Mr. Lindsay Unit 3 Chapters 4 & 10

Front 1

Muscle tissue

Back 1

A tissue characterized by the presence of cells capable of contraction; includes skeletal, cardiac, and smooth muscle tissues

Front 2

Muscle fibers

Back 2

Has several hundred nuclei just inside plasma membrane; individual muscle cells of skeletal muscle tissue

Front 3

Skeletal muscle tissue

Back 3

Cells are long, cylindrical, striated, and multinucleate.

Front 4

Cardiac muscle tissue

Back 4

Cells are short, branched, and striated, usually with a single nucleus; cells are interconnected by intercalated discs

Front 5

Smooth Muscle tissue

Back 5

Cells are short, spindle-shaped, and nonstriated, with a single, celtral nucleus

Front 6

Myosatellite cells

Back 6

Stem cells that persist in adult skeletal muscle tissue. Helps skeletal muscle tissue at least partially repair itself after injury because skeletal muscle fibers are incapable of dividing

Front 7

Striated voluntary muscle

Back 7

Skeletal muscle, doesn't usually contract unless stimulated by nerves, and the nervous system provides voluntary control over their activities

Front 8

Cardiocyte

Back 8

Typical cardiac muscle cell.

Front 9

Intercalated discs

Back 9

Cardiac muscle tissue consists of a branching network of interconnected cardiac muscle cells. This is the specialized reason where these cells are connected.

Front 10

Striated involuntary muscle

Back 10

Cardiac muscle tissue; the nervous system can alter the rate of pacemaker cell activity, but it does not provide voluntary control over individual cardiac muscle cells

Front 11

Pacemaker cells

Back 11

Specialized cardiac muscle cells that set a regular rate of contraction

Front 12

Nonstriated involuntary muscle

Back 12

Smooth Muscle tissue, because of its appearance and the fact the the nervous system usually does not voluntarily control smooth muscle contractions

Front 13

Skeletal muscle functions

Back 13

Produce skeletal movement; maintain posture and body position; support soft tissues; guard body entrances and exits; maintain body temperature; store butrients

Front 14

Epimysium

Back 14

A dense layer of collagen fibers that surrounds the entire muscle; separates the muscle from nearby tissues and organs and is connected to deep fascia

Front 15

Deep fascia

Back 15

A dense connective tissue layer

Front 16

Perimysium

Back 16

Divides skeletal muscle into compartments containing a fascicle

Front 17

Fascicle

Back 17

A bundle of muscle fibers

Front 18

Endomysium

Back 18

Within a fascicle, the delicate connective tissue which surrounds the individual skeletal muscle cells, muscle fibers, and loosely interconnects adjacent muscle fibers

Front 19

Aponeurosis

Back 19

Site at the end of each muscle where the collagen fibers of the epimysium, perimysium, and endomysium come together to form a broad sheet

Front 20

Tendon

Back 20

Site at the end of each muscle where the collagen fibers of the epimysium, perimysium, and endomysium come together to form a bundle.

Front 21

Myoblasts

Back 21

Groups of embryonic cells. These groups fuse forming individual multinucleate skeletal muscle fibers

Front 22

sarcolemma

Back 22

plasma membrane of a muscle fiber, surrounds the sarcoplasm. Has a characteristic membrane potential, also called the transmembrane potential due to more negative charges on its cytoplasmic side and more positive charges on its extracellular side.

Front 23

sarcoplasm

Back 23

cytoplasm of the muscle fiber

Front 24

Transverse tubules/T-tubules

Back 24

narrow tubes whose surfaces are continuous with the sarcolemma and extend deep into the sarcoplasm. Filled with extracellular fluid and form passageways through the muscle fiber. Able to conduct electrical charges, and the signal to contract is conducted through them.

Front 25

myofibrils

Back 25

Hundreds to thousands of cylindrical structures contained in each muscle fiber. As long at the entire cell and encircled by branches of T-tubules. Active shortening leads to skeletal muscle fiber contraction.

