peripheral nervous system

Question 1

what is the PNS

Answer 1

peripheral nervous system

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

Question 2

what 2 nerves are not known as peripheral nerves

Answer 2

cranial nerves 1 and 2

Question 3

what can the PNS be divided into

Answer 3

the somatic and autonomic nervous system

Question 4

what does the sensory division do

Answer 4

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

Question 5

what does the motor division do

Answer 5

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

Question 6

how many pairs of cranial nerves are there

Answer 6

12 pairs

Question 7

how many pairs of spinal nerves are there

Answer 7

31 pairs (emerge from spinal cord through intervertebral foramina)

Question 8

what do somatic afferent nerves do

Answer 8

convey info from skin, skeletal muscles and joints

Question 9

what do somatic efferent nerves do

Answer 9

convey info to skeletal muscles

Question 10

what does somatic mean

Answer 10

under voluntary control

Question 11

what is dermatome

Answer 11

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

Question 12

what is myotome

Answer 12

a group of muscles innervated by a single spinal nerve

Question 13

what do visceral afferent nerves do

Answer 13

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

Question 14

what can visceral efferent nerves be divided into

Answer 14

sympathetic and parasympathetic

Question 15

what do visceral sympathetic efferent nerves innervate

Answer 15

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

Question 16

what do visceral parasympathetic efferent nerves innervate

Answer 16

viscera only

Question 17

what does autonomic mean

Answer 17

involuntary responses

Question 18

what is a ganglion

Answer 18

a collection of cell bodies outside the CNS

Question 19

what is a nucleus

Answer 19

a collection of cell bodies inside the CNS

Question 20

what is a plexus

Answer 20

a network of interconnecting nerves

Question 21

where do visceral efferent nerves synapse

Answer 21

in a peripheral ganglion

Question 22

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

Answer 22

in spinal ganglia

Question 23

what does visceral mean

Answer 23

not under voluntary control

Question 24

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

Answer 24

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

Question 25

how are peripheral nerves classified (2 ways)

Answer 25

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)

Question 26

sensory receptors can direct either..

Answer 26

external or internal info

Question 27

how can sensory receptors be classified

Answer 27

by source of stimulus or | by mode of detection

Question 28

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

Answer 28

``` exteroceptors pain temp touch pressure ```

Question 29

two types of internal sensory receptors (source of stimulus)

Answer 29

proprioceptors - movement and joint position | enteroceptors - movement through gut and blood pH

Question 30

receptors by mode of detection

Answer 30

- chemoreceptors - photoreceptors - thermoreceptors - mechanoreceptors - nociceptors

Question 31

what are chemoreceptors

Answer 31

detector molecules which bind to receptor eg in olfactory bulb

Question 32

what are photoreceptors

Answer 32

detect light in retina

Question 33

what are thermoreceptors

Answer 33

detect temp in skin

Question 34

what are mechanoreceptors

Answer 34

mechanical opening of ion channels eg touch receptors in skin

Question 35

what are nociceptors

Answer 35

detect tissue damage - interpreted as pain

Question 36

what are 3 types of proprioceptors

Answer 36

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

Question 37

where are motor neurones found

Answer 37

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

Question 38

what is a motor unit

Answer 38

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

Question 39

in humans how many motor neurones are there

Answer 39

approx 420,000 motor neurones

Question 40

how many skeletal muscle fibres in humans are there

Answer 40

approx 250 million

Question 41

how many muscle fibres does each motor neurone supply

Answer 41

approx 600 muscle fibres

Question 42

what happens upon stimulation of one motor unit

Answer 42

contraction of all muscle fibres in that unit

Question 43

what is a reflex action

Answer 43

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

Question 44

STEPS for the reflex action arc

Answer 44

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

Question 45

describe the autonomic nervous system

Answer 45

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

Question 46

what is the visceral sensory NS

Answer 46

relays sensory info from the core | pain, fullness, BP

Question 47

what is the visceral motor NS

Answer 47

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

Question 48

actions of the parasympathetic NS

Answer 48

``` 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 ```

Question 49

actions of the sympathetic NS

Answer 49

``` 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 ```