Muscle Physiology II

Question 1

Summation Defintiion

Answer 1

Short time between APs means the contraction increases as the muscle hasn’t relaxed

Question 2

Unfused tetanus

Answer 2

Partial relaxation

Question 3

Complete Tetanus hits a max when

Answer 3

All cross-bridges formed and physically cant have more tension

Question 4

Complete Tetanus starts to decrease when

Answer 4

Fatigue

Question 5

Isometric COntraction

Answer 5

No shortening of muscle

Question 6

Isotonic

Answer 6

Muscle length changing occurs

Question 7

Concentric contraction occurs when

Answer 7

Muscle force > load force

Question 8

Eccentric contraction occurs when

Answer 8

Load force > muscle force

Question 9

Eccentric contractions cause

Answer 9

DOMS (delayed onset muscle soreness)

Question 10

Manually lengthening sarcomeres will increase

Answer 10

Passive force (before contraction)

Question 11

Manually lengthening sarcomeres will decrease

Answer 11

Active force

Question 12

Why does DOMS occur

Answer 12

Microdamage from laying down new long sarcomeres, (and the associated inflammation + oedema of microdamage)

Question 13

What is a rejected theory for DOMS

Answer 13

Lactic acid (concentric contractions also cause DOMS, and lactic acid levels are normal by 1 hour after exercise)

Question 14

Velocity is _____ proportional to load

Answer 14

Inversely

Question 15

Contraction is most efficient at ____ of max velocity

Answer 15

1/3

Question 16

Human muscle efficiency =

Answer 16

20-25% (ie lots of ATP used but only 20-25% directly contributes to muscle contraction)

Question 17

First ATP Source

Answer 17

Creatine Phosphate

Question 18

2nd ATP Source

Answer 18

Oxidative Phosphorlyation (Aerobic)

Question 19

3rd ATP Source

Answer 19

Glycolysis (Anaerobic Resp)

Question 20

In physiological pH is lactic acid dissociated?

Answer 20

Yes (>99% in form of La- and H+ (but buffered so minimal pH change))

Question 21

Type I Fibres are

Answer 21

Slow oxidative = low rate of ATP turnover

Question 22

Type II B fibres are

Answer 22

Fast glycolytic = high ATP turnover

Question 23

Type I fibres used for ___ exercise

Answer 23

Sustained (ie long distance running)

Question 24

Type II B fibres are used for _____ exercise

Answer 24

Burst (ie short sprint)

Question 25

3 Types of Muscle Weakness

Answer 25

1. Muscle Fatigue
2. Muscular Dystrophy (genetic)
3. Sarcopenia (age)

Question 26

Do we know the cause of muscle fatigue

Answer 26

No

Question 27

Pathways to treat muscle fatigue

Answer 27

Target the assumed pathways ie creatine, inc red blood cell count for more O2

Question 28

Central Muscle Fatigue

Answer 28

Decreased activation from CNS -> decreased number of motor units recruited

Question 29

Peripheral Muscle Fatigue

Answer 29

Cellular Mechanisms that control force in the muscle cell eg decreased Ca2+ sensitivity

Question 30

Duchenne’s Muscular Dustrophy cause

Answer 30

Loss of dystrophin protein due to mutation in dystrophin gene

Question 31

Duchenne’s Muscular Dystrophy cellular level change

Answer 31

Increase membrane permeability from holes in membrane = good things leave bad things enter

Question 32

Muscular Dystrophy common cause of death

Answer 32

Cardiac / swallowing issues with muscle

Question 33

Sarcopenia

Answer 33

Decrease in muscle mass - body mass ratio

Question 34

Sympathetic NS impact on fast muscles

Answer 34

Increases speed of all parts of process

Question 35

Sympathetic NS impact on slow muscles

Answer 35

Decreases response time = helps with posture