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Flashcards in Exam 2 Part one Deck (102):
1

Muscle fiber

Skeletal muscle cells are referred to as muscle fibers because of their length. All muscle tissue is composed of muscle cells & exhibits certain common properties: excitability, contractility, elasticity, extensibility

2

Fascicles are

Each skeletal muscle is composed of fascicles, which are bundles of muscle fibers

3

Endomysium

The innermost connective tissue layer. It surrounds & electrically insulates each muscle fiber. Has reticular fibers to help bind together neigboring muscle fibers

4

Perimysium

Surrounds the fascicles. Dense irregular connective tissue sheath. It contains arrays of blood vessels & nerves that branch to supply each individual fascicle

5

Epimysium

A layer of dense irregular connective tissue that surrounds the whole skeletal muscle

6

Tendon is

Connective tissue layers merge to form fibrous tendon at the ends of the muscle, which attaches the muscle to bone, skin or another muscle. Usually have a thick cordlike structure

7

Aponeurosis is

When tendons form a thin, flattened sheet

8

Origin

Upon contraction, one muscle moves, while the other remains fixed. The less mobile attachment of a muscle is called it's origin

9

Insertion is

The more mobile attachment of a muscle

10

Usually the insertion of a muscle is pulled towards?

The origin

11

Sarcolemma is

Plasma membrane of a muscle fiber. Surrounds muscle fiber and regulates entry and exit of materials

12

Transverse (T) Tubules are

Deep invaginations of the sarcolemma that extend into the sarcoplasm a of the skeletal muscle fibers as a network of narrow membranous tubules. Quickly transport a muscle impulse from the sarcolemma throughout the entire muscle fiber

13

Sarcoplasmic reticulum

Internal membrane complex. Smooth endoplasmic reticulum. Stores calcium ions needed for muscle contraction

14

Terminal cisternae

Expanded ends of the sarcoplasmic reticulum that are in contact with the transverse tubules. Site of calcium ion release to promote muscle contraction

15

Triad

Together, the two terminal cisternae and the centrally placed T-tubule form a structure called a triad

16

Satellite cells

When some myoblasts do not fuse with muscle fibers during development, they remain in adult skeletal muscle tissue as satellite cells

17

When are satellite cells useful?

If a skeletal muscle is injured, some satellite cells may be stimulated to differentiate & assist in its repair & regeneration

18

Myofilaments are

Myofibrils consists of bundles of short myofilaments. It takes many successive groupings of myofilaments to run the entire length of a myofibril

19

The bundles of myofilaments are classified as?

Thin myofilaments (thin filaments) & thick myofilaments (thick filaments)

20

Thick filaments are

Fine protein myofilament composed of bundles of myosin. They bind to thin filament & cause contraction

21

Thin filaments are

Fine protein myofilament composed of actin, troponin, & tropomyosin. The thick filaments bind to it & cause contraction

22

Actin is?

A double-stranded contractile protein. Binding site for myosin to shorten a sarcomere

23

Tropomyosin is

Double stranded regulatory protein. Covers the active sites on actin, preventing myosin from binding to actin when muscle fiber is at rest

24

Troponin is

Regulatory protein that holds tropomyosin in place & anchors to actin. When calcium ions bind to one of its subunits, troponin changes shape, causing the tropomyosin to move off the actin active site, this permits myosin binding to actin

25

Myosin is

Thick filaments are assembled from bundles of the protein myosin. Each myosin molecule in a thick filament consists of 2 strands; each strand has a free globular head & an attached, elongated tail. The myosin molecules are oriented on either end of the thick filament so the long tails point toward the center of the filament & the heads toward the edges & project outward toward the surrounding thin filaments

26

Cross-bridges are formed when?

During a contraction, myosin heads form cross bridges by binding thick filaments to actin in the thin filaments

27

A bands are

Dark bands. Contain the entire thick filament.

28

At either end of a thick filament is?

A light band region occupied by thin filaments that extend into the A band between the stacked thick filaments

29

I bands are

Light bands. Contain thin filaments but no thick filaments. They have protein filaments called titin

30

Z line

Also called Z disc. A thin transverse protein structure in the center of the I band that serves as an attachment site for thin filament ends

31

H zoned is

Also called the h band. A light, central region in the A band. Lighter shaded because only thick filaments are present. At maximal contraction, the thin filaments are pulled into this zone, and the H zone disappears

32

Dark band

Called the A bands

33

Light bands

Called the I bands

34

Sarcomere is

The functional contractile unit of a skeletal muscle fiber. Defined as the distance from one z disc to the next adjacent z disc

35

Sliding filament theory is

When a muscle contracts, thick and thin filaments slide past each other, and the sarcomere shortens

36

Neuromuscular junction is

The point where a motor neuron meets a skeletal muscle fiber

37

Motor neuron activity stimulates what?

Skeletal muscle contraction

38

What are the components of a neuromuscular junction?

1) Synaptic knob
2) Synaptic vesicle
3) Acetylcholine (ACh)
4) Motor end plate
5) Synaptic cleft
6) ACh receptors
7) Acetylcholinesterase (AChE)

39

Motor end plate is

Specialized region of the sarcolemma. Has folds & indentations to increase membrane surface area covered by the synaptic knob

40

Synaptic knob is

Of the neuron is an expanded tip of an axon. When it nears the sarcolemma of a muscle fiber, it expands further to cover a large surface area of the sarcolemma. A nerve impulse travels through the axon to the synaptic knob

41

Synaptic cleft is

A narrow space separating the synaptic knob & the motor end plate

42

Acetylcholine (ACh) is

Molecules of the neurotransmitter that are housed within synaptic vesicles (small membrane sacs) that are housed in the synaptic knob cytoplasm

43

Acetylcholinesterase (AChE) is

An enzyme which resides in the synaptic cleft. It rapidly breaks down molecules of ACh that are released into the synaptic cleft

44

AChE is need so that?

