NERVOUS SYSTEM - SENSORY RECEPTORS TACTILE AND PROPRIOCEPTIVE INPUTS

Question 1

What is the function of the somatosensory system

Answer 1

Provides information to CNS about the state of the body and its contact with the environment

Question 2

Dorsal column medial lemniscus

Answer 2

(fine discriminatory touch, proprioception; green and blue lines)

Question 3

spinothalamic

Answer 3

(pain and temperature; red line)

Question 4

Tactile touch is carried by what type of fibres?

Answer 4

Type III and type IV afferent fibres
Type III
Fibre diameter: 6-12 um
Conduction: 15-30 m/s
Type IV
Fibre diameter: 0.2-1.5
Conduction: 0.5-2 m/s

Question 5

Dermatomes:

Answer 5

area in the skin on your body that rely on specific nerve connections on your spine;

Question 6

Define dorsal root and ventral roots

Answer 6

Dorsal root: contain sensory neurons

Ventral root: motor neurons

Question 7

Define rostral and caudal

Answer 7

Rostral: enters spinal tract
Caudal: afferent limb of reflex arc

Question 8

Define: glabrous skin

Answer 8

Glabrous skin: palms of hands, soles of feet, face, ears

Question 9

What are the 4 types of sensory receptor afferrents on glabrous skin

Answer 9

1. Meissner’s corpuscles (superficial) - FA1 - fast adapting small receptive field
2. Pacinian corpuscles (deeper) - FA2 - fast adapting large receptive field
3. Merkel’s disk (superficial) - SA1 - slow adapting small receptive field
4. Ruffini endings (deeper) - SA2 - slow adapting large receptive field

Question 10

Transient Receptor Potential (TRP) ion channels
Are sensitive to what?

Answer 10

Sensitive to: Noxious heat, cold, wasabi, capsaicin, mustard oil, menthol

Question 11

Name the cold sensitive TRP and heat sensitive TRP

Answer 11

Cold sensitive: TRPM8
Hot sensitive: TRPV1

Question 12

Describe why the homunculus is so distorted

Answer 12

Receptor density in hand and face is much larger than other parts like the arm which is why the sensory homunculus is so distorted.