Ap 1 - Ch 10 - Muscle Tissue

Front 1

Name the 3 types of muscle tissue and whether they are (striated/non-striated) and (voluntary/involuntary).

Back 1

Skeletal (striated, voluntary). Cardiac (striated, involuntary). Smooth (nonstriated, involuntary).

Front 2

The heart has a pacemaker that initiates each contraction. This built-in rhythm is termed ___.

Back 2

Autorhythmicity

Front 3

What are the 4 functions of muscular tissue?

Back 3

1) Produce body movements. 2) Stabilize posture 3) Store/move substances within body. 4) Generate heat.

Front 4

Storage in the body is accomplished by sustained contractions of ringlike bands of smooth mm. called ___ which prevent outflow of contents of a hollow organ.

Back 4

Sphincter

Front 5

Process where heat is produced by muscular contraction.

Back 5

Thermogenesis

Front 6

What are 4 special properties of muscular tissue?

Back 6

1) Electrical excitability 2) Contractility 3) Extensibility 4) Elasticity

Front 7

What are the 2 main types of stimuli that trigger action potentials in muscle cells?

Back 7

1) Autorhythmic electrical signals from mm. Itself. 2) Chemical neurotransmitters, hormones, etc. from other sources.

Front 8

A muscle cell is also known as a ___.

Back 8

Muscle fiber

Front 9

Connective tissue layer separating muscle from skin, composed of areolar + adipose connective tissue.

Back 9

Subcutaneous layer (or hypodermis)

Front 10

Broad band of dense irregular connective tissue that lines the body wall and limbs, supports, surrounds muscles and other organs.

Back 10

Fascia

Front 11

Outermost layer of dense irregular connective tissue encircling entire muscle.

Back 11

Epimysium

Front 12

Layer of dense irregular connective tissue surrounding groups of 10-100+ muscle fibers, separating them into bundles called ___.

Back 12

Perimysium. Fascicles.

Front 13

Thin layer of areolar connective tissue separating individual muscle fibers from one another.

Back 13

Endomysium

Front 14

Cord of dense regular connective tissue composed of parallel bundles of collagen fibers that attach a muscle to the periosteum of bone.

Back 14

Tendon

Front 15

What 3 connective tissue layers form a tendon?

Back 15

Epimysium, perimysium, endomysium

Front 16

Tendon extending as a broad, flat layer.

Back 16

Aponeurosis

Front 17

Tubes of fibrous connective tissue that enclose certain tendons. Consists of a visceral + parietal layer, synovial fluid. Reduce friction.

Back 17

Tendon (synovial) sheath

Front 18

Neurons that stimulate skeletal muscle contractions are called ___.

Back 18

Somatic motor neurons

Front 19

Muscles are well supplied with nerves & blood vessels. Capillaries bring in ___, ___ and remove ___, ___ from muscle metabolism.

Back 19

Capillaries bring in oxygen, nutrients & remove heat and waste.

Front 20

Why are muscle fibers multinucleated?

Back 20

Because muscle fibers are derived from the fusion of many myoblasts during embryonic development.

Front 21

Enlargement of existing muscle fibers that occurs after birth.

Back 21

Hypertrophy

Front 22

Increase in number of muscle fibers.

Back 22

Hyperplasia

Front 23

Small number of myoblasts found in mature skeletal muscle are known as ___. Can fuse with one another or with damaged muscle fibers for repair.

Back 23

Satellite cells

Front 24

Process of replacement of muscle fibers by fibrous scar tissue.

Back 24

Fibrosis

Front 25

Plasma membrane of a muscle cell

Back 25

Sarcolemma

Front 26

Invaginations of sarcolemma that tunnel from surface to center of muscle fiber filled with interstitial fluid.

Back 26

Transverse tubule

Front 27

How do transverse tubules affect action potentials within a muscle fiber?

Back 27

Action potentials travel along sarcolemma through T tubules, quickly spreading throughout muscle fiber. T tubules ensure that action potential excites all parts of muscle fiber at same time.

Front 28

Cytoplasm of muscle fiber.

Back 28

Sarcoplasm

Front 29

What organic compound is largely found in the sarcoplasm for ATP synthesis?

