Body Systems: Musculatory System (Exercise And Muscle Contractions)

Question 1

Muscle twitch:

Answer 1

-muscle twitch: a single contraction of muscle fibres from a nerve impulse that lasts a mere fraction of a second.
-contraction of the individual fibres is all or none once it reaches a certain threshold.
-the contraction of the whole muscle can vary in strength depending on the number of muscle fibres contracting.

Question 2

Muscle contraction:

Answer 2

-a muscle twitch can be divided into 3 periods:
-1. Latent period: the period of time between stimulation and initiation of contraction.
-2. Contraction period: when the muscle shortens.
-3. Relaxation period: when the muscle returns to its former length.

Question 3

Summation:

Answer 3

-when a muscle is given rapid series of threshold stimuli, it can respond without relaxing completely.
-The second twitch is added to the first producing a greater force of contraction.
-The strength of the contraction depends on how close the second stimulus is to the first stimulus.

Question 4

Tetanus:

Answer 4

-maximal sustained contraction.
-once tetanus occurs, the graph no longer shows individual twitches.
-twitches blended completely into a straight line.
-tetanus continues until the muscle fatigues due to depletion (reduction) of energy reserves.
-fatigue is apparent when a muscle relaxes even though stimulation continues.

Question 5

There are two types of muscle fibres:

Answer 5

-type I: slow twitch.
-type II: fast twitch.

Question 6

Muscle fibres (type I: slow twitch):

Answer 6

-Contract slow, resist fatigue.
-found in long-distance runners, swimmers and bikers.
-Break down ATP slowly and efficiently.
-rely on aerobic respiration, many mitochondria.

Question 7

Muscle fibres (type II: fast twitch):

Answer 7

-Rapid generation of power.
-Found in sprinters and weightlifters.
-break down ATP quickly and inefficiently.
-rely on anaerobic respiration.

Question 8

Changing the fibres you are given: (low intensity, long duration training):

Answer 8

-affects slow twitch fibres.
-increases the number of mitochondria and blood vessels feeding these fibres.
-increases endurance (more energy).

Question 9

Changing the fibres you are given: (high intensity, short duration training):

Answer 9

-affects fast twitch fibers, causing them to increase diameter (add more actin and myosin).
-increases strength and muscles, but does not improve endurance (still fatigue fast).

Question 10

Changing the fibres you are given: hypertrophy:

Answer 10

-increase in size of skeletal muscle cells.

Question 11

Changing the fibres you are given: atrophy:

Answer 11

-lack of use causing a reduction in size of muscles.

Question 12

Slow twitch:

Answer 12

-efficient in using oxygen.
-delayed muscle firing.
-do not fatigue easily.
-best suited for: endurance sports, including cycling, marathon running, and long-distance triathlons.

Question 13

Fast twitch:

Answer 13

-do not burn oxygen to create energy.
-fast to fire; best for explosive body movements.
-tire out quickly.
-best suited for: short bursts of activity, including sprinting races, pole vaulting and cross fit-style events.

Question 14

Fitness:

Answer 14

•aerobic fitness: your body’s ability to take oxygen from the atmosphere and utilize it to produce muscle movement.
•factors that affect aerobic fitness:
-lung efficiency.
-cardiac function.
-gender.
-age.
-genetic makeup.

Question 15

Measuring fitness:

Answer 15

•VO2 max: the most oxygen that an individual can use during maximal intensity.
•unit of measurement:
-mL of oxygen/kg of body weight/minute.
•the maximal exertion test: work out at your highest intensity until you are physically unable to continue.

Question 16

Does type I preform a long contraction or short contraction?

Answer 16

Long contraction.

Question 17

Does type II preform a long contraction or short contraction?

Answer 17

Short contraction.