2. Muscular System Chp. 9 (exam 1) Flashcards Preview

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Flashcards in 2. Muscular System Chp. 9 (exam 1) Deck (48):
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Muscle diagram

Muscle-> fascicles-> muscle fiber-> myofibril-> myofilaments

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Covering of a bone

Fascia is a dense fibrous ct that surrounds and separate one muscle from another

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Aponeurosis

Extends to another muscle as this or as a tendon

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Epimysium

Surrounds skeletal muscle

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Perimysium

Surrounds bundles (fascicles) of muscle

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Endomysium

Surrounds each muscle fiber

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Muscle fiber

Single cell that contracts with stimulus and then relaxes. It may extend the full length of the muscle

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Actin

Is thin

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Myosin

Thick

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Sarcoplasm reticulum

Surrounds each myofibril, stores calcium ions and transports

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Transverse tubules

Membranous channels, open to the surface allowing the electrical impulse to reach the sarcoplasm reticulum

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C + T2 =

Triad

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Neuromuscular junction

The connection between a motor neuron and a muscle fiber with a specially modified membrane containing increased nuclei and mitochondria

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Synaptic cleft

Space between the motor neuron and muscle membrane

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Motor unit

A motor neuron and all the muscle fibers it controls

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Neurotransmitter

Chemical messenger released by a neuron

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Stimulus for contraction

The neurotransmitter for motor neurons is AcH. Synthesized in the cytoplasm and stored in vesicles. It is released as a result of nerve impulse reaching the end of the axon. Once released it's diffused across the cleft attaching to receptors and stimulating a muscle impulse.

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Excitation contraction coupling

The sr has high levels of ca ions due to pumps. The impulse increases the permeability of the cisternae causing calcium to flood the sarcoplasm specifically binding to the troponin

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Energy source

The existing muscle ATP is quickly depleted

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Oxygen debt

Equals the amount of oxygen that liver cells require to convert accumulated lactic acid into glucose, plus to restore muscle cells to their original concentrations

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Threshold stimulation

The minimum strength to cause a contraction (twitch)

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Myogram

Recording of movement of a twitch

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Summation

When series of stimuli don't allow complete relaxation, may produce tetanus

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Tetanus

Sustained muscle cell contraction without any relaxation

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Recruitment

A motor unit responds as all or none

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Sustained contraction

When summation, tetanus, and recruitment occur. Excess can produce muscle strain/pull/sprain

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Atrophy

Decrease in size or strength

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Hypertrophy

Increase in strength or size of muscle

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Fiber types

Red fibers
White fibers
Pink fibers

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Red fibers

Slow twitch, due to increased myoglobin and mito

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White fibers

Fast twitch, faster, stronger, faster ATPase

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Pink fibers or intermediate fibers

Fast twitch fatigue-resistant

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Myoglobin content

High in red fibers
Low in white muscle fibers

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Mitochondria

Red fibers has many
White fibers has less

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Size of fibers

Red fibers are thin
White fibers are thick

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Twitch

Red fibers are slow and weak
White fine are fast and strong

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Endurance

Red muscle have long endurance
White fibers have a short endurance

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Marathoners

Have high levels of red fibers

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Sprinters

Have high levels of white

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Joe average

Has intermediate fibers

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Botulism

Prevents the release of acetylcholine

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Curare

Binds to AcH receptor sites

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Venoms

Blocks release or explosive release of AcH

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Smooth muscle

Long tapering
Single nucleus
No striations

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Types of smooth muscles

Multiunit
Visceral

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Multiunit

Separate fibers
Ex iris, blood vessels

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Visceral

In sheets
Ex digestive

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Cardiac muscle

Short
Branched
3d like
Striated
Single nucleus
Intercalated discs