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Flashcards in Muscle physiology Deck (37):
1

Muscle is a group of what

Fascicles

2

What is the plasma membrane of muscle called?

Sarcolemma

3

What is the cytoplasm of the muscle

Sarcoplasm

4

myofibrils contain what?

Contractile machinery

5

Smooth ER in muscle is what

Sarcoplasmic reticulum, contains many mitochondira- high energy

6

what gives muscle striated appearance

myofibrils

7

What is myofibrils made of

It is bundle of overlapping thick and thin filaments made up from proteins actin and myosin

8

what is a sarcomere

Z line to Z line

9

What are the three proteins in thin filaments

Actin, Tropomyosin, and Troponin

10

What does actin have

Binding sites for myosin

11

What type of protein is Actin

Contractile

12

What does each g Actin have

Binding site for myosin

13

What is tropomyosin

Regulatory protein, overlaps binding sites on actin for myosin

14

What is Troponin

Regulatory protein

15

Troponins three proteins do what?

Attach to actin, attach to tropomysoin and binds calcium reversibly

16

What does calcium binding to troponin regulate?

Skeletal muscle contraction

17

The tails of thick filaments face what?

M-lines

18

Myosin head has how many binding sites

2, one for actin, one for ATP

19

What is TItin

Support protein, achors thick filaments between M-line and Z-line, provides structural support and elacticity

20

What happens within a sarcomere to ( A band , I band, H zone and sarcomere) during contraction

A band stays same length
I band shortens
H zone shortens
Sarcomere shortens

21

What is the crossbridge cycle

Cyclical formation of links between actin and myosin resulting in the sliding of thin filaments toward the M line of a sarcomere

22

During high energy form during cross cycle, what is bound to myosin and what is affinity for action

ADP and Pi bound to myosin, high affinity for actin

23

What does Crossbridge cycle rely on

ATP hydrolysis

24

Analogous to what

Rowing boat through water, our paddle is crossbridge

25

Link of thick filament to thin

Oar contact with water

26

Power stoke

Myosin head moves propelling thin filament toward center of muscle ( oar propelling boat)

27

Thick and thin filaments

Oar breaks contact with water

28

What is excitation contraction coupling. What does it depend on?

Sequence of events whereby an action potential in the sarcolemma causes contraction
Depends on neural input from motor neuron

29

What does excitation contraction coupling require

Calcium release from the sarcoplasmic reticulum

30

What occurs if no calcium in contraction?

Troponin holds tropomysoin over myosin binding sites on actin. No crossbrdiges form, muscle is relaxed

31

When calcium is present what is role in excitation contraction coupling

Calcium Present - binds to troponin, causing movement of troponin, causing movement of tropomyosin, exposing binding sites for myosin on actin
Crossbridges form, cycle occurs

32

List the steps of excitation contraction coupling

1. Action potential in sarcolemma.
2. Action potential down T tubles.
3. DHP receptors of T tubules open Ca2+ channels .
4. Calcium increases in cytosol
5. Calcium binds to troponin shifting tropomyosin
6. Cross bidge cycling occurs

33

What must occur to terminate the contraction?

Calcium must leave troponin, allowing tropomyosin to cover myosin binding sites on actin

34

ATP is used by muscle how?

Crossbridge cycle, splitting of ATP by myosin ATPase(power stroke)
Binding of fresh ATP to myosin to cause dissociation

35

Sources of ATP in muscle

Phosphorylation of ADP by creatine phosphate
Oxidative phosphorylation of ADP in mitochondria
Anaerobic Glycolysis

36

How to maintain adequate oxygen to muscle

Increase ventilation
Increase heart rate and contraction
Dilate vessels to muscle

37

Glucose is substrate for oxidative phosphorylatio for how long then what is after rthat

30 min, then fatty acids dominant