Chp 10 Muscular Tissue

Front 1

Skeletal Muscle

Back 1

An organ specialized for contraction, composed of striated muscle fibers (cells), supported by CT, attached to a bone by a tendon or an aponeurosis, and stimulated by somatic motor neurons.

Front 2

Cardiac Muscle

Back 2

Striated muscle fibers (cells) that form the wall of the hear; stimulated by an intrinsic conduction system and autonomic motor neurons.

Front 3

Smooth Muscle

Back 3

A tissue specialized for contraction, composted of smooth muscle fibers (cells), located in the walls of hollow internal organs, and innvervated by autonomic motor neurons.

Front 4

Thermogenesis

Back 4

The generation of heat as muscular tissue contracts.

Front 5

Excitability

Back 5

The ability to respond to certain stimuli by producing electrical signals called action potentials.

Front 6

Elasticity

Back 6

The ability of muscular tissue to return to its original length and shape after contraction or extension.

Front 7

Epimysium

Back 7

The outermost layer of CT encircling the entire muscle.

Front 8

Perimysium

Back 8

CT that surrounds groups of 10 to 100 or more muscle fibers.

Front 9

Fascicles

Back 9

The bundles that perimysium creates.

Front 10

Endomysium

Back 10

A thin sheath of areolar CT that surrounds each individual muscle fiber within the fascicle.

Front 11

Tendon

Back 11

A cord of dense regular CT composed of parallel bundlese of collagen fibers that attach a muscle to the periosteum of the bone.

Front 12

Aponeurosis

Back 12

When the CT elements extend as a broad, flat layer.

Front 13

Motor Unit

Back 13

Consists of a somatic motor neuron plus all the skeletal muscle fibers it stimulates.

Front 14

Synaptic Cleft

Back 14

A small gap that separates the neuron and the target cell.

Front 15

Axon Terminal

Back 15

Terminal branch of an axon where synaptic vesicles undergo exocytosis to release neurotransmitter molecules.

Front 16

Synaptic Bulb

Back 16

Expanded distal end of an axon terminal that contains synaptic vesicles.

Front 17

Neurotransmitter

Back 17

One of a variety of molecules within axon terminals that are released into the synaptic cleft in response to a nerve impulse and that changes the membrane potential of the postsynaptic neuron.

Front 18

Acetyl Choline (ACh)

Back 18

A neurotransmitter liberated by many peripheral nervous system neurons and some central nervous system neurons. It is excitatory at neuromuscular junctions but inhibitory at some other synapses (for example, it slows heart rate).

Front 19

Motor End Plate

Back 19

Region of the sarcolemma of a muscle fiber (cell) that includes ACh receptors, which bind ACh released by synaptic end bulbs of somatic motor neurons.

Front 20

Myofiber

Back 20

also known as "myotube"; the muscle cell

Front 21

Myofibril

Back 21

A threadlike structure, extending longitudinally through a muscle fiber (cell) consisting mainly of thick filaments (myosin) and thin filaments (actin, troponin, tropomyosin).

Front 22

Thin Filament

Back 22

Actin, Tropomyosin and Troponin

Front 23

Thick Filament

Back 23

Myosin

Front 24

Elastic Filament

Back 24

Filaments projecting from the M line and extending into the I bands.

Front 25

Sarcomere

Back 25

A contractile unit in a striated muscle fiber (cell) extending from one Z disc to the next Z disc.

Front 26

Z Disc

Back 26

Narrow, plate-shaped regions of dense material that separate one sarcomere from the next.

Front 27

A Band

Back 27

The dark, middle part of the sarcomere that extends the entire length of the thick filaments and also includes those parts of the thin filaments that overlap with the thick filaments.

Front 28

I Band

Back 28

The lighter, less dense area of the sarcomere that contains the rest of the thin filaments, but no thick filaments. A Z disc passes through the center of each I band.

Front 29

H Zone

Back 29

A narrow region in the center of each A band that contains thick filaments, but no thin filaments.

Front 30

M Line

Back 30

A region in the center of the H zone that contains proteins that hold the thick filaments together at the center of the sarcomere.

Front 31

Myosin

Back 31

A contractile protein that makes up the thick filament. A myosin molecule consists of a tail and two myosin heads, which bind to myosin-binding sites on actin molecules of a think filament during muscle contraction.

Front 32

Actin

Back 32

A contractile protein that is the main component of the thin filament. On each actin molecule is a myosin-binding site where a myosin head of a thick filament binds during muscle contraction.

Front 33

Troponin

Back 33

A regulatory protein that is a component of the thin filament, When calcium ions bind to troponin, it undergoes a change in shape; this conformational change moves tropomyosin away from myosin-binding sites on actin molecules, and muscle contraction subsequently begins as myosin binds to actin.

Front 34

Tropomyosin

Back 34

A regulatory protein that is a component of the thin filament. When a skeletal muscle fiber is relaxed, tropomyosin covers the myosin-binding sites on actin molecules, thereby preventing myosin from binding to actin.

Front 35

Sarcoplasmic Reticulum (SR)

Back 35

A fluid-filled system of membranous sacs that encircles each myofibril.

Front 36

Terminal Cisterns

Back 36

Dilated end sacs of the SR that store Ca ions when the muscle is relaxed and releases Ca to cause the muscle to contract.

