Neuron and Sensory receptors

Question 1

3 varieties of neurons

Answer 1

Afferent–> somatic or visceral
Efferent–> somatic or visceral
Interneurons–> connecting neurons

Question 2

What cells produce myelin in PNS

Answer 2

Schwann cells

Question 3

What cells produce myelin in CNS

Answer 3

Oligodendrocytes

Question 4

List afferent cutaneous nerve fibres

Answer 4

C fibres–> unmyelinated; (deep)pain and hot temp
A delta fibres–> thinly myelinated; (localised) pain and cold temp
A beta Fibres–> heavily myelinated; touch, stretch, pressure and vibration

Question 5

List Subcutaneous nerve fibres and their corresponding cutaneous nerve fibres

Answer 5

Subcutaneous for joints, muscles and tendons (everything under skin)
Group IV and III–> mechanoreceptors, thermoreceptors, ergo receptors, nocireceptors
Group II–> muscle has Ia afferent, tendon had Ib afferent (for tension)
Group IV= C fibres
Group III = A delta fibres
Group II = A beta fibres

Question 6

List efferent motor neurons

Answer 6

Somatic: both myelinated
Alpha Fibres–> skeletal muscle
Gamma fibres–> muscle spindle
Autonomic sympathetic and parasympathetic

Question 7

What is nociception

Answer 7

Transient (body’s natural warning system)

Question 8

what do somatosensory receptors detect

Answer 8

mechanical, thermal, chemical or nociceptive changes

Question 9

What are the encapsulated nerve endings

Answer 9

Pacinian Corpuscle (vibration and pressure)- Layered capsule
Meissner corposcle (fine/discriminate touch)- Layered capsule
Ruffini ending (pressure)--> thin capsule

Question 10

What are the non-encapsulated nerve endings

Answer 10

Endings around hair (touch)
Merkels endings (light touch)
Free nerve endings (pain temp, itch and touch)
Non-encapsulated lie deeper and receive more mechanical info

Question 11

In order for a pathway to have detection and interpretation of sensation it must have…

Answer 11

Stimulation, transduction, conduction, translation

Question 12

What is the RMP

Answer 12

-70mV (high K+ inside cell and high Na+ outside cell–> also large anions inside cell= -ve charge)

Question 13

What is the action threshold

Answer 13

-55mV (+15mv difference by Na+ moving in)

Question 14

What is depolarisation and what is the highest charge of membrane

Answer 14

More Na+channels open= +ve charge inside cell

Reaches +30 mV

Question 15

Repolarisation, hyperpolarisation and return to RMP

Answer 15

sodium postassium pump, moves 2xK+ ions in for every 3xNa+ ions out
overshoot to -90mV
Na+/K+ pump works to bring RMP back to -70mV

Question 16

Where does saltatory conduction occur

Answer 16

Only in myelinated fibres
actions potentials jump between nodes of ranvier (node to node)
Greater the distance b/w NOR, faster the conduction

Question 17

Unmyelinated conduction

Answer 17

chemical conduction–> AP must travel the whole length of axon, cant jump between nodes hence slower

Question 18

What is in a typical synapse

Answer 18

Presynaptic terminal
Synaptic cleft
Postsynaptic terminal
Neurotransitters
Mitochondria 
Synaptic vessels

Question 19

Examples of neurotransmitters

Answer 19

small amine molecules, amino acids, neuropeptides

E.g. actylcholine, dopamine, serotonin, neurotensin, substance P (neuropeptide, important in pain pathways)

Question 20

What are the 2 encapsulated receptors in muscle

Answer 20

Muscle spindle–> detect change in length

Golgi tendon organs–> detect change in tension