Skeletal Muscle Physiology 1 Flashcards Preview

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Flashcards in Skeletal Muscle Physiology 1 Deck (27):
1

What are muscles capable of?

of developing tension and producing movement through contraction

2

Are smooth muscles striated?

No

3

What kind of muscle are skeletal and cardiac?

striated muscle

4

What causes the light and dark bands in striate muscles?

light - actin thin filaments
dark - myocin thick filaments

5

What innervates skeletal muscles?

Somatic nervous system and are therefore subject to voluntary control

6

What kind of nerve innervates cardiac and smooth muscle?

autonomic nervous system - involuntary

7

List the functions of skeletal muscle

- Maintenance of posture
- Purposeful movement in relation to external environment
- Respiratory movements
- Heat production - shivering
- Contribution to whole body metabolism

8

What is a motor unit?

The motor unit is a single alpha motor neuron and all the skeletal muscle fibres it innervates

9

Why do muscles which serve fine movements have fewer fibres per motor unit? Give examples of these muscles

because precision is more important than strength
intrinsic hand muscles and extra-occular muscles

10

What is a sarcomere?

Functional unit made up of actin and myocin filaments

11

What do actin and myocin form?

cytoskeletal elements of skeletal muscle

12

Why are there no gap junctions in skeletal muscle?

to allow rapid propagation of AP through muscle cells

13

Does Ca induced Ca release occur in cardiac or skeletal muscles or both?

cardiac muscles only

14

In skeletal muscle, where does the Ca required for excitation contraction coupling come from?

Entirely from the lateral sacs of the sarcoplasmic reticulum

15

What is excitation contraction coupling?

process whereby the surface action potential results in activation of the contractile mechanism of the muscle fibre

16

After the AP is initiated, where does it spread down in skeletal muscle?

the tranverse (T)-tubules - this traiggers the release of Ca from the lateral sacs of SR

17

Which molecule acts as the neurotransmitter at the neuromuscular junction?

Acetylcholine

18

What is the function of myofibrils?

contractile structures made up of actin and myocin filaments arranged into sarcomeres

19

How long are skeletal muscles?

Usually extend the entire length of muscle

20

What are skeletal muscles usually attached to?

attached to bone by means of a tendon

21

What actually is a functional unit of an organ?

The smallest component capable of performing all the functions of that organ

22

What separates sarcomeres?

Z line

23

What are the 4 zones of sarcomeres?

A-band
H-zone
M-line
I-band

24

How is muscle tension produced?

Sliding filaments theory - sliding of actin filaments on myocin filaments

25

What does force generation within muscles depend on?

ATP-dependent interaction between thick (myosin) and thin (actin) filaments

26

When is Ca2+ needed?

- switch on cross bridge formation
- Ca2+ is the link between excitation and contraction
- Ca2+ is entirely derived from sarcoplasmic reticulum in skeletal muscle

27

When is ATP required?

during muscle contraction to power cross bridges

during relaxation to release cross bridges and to pump Ca2+ back into the sarcoplasmic reticulum