Front 37

Transverse Tubules (T-Tubules)

Back 37

Thousands of tiny invaginations of the sarcolemma allowing for action potential to travel along the tubules and spread all throughout the muscle faster.

Front 38

Power Stroke

Back 38

When myosin crossbridges rotate toward the center of the sarcomere.

Front 39

Rigor Mortis

Back 39

After death, cellular membranes become leaky and calcium ions leak out of the SR into the cytosol and allow myosin heads to bind to actin. ATP synthesis ceases shortly after breathing stops, however, so the crossbridges cannot detach from actin, causing a state of rigidity. Can last for 24 hrs.

Front 40

Acetylcholinesterase (AChE)

Back 40

An enzyme that stops ACh from bonding to NT receptors.

Front 41

Twitch Contraction

Back 41

The contraction of small muscle units, manifested as a quick, simple, spasmodic contraction of a muscle

Front 42

Myogram

Back 42

The tracing of muscular contractions made by a myograph.

Front 43

Temporal Summation

Back 43

Occurs in the transmission of nerve impulses when a volley of impulses arrives at a synapse so that the duration of the impulses is briefer than the postsynaptic potential and their deliveries of transmitter are combined to create a larger than normal response.

Front 44

Numerical Summation (Recruitment)

Back 44

The orderly increase in number of activated motor units with increasing strength of voluntary muscle contractions.

Front 45

Hypotonia

Back 45

A condition in which there is diminution or loss of muscular tonicity, resulting in stretching of the muscles beyond their normal limits

Front 46

Flaccid

Back 46

Lacking firmness, resilience, or muscle tone.

Front 47

Hypertonia

Back 47

Extreme tension of the muscles or arteries.

Front 48

Spasticity

Back 48

Increased mucle tone, or stiffness, which leads to uncontrolled, awkward movements.

Front 49

Rigidity

Back 49

The quality or state of stiffness or inflexibility

Front 50

Isotonic Contraction

Back 50

The tension developed by the muscle remains almost constant while the muscle changes its length.

Used for body movements and for moving objects.

Front 51

Isometric Contraction

Back 51

The tension generated is not enough to exceed the resistance of the object to be moved and the muscle does not change its length.

Ex: Holding a book steady using an outstretched arm.

Front 52

Anaerobic Respiration

Back 52

A series of ATP-producing rxns that do not require oxygen. Involves Glycogen and Lactic Acid. Provides bursts of energy. Creates 2 ATP.

Front 53

Aerobic Respiration

Back 53

A series of oxygen-requiring rxns that produce ATP in mitochondria. Comes from the blood supply that cares Oxygen. Provides endurance. Creates 36 ATP.

Front 54

Cellular Respiration

Back 54

The process of cell catabolism in which cells turn food into usable energy in the form of ATP.

Front 55

Pyruvate

Back 55

A salt, ester, or ionized form of pyruvic acid, containing the group CH3COCOO.

Front 56

Lactic Acid

Back 56

A syrupy, water-soluble liquid, C3H6O3, produced in muscles as a result of anaerobic glucose metabolism.

Front 57

Hemoglobin

Back 57

The iron-containing respiratory pigment in red blood cells of vertebrates, consisting of about 6 percent heme and 94 percent globin.

Front 58

Myoglobin

Back 58

A single-chain, iron-containing protein found in muscle fibers, structurally similar to a single subunit of hemoglobin and having a higher affinity for oxygen than hemoglobin of the blood.

Front 59

Oxygen Debt

Back 59

The amount of extra oxygen required by muscle tissue during recovery from vigorous exercise.

Front 60

Intercalated Disc

Back 60

An undulating double membrane separating adjacent cells in cardiac muscle fibers. Intercalated discs support synchronized contraction of cardiac tissue. They can easily be visualized by a longitudinal section of the tissue.

Front 61

Autorhythmicity

Back 61

Involuntary rhythm of contractions that is only found in cardiac muscle.

Front 62

Dense Bodies

Back 62

Electron-dense portions of smooth muscle which thin filaments(actin and tropomyosin namely) bind

Front 63

Calmodulin

Back 63

A regulatory protein that binds to Calcium ions in the cytosol and activates an enzyme called myosin light chain kinase.

Front 64

Myosin Light Chain Kinase

Back 64

This enzyme uses ATP to add a phosphate group to a portion of the myosin head. The head can then bind to actin and contraction can occur.

Front 65

Hypertrophy

Back 65

The increase of the size of an organ or in a select area of the tissue.

Front 66

Hyperplasia

Back 66

a general term referring to the proliferation of cells within an organ or tissue beyond that which is ordinarily seen in e.g. constantly dividing cells. Hyperplasia may result in the gross enlargement of an organ, the formation of a benign tumor, or may be visible only under a microscope.

Front 67

Satellite Cells

Back 67

small mononuclear progenitor cells with virtually no cytoplasm found in mature muscle. They are found sandwiched between the basement membrane and sarcolemma (cell membrane) of individual muscle fibres, and can be difficult to distinguish from the sub-sarcolemmal nuclei of the fibres. Satellite cells are able to differentiate and fuse to augment existing muscle fibres and to form new fibres.