Muscle System Mcat

Front 1

What are some properties of skeletal muscle?

Back 1

Voluntary, so innervated by the somatic nervous system
Striated due to Z lines, and multinucleate

Front 2

What is the organization of skeletal muscles? (narrow to broad)

Back 2

sarcomere, myofibril, sarcoplasmic reticulum, sarcoplasm, sarcolema, myocyte

Front 3

What are the T tubules?

Back 3

In skeletal muscles, a way for ions to flow between sarcomeres so an action potential can propagate?

Front 4

What is the purpose of the sarcoplasmic reticulum?

Back 4

It stores Ca 2+ that can be released due to depolarization

Front 5

What is myoglobin?

Back 5

A protein in the muscle that binds to O2 with a higher affinity than hemoglobin

Front 6

What are red fibers known as?

Back 6

"slow twitch"; has a higher concentration of myoglobin, more mitochondria and uses aerobic respiration. Long distance runners have more red fibers than white.

Front 7

What are white fibers known as?

Back 7

"Fast twitch", contract quicker than red fibers but fatigue quicker. Use anaerobic respiration, so they have less myoglobin and less mitochondria. Short distance runners have more white fibers than red.

Front 8

What is calcium's role in a muscle contraction?

Back 8

Calcium must be released by the sarcoplasmic reticulum during depolarization in order to bind to troponin, which moves tropomyosin away to reveal the myosin binding sites on actin.

Front 9

What occurs in the first step of a muscle contraction, "initiation?"

Back 9

signal -- motor neuron -- nerve terminal -- acetylcholine released in neuromuscular junction -- binds to muscle cell receptors

Front 10

What occurs in the second step of a muscle contraction, the shortening of the sarcomere?

Back 10

The action potential goes through the T-Tubules to the sarcoplasmic reticulum. Calcium is released, binds to troponin making tropomyosin move to reveal the myosin binding cites on actin. An actin/myosin cross bridge forms and ADP/P is released, pulling on fibers.

Front 11

What bands in the sarcomere shorten during contraction? Which stay the same?

Back 11

H, I, Z bonds shorten. H is the thick fibers, I is the thin fibers and Z is the boundary between sarcomeres.

The A band, which is the overlap of thick and thin fibers, stays the same.

Front 12

What occurs during muscle relaxation?

Back 12

ATP binds to myosin, causing it to release and relax. This ATP must be hydrolyzed to make the myosin change confirmation again, and Ca2+ must be added so the myosin binding sites can be revealed.

Front 13

What determines the force of a contraction?

Back 13

The number of muscle fibers stimulated simualtaneously

Front 14

What is Tonus?

Back 14

A state of constant low level contraction

Front 15

What occurs in a simple twitch?

Back 15

A latent period (has not hit threshold value yet), contraction, refractory period (absolute=cannot be stimulated at all; relative=can be stimulated but must have more force to do so)

Front 16

What are the properties of smooth muscle?

Back 16

Myogenic (does not need external signals to contract), controlled by the autonomic nervous system, uninucleate.

Occurs in the digestive tract, bladder, uterus, blood vessel walls, etc.

Front 17

What are the properties of cardiac muscle?

Back 17

Uninucleate, involuntary, myogenic, striated

Front 18

What is the purpose of creatine phosphate?

Back 18

Can be hydrolyzed to create ATP immediately without going through cellular respiration first

Front 19

How is myoglobin useful during exercising?

Back 19

Can use the O2 it's holding on to in order to keep aerobic respiration going when O2 concentration is low

Front 20

What are ligaments?

Back 20

Dense connective tissue that holds bones together at the joints

Front 21

What are tendons?

Back 21

Dense connective tissue that holds bones and muscles together

Front 22

What is connective tissue?

Back 22

Made up of a sparsely scattered population of cells in a amorphous substance.

Front 23

What are the three fiber types of connective tissue?

Back 23

Collagenous fibers=composed of collagen, have great strength

elastic fibers=composed of elastin, give resilience

reticular fibers=branched fibers joining connective tissue to other tissues

Front 24

What are the two major cell types in connective tissue?

Back 24

fibroblasts = secrete substances that are components of extracellular fibers

macrophages=engulf bacteria and dead cells

Front 25

What is dense connective tissue?

Back 25

Connective tissue with a high proportion of collagenous fibers

Front 26

What is the end of the muscle attached to stationary bone called?

Back 26

The origin (in limb muscles, proximal)

Front 27

What is the end of the muscle attached to the bone that moves during contraction called?

Back 27

The insertion (distal end in limb muscles)

Front 28

How do muscles work antagonistically?

Back 28

They work in pairs; one relaxes while the other contracts.

Front 29

How do muscles work synergistically?

Back 29

Other muscles assist the principle muscles during movement

Front 30

What does a flexor muscle do?

Back 30

Contract to decrease the angle of a joint

Front 31

What does an extensor muscle do?

Back 31

Contract to straighten a joint

Front 32

What does an abductor muscle do?

Back 32

Moves part of the body away from the midline

Front 33

What does an adductor muscle do?

Back 33

Moves part of body toward the midline