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bioregulatory systems 🦠 > peripheral nervous system > Flashcards

peripheral nervous system Flashcards

1
Q

what is the PNS

A

peripheral nervous system

nerves (cranial and spinal) and ganglia (collection of cell bodies) outside the brain and spinal cord

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2
Q

what 2 nerves are not known as peripheral nerves

A

cranial nerves 1 and 2

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3
Q

what can the PNS be divided into

A

the somatic and autonomic nervous system

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4
Q

what does the sensory division do

A

composed of sensory neurons
conducts signals from receptors to CNS
afferent nerves - info to CNS

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5
Q

what does the motor division do

A

composed of motor neurones
conducts signals from CNS to effectors
efferent nerves away from CNS

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6
Q

how many pairs of cranial nerves are there

A

12 pairs

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7
Q

how many pairs of spinal nerves are there

A

31 pairs (emerge from spinal cord through intervertebral foramina)

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8
Q

what do somatic afferent nerves do

A

convey info from skin, skeletal muscles and joints

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9
Q

what do somatic efferent nerves do

A

convey info to skeletal muscles

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10
Q

what does somatic mean

A

under voluntary control

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11
Q

what is dermatome

A

an area of skin that is supplied by a single spinal nerve

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12
Q

what is myotome

A

a group of muscles innervated by a single spinal nerve

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13
Q

what do visceral afferent nerves do

A

carry info from viscera (thoracic, abdominal and pelvic organs)

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14
Q

what can visceral efferent nerves be divided into

A

sympathetic and parasympathetic

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15
Q

what do visceral sympathetic efferent nerves innervate

A

the viscera (organs) and periphery (sweat glands and vasculature)

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16
Q

what do visceral parasympathetic efferent nerves innervate

A

viscera only

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17
Q

what does autonomic mean

A

involuntary responses

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18
Q

what is a ganglion

A

a collection of cell bodies outside the CNS

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19
Q

what is a nucleus

A

a collection of cell bodies inside the CNS

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20
Q

what is a plexus

A

a network of interconnecting nerves

21
Q

where do visceral efferent nerves synapse

A

in a peripheral ganglion

22
Q

where do all afferent (somatic and visceral) fibres have their cell bodies

A

in spinal ganglia

23
Q

what does visceral mean

A

not under voluntary control

24
Q

structure of peripheral nerves, how are they arranged, how many layers of connective tissue is around the nerve and name them

A

arranged in fasciculi
3 layers of connective tissue around entire nerve
external vascular layer = epineurium
individual fascicles are covered in perineurium
individual axons are covered in endoneurium

25
Q

how are peripheral nerves classified (2 ways)

A

based on conduction velocity (uses A/B/C where A is the fastest)
based on axonal diameter (sensory only - using roman numerals I-IV with I being largest diameter)

26
Q

sensory receptors can direct either..

A

external or internal info

27
Q

how can sensory receptors be classified

A

by source of stimulus or

by mode of detection

28
Q

external sensory receptors are called.. and they detect… (source of stimulus)

A 
exteroceptors 
pain
temp
touch
pressure
29
Q

two types of internal sensory receptors (source of stimulus)

A

proprioceptors - movement and joint position

enteroceptors - movement through gut and blood pH

30
Q

receptors by mode of detection

A
  • chemoreceptors
  • photoreceptors
  • thermoreceptors
  • mechanoreceptors
  • nociceptors
31
Q

what are chemoreceptors

A

detector molecules which bind to receptor eg in olfactory bulb

32
Q

what are photoreceptors

A

detect light in retina

33
Q

what are thermoreceptors

A

detect temp in skin

34
Q

what are mechanoreceptors

A

mechanical opening of ion channels eg touch receptors in skin

35
Q

what are nociceptors

A

detect tissue damage - interpreted as pain

36
Q

what are 3 types of proprioceptors

A

muscle spindles - detect changes in muscle length
golgi tendon organs - detect changes in tension in tendons
joint receptors - found in joint capsules - detect start and end of movement

37
Q

where are motor neurones found

A

neuromuscular junction - specialised synapse between a motor neurone and a muscle fibre

38
Q

what is a motor unit

A

a single motor neurone together with all the muscle fibres that it innervates
the smallest functional unit with which to produce force

39
Q

in humans how many motor neurones are there

A

approx 420,000 motor neurones

40
Q

how many skeletal muscle fibres in humans are there

A

approx 250 million

41
Q

how many muscle fibres does each motor neurone supply

A

approx 600 muscle fibres

42
Q

what happens upon stimulation of one motor unit

A

contraction of all muscle fibres in that unit

43
Q

what is a reflex action

A

an involuntary coordinated pattern of muscle contraction and relaxation elicited by peripheral stimuli

44
Q

STEPS for the reflex action arc

A

1) stretching stimulates sensory receptor (muscle spindle)
2) sensory neurone activated
3) within integrating centre (spinal cord) sensory neuron activates motor neuron
4) motor neuron activated
5) effector (same muscle) contracts and relieves the stretching

45
Q

describe the autonomic nervous system

A

has visceral afferent and efferent parts
efferent has sympathetic and parasympathetic nervous systems
which have opposing actions
have pre and post ganglionic neurons
release ACh at preganglionic synapses
releases NA (sympathetic) - exceptions being sweat glands where ACh is released or acetylcholine (parasympathetic) at post ganglionic neurons

46
Q

what is the visceral sensory NS

A

relays sensory info from the core

pain, fullness, BP

47
Q

what is the visceral motor NS

A

outflow to core and body wall
controls pupils, sweat glands, salivary glands, heart muscle and airways
thoracolumbar and craniosacral outflow

48
Q

actions of the parasympathetic NS

A 
eyes - constricts pupils
salivary glands - stimulates salivation
heart - slows heartbeat
lungs - constrict bronchi 
stomach - stimulates digestion
liver - stimulates bile release
intestines - stimulates peristalsis and secretion
bladder - contracts bladder
49
Q

actions of the sympathetic NS

A 
eyes - dilates pupils
salivary glands - inhibits salivation
heart - accelerates heartbeat
lungs - dilates bronchi
stomach - inhibits digestion
liver - stimulates glucose release
kidneys - stimulates epinephrine and norepinephrine release
intestines - inhibits peristalsis and secretion
bladder - relaxes bladder

bioregulatory systems 🦠 (54 decks)

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