Bio 22 Lecture Exam

Front 1

skeletal ( location, function, appearance, control)

Back 1

skeleton, move bone, multi nucleated and striated, voluntary.

Front 2

Cardiac

Back 2

heart, pump blood, one nucleus striated and intercalated discs, involuntary

Front 3

Smooth muscle (visceral)

Back 3

various organs ex. GI, various functions ex. peristalsis, one nucleus and no striations

Front 4

Epimysium

Back 4

outer layer encircling the entire muscle

Front 5

Perimysium

Back 5

surrounds groups of 10 to 100 muscle fibers separating them into bundles called fascicles

Front 6

Endomysium:

Back 6

penetrates the interior of each fascicle and separates individual muscle fibers from one another

Front 7

Sarcolemma

Back 7

the plasma membrane of a muscle cell

Front 8

Sarcoplasm:

Back 8

the muscle cell cytoplasm and contains a large amount of glycogen for energy production and myoglobin for oxygen storage.

Front 9

Transverse tubules

Back 9

tiny invaginations of the sarcolemma that quickly spread the muscle action potential to all parts of the muscle fiber

Front 10

Sarcoplasmic reticulum:

Back 10

encircles each myofibril and is like the smooth endoplasmic reticulum in non-muscle cells and in the relaxed muscle. It functions to store calcium ions

Front 11

Myofibril:

Back 11

Threadlike structures extending longitudinally through a muscle fiber consisting mainly of thick filaments (myosin) and thin filaments (actin, troponin, and tropomyosin).

Hint 11

Within myofibrils are smaller protein structures:

Front 12

Actin:

Back 12

thin filaments

Hint 12

Within myofibrils are smaller protein structures:

Front 13

Myosin:

Back 13

thick filaments

Hint 13

Within myofibrils are smaller protein structures:

Front 14

Why are Sarcomeres and z discs important?

?

Back 14

Sarcomeres are the basic functional units of a myofibril. Z discs are regions of dense protein that separate

Front 15

The Arrangement of a Sarcomere

Back 15

Two actin filaments overlap one myosin filament and are both involved in the contractile processFilaments are arranged in compartments called sarcomeres

Front 16

Z dics

Back 16

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

Front 17

A band

Back 17

Dark, middle part sarcomere that extends entire length of thick filaments and includes those parts of thin filaments that overlap thick filaments

Front 18

I band

Back 18

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

Front 19

H zone

Back 19

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

Front 20

M line

Back 20

region in center of H zone that contains proteins that hold thick filaments together at center of Sarcomere

Front 21

Contractile

Back 21

MyosinActin

Hint 21

Muscle proteins. Myofibrils are built from three types of protein

Front 22

Regulatory

Back 22

TroponinTropomyosin

Hint 22

Muscle proteins. Myofibrils are built from three types of protein

Front 23

Structural

Back 23

TitinNebulinAlpha-actinMyomesinDystrophin

Hint 23

Muscle proteins. Myofibrils are built from three types of protein

Front 24

Thick filaments

Back 24

are mostly myosin and function as a motor proteins that pull various cellular structures to achieve movement

Hint 24

Muscle proteins: contractile

Front 25

Thin filaments

Back 25

are mostly actin twisted into a helix with a binding site for myosin Troponin and Tropomyosin are regulatory proteins that block the myosin binding site in a relaxed state

Hint 25

muscle proteins: contractile

Front 26

The sliding filament mechanism

Back 26

During muscle contraction, myosin cross bridges pull on actin filaments, causing the thin filament to slide inwardConsequently, Z discs move toward each other and the sarcomere shortens Myosin and Actin do not change in lengthThanks to the structural proteins, there is a transmission of force throughout the entire muscle, resulting in whole muscle contraction

Front 27

The Contraction Cycle: ATP Hydrolysis

Back 27

myosin heads hydrolyze ATP and become reoriented and energized

Front 28

The Contraction Cycle : attachment

Back 28

myosin heads bind to actin, forming cross-bridges

Front 29

The Contraction Cycle: power stroke

Back 29

myosin cross-bridges rotate towards center of Sarcomere

Front 30

The Contraction Cycle: detachment

Back 30

as myosin heads bind ATP the cross-bridges detach from actin

Front 31

ATP hydrolysis:

Back 31

Myosin head includes an ATP-binding site and an ATPase, an enzyme that hydrolyzes ATP into ADP (adenosine diphosphate) and a phosphate group.

This hydrolysis reaction reorients and energizes the myosin head.

Front 32

Attachment of myosin to actin to form cross-bridges

Back 32

Myosin head attaches to the myosin-binding site on actin and releases the previously hydrolyzed phosphate group (formation of cross-bridges)

Front 33

Power stroke:

Back 33

During the power stroke, the site on the cross-bridge where ADP is still bound opens the cross-bridge rotates and releases the ADP

The cross-bridge generates force as it rotates toward the center of the sarcomere, sliding the thin filament past the thick filament toward the M line.

Front 34

Detachment of myosin from actin.

Back 34

The cross-bridge remains firmly attached to actin until it binds another molecule of ATP.As ATP binds to the ATP-binding site on the myosin head, the myosin head detaches from actin.

Front 35

Excitation-Contraction Coupling

Back 35

This concept connects the events of a muscle action potential with the sliding filament mechanism

Front 36

Excitation-Contraction Coupling 2

Back 36

Increase in intracellular Ca2+ starts the contractionAs a muscle action potential propagates along the sarcolemma and into the T tubules, it causes Ca2+ release channels in the SR membrane to open

Front 37

Excitation-Contraction Coupling 3

Back 37

Ca2+ increase occurs because of release from the SR The released calcium ions combine with troponin, causing it to change shape (contraction cycle begins).

