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BIOL 251 - A&P 1 > Ch 9 - Muscles & Muscle Tissue > Flashcards

Ch 9 - Muscles & Muscle Tissue Flashcards

1
Q

Functions of Muscle Tissue

A

1) Movement
2) Body posture & body position
3) Joint stability
4) Maintaining body temperature

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2
Q

Muscle Characteristics

A

1) Excitability - Generate action potentials in response to stimulus
2) Contractility - Muscle cells shorten when they contract
3) Exensibility - Muscles cells can lengthen/stretch
4) Elasticity - Healthy muscle cells return to their original shape

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3
Q

Types of Muscle Tissue

A

1) Skeletal muscle tissue
2) Smooth muscle tissue
3) Cardiac muscle tissue

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4
Q

Muscle tissue identification

Voluntary muscle tissue, striated

A

Skeletal muscle tissue
Creates most force, but needs most rest, adaptable

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5
Q

Muscle tissue identification

Involuntary muscle tissue, not striated

A

Smooth muscle tissue
moves fluid through body
uninucleate

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6
Q

Muscle tissue identification

Involuntary muscle tissue, striated

A

Cardiac muscle tissue
moves blood through the body (rate set by pacemaker cells)
uninucleate

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7
Q

Innervation & Vascularization of Skeletal Muscle

A

Innervation: each muscle fiber synapses with 1 motor nerve, can be served by multiple motor neurons
Vascularizaton: each muscle recieves 1 artery, 1+ vein (bring in nutrients, remove waste)

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8
Q

Connective Tissue Sheaths of Muscle Tissue

A

1) Endomysium: innermost layer (ind. muscle fibers; called myocytes)
2) Perimysium: middle layer (grouped muscle fibers - form fascicles)
3) Epimysium: outermost layer (entire muscle)

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9
Q

Individual muscle fiber/cell is called

A

myocyte

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10
Q

Groups of muscle fibers joined by perimysium

A

fascicles

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11
Q

Skeletal Muscle Attachment Types

A

Direct: epimysium of muscle fuses directly to bone/cartilage
Indirect: involves tendons

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12
Q

Skeletal Muscle Attachment Points

A

1) Origin: where the muscle attaches to a less movable bone (always proximal)
2) Insertion: where the muscle attaches to a movable bone (always distal)

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13
Q

Plasma membrane of muscle fiber

A

Sarcolemma

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14
Q

Cytoplasm of muscle fiber

A

Sarcoplasm

Contains high numbers of
A) Glycosomes (glycogen organelle)
B) Myoglobin (oxygen organelle)

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15
Q

Protein filaments in muscle tissue (& types)

A

Myofilaments
1) Myosin - thick filament
2) Actin - thin filament

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16
Q

Thick filament of muscle tissue

A

Myosin
has 2 heavy chains, with myosin head found at end of each chain

Myosin head used to link two types of myofilaments during contraction

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17
Q

Binding sites of myosin

A

2 total;
1 for ATP
1 for actin

Myosin head used to link two types of myofilaments during contraction

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18
Q

Thin filament of muscle tissue

A

Actin
Chains of G actin proteins with myosin binding sites

Myosin head binds to myosin binding site of actin during muscle contraction

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19
Q

Actin regulatory proteins

A

1) Tropomyosin: arranged along length; blocks myosin binding sites when muscle is relaxed
2) Troponin: globular protein; binds tropomyosin to position it on the actin filament

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20
Q

Rod-like organelles inside muscle cells that create striations

A

Myofibrils
Made up of bands of actin & myosin

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21
Q

Myofibril bands

A

1) A band: region of myofibril where actin and myosin filaments overlap
2) I band: region of myofibril with only actin filaments (z disc at center holds actin filaments in place)

22
Q

Region of myofibril where actin and myosin filaments overlap

A

A band

23
Q

Region of myofibril with only actin filaments

A

I band

24
Q

Center of I band, which holds the actin filaments in place

A

Z disc

25
Q

Region of a myofibril found between neighboring Z discs

A

Sarcomere - the smallest contractile unit of skeletal muscle tissue

26
Q

Extensions of the sarcolemma that wrap around deeper myofibrils

A

T-Tubules - increase surface area of sarcolemma

importance: changes in membrane potentia can reach myofibrils that are not in direct contact with sarcolemma

27
Q

Organelle that wraps around myofibrils

A

Sarcoplasmic reticulum - stores and releases Ca2+ for muscle contraction & relaxation

: : Form terminal cisterns around T-tubules; action potentials travel down T-tubules to stimulate release of Ca2+

28
Q

Site of synapse between a somatic motor neuron and a muscle fiber

A

Neuromuscular Junction
ACh released

29
Q

Steps for muscle fiber stimulation to occur

A

1) Neuromuscular junction ACh release
2) Generation of EPP & action potential across sacrolemma- ACh opens ion channels to generate an End Plate Potential (graded potential) - depolarizing
3) Excitation-Contraction Coupling - occurs when action potential spreads from sarcolemma to T-tubules
4) Cross Bridge Formation & Muscle Contraction - attachment of myosin to actin

30
Q

Process of Cross Bridge Formation

A

a) Ca2+ binds troponin - troponin changes shape
b) Change in troponin shape - tropomysin rolls to the side
c) When tropomyosin is moved - myosin binding site on actin is exposed
d) Myosin head splits APT into ADP + P (allows myosin head to bind to actin)
e) ADP + P is released from myosin head, causing the myosin head to change shape & bend (pulls actin fillament toward center of sarcomere - called power stroke)
f) Myosin head binds to another ATP - myosin head detaches from actin binding site

Need to write out!!

