A&P Chapter 10 Flashcards Preview

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Flashcards in A&P Chapter 10 Deck (54):
1

Functions of muscular tissue

1. Producing body movements
2. Stabilizing body position
3. Storing and moving substances within the body
4. Generating heat

2

Properties of muscular tissue

1. Electrical excitability (action potentials/impulses)
2. Contractility
3. Extensibility
4. Elasticity

3

Epimysium

Outermost layer of dense, irregular connective tissue, encircling the entire muscle

4

Perimysium

Dense, irregular connective tissue that surrounds groups of 10 to 100 or more muscle fibers

5

Fascicles

Bundles of 10 to 100 or more muscle fibers

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Endomysium

Penetrates the interior of each fascicle and separates individual muscle fibers from one another. Mostly reticular fibers.

7

Aponeurosis

When the connective tissue elements extend as a broad, flat sheet

8

Somatic motor neurons

Neurons that stimulate skeletal muscle to contract

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Sarcolemma

Plasma membrane of a muscle cell

10

Transverse (T) tubules

Tiny invaginations of the sarcolemma that tunnel in from the surface toward the center of each muscle fiber.

11

Sarcoplasm

Cytoplasm of a muscle fiber (within the sarcolemma)

12

Myoglobin

Red-colored protein found only in muscle. Binds oxygen molecules that diffuse into muscle fibers from interstitial fluid.

13

Myofibrils

Contractile organelles of skeletal muscle. Their prominent striations make the entire skeletal muscle appear striped (striated).

14

Sarcoplasmic Reticulum (SR)

Fluid-filled system of membranous sacs that encircle each myofibril. Similar to Smooth ER in non-muscular cells.

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Terminal cisterns

Dilated end sacs of the SR.

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Triad

Formed by a transverse tubule and the two terminal cisterns on either side of it.

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Filaments or Myofilaments

Smaller protein structures within myofibrils

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Sarcomeres

Compartments that hold the filaments inside a myofibril. The basic functional units of a myofibril

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Z discs

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

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A band

Darker middle part of the sarcomere. Extends the entire length of the thick filaments.

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I band

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

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H zone

In the center of each A band. Contains thick but not thin filaments.

23

M line

Formed by supporting proteins that hold the thick filaments together at the center of the H zone. At the middle of the sarcomere.

24

Three kinds of proteins that build myofibrils

1. Contractile: generate force during contraction
2. Regulatory: help switch the contraction process on and off
3. Structural: Keep the thick and thin filaments in the proper alignment, give the myofibril elasticity and extensibility, and link the myofibrils to the sarcolemma and extracellular matrix

25

Two contractile proteins in muscle

Myosin and actin

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Myosin

Main component of thick filaments and functions as a motor protein in all three types of muscle tissue.

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Actin

Main component of thin filaments which are anchored to Z discs. Individual actin molecules join to form an actin filament that is twisted into a helix.

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Titin

Third most plentiful protein in skeletal muscle.

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Actinin

molecules which bind to actin molecules of the thin filament and to titin.

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Myomesin

Protein molecules that form the M line. Bind to titian and connect adjacent thick filaments to one another.

31

Nebulin

A long, nonelastic protein wrapped around the entire length of each thin filament. Helps anchor thin filaments to the Z discs and regulates the length of thin filaments during development.

32

Dystrophin

Links thin filaments of the sarcomere to integral membrane proteins of the sarcolemma, which are attached in turn to proteins in the connective tissue extracellular matrix that surrounds muscle fibers.

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Contraction cycle

Repeating sequence of events that causes the filaments to slide

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Four steps of contraction cycle

1. ATP hydrolysis: Myosin heads hydrolyze ATP and become reoriented and energized.
2. Attachment of myosin to actin to form cross-bridges.
3. Power stroke: Myosin cross-bridges rotate toward center of sarcomere.
4. Detachment of myosin from actin.

35

Neuromuscular Junction (NMJ)

The synapse between two neurons, or between a neuron and a target cell - in this case, between a somatic motor neuron and a muscle fiber.

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Synaptic cleft

Small gap that separates the two cells

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Axon terminal

End of the motor neuron.

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Synaptic end bulbs

Neural part of the NMJ

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Synaptic vesicles

Membrane-enclosed sacs suspended in the cytosol within each synaptic end bulb

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Acetylcholine (ACh)

Molecules of the neurotransmitter inside each synaptic vesicle released at the NMJ.

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Motor end plate

Region of the sarcolemma opposite the synaptic end bulbs

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Acetylcholine receptors

Integral transmembrane proteins to which ACh specifically binds

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Junctional folds

Deep grooves in the motor end plate that provide a large surface area for ACh

44

Nerve impulse (nerve action potential) elicits a muscle action in the following way:

1. Release of acetylcholine
2. Activation of ACh receptors
3. Production of muscle action potential
4. Termination of ACh activity

45

Three ways muscle fibers produce ATP

1. From creatine phosphate
2. By anaerobic cellular respiration
3. By aerobic cellular respiration

46

Creatine phosphate

An energy rich molecule that is found in muscle fibers.

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Creatine

Small, amino acid-like molecule that is synthesized in the liver, kidneys, and pancreas and then transported to muscle fibers.

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Anaerobic cellular respiration

A series of ATP-producing reactions that do not require oxygen

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Aerobic cellular respiration

A series of ATP-producing reactions that require oxygen

50

Muscle fatigue

The inability of a muscle to maintain force of contraction after prolonged activity

51

Oxygen debt/Recovery oxygen uptake

Added oxygen, over and above the resting oxygen consumption, that is taken into the body after exercise.

52

Motor unit

A somatic motor neuron plus all the skeletal muscle fibers it stimulates

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Twitch contraction

Brief contraction of all the muscle fibers in a motor unit in response to a single action potential in its motor neuron

54

Myogram

Record of a muscle contraction