Ch 11: Behavior of whole muscle

Question 1

Length – tension relationship

Answer 1

Ideal length intention of sarcomere at rest that allows for maximum contraction and tension when stimulated

Question 2

Myogram

Answer 2

Map of the timing and strength of a muscle contraction

Question 3

Muscle twitch

Answer 3

Cycle of contraction and relaxation when action potential is fired

Question 4

Phases of muscle twitch

Answer 4

1. Latent phase
2. Contraction phase
3. Relaxation phase

Question 5

Latent phase of muscle twitch

Answer 5

Time between stimulation and contraction occurring; AP has to travel down to tubules and release calcium and have sequence of events before next phase

Question 6

Contraction phase of muscle twitch

Answer 6

Pulling of actin filaments by myosin heads towards M line to shorten sarcomeres

Question 7

Relaxation phase of muscle twitch

Answer 7

Calcium re-sequestered, stimulation stops. Tropomyosin covers actin’s active sites and sarcomere lengthens

Question 8

Duration of a muscle twitch

Answer 8

Between 7 -100 ms

Question 9

Factors that affect contraction strength:

Answer 9

1. Stretch
2. Fatigue (lack of Ca^2+ or ATP)
3. Temperature of muscle
4. Stimulus frequency

Question 10

Effect of stimulus intensity on muscle twitch

Answer 10

Greater voltage of the tumulus equals more muscle fibers recruited because more action potentials are sent along more muscle fibers. Or muscle fibers recruited equal stronger contraction

Question 11

Effects of stimulus frequency on muscle twitch

Answer 11

Temporal summation (wave)
Fused to tetanus

Question 12

Temporal (wave) summation

Answer 12

Build up of additional recruitment of neurons due to increasing frequency; each new twitch rides on the previous ones generating higher tension

Question 13

Incomplete (unfused) tetanus

Answer 13

Contractions don’t fully relaxation before another contraction comes

Question 14

Complete (fused) tetanus

Answer 14

Isolated muscle stimulated at such a frequency that all the twitch is fused into a single common on fluctuating contraction.

Only achievable in a laboratory setting

Question 15

Isometric muscle contraction

Answer 15

Premovement
Important in postural muscle function
Ex: Pick up dumbbell, PLANK

Question 16

Isotonic contraction

Answer 16

Muscle changes in length with no change in tension

Question 17

Concentric isotonic contraction

Answer 17

Muscle shortens as it maintains tension
EX: bicep curl: curling weight up

Question 18

Eccentric isotonic contraction

Answer 18

Muscle lengthens as it maintains tension
Ex: bicep curl: uncurling weight down

Question 19

Muscle fatigue

Answer 19

Decrease in fiber tension of the fiber even a stimulation is occurring

Question 20

Psychological muscle fatigue

Answer 20

“Mind over matter” Telling yourself you can’t do it even though it’s still physically possible

Question 21

Physiological muscle fatigue

Answer 21

Fatigue from decreasing ATP concentration, increase in ADP
Cause: Constant stimuli, dietary deficiency, sickness, etc.)

Question 22

Excess post Dash exercise oxygen consumption (EPOC)

Answer 22

Oxygen debt after exercise

Question 23

Short term energy

Answer 23

Quick burst of energy (30-40 secs) from anaerobic respiration; buildup of lactic acid from glycolysis

Question 24

Long-term energy

Answer 24

Reliant on cardio and respiratory systems catching up for oxygen delivery; aerobic respiration

Question 25

Types of skeletal muscle fibers

Answer 25

1. Type 1: Slow – oxidative fibers 2. Type 2A: (intermediate) fast – oxidative – glycolytic fibers (animals) 3. Type 2B: fast glycolytic fibers

Question 26

Slow – oxidative fibers -type 1

Answer 26

Red fibers. Slow twitch; endurance fibers High myosin – ATPase activity and high oxidative capacity

Question 27

Fast – glycolytic fibers (type 2B)

Answer 27

White fibers because lack myoglobin. Fast twitch, no endurance.  Hi myosin-ATPase activity and high glycolytic activity

Question 28

Myasthenia gravis: Symptoms, cause, treatment

Answer 28

Symptoms: muscle fatigue and weakness that get progressively worse as muscle is used Cause: autoimmune destruction of nicotinic ACH receptor proteins of the motor end plate treatment:AChE inhibitors 

Question 29

Rigor mortis: what is it? Cause of it, time

Answer 29

Hardening of muscles and stiffening of body, starts 3 to 4 hours after death. Cause: Deteriorating of SR: calcium all released so muscle contracts, but can’t relax. Fibers remain contracted Until myofilaments decay.  Peaks at 12 hours, diminishes over next 48 to 60 hours