one another by membranes
...
They are made of three
interconnected, loop-shaped tubes at right angles to one another
...

Auditory nerve- the nerve that carries impulses from the inner ear to the brain during the
process of hearing
Rarefactions – low density areas in the air
Compression –high density areas in the air
Sympathetic vibration - a vibration produced in one body by the vibrations of exactly the
same period in a neighboring body
How the ear hears sound

-sound waves are collected by the outer ear and passed down the auditory canal to the
eardrum

-the waves cause the eardrum to vibrate

-the vibrations are carried across the middle ear by the hammer, anvil and stirrup

-vibrations of the stirrup cause vibrations in the oval window

-vibrations cause fluid within the cochlea to vibrate

-movement of the fluid causes vibrations in cilia lining one of the membranes in the cochlea

-vibrations start impulses in nerve endings around the cells

-impulses are carried out to the cerebral cortex where they are interpreted
...
It helps to give the eye shape and protects the inner
parts of the eye
...

Blind spot –the point where the optic nerve leaves the eye and contains no rods or cones

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