Front 26

Myofilaments

Back 26

Bundles of protein filaments within myofibrils

Front 27

Thin filaments

Back 27

A type of myofilament composed primarily of actin

Front 28

Thick filaments

Back 28

A type of myofilament composed primarily of myosin

Front 29

Titin

Back 29

elastic myofilament associated with the thick filaments

Front 30

Sarcoplasmic reticulum

Back 30

Form a tubular network around each individual myofibril. Exports Ca2+ out of the cytosol

Front 31

Terminal cisternae

Back 31

Expanded chambers formed on either side of a T tubule and the tubules of the SR enlarging and fusing. Contain the protein calsequestrin, which reversibly binds Ca2+

Front 32

Triad

Back 32

Combination of a pair of terminal cisternae plus a T tubule; bound tightly together but their fluid contents are separate and distinct

Front 33

Sarcomeres

Back 33

myofilaments organized into repeating functional units; smallest functional units of the muscle fiber. Interactions between thick and thin filaments contained are responsible for muscle contractions.

Front 34

Sarcomeres contain

Back 34

thick filaments, thin filaments, proteins that stabilize the positions of the thick and thin filaments, and proteins that regulate the interactions between thick and thin filaments

Front 35

A bands

Back 35

Ansiotropic, Dark bands within a sarcomere

Front 36

I bands

Back 36

Isotropic, light bands within a sarcomere

Front 37

M line

Back 37

in the center of the A band; proteins within it connect with the central portion of each thick filaments to neighboring thick filaments. These dark staining proteins help stabilize the positions of the thick filaments

Front 38

H band

Back 38

A band; lighter region on either side of the M line, in a resting sarcomere. Contains thick filaments, but no thin filaments

Front 39

zone of overlap

Back 39

A band; A dark region where thin filaments are located between the thick filaments. Here three thick filaments surround each thin filament, and six thin filaments surround each thick filament.

Front 40

Z lines

Back 40

I band; bisect the I bands and mark the boundary between adjacent sarcomeres. Consist of proteins called actinins which interconnect with thin filaments of adjacent sarcomeres

Front 41

Titin

Back 41

I band, strand of elastic protein which extend from the tips of the thick filaments to attachment sites at the Z line. Helps keep thick and thin filaments in proper alignment and aids in restoring resting sarcomere length after contraction; also helps muscle fiber resist extreme stretching that would otherwise disrupt the contraction mechanism

Front 42

Filamentous actin, F-actin

Back 42

is a twisted strand composed of two rows of 300-400 individual globular molecules of G-actin

Front 43

nebulin

Back 43

Long strand extends along the F-actin strand in the cleft between the rows of G-actin molecules; hold F-actin strand together

Front 44

Active site

Back 44

Contained within each G-actin. Where myosin can bind. Under resting conditions, however, the troponin-tropomyosin complex prevents myosin binding

Front 45

Tropomyosin

Back 45

Strands which cover the active sites on G-actin and prevent actin-myosin interaction. It is a double stranded protein that covers seven active sites and it is bound to one molecule of troponin midway along its length

Front 46

troponin

Back 46

molecule consists of three globular subunits. One subunit binds to tropomyosin, locking them together as a troponin-tropomyosin complex, and a second subunit binds to one G-actin, holding the troponin-tropomyosin complex in position. The third subunit has a receptor that binds two calcium ions.

Front 47

cross-bridges

Back 47

When the myosin head interact with thin filaments during a contraction

Front 48

sliding filament theory

Back 48

The H bands and I bands of the sarcomeres narrow, the zones of overlap widen, the Z lines move closer together, and the width of the A band remains constant. These observation only make sense if the thin filaments are sliding toward the center of each sarcomere, alongside the thick filaments

Front 49

polarized

Back 49

unequal charge distribution among cells

Front 50

depolarization

Back 50

An influx of sodium ions which makes the membrane potential less negative

Front 51

hyperpolarization

Back 51

Movement of potassium ions out of a cell as the membrane potential becomes more negative

Front 52

repolarization

Back 52

A return to the resting potential

Front 53

Excitable membranes

Back 53

Permit rapid communication between different parts of a cell. Contain voltage-gated channels that are activated and inactivated by changes in the membrane potential

Front 54

Neuromuscular Junction (NMJ)

Back 54

The synapse when communication is between a neuron and a skeletal muscle fiber. It is made up of an axon terminal (synaptic terminal) of a neuron, a specialized region called the motor end plate, and, in between, a narrow space called the synaptic cleft.