31
Q

How does the cross-bridge formation end

A
  • Motor impulses no longer sent to muscle fiber
  • Ca2+ is returned to sarcoplasmic reticulum
  • When Ca2+ levels in sarcoplasm drop, it can no longer bind to troponin
  • Troponin returns to original shape; tropomyosin covers actin binding sites again
32
Q

How does the sliding filament model of contraction work?

A

Myosin heads “slide” thin filaments toward the center of the sarcomere, shortening the sarcomere without changing length of filaments

33
Q

Definition

Motor unit

A

A single motor neuron and all the muscle fibers it innervates

34
Q

Rules of a motor unit

A

1) when the motor unit fires, all fibers it innervates will contract (can be spread out in muscle)
2) number of muscle fibers a motor neuron innervates influences movement

35
Q

Muscle contraction that is modified by the nervous system to produce varying amounts of force

A

Graded Muscle Contractions:
1) Temporal summation - increasing frequency of stimulation
2) Motor unit summation - increasing the number of motor units used

36
Q

Types of temporal summation:

A

1) Unfused (incomplete) tetanus - muscle fiber has very little time to relax before next stimulus
2) Fused (complete) tetanus - no relaxation occurs in the muscle fiber (contractions from individual stimuli fuse into one contraction)

37
Q

Increasing muscle force by increasing the number of motor units used during contraction

A

Motor unit summation
Motor units recruited asynchronously, with a size principal - motor units w/ smallest muscle fibers recruited first, increases incrementally

38
Q

Muscle tone

A

Relaxed muscles are always slightly contracted - called muscle tone

Does not produce movememt, keeps tissue healthy and responsive, stabilizes joints, maintains posture

39
Q

Types of Muscle Contraction

A

1) Isotonic Contraction: muscle tension develops to overcome the load & muscle shortening occurs
2) Isometric Contraction: tension develops in a muscle, but the length of the muscle does not change

40
Q

Types of Isotonic Contraction

A

1) Concentric contraction: muscle shortens and does work
2) Eccentric contraction: muscle lengthens while under tension

41
Q

How does Isometric Contraction work?

A

Cross bridge formation still occurs, but the sarcomeres do not shorten

42
Q

How is ATP used/generated in Muscle Contraction

A

Attaches to Myosin to allow binding, will only produce the amount of ATP as needed

43
Q

Pathways for ATP Regeneration

A

1) Direct phosphorylation
2) Anaerobic pathways
3) Aerobic pathways

44
Q

Direct Phosphorylation Reaction

A

Creates ATP using creatine phosphate (CP) via criatine kinase - 1 ATP per CP molecule
Whole process supplies ~15s worth of ATP

Does not require oxygen

45
Q

Anaerobic Pathway: Glycolysis

A

Glucose broken down to form 2 ATP & pyruvic acid and converted to lactic acid

Creatine phosphate and glycolysis provide ~1 minute of ATP

46
Q

Benefits and Drawbacks of Anaerobic Pathway

A

Benefits: does not require oxygen, produces ATP quickly
Drawbacks: low ATP yeild (2 ATP per glucose) lactic acid build-up MIGHT cause muscle fatige or soreness

47
Q

Aerobic Pathway:
Cellular Respiration

A

Produces 30-32 ATP per glucose, ~95% of ATP used by muscle during rest and light-to-moderate long-term exercise

48
Q

Benefits and Drawbacks of
Cellular Respiration

A

Benefits: produces 30-32 ATP
Drawbacks: slow, requires mitochondria, constant O2 and glucose

49
Q

When muscle is physiologically incapable of contracting

A

Muscle Fatigue - rate & duration depends on activity
High intensity = quicker rate, lower duration, vice versa

50
Q

Factors that affect speed of contraction

A

1) How fast ATP is split - how fast cross bridges can form & break
2) Electrical activity of motor neurons - fast neurons = fast connections
3) Pathway of ATP production

51
Q

Types of Muscle Fibers (velocity and duration)

A

1) Fast glycolytic fibers - contract quickly, use anaerobic pathways (high glycogen, low myoglobin/mitochondria/blood)
2) Fast oxidative fibers - contract quickly, use aerobic pathways (some glycogen, lots of myoglobin/mitochondria/blood)
3) Slow oxidative fibers - contract slowly, use aerobic pathways (low glycogen, high myoglobin, lots of mitochondria/blood)

52
Q

Gross anatomy of smooth muscle tissue

A

2 layers of smooth muscle that never contract simultaneously:
1) Longitudinal layer along the length of the organ (widening)
2) Circular layer muscle fiber runs the circumference of the organ (narrowing)

BIOL 251 - A&P 1 (15 decks)

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