Week 5 - Nervous System

Question 1

outside the central nervous system

Answer 1

-clusters of cell bodies are called ganglion
-groups of axons are called nerves

Question 2

inside the central nervous system

Answer 2

-groups of cell bodies are called grey matter
-a collection of axons is called a tract
-a group of trats is called white matter

Question 3

somatic nervous system

Answer 3

efferent neurons under voluntary control

Question 4

autonomic nervous system

Answer 4

efferent neurons under involuntary control

Question 5

sympathetic

Answer 5

emergency system: increase heart rate, bronchodilation, decrease peristalsis, increased sweat gland secretion, inhibit voiding

Question 6

parasympathetic

Answer 6

control under normal conditions: decrease heart rate, bronchoconstriction, increase peristalsis, increase digestive juice secretion (including saliva), micturition reflex, defecation reflex

Question 7

meninges

Answer 7

set of connective tissue membranes that surround the central nervous system (brain and spinal cord)
-from inside to out: PAD
-pia mater, arachnoid mater, dura mater

Question 8

meninges functions

Answer 8

cover and protect the CNS, protect blood vessels and enclose venous sinuses, contain CSF found between the arachnoid mater and pia mater, form partitions within the skull

Question 9

functions of cerebrospinal fluid

Answer 9

forms a liquid cushion that gives buoyancy to the CNS organs, prevents the brain from crushing under its own weight, protects the CNS from blows and other trauma, nourishes the brain and carries chemical signals throughout it

Question 10

cerebrum

Answer 10

controls our ability to read, write, think, speak, remember, feel, and move; interpretation of sensory information; motor function
-four external lobes: frontal, parietal, temporal, occipital lobes

Question 11

thalamus

Answer 11

receives and passes on sensory information; sorts out, edits, and relays impulses of similar function; associated with the interpretation of pain and pleasure

Question 12

hypothalamus

Answer 12

controls the autonomic nervous system and production of hormones by acting on the pituitary gland

Question 13

brain stem

Answer 13

controls automatic behaviours necessary for survival
-midbrain, pons, medulla oblongata

Question 14

midbrain

Answer 14

reflex center for head and eye movements in response to sight and sounds

Question 15

pons

Answer 15

all sensory and motor fibers pass through the pons; helps to regulate breathing

Question 16

medulla oblongata

Answer 16

crossover of motor fibers
-cardiovascular center – regulates heart rate
-respiratory center – regulates rate and depth of breathing
-vasomotor center – regulates blood pressure
-also regulates swallowing, sneezing and vomiting

Question 17

cerebellum

Answer 17

coordination; maintains posture; maintains equilibrium using sensory input from inner ear (balance)

Question 18

functions of spinal cord

Answer 18

1. carries information
   -sensory impulses from periphery to brain
   -motor impulses from brain to periphery
2. integrating reflexes
   -reflex centers for faster response for a particular stimulus
   -passes a nerve impulse from a sensory neuron to a motor neuron

Question 19

reflex arc

Answer 19

fast, automatic, unplanned sequence of actions in response to a stimulus

Question 20

components of a reflex arc

Answer 20

1. receptor detects change in environment and initiates a nerve impulse
2. sensory neuron passes the impulse to the spinal cord
3. spinal cord integrates the message and passes it directly to a motor neuron
4. a motor neuron transmit the nerve impulse to the effector
5. the effector responds to the nerve impulse (the response = reflex)

Question 21

resting membrane potential

Answer 21

present in all cells; the inside of the plasma membrane is negative relative to the outside of the plasma membrane

Question 22

3 resting membrane potential key factors

Answer 22

1. action of sodium-potassium pump: 3 Na+ pumped out for every 2K+ pumped in
2. intracellular protein anions are trapped
3. plasma membrane is more permeable to potassium than to sodium

Question 23

leakage channels

Answer 23

random opening and closingl

Question 24

ligand-gated channels

Answer 24

open with binding of a specific neurotransmitter

Question 25

mechanically-gated channels

Answer 25

open or close in response to mechanical stimulation

Question 26

voltage-gated channels

Answer 26

open and close in response to membrane potential

Question 27

phases of action potential

Answer 27

1. resting state (resting membrane potential)
2. depolarization (Na+ gates open)
3. repolarization (voltage-gated Na+ channels close and voltage-gated K+ channels open) and K+ rush out of the cell
4. hyperpolarization (voltage-gated Na+ channels are reset, but voltage-gated K+ channels remain open for slightly longer) - as a result the membrane potential dips

Question 28

events at the synaptic cleft

Answer 28

1. the action potential reaches the axon bulb of the presynaptic neuron
2. this activates voltage-gated Ca2+ channels to open, allowing Ca2+ to flood in
3. Ca2+ causes synaptic vesicles that contain a specific neurotransmitter to move to the axon end and the vesicles fuse with the membrane, resulting in exocytosis of the neurotransmitter into the synaptic cleft
4. neurotransmitters diffuse across the synaptic cleft and bind to ligand-gated channels on the postsynaptic neuron
5. these ligand-gated channels open and Na+ rushes in, starting an action potential on the postsynaptic neuron