Front 38

Excitation-Contraction Coupling 4

Back 38

Ca2+ active transport pumps that use ATP to move Ca2+ constantly from the sarcoplasm into the SR

Front 39

Calesequestrin

Back 39

is a calcium binding protein that helps concentrate the Ca2+ near the site for release for the sarcoplasmic reticulum

Front 40

The Neuromuscular Junction (NMJ) The events at the NMJ produce a muscle action potential:1

Back 40

Voltage-gated calcium channels open resulting in an influx of calcium.

Hint 40

5 steps

Front 41

The Neuromuscular Junction (NMJ)The events at the NMJ produce a muscle action potential: 2

Back 41

This causes exocytosis of neurotransmitter (NT) into the synaptic cleft (Acetylcholine).

Front 42

The Neuromuscular Junction (NMJ)The events at the NMJ produce a muscle action potential: 3

Back 42

NT binds to ligand-gated Na+ channels on the motor endplate which cause an influx of Na+ into the muscle.

Front 43

The Neuromuscular Junction (NMJ)The events at the NMJ produce a muscle action potential: 4

Back 43

This depolarizes it and results in Ca2+ release from the SR

Front 44

The Neuromuscular Junction (NMJ)The events at the NMJ produce a muscle action potential: 5

Back 44

Acetylcholine gets broken down by acetylcholinesterase

Front 45

Muscle Metabolism

Creatine phosphate:

Back 45

First energy source when muscle contraction begins (first 15 seconds)Excess ATP is used to synthesize creatine phosphate which is used to quickly generate ATP through phosphorylation of ADP

Hint 45

How do muscles derive the ATP necessary to power the contraction cycle?

Front 46

Muscle Metabolism

Anaerobic glycolysis:

Back 46

Partial catabolism of glucose to generate ATP occurs in anaerobic cellular respiration Lactic acid is produced and diffuses into bloodThis system can provide enough energy for about 30-40 seconds of maximal muscle activity

Hint 46

How do muscles derive the ATP necessary to power the contraction cycle?

Front 47

Muscle Metabolism

Cellular respiration:

Back 47

Aerobic respiration supplies enough ATP for muscles during periods of rest or light to moderate exercise provided enough oxygen and nutrients are availableIn activities that last from several minutes to an hour or more, aerobic respiration provides nearly all the needed ATP

Hint 47

How do muscles derive the ATP necessary to power the contraction cycle?

Front 48

Muscle Fatigue

Back 48

Due to: Inadequate release of Ca2+ from SR

Depletion of CP, oxygen, and nutrients

Build up of lactic acid and ADP

Insufficient release of ACh at NMJ

Hint 48

The inability to maintain force of contraction after prolonged activity

Front 49

Oxygen Consumption After Exercise

Oxygen debt:

Back 49

extra oxygen used to pay back or restore metabolic conditions in three ways

Hint 49

Why do you continue to breathe heavily for a period of time after stopping exercise?

Front 50

Oxygen Consumption After Exercise

Back 50

1. Replenish CP stores and ATP in muscle fibers2. Convert lactic acid into pyruvate and glycogen stores in the liver3. Reload O2 onto myoglobin

Hint 50

Why do you continue to breathe heavily for a period of time after stopping exercise? 3 steps

Front 51

Factors that Influence Muscle Tension

Back 51

Amount of tension produced depends on:1. Sarcomere length2. Frequency of stimulation (number of impulses per second)3. Motor unit size Recruitment of motor units

Hint 51

More tension = generates contraction

Front 52

Length-Tension Relationship

Back 52

The force of a muscle contraction depends on the length of the sarcomeres prior to the contraction

Front 53

Length-Tension Relationship

Back 53

At a sarcomere length of about 2.0–2.4: Zone of overlap is optimal Muscle fiber can develop maximum tension

As the sarcomeres of a muscle fiber are stretched to a longer length:Zone of overlap shortensthe tension the fiber can produce decreases

Front 54

Isotonic contraction:

Back 54

tension is constant while the muscle changes lengthUsed for body movements and for moving objectsConcentric isotonic contraction – when the length of the muscle shortens and the object is moved Eccentric isotonic contraction – when the length of the muscle increases or lengthens during contraction

Front 55

Isometric contraction:

Back 55

muscle contracts but does not change in lengthImportant in maintaining body posture and position

Front 56

Skeletal Muscle Fiber Types

Back 56

Differ in composition, function, myoglobin content, speed of contraction and relaxation, metabolic reactions for ATP generation and how quickly they fatigueSlow oxidative: Small, dark red, fatigue resistantFast oxidative glycolytic: Intermediate size, dark red, moderately resistant to fatigueFast glycolytic: low resistance to fatigue

Front 57

Cardiac Muscle

Back 57

Cardiac muscle has the same arrangement as skeletal muscle but also:Intercalated discs – contain desmosomes and gap junctions that allow muscle action potentials to spread from one muscle fiber to anotherContractions last 10 - 15 times longer than skeletal muscle Mitochondria are larger and more numerousStimulated by own autorhythmic muscle fibers

Front 58

Smooth Muscle

Back 58

Smooth muscle contractions start more slowly and last longer than skeletal and cardiac muscle contractionsSmooth muscle can shorten and stretch to a greater extentUsually activated involuntarily

Front 59

Smooth Muscle: Single unit (visceral):

Back 59

more common and contract as one single unit, similar to cardiac muscle (autorhythmic)

Front 60

Smooth Muscle: Multi-unit:

Back 60

consists of individual fibers that contract independently