Lec 11

Question 1

which type of receptor are each I, II, III, and IV, nociceptor or mechanoreceptor

Answer 1

I, II, and III are mechano

IV is nociceptor

Question 2

mechano vs nociceptor

Answer 2

mechano respond to mechanical tensio and nociceptor respont to potentially harfmuff stimuli e.g. pain

Question 3

type I receptors characeristics

Answer 3

• Low threshold,
• slow adapting,
• ovoid shape (ruffini receptors)
• Located mainly in superficial layers of joint capsule
• have more in proximal joints

Question 4

type II joint receptors classification

Answer 4

• Low threshold
• cylindrical corspuscle (modified pacinian)
• mainly in deep joint layers
• have more in distal articulations

Question 5

type III joint receptors classification

Answer 5

• High threshold
• slow adapting
• fusiform corspuscles
• primarily in intrinsic and extrinsic joint ligaments (ligaments inside or outside joint)

Question 6

what info do joint receptors provide

Answer 6

• when joint is at limits of range of motion (upper or lower limit of flex and extend), but can’t tell if the joint is in flexion or extension.
• this is due to joint pressure from external tension, or internal pressure such as swelling.
• joint can also tell when you start and stop moving/when joint start/stop rotating, and velocity of that.

Question 7

how do joint receptors modify their behaviour when a muscle contracts and what does this imply?

What effect do high threshold receptors have on passive pressure.

Answer 7

modify and influence gamma motor neuroins more than alpha.

can help with protective reflexes preventing joint damage and contribute to proprioception via connection to muscle spindles and gamma motor neurons.

The connection to alpha motor neurons is weak, but high threshold receptors can trigger a protective response.

Question 8

How do joint receptors contribute to proprioception

how would damaged joint lead to decreased proprioception

Answer 8

Joint receptors influence proprioception by modulating gamma motor neuron activity, which adjusts muscle spindle sensitivity and improves body awareness of joint position and movement

damaged joint receptors don’t give as much feedback to CNS to adjust spindle sensitivity.