Back 29

Glycogen

Front 30

Red-colored protein found only in muscle that binds oxygen diffused into muscle fiber from interstitial fluid. It releases oxygen when needed by mitochondria for ATP production.

Back 30

Myoglobin

Front 31

Contractile organelles of skeletal muscle.

Back 31

Myofibril

Front 32

Fluid-filled sacs encircling each myofibril (similar to smooth ER) that stores Ca2+ ions which trigger muscle contraction.

Back 32

Sarcoplasmic reticulum

Front 33

Area of sarcoplasmic reticulum that touches transverse tubule from both sides.

Back 33

Terminal cisterns

Front 34

What 3 structures form the triad?

Back 34

1 transverse tubule, 2 terminal cisterns

Front 35

Condition of muscles wasting away.

Back 35

Muscular atrophy

Front 36

Basic functional unit of a myofibril composed of thick and thin filaments.

Back 36

Sarcomere

Front 37

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

Back 37

M line

Front 38

Narrow region in center of A band of sarcomere that contains thick filaments but no thin filaments.

Back 38

H zone

Front 39

Lighter, less dense area of sarcomere that contains thin filaments but no thick filaments. A Z disc passes through the center of this band.

Back 39

I band

Front 40

Dark, middle part of sarcomere that extends entire length of thick filament and includes zone of overlap with thin filaments.

Back 40

A band

Front 41

Narrow region of dense material that separates 1 sarcomere from the next.

Back 41

Z discs

Front 42

What are the 3 classes of proteins that build myofibrils and what 2 proteins fall in each category?

Back 42

Contractile (generate force) - actin/myosin. Regulatory (switch contraction on/off) - troponin/tropomyosin. Structural (align filaments, provide elasticity/extensibility, link myofibrils to sarcolemma) - titin/dystrophin.

Front 43

Contractile protein that makes up thick filament. Consists of tail and 2 heads that bind to actin thin filament during muscle contraction.

Back 43

Myosin

Front 44

Contractile protein that makes up thin filament. Contains a binding site for myosin head of thick filament during contraction.

Back 44

Actin

Front 45

Regulatory protein that is component of thin filament. When skeletal muscle is relaxed, it covers the binding site on actin filament and prevents myosin from binding to actin.

Back 45

Tropomyosin

Front 46

Regulatory protein that is component of thin filament. When calcium ions bind to this protein, it changes shape and moves tropomyosin away from binding site on actin molecules, beginning muscle contraction as actin binds to myosin.

Back 46

Troponin

Front 47

Structural protein that connects Z disc to M line of sarcomere, helping to stabilize position of thick filament. Because it can stretch and spring back unharmed, it accounts for elasticity & extensibility of myofibrils.

Back 47

Titin

Front 48

Structural protein that links thin filaments of sarcomere to integral membrane proteins of sarcolemma, which attach to proteins in connective tissue matrix. Reinforces sarcolemma and helps transmit tension from muscles to tendons.

Back 48

Dystrophin

Front 49

Which proteins connect into the Z disc? Which proteins are present in the A band? In the I band?

Back 49

Actin, titin anchor into Z disc. A bands contain myosin, actin, troponin, tropomyosin, titin. I band contains actin, troponin, tropomyosin, titin.

Front 50

At the onset of contraction, what organelle releases what substance into the muscle cell? What causes the myosin binding sites on actin to open?

Back 50

Sarcoplasmic reticulum releases calcium ions. Ca2+ binds to troponin which moves tropomyosin away from myosin-binding sites on actin.

Front 51

What are the 4 steps of the contraction cycle?

Back 51

1) ATP hydrolysis - ATP is broken down into ADP & phosphate by ATPase on the myosin head. Energy from hydrolysis reorients and energizes myosin head. 2) Myosin attaches to actin to form cross-bridges - Energy from hydrolysis causes myosin head to attach to myosin-binding site on actin & releases phosphate. 3) Power stroke - crossbridge rotates and releases ADP. Slides thin filament past thick filament toward M line. 4) Detachment of myosin from actin - ATP binds to myosin head and causes it to detach from actin.

Front 52

During full contraction, what happens to the H zone, Z line, I & A bands?

