Unit 2_Muscle Sensation and Proprioception

Question 1

What are the physiological steps that follow when we “sense” a stimulus?

Answer 1

1. A receptor ending (or free nerve ending) is exposed to a stimulus.
2. Depolarization or cell membrane creates receptor potential.
3. Receptor potential sends towards cell body. Action potential is created and flows down axon.
4. Action potential reaches axon terminal.

Question 2

As an axon diameter increases, it does what?

Answer 2

Decreases resistance

Question 3

As myelination increases, it does what?

Answer 3

Decreases capacitance

Question 4

In sensory neurons, as the axon diameter increases (decreases resistance), and myelination increases (decreases capacitance), what occurs?

Answer 4

Conduction velocity increases

Question 5

What type of neurons are cutaneous?

Answer 5

Type C, Type A delta, Type A beta

Question 6

What type of neurons are muscles?

Answer 6

Group IV, Group III, Group II, Group 1 (a and b- not sensory)

Question 7

What receptor type includes:
Group I (a and b)
Type A beta, Group II
Type A delta, Group III

Answer 7

Mechanoreceptors

Question 8

What receptor type includes:
Type C, Group IV

Answer 8

Chemoreceptors

Question 9

What receptor type(s) includes:
Type A delta, Group III
Type C, Group IV

Answer 9

Thermoreceptors and Nociceptors

Question 10

What process occurs when receptors convert physical and chemical energy into electrical signals?

Answer 10

Transduction

Question 11

What process are the following steps associated with:

1. local event (stimulus) at a receptor leads to a change in membrane conductance for specific ions (Na+, K+). The result is a net movement of + charge into the cell leading to a decrease in membrane potential or depolarization.
2. depolarizes the receptor membrane and produces a RECEPTOR or GENERATOR POTENTIAL (these will be summed for action potentials).

Answer 11

Transduction

Question 12

What are a local graded potential which are depended on the stimulus intensity and maybe subthreshold, threshold, or suprathreshold?

This is transmitted around the receptor membrane until it reaches the beginning of the distal end of the axon or first node of ranvier (if axon is myelinated).

This area contains the voltage gated channels and where the stimulus can reach threshold and produce an action potential.

Answer 12

Receptor potentials

Question 13

What are sensory receptors in the muscle, are stretch receptors within muscle belly (both afferent and efferent fibers) and give us information on length of muscle and velocity of length change?

Answer 13

Muscle Spindles

Question 14

What are sensory receptors in the muscle, are in the musculotendinous junction and give us information on force of contraction?

Answer 14

Golgi Tendon Organs

Question 15

What muscle fibers in muscle spindles stretch but also contract?

Answer 15

Intrafusal spindle muscle fibers

Question 16

What muscle fibers in muscle spindles generate force and do muscle work?

Answer 16

Extrafusal muscle fibers

Question 17

Muscle spindle sense ______ ______ _____ (static) and ______ ____ ____ ______ (dynamic; velocity)

Answer 17

absolute muscle length (static)
change in muscle length (dynamic; velocity)

Question 18

What neurons from the ventral horn improve sensitivity of muscle spindles?

Answer 18

Gamma motor neurons

Question 19

What sensory receptors in the muscle are in the musculotendinous junction?

Answer 19

Golgi tendon organs

Question 20

Where do the following steps occur:

Axons of sensory afferent Ib fibers get twisted through the collagen and are stimulated by active contraction in the muscle.

These Ib sensory fibers are very sensitive to tension/force development in muscle.

They respond to multiple motor units, so they also register motor recruitment.

Answer 20

Golgi tendon organs

*there is no efferent motor innervation