Front 55

excitation contraction coupling

Back 55

The link between the generation of an action potential in the sarcolemma and the start of a muscle contraction. This coupling occurs at the triads

Front 56

The Contraction Cycle and Cross-Bridge Formation

Back 56

Series of molecular events that enable muscle contraction. First, active sites are exposed and the energized myosin head bind to them forming cross bridges. Second, myosin head pivots toward M lin (powerstroke), ADP and P release. Third, link between active site and actin molecule is broken. Fourth, free myosin head splits ATP into ADP and P, myosin head is recocked.

Front 57

Tetanus

Back 57

Disease caused by infection by bacterium Clostridium tetani. Symptoms include: headache, muscle stiffness, and difficulty swallowing. Prevention is getting the immunization. However, an antitoxin can be administered to an unimmunized individual.

Front 58

Relaxation

Back 58

Factors determining how long a contraction lasts include: period of stimulation at the neuromuscular junction, presence of free Ca2+ in cytosol and availability of ATP.

Front 59

Rigor Mortis

Back 59

Death brings about ceasing circulation and skeletal muscles are deprived of nutrients and oxygen. Lack of ATP lead to muscles locking in contracted position.

Front 60

Twitch

Back 60

A single stimulus-contraction-relaxation sequence in a muscle fiber. A single twitch can be divided into a Latent period, Contraction phase, and Relaxation phase.

Front 61

Latent period

Back 61

Period in a twitch where action potential sweeps across the sarcolemma, and the SR releases Ca2+

Front 62

Contraction phase

Back 62

Phase in a twitch where Tension increases, Ca2+ are binding to troponin, active sites on thin filaments are being exposed and cross-bridge interaction are occurring.

Front 63

Relaxation phase

Back 63

Phase in a twitch where Ca2+ levels are decreasing, active sites are being covered by tropomyosin, and the number of active cross-bridges is declining as they detach. As a result, tension decreases to resting levels.

Front 64

Wave Summation

Back 64

Occurs when successive stimuli arrive before the relaxation phase has been completed

Front 65

Motor Unit

Back 65

All the muscle fibers controlled by a single motor neuron

Front 66

Recruitment

Back 66

The smooth but steady increase in muscular tension produced by increasing the number of active motor units. Muscle contraction begins with activation of small motor units. If more tension is needed, larger muscle units are activated.

Front 67

muscle tone

Back 67

The resting tension in a skeletal muscle. Lack of it results in lack of movement.

Front 68

Isotonic Contraction

Back 68

Tension increases and the skeletal muscle's length changes. Ex: lifting an object off a desk, walking, and running

Front 69

Isometric Contraction

Back 69

The muscle as a whole does not change length, and the tension produced never exceeds the load. Ex: carrying a bag of groceries, holding our heads up.

Front 70

Creatine Phosphate

Back 70

High energy compound created from ATP and creatine. ATP + creatine --> ADP +___________

Front 71

Glycolysis

Back 71

An anaerobic breakdown of glucose to pyruvate in the cytoplasm of a cell

Front 72

Anaerobic process

Back 72

Do not require oxygen; ex: glycolysis

Front 73

Aerobic metabolism

Back 73

Normally provides 95% or the ATP demands of a resting cell. In this process, mitochondria absorb oxygen, ADP, phosphate ions, and organic substrates (such as pyruvate) from the surrounding cytoplasm. Ex: citric acid cycle

Front 74

Muscle fatique

Back 74

When a skeletal muscle can no longer perform at the required level of activity. Has been correlated with: depletion of metabolic reserves within the muscle fibers, damage to the sarcolemma and sarcoplasmic reticulum, a decline in pH within the muscle fibers and the muscle as a whole, and a sense of weariness and a reduction in the desire to continue the activity due to the effects of low blood pH and the sensations of pain

Front 75

Recovery Period

Back 75

conditions in muscle fibers are returned to normal, pre-exertion levels

Front 76

Oxygen Debt/Excess Postexercise Oxygen Consumption (EPOC)

Back 76

The amount of oxygen required to restore normal, pre-exertion conditions. The more ATP require, the more oxygen will be needed.

Front 77

Hypertrophy

Back 77

The enlargement of a stimulated muscle. The number of muscle fibers does not change significantly but the muscle as a whole enlarges because each muscle fiber increases in diameter.

Front 78

Atrophy

Back 78

Reduction in muscle size, tone, and power. Skeletal muscles not regularly stimulated by a motor neuron loses muscle tone and mass, they become flaccid, and the muscle fibers become smaller and weaker.