Back 52

H zone disappears, Z line moves closer together, I band shortens, A band stays the same.

Front 53

The process of an action potential spreading into T tubule to the sliding of filaments is called ___.

Back 53

Excitation-contraction coupling (aka sliding filament theory)

Front 54

Calcium-binding protein that enables many Ca2+ to be stored in sarcoplasmic reticulum. Concentration of Ca2+ is 10,000 higher in SR than in cytosol.

Back 54

Calsequestrin

Front 55

Each of the 600 crossbridges in one thick filament attaches and detaches about ___ times per second.

Back 55

5 times per second

Front 56

Condition where muscles are in a state of rigidity. Begins 3-4 hours after death and lasts 24 hrs. Caused by Ca2+ leakage into cytosol which allows myosin to bind to actin. Lack of ATP causes myosin to stay binded to actin.

Back 56

Rigor mortis

Front 57

In regards to the length-tension relationship in a skeletal muscle, why would tension decrease in a muscle fiber that is stretched to a longer length? Why would tension again decrease in a shorter than optimum length?

Back 57

In a longer than normal muscle fiber, the zone of overlap shortens so fewer myosin heads can make contact with actin to contract so tension is zero. In a shorter muscle fiber, thick filaments crumple as they are compressed by Z discs so fewer myosin heads bind with actin.

Front 58

The synapse between a somatic motor neuron and skeletal muscle fiber.

Back 58

Neuromuscular junction

Front 59

Region where communication occurs between 2 neurons, or between a neuron and target cell, ex. Muscle fiber.

Back 59

Synapse

Front 60

Small gap at synapse separating 2 cells.

Back 60

Synaptic cleft

Front 61

What happens to acetylcholine (Ach) after it binds with Ach receptor on the sarcolemma?

Back 61

It is broken down by enzyme acetylcholinerase into acetyl and choline so it cannot activate Ach receptor.

Front 62

List the events that lead to contraction and relaxation in a muscle fiber starting with the presynaptic end bulb.

Back 62

Action potential arrives at presynaptic end bulb and causes Ca2+ voltage-gated channels to open. Ca2+ flows inward and triggers release of synaptic vesicles containing neurotransmitter Acetylcholine via exocytosis. Ach binds to ligand-gated channels which opens Na+ ion channels and causes inflow of Na+. AchE destroys Ach in synaptic cleft. Na+ in muscle fiber triggers voltage-gated Ca2+ channels to open on sarcoplasmic reticulum and Ca2+ flow into sarcoplasm. Ca2+ binds to troponin and causes it to move tropomyosin so myosin binding sites are exposed. ATP is hydrolized into ADP + phosphate by ATPase on myosin head and released energy causes myosin head to bind to actin, forming crossbridge, and phosphate releases. Powerstroke is caused by ADP release which powers myosin to push actin towards M line (contraction). Ca2+ voltage-gated channels in SR close and Ca2+ active transport pumps use ATP to restore low levels of Ca2+ in sarcoplasm. Low Ca2+ restores troponin-tropomyosin complex which blocks myosin binding site. Muscle relaxes.

Front 63

Substance produced by bacteria that blocks exocytosis of NT at neuromuscular junction and causes paralysis.

Back 63

Botulinum toxin (Botox)

Front 64

Plant derivative that causes muscle paralysis by binding to and blocking Ach receptors so ion channels don't open.

Back 64

Curare

Front 65

Energy-rich molecule found only in muscle fibers synthesized from excess ATP.

Back 65

Creatine phosphate

Front 66

Creatine phosphate & ATP provide enough energy for muscles to contract maximally for (duration).

Back 66

15 seconds

Front 67

What is the role of creatine phosphate?

Back 67

Excess ATP causes an ATP molecule to donate 1 phosphate head to creatine, forming creatine phosphate and ADP. When contraction begins and ADP levels rise, creatine phosphate returns its phosphate to ADP so ATP is regenerated quickly while other ADP return to mitochondria for ATP regeneration.

Front 68

Series of ATP producing reactions that do not require oxygen.

Back 68

Anaerobic respiration

Front 69

What are the steps in anaerobic respiration? What duration of muscle activity does it provide?

