Phys - Skeletal Muscle Flashcards Preview

Block 5 Material > Phys - Skeletal Muscle > Flashcards

Flashcards in Phys - Skeletal Muscle Deck (20):
1

Which regions shorten during contraction?

H zone (disappears)
I band

2

Troponin T

Binds troponin complex to tropomyosin

3

Troponin I

Binds myosin to actin

4

Troponin C

Binding site for Ca++

5

Titin

Connects Z line to M line

Connectin

Acts as a spring, contributes to elasticity of muscle

6

Dystrophin

Scaffolding for myofibrils

Associated with transmembrane sarcoglycans

7

Skeletal muscle resting Em

-90mV

8

Action potentials of skeletal muscles

What is released?
Receptors?

Acetylcholine is released

Nicotinic receptor

9

Cross-bridge cycling

1. Actin binding

2. Power stroke

3. ATP binding and cross bridge detachment

4. ATP hydrolysis

10

What happens to the cross bridges?

They do not detach

Rigor

11

What happens if Ca++ transported into the SR is inhibited?

The muscle remains contracted

12

What causes the myosin head to "re-cock"?

ATP hydrolysis to ADP and Pi

13

The velocity of muscle shortening is inversely related to the ___

Initial load

14

Isometric contraction

No external shortening
Velocity = 0

The load exceeds the ability to create tension

15

Twitch contraction

Single contractile event

16

Isotonic contraction

External shortening

The load is less than the ability to create tension

Concentric contraction

17

Eccentric contraction

Contraction with external lengthening

Example: going down stairs

18

What is a motor unit?

A single alpha motor neuron and all the muscle fibers it innervates

19

Motor neurons and muscle fibers are recruited from ___ to ____

Smallest to largest

*this permits development of smooth, graded increases in muscle tension

20

Are action potentials more easily elicited in small or large neuron cell bodies?

Small