Muscly physiology part b Flashcards Preview

Physiology > Muscly physiology part b > Flashcards

Flashcards in Muscly physiology part b Deck (36):
1

What is rate limiting step for cycle

ATP hydrolysis

2

Fast fibers=

Myosin with fast ATPase activity

3

Slow fibers=

Myosin with slow ATPase activity

4

Slow fiber contractions last how much longer then fast

10 times

5

How to classify as oxidative or glycolitic

based on primary source of energy

6

Oxidative fibers primary energy source is

oxidative phosphorylation

7

Properties of oxidative fibers

Many mitochondria
Myoglobin (red)
Small diameter
Resistant to fatigue

8

Glycolytic fibers properties

Fewer mitochondria
Many glycolytic enzymes
High glycogen stores
Use little oxygen - anaerobic
Large diameter
Rapid to fatigue

9

What are the three types of muscle fiber types

Slow oxidative
Fast oxidative
Fast glycolytic

10

Properties of slow oxidative fibers

Low myosin ATPase
High oxidative capacity- aerobic
Mitochondria
Rich blood supply
Myoglobin (red)
Small diameter
Little tension
Small diffusion barrier)
Fatigue slowly

11

Properties of fast glycolytic fibers

High myosin ATPase activity
High glycolytic capacity
High glycogen stores
Many glycolytic enzymes
No myoglobin (white)
Large diameter
Greater tension
Fatigue rapidly

12

Properties of Fast oxidative fibers

High myosin ATPase activity
High oxidative capacity - Aerobic
Myoglobin
Slow to fatigue, but more rapid than slow oxidative
Intermediate diameter

13

Proportions of fibers in a muscle depends on what

Function of muscle, postural muscle more slow oxidative

14

What is the recruitment order of fibers?

Slow oxidative, fast oxidative, fast glycolytic

15

Causes of muscle fatigue in high intensity exercise

Build up of lactic acid
Compression of blood vessels
Depletion of acetylcholine (neuromuscular fatigue)

16

Causes of fatigue in low intensity exercise

Depletion of energy reserves

17

What are other possibilities of fatigue

Build up of inorganic phosphates
Changes in ion distribution

18

What is central fatiue

psychological fatigue

19

What is change is muscle size due to?

Change in size of individual cells

20

What is disuse atrophy

Decrease in size( lose myofibrils)

21

What is denervation atrophy

Motor neuron destroyed so no excitation, atrophy due to lack of use

22

What is hypertrophy

Increase in size (increase myofibrils)
Increase production of actin & myosin

23

Aerobic exercise adapts muscle how

Increases oxidative capacity of muscle
More mitochondria
Increase blood supply (capillaries)
Decrease in diameter

24

how does anaerobic ex adapt muscle

Increases ability of muscle to generate more tension (strength)
Increases amount actin & myosin
Increases number of myofibrils
Increases diameter of muscle fiber
Increases glycolytic enzymes
Decreases oxidative capacity

25

Does smooth muscle contain actin and myosin

yes

26

Some properties of smooth muscle

No sarcomeres
higher actin:myosin ratio
actin and myosin much longer
myosin heads over entire length
arranged diagonally
One nucleus
Tropomyosin
No troponin
Dense bodies analogous to Z line
Slow myosin ATPase
Myosin has light chains
Little sarcoplasmic reticulum

27

Steps of excitation-contraction coupling for smooth muscle

Opening of calcium channels in plasma membrane
-Voltage
-Receptor
-Mechanically-gated
2. Calcium triggers release of calcium from sarcoplasmic reticulum
3.Calcium binds to calmodulin
4.Ca-Calmodulin activates MLCK
5.MLCK phosphorylates myosin
6.Crossbridge cycling

28

how does relaxation of smooth muscle occur

Phosphatase removes phosphate from myosin
Calcium removed from cytoplasm
Ca-ATPase
Ca-Na counter transport

29

Is myosin ATPase slower or faster in smooth or skeletal muscle

SLower

30

Action potential in smooth muscle are mediated by what

Calcium

31

What determines tension

Intracellular Ca

32

Intracellular Ca influenced by what

Neural control - Autonomic NS
Hormonal control
Paracrines (local controls)

33

What is the most common type of smooth muscle. Where are these found?

Single unit.
Intestinal tract
Blood vessels
Respiratory tract

34

Where are multi-unit smooth muscle found

Large airways and arteries, eye

35

Similarities of cardiac muscle with skeletal muscle

Striated - sarcomeres
Troponin & Tropomyosin regulation
T tubules
Sarcoplasmic reticulum, but not as well developed
Similar to slow oxidative fibers
myoglobin
mitochondria
slow to fatigue

36

What is lacking in cardiac muscle?

Summation, action potential lasts almost as long as tension