Unit 4: Muscular System

Front 1

skeletal

Back 1

Muscle whose function is moving bones of the skeleton. Voluntary and striated.

Front 2

cardiac

Back 2

Muscle tissue that is found only in the heart. Involuntary and striated.

Front 3

smooth

Back 3

Muscle located in the walls of hollow internal structures (organs, blood vessels, airways, etc.). Involuntary and not striated.

Front 4

striated

Back 4

Striations are alternating light and dark bands. If a muscle has striations it is striated.

Front 5

intercalcated disc

Back 5

Irregular transverse thickenings of the sarcolemma where cardiac muscle fibers connect.

Front 6

agonist

Back 6

A muscle that causes a desired action. (Flexing arm at elbow)

Front 7

antagonist

Back 7

A muscle that has an action opposite that of the agonist and yields to the movement of the agonist. (Extending arm at elbow)

Front 8

fixator

Back 8

A muscle that stabilizes the origin of the agonist so that the agonist can act more efficiently.

Front 9

tendon

Back 9

Combination of epimysium, perimysium, and endomysium that extends together beyond the muscle fibers and attaches to the periosteum of a bone. MUSCLE-TO-BONE.

Front 10

functions of muscle

Back 10

Producing body movements
Stabilizing body positions
Storing and moving substances within the body
Generating heat

Hint 10

PSSG

Front 11

flexor

Back 11

Muscle that decreases a joint angle.

Front 12

extensor

Back 12

Muscle that increases a joint angle.

Front 13

thin filament

Back 13

See picture... Within myofibrils are smaller structures, filaments which are directly involved in the contractile process. Consists of tropomyosin, toponin, and actin.

Front 14

thick filament

Back 14

See picture... Within myofibrils are smaller structures, filaments which are directly involved in the contractile process. Consists of myosin.

Front 15

Z discs

Back 15

Z discs separate one sarcomere from the next.

Front 16

I-band

Back 16

The I-band is a lighter, less dense area that contains thin filaments but no thick filaments.

Front 17

A-band

Back 17

The darker middle of the sarcomere is called the A-band, which extends the entire length of the thick filaments.

Front 18

myosin

Back 18

Myosin functions as a motor protein in all three types of muscle tissue. Thick filaments are made up of myosin, one molecule of which looks like two golf clubs twisted together.

Hint 18

golf clubs

Front 19

actin

Back 19

The main component of thin filaments. Individual actin molecules join to form an actin filament that is twisted into a helix. On each actin moleculer there is a myosin binding site.

Front 20

tropomyosin

Back 20

Regulatory protein in thin filaments. Tropomyosin block the myosin binding sites on actin when a muscle is relaxed.

Front 21

troponin

Back 21

One of the two regulatory proteins in thin filaments. When a signal is sent for a muscle to contract, troponin pulls on tropomyosin and exposes the myosin binding sites.

Front 22

sarcomere

Back 22

The basic functional unit of a myofibrils (muscle fibers are in fascicles, myofibrils are in muscle fibers).

Front 23

transverse tubules

Back 23

...or T-tubules, are tunnel-like extentions of the sarcolemma (the plasma membrane of a muscle fiber) that extend towards the center of each muscle fiber. Filled with interstitial fluid.

Front 24

sarcoplasmic reticulum

Back 24

...or SR is a fluid-filled system of membranous sacs. The SR releases Ca2+ when there is a signal to contract.

Front 25

cross-bridges

Back 25

The term used to describe myosin heads that are attached to actin.

Front 26

powerstroke

Back 26

During a powerstroke, the myosin head rotates or swivels and releases the ADP. The myosin head generates force as it rotates towards the center of the sarcomere, sliding the thin filament past the thick filament toward the M line (the middle).

Front 27

neuromuscular junction

Back 27

The structural point of synaptic contact and functional site of communication between a motor neuron and a skeletal muscle.

Front 28

synapse

Back 28

A region where communication occurs between a neuron and another cell (ex: a muscle fiber).

Front 29

synaptic cleft

Back 29

A small gap that separates a motor neuron and another cell (ex: a muscle fiber).

Front 30

acetylcholine

Back 30

The neurotransmitter (found inside synaptic end bulb vesicles)released at the neuromuscular junction.

Front 31

acetylcholinesterase

Back 31

An enzyme in the synaptic cleft that breaks down acetylcholine into products that cannot activate the ACh receptor.

Hint 31

AChase

Front 32

rigor mortis

Back 32

State of partial contraction of muscles after death due to lack of ATP; myosin heads remain attached to actin, thus preventing relaxtion.

Front 33

twitch

Back 33

A twitch contraction is the brief contraction of all the muscle fibers in a motor unit in response to a single nerve impulse in its motor neuron.

Front 34

summation

Back 34

...or wave summation is a phenomenon in which stimuli arriving in close sequence cause larger contractions.

Front 35

recruitment

Back 35

The process in which the number of contracting motor units is increased.

Front 36

lag time (latent period)

Back 36

The brief delay that occurs between application of the stimulus and the beginning of contraction. During the latent period, Ca2+ ions are released from the SR and bind to troponin, which allows the myosin heads to start binding to actin.

Front 37

glycolysis

Back 37

A series of reactions that quickly break down each glucose molecule into two molecules of pyruvic acid. (Uses 2 ATP with a net gain of 2)

Front 38

creatine phosphate

Back 38

An energy-rich molecule that is found only in muscle fibers. (Creatine + Phosphate group from ATP = Creatine phosphate)

Front 39

aerobic respiration

Back 39

A series of oxygen-requiring reactions to produce ATP in mitochondria.

Front 40

slow oxidative

Back 40

...or SO fibers are smallest in diameter and thus are the least powerful type of skeletal muscle fibers. Large amounts of myoglobin and many blood capillaries Many mitochondria means that SO fibers produce ATP mainly by aerobic cellular respiration. Resistant to fatigue.

Front 41

fast oxidative

Back 41

...or FOG (fast oxidative-glycolytic)fibers intermediate in diameter between the other two types of fibers. They contain large amounts of myoglobin and many capillaries. FOG fibers can generate ATP using glycolysis and aerobic respiration. Moderately high resistance to fatigue.

Front 42

fast glycolytic

Back 42

...or FG fibers are largest in diameter and contain the most myofibrils. This means that they can generate the most powerful contractions. Low myoglobin content and relatively few blood capillaries pared with large amounts of glycogen means that FG fibers create ATP mainly by glycolysis. Low fatigue resistance.

Front 43

ATP/ADP

Back 43

The main energy currency of in living cells; used to transfer the chemical energy needed for metabolic reactions. Adenine + Ribose + 3 phosphate groups = ATP (-1 phosphate group = ADP)

Front 44

myoglobin

Back 44

The oxygen-binding, iron-containing protein present in the sarcoplasm of musle fibers; contributes to red color of muscle.

Front 45

atrophy

Back 45

Wasting away or decrease size of a part, dur to a failure, abnormality of nutrition, or lack of use.