Kns Final

Front 1

What is a motor unit and what does it consist of?

Back 1

basic functional unit of the human neuromuscular system
consists of motor neurons and the muscle fibers it innervates

Front 2

myofilaments

Back 2

actin(thin) and myosin(thick)

Front 3

sarcomere

Back 3

smallest contractile unit of skeletal muscle
z-line to z-line
consist of actin and myosin that form cross bridges

Front 4

sarcoplasmic reticulum

Back 4

surrounds each myofibril
stores calcium ions in the vesicles
runs perpendicular to t-tubules

Front 5

muscular contraction is regulated by

Back 5

calcium

Front 6

what is an action potential?

Back 6

an electrical nerve impulse

Front 7

sliding filament theory

Back 7

states that actin filaments at each end of the sarcomere slide inward on myosin filaments, pulling the z-lines toward the center of the sarcomere, thus shortening the muscle fiber

Front 8

5 phases of the sliding filament theory

Back 8

resting phase = little calcium is in the myofibril, few myosin are bound to actin, no tension is developed in the muscle (said to be "at rest")
excitation-contraction phase = sarcoplasmic reticulum releases calcium which binds to troponin. tropinin causes a shift to occur in tropomyosin and flexion of the cross bridges occur
contraction phase = breakdown of ATP into ADP and phosphate. this all occurs due to ATPase
recharge phase = the period when calcium, ATP, and ATPase have run out and need to be "refueled"
relaxation phase = stimulation of the motor nerve stops and actin and myosin return to their unbound state

Front 9

how is a muscle activated

Back 9

an action potential causes the release of acetylcholine that diffuses across the NMJ causing an excitation of the sarcolemma. Once a sufficient amount of acetylcholine is released, the action potential goes across the sarcolemma and the fiber contracts. All fibers contract at once

Front 10

all or none principle

Back 10

all muscle fibers contract at one time...
a stronger action potential does not produce a stronger contraction

Front 11

type I fibers

Back 11

slow twitch fibers (develop force and relax slowly but have a long twitch time)

efficient and fatigue resistant
high aerobic energy supply, but limited potential for rapid force development, low anaerobic power

Front 12

type IIa and IIb fibers

Back 12

fast twitch fibers (develops force and relaxes rapidly but has a short twitch time)

ineffiecient and fatigable
low aerobic power, rapid force development, high anaerobic power

Front 13

How to vary force output of a muscle?

Back 13

through change in the frequency of activation of individual motor units(called recruitment) or the change in the number of activated motor units

Front 14

preloading

Back 14

the preparation of the muscle fibers due to them not running the entire length of a muscle

helps in the development of strength early on

Front 15

proprioception

Back 15

muscle spindles = consisst of several modified muscle fibers enclosed in a sheath of connective tissue. provide information related to muscle length and the rate in which they change length - sending signals to the spinal cord which then lead to the activation of motor neurons

Golgi Tendon Organs = located in the tendons near the myotendinous junction, activated when the tendon attached to an active muscle is stretched, as tension increases so does the discharge of GTOs - sends signals to the spinal cord to inhibit muscle activation (mechanism to protect the muscles against too much tension)

Front 16

what are muscles like in older people?

Back 16

muscle function is reduced (weight bearing extensor muscles)
muscle atrophy results in the loss of number and size of muscle fibers
*inactivity is the major reason*

Front 17

How can athletes improve force production?

Back 17

1. recruit large muscle groups during activity
2. increase cross sectional area
3. preload the muscle before concentric action

Front 18

heart

Back 18

- right side pumps blood through lungs
- left side pumps blood through the body

Front 19

heart conduction path

Back 19

SA node = pacemaker, sends impulses
AV node = delays the impulses before sending them to the ventricles
AV bundle = conducts the impulse to the ventricles
Purkinje fibers = send impulses to all parts of the ventricles

Front 20

electrocardiogram

Back 20

P wave, QRS complex, T-wave

shows ventricular depolarization and repolarization

Front 21

arteries, capillaries, veins

Back 21

arteries = carry blood away from the heart - have strong muscular walls

capillaries = exchange site of oxygen - have thin walls that make them permeable

veins = transport blood back to the heart - have thin, muscular walls with valves that help pump the blood back up

Front 22

blood

Back 22

- transport oxygen from the lungs to the tissues for cellular metabolism
- removal of CO2 (byproduct of metabolism)

hemoglobin acts as an acid base buffer

Front 23

cardiac output

Back 23

Q = HR x SV

increase from rest to exercise

Front 24

end diastolic volume

Back 24

amount of blood in the left ventricle before contraction

Front 25

starlings law

Back 25

more back, more out

Front 26

fick's equation

Back 26

VO2 = Q x a-v O2 difference