Lecture 13

Question 1

What is muscle tension?

Answer 1

The force exerted by a muscle/ fiber determined by number of cross bridges formed

Question 2

What determines how many cross bridges are formed?

Answer 2

Fiber length
Fiber size
Fatigue

Question 3

What does a single muscle stimulus produce?

Answer 3

A twitch

Question 4

How long does each section of a muscle movement last?

Answer 4

Action potential : 1 to 2 msec
Latent period : 2 msec
Contraction : 10 - 100 msec
Relaxation : depends

Question 5

Single twitch vs. Wave summation

Answer 5

Single : 1 AP and relaxation
Wave : 2 AP and 1 relaxation with the second AP releasing more Ca+ for more tension

Question 6

What is unfused tetanus?

Answer 6

Multiple wave summations building off one another with partial relaxation between contractions (quivering)

Question 7

What is fused tetanus?

Answer 7

High frequency stimulus with no relaxation

Sustained contraction (complete tetanus)

All troponin are saturated with Ca+

Question 8

What state is optimal for muscles and why?

Answer 8

Resting fiber length

Allows for max cross bridges = max tension

Question 9

Why is shortened or lengthened fiber lengths not optional?

Answer 9

Short - thin filaments overlap = less cross bridges

Long - not all myosin heads interact with actin filaments

Question 10

What does fiber size matter?

Answer 10

Thicker fibers mean more myofibrils which means more tension

Question 11

What encourages muscle fiber growth?

Answer 11

Fibers thicken in response to exercise and testosterone

Question 12

What effect does fatigue have on muscles?

Answer 12

Less contraction = reduced max muscle tension

Result in micro tears from strenuous exercise

Question 13

What are the two types of muscle fibers?

Answer 13

Fast - contract ad relax rapidly ( white with low myoglobin)

Slow - contract and relax slow ( red with high myoglobin)

Question 14

What type of muscle fiber would be used for marathons?

Answer 14

Slow muscle fibers because the myoglobin in it beings in more respiratory ATP

Is slow to work but lasts for longer time using respiratory ATP

Question 15

What is the tension of whole muscles affected by?

Answer 15

Number of fibers contracting ( more motor units = greater tension)

Number of fibers per motor unit (100 fibers vs 100 fibers/ neurons)

Size of muscle (large muscle = more fibers = more tension)

Fatigue

Question 16

How is muscle tone maintained?

Answer 16

By alternatively stimulating different motor units at low levels

Question 17

What is the purpose of muscle tone?

Answer 17

Firmness to muscles

Question 18

Isotonic vs. Isometric

Answer 18

Isotonic - muscle length changes and tension exceeds resistance is load (the lift)

Isometric - the muscle length is unchanged and tension does not exceed the resistance of the load (the hold)

Question 19

Which whole muscle contraction requires ATP?

Answer 19

Both isometric and isotonic

Question 20

What are the 3 ATP systems?

Answer 20

Creatine phosphate

Glyocolysis

Aerobic respiration

Question 21

How is energy used during resting?

Answer 21

Using fatty acids through aerobic respiration

Question 22

When is creatine phosphate produced?

Answer 22

During resting an excessive amount CrP ATP is created and stored

Question 23

What is the duration of energy in a CrP unit?

Answer 23

15 seconds

Question 24

What is the stored version of glucose?

Answer 24

Glycogen

Question 25

Is ATP required to convert Glucose to its resting state?

Answer 25

Yes because it is an anabolic process

Question 26

What is the order of ATP system used?

Answer 26

Free ATP - < 15 sec Pcr - atp from creatine - < 15 sec Glycolysis anaerobic - < 1 min Aerobic respiration - 1 < + hrs

Question 27

Where does aerobic respiration retrieve energy from?

Answer 27

Glucose from the liver and then fatty acids Fatty acids take longer to convert to usable energy

Question 28

What colour reflects the amount of myoglobin in muscles?

Answer 28

White = none to little Pink = medium Red = lots

Question 29

Why do muscles show fatigue?

Answer 29

Due to the depletion of glycogen Build up of end products (lactic acid reduces O2 delivery) / (Pi binds to Ca+ and slows cross bridges) Failed AP (more K+ in tubules and stops Ca+ release) CNS fails to command muscles effectively from lactic acid

Question 30

What occurs after long term muscle fatigue?

Answer 30

Neurons run out of Ach even in healthy people

Question 31

What is oxygen dept?

Answer 31

The recovery of oxygen consumption

Question 32

What is oxygen used for?

Answer 32

Replenish glycogen, creatine, phosphate, O2 on hemo and myoglobin Convert lactic acid to Krebs cycle and liver as glucose

Question 33

Why does the body temp increase in exercise?

Answer 33

To increase O2 demand Increases rate of chemical reactions means more ATP and more O2 in ETC to make ATP

Question 34

Spasm vs. Cramp

Answer 34

Sudden involuntary contraction of single muscle Painful and involuntary contraction of muscle

Question 35

Why do cramps occur?

Answer 35

Inadequate blood flow to muscle Prolonged position Dehydration Overuse of muscle Electrolyte decrease Injury