Week 2- Peripheral Nervous System

Question 1

How can the PNS be divided up?

Answer 1

Somatic and autonomic.

Sensory (afferent) carry info towards CNS

Motor (efferent) nerves carry info away from CNS

Question 2

How many pairs of cranial nerves do we have?

Answer 2

12 (have names)

Question 3

How many pairs of spinal nerves do we have?

Answer 3

31 (spinal nerves have a letter and number)

Question 4

What do the somatic afferent and efferent nerves do?

Answer 4

Afferent: from skin, skeletal muscle and joints
Efferent: to skeletal muscles

Question 5

What is a dermatome?

Answer 5

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

Question 6

What is a myotome?

Answer 6

A group of muscles innervated by a single spinal nerve

Question 7

What does anasthesia mean?

Answer 7

No sensation

Question 8

How can visceral (autonomic) nerves be catagorised?

Answer 8

They carry info from viscera (organs)

Can be divided into…
Parasympathetic: innervate viscera only
Sympathetic: innervate viscera and periphery

Question 9

What’s a ganglion?

Answer 9

A collection of cell bodies outside the CNS

Question 10

What’s a nucleus?

Answer 10

A collection of cell bodies inside CNS

Question 11

What’s a plexus?

Answer 11

A network of interconnecting nerves

Question 12

Where are the cell bodies of afferent fibres found?

Answer 12

In the spinal ganglia

Question 13

Where do visceral efferent nerves synapse?

Answer 13

In a peripheral ganglion

Question 14

What are the bundles that peripheral nerves are arranged into?

Answer 14

Fasciculi

Question 15

What are the layers of connective tissue of a nerve?

Answer 15

Epineurium: external vascular layer
Perineurium: individual fascicles covered in
Endoneurium: individual axons covered by this layer

Question 16

How are peripheral nerves classified?

Answer 16

Letters A-C (A being fastest) based on conduction velocity

Numbers I-IV (I being largest) based on axonal diameter

Question 17

How are sensory receptors classified?

Answer 17

They can detect external or internal info

External: exoreceptors (pain, temp, touch, pressure)
Internal: proprioreceptors (movement, joint position)/enteroreceptors (movement through gut, blood pH)

Or by mode of detection: chemo/photo/thermo/mechano receptors or nociceptors

Question 18

What are the structures in the proprioreceptors and their functions?

Answer 18

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 19

What’s a neuromuscular junction?

Answer 19

A specialized synapse between a motor neuron and a muscle fibre

Question 20

What is a motor unit?

Answer 20

A single motor neuron and all the muscle fibres it innervates, stimulation of it causes contraction of all muscle fibres in that unit

Question 21

What is required for a reflex action?

Answer 21

An afferent and efferent limb

Question 22

What is a reflex action?

Answer 22

An involuntary pattern of muscle contraction and relaxation elicited by peripheral stimuli

Question 23

What does the visceral sensory part of the autonomic nervous system do?

Answer 23

Relays sensory information from the core ie pain, fullness, blood pressure

Question 24

What nerves are part of the visceral sensory autonomic nervous system?

Answer 24

T1-L2, S2-S4, cranial nerves 9&10

Question 25

What does the visceral motor part of the autonomic nervous system do?

Answer 25

Outflow to core and body wall, controls pupils, sweat and salivary glands, heart muscle, airways

Question 26

What nerves are part of the visceral motor autonomic nervous system?

Answer 26

Thoracolumbar T1- L2, craniosacral outflow ie cranial nerves 3/7/9/10

Question 27

Describe the anatomy of sympathetic outflow to the periphery

Answer 27

T1- L2 has an extra part of grey matter. 1. Efferent fiber comes out and goes down spinal nerve 2. The nerve synapses in the sympathetic paravertebral trunks (enlarged due to ganglionic neurones) 3. They then go up, down or straight out to the skin

Question 28

Describe the anatomy of sympathetic outflow to the viscera

Answer 28

Same as outflow to periphery but the nerves don’t synapse in the sympathetic trunk, they synapse in the pre aortic ganglia

Question 29

Describe the anatomy of parasympathetic outflow to the viscera

Answer 29

Cranial outflow: cranial nerves 3/7/9/10 Sacral outflow: via splanchnic nerves S2-S4

Question 30

Describe the effect of the parasympathetic and sympathetic branches of the autonomic nervous system on eyes

Answer 30

P: pupil constricts S: pupil dialates

Question 31

Describe the effect of the parasympathetic and sympathetic branches of the autonomic nervous system on the salivary glands

Answer 31

S: inhibits P: enhances

Question 32

Describe the effect of the parasympathetic and sympathetic branches of the autonomic nervous system on the heart

Answer 32

S: increases rate and force of outflow P: decreases rate and force of outflow

Question 33

Describe the effect of the parasympathetic and sympathetic branches of the autonomic nervous system on the lungs

Answer 33

S: dilates bronchus P: constricts bronchus

Question 34

Describe the effect of the parasympathetic and sympathetic branches of the autonomic nervous system on the stomach

Answer 34

S: inhibits digestion P: stimulates digestion

Question 35

Describe the effect of the parasympathetic and sympathetic branches of the autonomic nervous system on the kidneys

Answer 35

S: stimulates secretion of epinephrine and norepinephrine P: none

Question 36

Describe the effect of the parasympathetic and sympathetic branches of the autonomic nervous system on the liver

Answer 36

S: stimulates glucose release P: stimulates bile release

Question 37

Describe the effect of the parasympathetic and sympathetic branches of the autonomic nervous system on the intestine

Answer 37

S: stimulates peristalsis and secretion P: inhibits peristalsis and secretion

Question 38

Describe the effect of the parasympathetic and sympathetic branches of the autonomic nervous system on the bladder

Answer 38

S: relaxes bladder P: contracts bladder