Back 69

When creatine phosphate supply is depleted, glucose (from blood & storage in muscle fibers) is broken down in a process called glycolysis. This produces pyruvic acid + 2 ATP. If oxygen is present, pyruvic acid enters aerobic respiration pathway to produce more ATP. If no oxygen is present, anaerobic RNXs convert pyruvic acid into lactic acid which is carried away by blood. It provides 30-40 sec of muscle activity.

Front 70

Series of oxygen-requiring RXNs that produce ATP in mitochondria.

Back 70

Aerobic respiration

Front 71

What are the steps in aerobic respiration? What are the 2 sources of oxygen? What duration of muscle activity does it provide?

Back 71

Pyruvic acid enters mitochondria where it is oxidized in RXNs that generate ATP, carbon dioxide, H2O, heat. It's slower than anaerobic respiration but yields 36 ATP. Oxygen comes from hemoglobin in blood and myoglobin in muscle fibers (both are oxygen-binding proteins). Provides 90%+ of needed ATP in activities more than 10 mins.

Front 72

Inability of muscle to maintain force of contraction after prolonged activity.

Back 72

Muscle fatigue

Front 73

What are 6 factors that contribute to muscle fatigue?

Back 73

Inadequate release of Ca2+ from SR, depletion of creatine phosphate, insufficient oxygen, depletion of glycogen & other nutrients, buildup of lactic acid & ADP, failure of motor neuron to release enough Ach.

Front 74

The added oxygen that is taken into the body after exercise.

Back 74

Oxygen debt / Recovery oxygen uptake

Front 75

What are the 3 ways oxygen is used to restore muscle cells to the resting level after exercise?

Back 75

1) Convert lactic acid into glycogen. 2) Synthesize creatine phosphate & ATP. 3) Replace oxygen removed from myoglobin.

Front 76

The total tension a whole muscle can produce depends on ___.

Back 76

# of muscle fibers contracting in unison.

Front 77

Maximum tension is dependent on what 4 factors?

Back 77

1) Rate at which nerve impulses arrive. 2) Amount of stretch before contraction. 3) Nutrient & oxygen availability. 4) Size of motor unit.

Front 78

Complex consisting of somatic motor neuron plus all muscle fibers it stimulates.

Back 78

Motor unit

Front 79

Brief contraction of muscle fibers in a motor unit in response to an action potential lasting from 20 to 200 msec.

Back 79

Twitch contraction

Front 80

Brief delay between stimulus and muscular contraction when action potential sweeps over sarcolemma and Ca2+ is released from SR.

Back 80

Latent period

Front 81

Period where Ca2+ binds to troponin and crossbridges form.

Back 81

Contraction period

Front 82

Period where Ca2+ is actively transported back to SR, myosin binding sites are covered by tropomyosin, and myosin heads detach from actin.

Back 82

Relaxation period

Front 83

Period during muscle fiber contraction where it temporarily cannot respond to another action potential.

Back 83

Refractory period

Front 84

Stimuli arriving at different times causing larger contractions in muscle fiber.

Back 84

Wave summation

Front 85

What is the difference between unfused vs. fused tetanus?

Back 85

Unfused tetanus is a sustained but wavering contraction (it can partially relax between stimuli - 20-30x per sec). Fused tetanus is a sustained contraction in which individual twitches cannot be detected (80-100x per sec).

Front 86

The process in which the number of active motor units increases. What is this process responsible for?

Back 86

Motor unit recruitment is responsible for producing smooth movements rather than a series of jerks.

Front 87

Small amount of tension in muscle due to weak, involuntary contractions of motor units. Small groups of motor units are alternatively active and inactive in a constant pattern.

Back 87

Muscle tone

Front 88

State of limpness in which muscle tone is lost.

Back 88

Flaccid

Front 89

What is the difference between hypotonia vs. hypertonia? What is the difference between spasticity vs. rigidity?

Back 89

Hypotonia - decrease in muscle tone. Hypertonia - increase in muscle tone. Spasticity - increased muscle tone due to reflexes where as rigidity does not involve reflexes.

Front 90

Tension developed by muscle remaining almost constant while muscle changes in length is called ___.

