Lecture 12 - Golgi Tendons Organs and Joint Receptors

Question 1

Imflammatory Response to Tissue Damage

Answer 1

When the skin is damaged, nociceptors go off, these are pain receptors. Also known has chemoreceptors which measure inflammation in response to damage. Measuring information

Question 2

Thermally Gated Receptors

Answer 2

Respond to heat. At rest is closed but heat deforms protein channels for ions to flow in (open)

Question 3

Thermoreceptor VS Nociceptor

Answer 3

Thermoreceptors measure heat until a certain temperature. Then when it starts damaging skin, the thermoreceptors stop firing AP and remains constant as it can’t tell difference.

Nociceptors, pain receptors then take over letting the severity based on level of pain. When thermorecepotors turn reacj threshold, nociceptors turn on

Question 4

What makes foods spicy hot

Answer 4

Spice chemical called Capsaicin. Increased concentration in seeds. Capsaicin is lipid based and is able to pass through phospholipid bilayer as it is recognized as its own. Pass diffusively. Creates artifical heat, increases dilation to release heat, creating the sensation

Question 5

Golgi Tendon Organ (GTO)

Answer 5

• Similar to Ruffini ending. One end connects to muscle fibers, other tendons.
• Inside capsule there is collagen stands that stretch and taut. When the muscle contracts it decreases the amount of area and the branch of 1b afferent axon in crushed which allows sodium inside
• Multiple muscle fibers per GTO

-Not all muscle fibres connect to GTO, some connect to tendons

-provides feedback based on muscle force production. GTOs very sensitive to active force production by muscle fibres.
This is a stretch and its of force

-GTO not useful for muscle stretch

Question 6

Coding of muscle force output

Answer 6

Muscle passively stretched
- Muscle spindle: muscle stretch = fire AP
- Golgi Tendon Organ: not sensitive to muscle stretch

Muscle actively Contracted
- Muscle spindle: Afferent attraction decreases, no stretch
-Golgi Tendon Organ: Active, muscle force production, stimulates alpha motor neuron. large firing, muscle shorten

NO muscle activity: No GTO, EMG or Force.

Muscle activity, turns muscle on. GTO, EMG and Force.

GTO and EMG similar. Linear relationship between GTO and force

Question 7

Joint receptor anatomy

Answer 7

Don’t need to know types. Just need to know it codes for pressure or extreme ranges of motion.

-Joint receptors can’t differ from pressure, flexion and extension
-Can just tell something going on in joint
- Joint receptors don’t given angle info. Joint receptors just tell us when we at end of range of motion
- Joint receptors not useful for proception

Question 8

Summary of axon types

Answer 8

Axons differ in diameter, myelination and therefor the speed they conduct AP at. Smaller the axon diameter the slower the AP

Question 9

1a, 1b, II

Answer 9

1a= muscle spindle, primary afferent, calculate for velocity of stretch

1b= Golgi tendon, force production

2= chain type, flower

Question 10

Afferents and Axons

Answer 10

Proprioception: In muscle spindle and GTO, 1a, 1b and II are axon types with a diameter of 13-20um and conduction velocity of 80-120m/s (fastest)

Touch: merkel cell, messiner corpuscles, Ruffini ending, Pacinian corpuscles and Joint receptors. A beta axon type with diameter of 6-12um. Conduction velocity of 35-75m/s

Pain, temp : free nerve endings. A theta axon type with diameter of 1-5um. Conduction velocity of 5-30m/s

Pain, temp, itch (non discriminative) : free nerve endings (unmyelinated). C axon type with diameter of 0.2-1.5um. Conduction velocity of 0.5-2m/s