peripheral nervous system

Question 1

What is the central nervous system

Answer 1

brain and spinal cord

Question 2

what is the peripheral nervous system

Answer 2

everything but brain and spinal cord

Question 3

somatic vs autonomic

Answer 3

both in peripheral, somatic-voluntary,
autonomic-involuntary

Question 4

two subsections of autonomic

Answer 4

sympathetic - fight +flight
parasympathetic - rest+digest

Question 5

what does sensory system contain

Answer 5

different receptors and sensory neurons, heads in CNS so afferent

Question 6

what does motor system do

Answer 6

conducts impulses from cns to muscles and glands so efferent

Question 7

segmental reflex definition

Answer 7

only in one segment of the spinal cord - dont involve brain (no selection of motor response). stimulus detected by sensory nerve - passes through sensory ganglion - enters dorsal horn of spinal cord - synapse on motor neurone in ventral grey matter - motor neurone causes response in motor organ

Question 8

ganglion definition

Answer 8

collection of neuronal bodies found in pns, synaptic relay stations

Question 9

difference between dorsal and ventral

Answer 9

dorsal is top, sensory comes in = afferent
ventral is bottom, motor goes out = efferent

Question 10

grey vs white matter

Answer 10

grey matter contains cell bodies
white matter contains pathways in specific anatomical places

Question 11

what does cell body contain

Answer 11

nucleus= soma = perikaryon

Question 12

what is a nissl body

Answer 12

rough er that contains RNA and ribosomes. produces and secretes protiens

Question 13

what is the axon hillock

Answer 13

connects axon to cell body and generates action potential

Question 14

define refractory period

Answer 14

time following an action potential where a cell is unable to generate another due to hyperpolarisation of cell membrane

Question 15

absolute vs relative refractory period

Answer 15

absolute = interval during which another action potential cannot be initiated no matter how big the stiumulus is, as all na channels are inactivated
relative = interval during which initiation of second action potential is inhibited but possible due to some na channels still activated and increased k conductance after hyperpolarisation

Question 16

saltory conduction

Answer 16

impulse jumps from one node of ranvier to another as myelin sheath blocks entry of na ions, conduction is quicker

Question 17

4 types of fibres

Answer 17

a, a delta, b and c

Question 18

difference in types of fibres a, a delta and c

Answer 18

a - large, myelinated = fast transmission, touch and pressure
a delta - small, lightly myelinated = pain transmission
c - small, unmyelinated = slow transmission, sensory and autonomic motor neurones = inflammatory pain

Question 19

what causes exocytosis of neurotransmitter

Answer 19

influx of ca ions in the presynaptic neurone

Question 20

what is a neuromuscular junction

Answer 20

synapse between neurone and muscle, muscle membrane starts off slightly more negative

Question 21

differences between nmj and neurone synapse

Answer 21

skeletal muscle membrane starts off more negative, action potential is slower in muscle fibre as goes through whole muscles rather than just along neurone surface causing muscle to contract. different structure of ca channels in muscle to be released in muscle centre to cause muscle contraction

Question 22

what effects conduction velocity

Answer 22

fibre diameter
myelination
temperature

Question 23

what is a synapse

Answer 23

junction between 2 neurones which causes an electrical signal to be passed on due to a chemical transmission

Question 24

what are the 3 types of ‘pre-synaptic’ calcium channels

Answer 24

l-type, n-type and t-type
blocked by several types of toxins
l-type = main type (slow release - long lasting activation length so higher voltage)
n-type= never terminals and dendrites on neuroendocrine cells
t-type = low voltage but quick activated

Question 25

order of synapse happenings

Answer 25

1) Ca intake causes acetylcholine to be packaged into vesicles
2) vesicles leave pre-synaptic neurone by exocytosis
3) acetylcholine diffuses across synaptic cleft and bends with post-synaptic membrane
4) causes action potential in post synaptic membrane
5) enzyme breaks down neurotransmitter into choine
6) choline is reuptaken into presynaptic neurone
7) CAT (choline acetlytransferase) remakes acetylcholine

Question 26

what are the postsynaptic receptors

Answer 26

complex, multi-unit trans-membrane protiens with a central pore. pore diameter is altered when the transmitter binds to receptor pore changes

Question 27

what are ionotropic receptors

Answer 27

ligand-activated ion channels, undergo a change in shape when neurotransmitter binds causing channel to open. can be excitatory or inhibitory effect depending on ions that can pass through the channel + concentrations inside/outside cell

Question 28

what is the effect of too much K on membrane potential

Answer 28

hyperkalaemia - cuses depolarisation (more positive), resting membrane potential is closer to threshold so neurons are more excitable = tremors

Question 29

what is the effect of toolittle K on membrane potential

Answer 29

hypokalaemia - causes hyperpolarisation (more negative) resting membrane potential further from threshold causing skeletal muscle weakness