Human Physiology- Muscles

Front 1

Excitability of Muscles

Back 1

capacity of muscle to respond to a stimulus

Front 2

Contractility of Muscles

Back 2

ability of muscle to shorten and generate pulling force

Front 3

Extensibility of Muscle

Back 3

muscle can be stretched back to its original length

Front 4

Elasticity of Muscle

Back 4

ability of muscle to recoil to original resting position

Front 5

Sarcoplasmic Reticulum

Back 5

modified ER in muscle cell that contain Ca++

Front 6

Muscle Fiber

Back 6

Structural unit of muscle formed by fusion of myoblasts

Front 7

Myofilaments

Back 7

contractile protein of muscle, thin (actin), thick (myosin); bundles of myofibrils make up myofilaments

Front 8

Sarcoplasm

Back 8

muscle cell's semifluid cytoplasm, packed with mitochondria and myofibrils

Front 9

What is the main ion responsible for contraction?

Back 9

Calcium (Ca++)

Front 10

Transverse Tubules

Back 10

invaginations of sarcolemma into center of cell and house mitochondria; allows action potential to travel down

Front 11

Steps of Muscle Contraction

Back 11

1- Na+ influx -->action potential -->Ca++ released from SR --> Ca++ binds to troponin --> exposes mysin binding sites on actin --> myosin binds to actin = cross-link -->binding causes release of ADP + P in myosin head --> ATP binds to myosin --> causes actin to be released from myosin head --> ATP hydrolyzes to ADP +P causing conformational change --> Ca2+ actively transported back into SR

Front 12

What molecule is required for muscle contraction?

Back 12

ATP

Front 13

Troponin

Back 13

3 protein complex that binds to actin, tropomyosin and Ca++

Front 14

When Ca++ is absent, then what does troponin do?

Back 14

induces tropomyosin to cover binding sites

Front 15

When Ca++ is present, then what does troponin do?

Back 15

allows tropomyosin to uncover binding sites

Front 16

What bands move within the sarcomere?

Back 16

H and I bands

Front 17

Electrochemical message

Back 17

muscle cell excitation is electrical and chemical in nature; releases Ach at synaptic cleft

Front 18

What enzyme is responsible for the breakdown of Ach?

Back 18

AchE (acetylcholinenesterase)

Front 19

Why does AchE need to be present?

Back 19

to help return the muscle back to its original state so it can be ready for another contraction

Front 20

Ach is released from where _______ at the _________

Back 20

presynaptic cleft; neuromuscular junction

Front 21

Motor unit

Back 21

amount of muscle fibers that one nerve innervates

Front 22

What is the muscle/nerve ration of the eye muscles?

Back 22

1:1

Front 23

Muscle Fatigue

Back 23

if muscle over stimulated, then strength of contractions becomes weaker/inability of muscle to maintain force of contraction after prolonged activity

Front 24

Characteristics of Muscle Fatigue

Back 24

reduced Ach, reduced ATP, reduced O2, reduced glycogen, increased lactic acid

Front 25

Cholinesterase Inhibitors

Back 25

-DFP, -Parathion, -Sarin, -Neostigmine

Front 26

Muscle Relaxants

Back 26

-atropine, curare

Front 27

Atropine

Back 27

antidote for cholinesterase inhibitors (muscle relaxant)

Front 28

Curare

Back 28

blocks Ach action/ blocks neuromuscular junction

Front 29

What was curare replaced with?

Back 29

Flexeril

Front 30

Botulism

Back 30

toxin preventing release of synaptic vesicles containing Ach; therefore blocks nerve transmission

Front 31

What two things can effect the neuromuscular junction?

Back 31

Botulism and Curare

Front 32

Contraction Cycle

Back 32

repeating sequence of events that cause think and thick filaments to move past each other

Front 33

Steps of the Contraction Cycle

Back 33

ATP hydrolysis--> crossbridge --> powerstroke --> detachment

Front 34

How long with the contraction cycle repeat?

Back 34

as long as there is enough ATP and Ca++

Front 35

Myoglobin

Back 35

inside muscle that stores oxygen

Front 36

Types of Muscle Contractions

Back 36

isotonic
isometric

Front 37

Isotonic Muscle Contraction

Back 37

Normal

Front 38

Isometric Muscle Contraction

Back 38

Tension increase but muscle does not shorten

Front 39

Types of Individual Fibers

Back 39

Fast and Slow

Front 40

Fast Fibers

Back 40

Type II a and b fibers; fast oxidative glycolytic fibers; has lots of mitochondria and myoglobin

Front 41

Who usually have fast fibers?

Back 41

power athletes and sprinters

Front 42

Slow Fibers

Back 42

Type I fibers; slow oxidative fibers; good for endurance training

Front 43

What two things does slow fibers increase?

Back 43

mitochondrial volume and myoglobin concentration

Front 44

Who typically has slow fibers?

Back 44

endurance athletes because they resists fatigue

Front 45

Who typically has fast glycolytic fibers (fast twitch B)?

Back 45

weight lifters, anaerobic movements and short duration

Front 46

What are the ways to generate ATP?

Back 46

1- Oxidative Phosphorylation (aerobic)
2- Glycolysis (anaerobic)
3- Phosphocreatine

Front 47

Neuromuscular Junction

Back 47

site where motor neuron meets the muscle fiber; release Ach

Front 48

Which muscles are striated?

Back 48

skeletal and cardiac

Front 49

What does exercise do?

Back 49

increases muscle size, strength, efficiency and more fatigue resistant by adding more proteins within a single cell (do not get more muscle cells)

Front 50

What controls smooth muscle contraction?

Back 50

hormones, paracrine, and neurotransmitters

Front 51

Calmodulin

Back 51

Ca++ binds to calmodulin in smooth muscle and troponin in skeletal muscle

Front 52

Ciliary Muscle

Back 52

multiunit smooth muscle that have 1:1 muscle/nerve innervation; no gap junctions