Muscle Phys III

Question 1

what is tension vs load

Answer 1

tension- the force exerted by the muscle on the object

Load- The force exerted by an object on the mm

Question 2

What are the 2 components of the mm

Answer 2

Elastic component-

1. parallel elastic component (stetches when mm is stretched)
2. Series elastic component ( mm tendon, acts as spring)

Contractile component-

Question 3

Isotonic contraction

Answer 3

The force generated by the mm is greater than the load (both concentric + eccentric)

Question 4

Isometric contraction

Answer 4

The force of the mm is not sufficient to move the load (the mm does not shorten or lengthen)

Question 5

Polysynaptic vs monosynaptic reflex

Answer 5

poly- 2 or more synapses

mono- one synapse

Question 6

How does the flexor withdrawl reflex

Answer 6

sensory receptors in skin are stimmed and connect to interneurons
the antagosit mm will be flexed and the extensor group will undergo reciprocal inhibition

Question 7

How does the crossed extensor reflex work

Answer 7

1. Ipsilat leg flexors are activated and extensors are inhibited
2. Contralat leg extensors are activated and extensors flexors inhibited (to balance)

Question 8

What are the 2 types of muscle spindle fibres

Answer 8

1. Nuclear bag fibres (dyanamic and static)

2. Nuclear chain fibres

Question 9

What are Ia fibres to muscle spindles detect for

Answer 9

Detects change in mm length (both static + dynamic)

sensitive to velocity of change in mm length

Question 10

What do II fibres detect for + inm

Answer 10

Inn static nuclear bags and chain fibres

-Detect static changes in mm length (body pos in space)

Question 11

What do gama motor neurons inn

Answer 11

inervates the contractile parts of the intrafusal fibres

Question 12

When the mm is relaxed what happens to the gamma motor neurons

Answer 12

when the mm becomes slack the muscle spindles are insensitive to further stretching so the gamma motor neurons fire causing the spindle to contract to restore sensitivity

Question 13

How does the dynamic stretch reflex work (mm spindles)

Answer 13

sudden stretch of nuclear bag fibers- impusle travels thru Ia fibres stimming contraction

(reciprocal inhibation also takes place)

Question 14

How does the static stretch reflex work (mm spindles)

Answer 14

steady stretch of mm- stretch nuclear chain and bag fibres- impulse thru Ia and II fibes- continous partial mm contraction

Question 15

Why does a mm have a continous mm tone

Answer 15

Signals from mm spindle

Singles transmitted from brain to spinal cord ant horn

Question 16

what does GTOs sense and how does it work

Answer 16

moniters muscle tensio and protects the muscle from execissvely heavy loads causing muscle to relax and drop load

Question 17

Muscle tone and DTR of LMN & UMN lesion

Answer 17

LMN- flaccidity + hyporeflexia

UMN- Spacicity/rigitity and hyperreflexia

Question 18

At what week of develpment in the number of mm fibres set

Answer 18

24w

Question 19

Adults lose muscle mass and strength at approx what %% after 50

Answer 19

muscle mass- 1-2% per year

Strength- 3-4% a year