Back 90

Isotonic contraction

Front 91

Type of contraction where muscle shortens to produce force and movement.

Back 91

Concentric isotonic contraction

Front 92

Type of contraction where muscle lengthens to produce force and movement.

Back 92

Eccentric isotonic contraction

Front 93

Type of contraction where no movement occurs. Tension is generated without muscle shortening.

Back 93

Isometric contraction

Front 94

Type of skeletal muscle fiber that has an increase in blood supply, oxygen, mitochondria, and is therefore aerobic, slow ATP production. Ex. Marathon runner. (red/white)

Back 94

Red fiber

Front 95

Type of skeletal muscle fiber that has less blood supply, oxygen, and is therefore anaerobic, quick ATP production. Ex. Sprinter. (red/white)

Back 95

White fiber

Front 96

Type of muscle fiber with abundant mitochondria and blood supply. Red. High ATP generation via aerobic respiration. Slow ATP hydrolysis, slow contraction, high fatigue resistance, low glycogen. Recruited first. Found in postural muscles ie. Neck. Function - maintain posture & aerobic endurance activities.

Back 96

Slow oxidative fibers

Front 97

Type of muscle fiber with abundant mitochondria and blood supply. Red-pink. Intermediate ATP generation via aerobic & anaerobic respiration (glycolysis). Fast ATP hydrolysis, fast contraction, medium fatigue resistance, intermediate supply glycogen. Recruited second. Found in lower limb mm. Function - walking, sprinting.

Back 97

Fast oxidative-glycolytic fibers

Front 98

Type of muscle fiber with few mitochondria and blood supply. White. Low ATP generation via anaerobic respiration (glycolysis). Fast ATP hydrolysis, fast contraction, low fatigue resistance, high glycogen. Recruited third. Found in upper limb mm. Function - rapid, intense movements of short duration.

Back 98

Fast glycolytic fibers

Front 99

List the skeletal muscle fibers in the order that they are recruited.

Back 99

SO, FOG, FG

Front 100

Irregular transverse thickenings of sarcolemma that connect ends of cardiac muscle fibers to eachother.

Back 100

Intercalated discs

Front 101

What 2 types of cell junctions are present in intercalated discs in cardiac muscle tissue? What type of connective tissue lining does it lack?

Back 101

Desmosomes (support), gap junctions (spread action potential). Lacks epimysium.

Front 102

Why do cardiac & smooth muscle contractions last longer than skeletal muscle contractions?

Back 102

In cardiac/smooth muscle fibers, Ca2+ enters sarcoplasm from sarcoplasmic reticulum (like skeletal muscle) and interstitial fluid. In cardiac mm, channels for Ca2+ from interstitial fluid stay open longer. In smooth muscle there are no transverse tubules so Ca2+ takes longer to reach all filaments.

Front 103

What is the difference between visceral single-unit smooth muscle tissue vs. multiunit smooth muscle tissue?

Back 103

Stimulation of 1 visceral muscle fiber causes contraction of many adjacent fibers. Stimulation of 1 multiunit fiber causes contraction of that fiber only.

Front 104

Smooth tissue lack transverse tubules & have low Ca2+ sarcoplasmic reticulum storage. Instead it has small pouchlike invaginations of the plasma membrane called ___ that contain extracellular Ca2+ for muscle contraction.

Back 104

Caveolae

Front 105

Structure in smooth mm similar to Z disc in striated muscle fiber. Thin/intermediate filaments attach to it.

Back 105

Dense bodies

Front 106

Process that allows smooth mm to undergo great changes in length while retaining ability to contract effectively.

Back 106

Stress-relaxation response

Front 107

Almost all muscle in the body is derived from what embryonic tissue?

Back 107

Mesoderm

Front 108

Why does muscle strength decrease with aging?

Back 108

With aging, muscle is replaced by connective & adipose tissue. Slow oxidative fibers appear to increase.

Front 109

What 3 types of stimuli trigger smooth muscle?

Back 109

Neurotransmitters, hormones, autorhythmic signals.

Front 110

Smooth muscle contract/relax in response to what 6 factors?

Back 110

Action potentials from ANS, stretching, hormones, changes in pH, oxygen/carbon dioxide levels.