L8 - Cutaneous senses

Question 1

what are the 3 function of feeling physical stimuli?

Answer 1

provides feedback from objects
indicated body positioning
serves as a warning signals to protect the body

e.g., Loss of feeling can lead to grasping objects with inappropriate force.

Loss of body feeling can cause a floating sensation when lying down.

Hot surfaces trigger a reflex to move the hand away to prevent burns.

Question 2

what’s proprioception?

Answer 2

knowing the position of limbs without visual confirmation

Question 3

What are the components of the cutaneous system?

Answer 3

the skin, mechanoreceptors, pathways to the brain + somatosensory cortex

Question 4

what are the 3 functions of the skin?

Answer 4

protects from bacteria, chemicals and dirt

keeps bodily fluids in

provides information about the environment e.g., warmth, pressure, pain etc.

Question 5

What are the 4 types of mechanoreceptors?

Answer 5

merkel receptor

ruffini cylinder

meissner corpuscle

pacinian corpuscle

Question 6

What’s the merkel receptor sensitive to?

Answer 6

sensitive to fine spatial detail, slowly adapting

Question 7

What’s the ruffini cylinder sensitive to?

Answer 7

stretching, slowly adapting

Question 8

What’s the meissner corpuscle involved in?

Answer 8

hand-grip control and light touch, rapidly adapting

Question 9

What’s the pacinian corpuscle sensitive to?

Answer 9

vibration + pressure texture, rapidly adapting

Question 10

what is meant by slow and rapid adaption?

Answer 10

slow - these receptors continue to respond to a stimulus for as long as it is applied. They provide continuous information about the stimulus.

rapid - these receptors respond quickly at the onset of a stimulus but then stop responding if the stimulus remains constant. They are sensitive to changes in stimuli.

Question 11

What’s the spinothalamic tract?

Answer 11

the beginning of the pathway from the skin –> brain

carries signals responding to pain and temp

Question 12

what’s they medial lemniscus pathway?

Answer 12

the second stage of the pathway from skin –> brain

carries signals representing the limb positions (proprioception) + touch

high speed important for controlling movement and responding to touch

Question 13

what’s the somatosensory cortex?

Answer 13

the final stage of the pathway from skin –> brain

signals travel to the somatosensory receiving area (S1) in the parietal lobe and the second somatosensory cortex (S2).

the cortex is organised into maps representing body locations

Question 14

what’s the organisation of the homunculus (S1)

Answer 14

body parts like the hands have a large part of S1 devoted to the due to high sensitivity?

experience-dependent plasticity - cortical areas increase with use (e.g., musicians’ fingers)

Question 15

what’s the role of the merkel receptors?

Answer 15

involved in receiving detail

higher density of merkel receptors is associated with better acuity

Question 16

what’s the role of the pacinian corpuscles?

Answer 16

primarily responsible for sensing vibrations

responds poorly to continuous pressure but well to high rates of vibration

role in texture perception

Question 17

what are the components of haptic perception?

Answer 17

sensory system –> detects touch, texture, temp etc.

motor system –> involves moving fingers and ands

cognitive system –> integrates sensory and motor info + holds it in memory

Question 18

what’s the function of the mechanoreceptors for shape perception?

Answer 18

objects typically stimulate multiple mechanoreceptors

receptors at the point of contact respond most intensely

provides information about the objects curvature and shape