Muscly physiology part b

Question 1

What is rate limiting step for cycle

Answer 1

ATP hydrolysis

Question 2

Fast fibers=

Answer 2

Myosin with fast ATPase activity

Question 3

Slow fibers=

Answer 3

Myosin with slow ATPase activity

Question 4

Slow fiber contractions last how much longer then fast

Answer 4

10 times

Question 5

How to classify as oxidative or glycolitic

Answer 5

based on primary source of energy

Question 6

Oxidative fibers primary energy source is

Answer 6

oxidative phosphorylation

Question 7

Properties of oxidative fibers

Answer 7

Many mitochondria
Myoglobin (red)
Small diameter
Resistant to fatigue

Question 8

Glycolytic fibers properties

Answer 8

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

Question 9

What are the three types of muscle fiber types

Answer 9

Slow oxidative
Fast oxidative
Fast glycolytic

Question 10

Properties of slow oxidative fibers

Answer 10

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

Question 11

Properties of fast glycolytic fibers

Answer 11

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

Question 12

Properties of Fast oxidative fibers

Answer 12

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

Question 13

Proportions of fibers in a muscle depends on what

Answer 13

Function of muscle, postural muscle more slow oxidative

Question 14

What is the recruitment order of fibers?

Answer 14

Slow oxidative, fast oxidative, fast glycolytic

Question 15

Causes of muscle fatigue in high intensity exercise

Answer 15

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

Question 16

Causes of fatigue in low intensity exercise

Answer 16

Depletion of energy reserves

Question 17

What are other possibilities of fatigue

Answer 17

Build up of inorganic phosphates

Changes in ion distribution

Question 18

What is central fatiue

Answer 18

psychological fatigue

Question 19

What is change is muscle size due to?

Answer 19

Change in size of individual cells

Question 20

What is disuse atrophy

Answer 20

Decrease in size( lose myofibrils)

Question 21

What is denervation atrophy

Answer 21

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

Question 22

What is hypertrophy

Answer 22

Increase in size (increase myofibrils)

Increase production of actin & myosin

Question 23

Aerobic exercise adapts muscle how

Answer 23

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

Question 24

how does anaerobic ex adapt muscle

Answer 24

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

Question 25

Does smooth muscle contain actin and myosin

Answer 25

yes

Question 26

Some properties of smooth muscle

Answer 26

``` 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 ```

Question 27

Steps of excitation-contraction coupling for smooth muscle

Answer 27

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

Question 28

how does relaxation of smooth muscle occur

Answer 28

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

Question 29

Is myosin ATPase slower or faster in smooth or skeletal muscle

Answer 29

SLower

Question 30

Action potential in smooth muscle are mediated by what

Answer 30

Calcium

Question 31

What determines tension

Answer 31

Intracellular Ca

Question 32

Intracellular Ca influenced by what

Answer 32

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

Question 33

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

Answer 33

Single unit. Intestinal tract Blood vessels Respiratory tract

Question 34

Where are multi-unit smooth muscle found

Answer 34

Large airways and arteries, eye

Question 35

Similarities of cardiac muscle with skeletal muscle

Answer 35

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

Question 36

What is lacking in cardiac muscle?

Answer 36

Summation, action potential lasts almost as long as tension