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OSSF > Muscle (Physiology and Histology) > Flashcards

Muscle (Physiology and Histology) Flashcards

1
Q

What are the 3 types of muscle?

A

-Skeletal
-Cardiac
-Smooth

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2
Q

What are the features of skeletal muscle?

A

-Voluntary
-Striated
-Many nuclei on the periphery of the cell

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3
Q

What are the features of cardiac muscle?

A

-Nonvoluntary
-Striated
-Once centrally located nuclei
-smaller/shorter cells

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4
Q

What are the features of smooth muscle

A

-Involuntary
-Non striated
-one centrally located nucleus

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5
Q

What are the 4 functional characteristics of skeletal muscle?

A

-Excitability
-Contractility
-Extensibility
-Elasticity

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6
Q

Describe the structure of the sarcomere

A

the contractile unit of the myrofibril
-I band
-A band
-Z disc
-H zone
-M line

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7
Q

What is the sarcolemma?

A

The membrane of a muscle cell

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8
Q

Explain the sliding filament model of contraction

A

actin has myosin binding sites that are covered by tropomyosin which are held in place by troponin. Once Ca moves into the cell, troponin moves, allowing tropomyosin to move. Once ATP bind to the myosin, it can bind to actin. The power stroke occurs (contraction), once ATP bind to myosin again, it unbind actin.

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9
Q

Explain signal transmission at a neuromuscular (skeletal) junction

A

-Signal travels down axon
-Reaches motor end plate
-Acetylcholine vesicles release and bind to receptor on postsynaptic cell
-depolarizes cell
-signal travels down t tubule of postsynaptic cell
-activates DHPR, which activates RyR
-RyR opening allows Ca to flow out of SR into intracellular space
-Ca initiates troponin movement

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10
Q

What are the 7 problems that can occur at the neuromuscular junction?

A

-Synaptic fatigue
-Hypocalcemia
-Denervation hypersensitivity
-Botulinum toxin
-Alpha toxin
-Myasthenia gravis
-Nerve gas

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11
Q

What is titan?

A

the molecular spring of the sarcomere

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12
Q

What are the proteins that anchor titan to the M band?

A

Myomesin and M-protein

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13
Q

What is the major neurotransmitter of the peripheral nervous system?

A

Acetylcholine

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14
Q

What are the 3 phases of a muscle twitch?

A

-Latent
-Period of contraction
-Period of relaxation

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15
Q

What is the order of motor neuron recruitment?

A

-Motor 1: slow oxidative
-Motor 2: fast oxidative
-Motor 3: fast glycolytic

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16
Q

What is the term for complete contraction?

A

fused tetanus

17
Q

When does fused tetanus occur?

A

at complete contraction when ALL motor neurons are recruited

18
Q

What are the differences between smooth muscle and skeletal

A

-Dense bodies (similar to z discs) which connect to other cells
-No t tubules, instead the sarcolemma has calveoli
-No neuromuscular junction
-Can propagate signal through gap junctions

19
Q

What are calveoli?

A

invaginations of the smooth muscle sarcolemma that contain a high density of Ca channels

20
Q

How do neurotransmitters reach the postsynaptic cell of smooth muscle?

A

Multiple varicosities release neurotransmitter across a wide synaptic cleft

21
Q

What accounts for longer lasting contraction effects of smooth muscle?

A

alot of metabotropic receptors

22
Q

Define isotonic contraction

A

-Concentric/eccentric contraction

23
Q

Define isometric contraction

A

z discs stay in place but actin and myosin are bound

24
Q

Why are type I (slow oxidative) muscle fibers so dark?

A

They have alot of myoglobin to use in aerobic mechanisms

25
Q

List 4 histological features of skeletal muscle

A

-long unbranched fibers
-continuous basement membrane around each fiber
-no cell-cell communication
-nuclei pushed out to periphery

26
Q

What is a satellite cell?

A

a skeletal muscle nucleus that contains stem cells

27
Q

What is the difference between epimysium, perimysium, endomysuim?

A

-Epimysium: dense irregular CT around muscle belly
-Perimysium:CT that creates fascicles
-Endomysium: loose CT, mostly reticular fibers that surround in between individual muscle fibers

28
Q

What CT continues into muscle tendon?

A

epimysium

29
Q

What are intrafusal fibers?

A

specialized muscle fibers in the muscle spindle

30
Q

What is the muscle spindle?

A

a sensory organ in the muscle that relays information about where the muscle is in space

31
Q

What is the role of the tendon organ?

A

Located within tendons, attached to the epimysium that conveys stretch information

32
Q

What are the 3 main histologic differences between skeletal and cardiac muscles?

A

cardiac is shorter/branched, has intercalated discs, and one central nucleus

33
Q

What is an intercalated disc?

A

Where cardiac muscle cells fuse

34
Q

What helps cardiac muscle with coordinated contraction?

A

gap junctions

35
Q

Where do cardiac muscle gap junctions typically sit?

A

intercalated discs

36
Q

True/False: cardiac muscles have an epimysium

A

False

37
Q

Name 3 specialized myocytes of the heart

A

SA node, AV node, purkinje fibers

38
Q

What are Purkinje fibers?

A

Specialized myocytes that are conducting fibers of the heart

39
Q

What muscle type has limited CT (endomysium)?

A

smooth muscle

OSSF (37 decks)

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