ACh will not continuously stimulate the muscle

45

Motor unit is

Composed of a single motor neuron and all of the muscle fibers it controls. Typically controls only some of the muscle fibers in an entire muscle

46

All or none principle

States that a muscle fiber either contracts completely or does not contract at all.

47

Myoglobin is

Red pigment. A globular, oxygen binding, reddish-appearing protein that is structurally related to hemoglobin

48

Hemoglobin is

The oxygen binding protein in erythrocytes

49

Anaerobic is

A metabolic reaction that does NOT require oxygen

50

What is required for the production of the maximum amount of ATP?

Oxygen

51

What happens during muscle atrophy?

A wasting of tissue that results in a reduction in muscle size, tone, & power

52

What happens during hypertrophy?

An increase in muscle fiber size. An increase in the number of myofibrils per fiber in fast fibers

53

Why might atrophy be permanent?

When extreme atrophy occurs, the loss of gross muscle function is permanent

54

Sphincter (circular)

The muscle fibers are concentrically arranged around an opening or recess. Called a sphincter because contraction of the muscle closes off the opening

55

Parallel muscle (shape)

The fascicles run parallel to its long axis. Each muscle fiber exhibits the functional characteristics of the entire parallel muscle. They have central body called the belly or gaster

56

Transmits motor information

Motor nervous system

57

Makes myelin sheaths in CNS

Oligodendrocyte

58

Stain darkly with basic dyes

Chromatophilic substance

59

Side branches of axons

Collaterals

60

Respond to CNS infection

Microglial cells

61

Neurons with multiple dendrites

Multipolar neurons

62

Sensory to motor neuron communication

Interneuron

63

Uses a neurotransmittter

Chemical synapse

64

Neuron part that usually receives incoming impulses

Dendrite

65

Skeletal muscle fiber

Effector

66

The cell body of a mature neuron does not contain

A centriole

67

Neurons that have only two processes attached to the cell body are called?

Bipolar

68

Which neurons are located ONLY within the CNS?

Unipolar neurons

69

A structure or cell that collects sensory information is a?

Receptor

70

The glial cells that help produce CSF in the CNS are?

Ependymal cells

71

Is the neurolemmocyte a part of the CNS?

No

72

Which of these cells transmits, transfers, & processes a nerve impulse?
a) Neurolemmocyte
b) Astrocyte
c) Neuron
d) Oligodendrocyte

Neuron

73

Slow fibers

1) Small in diameter
2) Contract slowly
3) Specialized to continue contracting for extended periods of time
4) Vascular supply more extensive than network of capillaries around fast fibers
5) Supply of nutrients & O2 increased
6) Called red fibers because they contain red pigmented myoglobin
7) Resting slow fibers contain O2 reserves that can be used during contraction to provide needed ATP
8) Large # of mitochondria which permits them to produce more ATP than fast fibers while contracting, making it less dependent on anaerobic metabolism
9) Requires O2 to produce ATP
10) Metabolic reactions termed aerobic

74

Intermediate fibers

1) Exhibit properties that are between slow & fast fibers
2) Contract faster than slow & slower than fast fibers
3) Resemble fast fibers
4) Greater resistance to fatigue
5) Require O2 to produce ATP
6) Aerobic

75

Fast fibers

1) Large in diameter
2) Contain large glycogen reserves
3) Densely packed myofibrils
4) Few mitochondria
5) Called white fibers because they are pale in color due to lack of myogloblin
6) Majority of skeletal muscle fibers in the body are fast
7) Fast because of their contraction
8) Produce powerful contractions because of the large amount of sarcomeres
9) Contractions uses vast quantity of ATP
10) Primary activity supported by Anaerobic metabolic reactions
11) Fatigue rapidly

76

Considering "the all-or-none" rule of muscle contraction, how is it that we are able to have smooth and refined body movements?

.

77

What are the various functions of the muscular system?

1) Body Movement
2) Maintenance of Posture
3) Temperature Regulation
4) Storage and movement of Materials
5) support
6) Respiration due to movements of the muscles of the thorax
7) Heartbeat (muscle contraction)

78

Neuromuscluar fatigue

Decreased levels of Ach

79

What stimulates skeletal muscle contraction?

The motor neuron activity

80

When does muscle contraction begin?

Begins when a nerve impulse stimulates an impulse in a muscle fiber

81

Each muscle fiber is controlled by?

One motor neuron

82

The motor neuron transmits the effect of a nerve impulse to the muscle fiber at a?

Neuromuscular junction

83

Thin filaments are

1) Primarily composed of two strands of the protein actin
2) Two regulatory proteins, tropomyosin & troponin

84

The tropomyosin (protein) molecule in the thin filaments are

A short, thin, twisted filament that covers small sections of the actin strands

85

The troponin protein in the thin filament of the sarcomere has 3 functions

1) Structurally, it attaches to actin to anchor itself in place
2) Attaches to tropomyosin to hold it in place over the surface of the actin
3) Functionally, it provides a binding site for calcium ions

86

Thick filaments are

1) Twice size as thin filaments
2) Assembled from bundles of the protein myosin

87

Myosin in the thick filament of a sarcomere consists of?

Two strands; each strand has a free, globular head & an attached, elongated tail. The tails point toward the center of the filament & the head toward the edge & project outward. During contraction the heads form cross bridges by binding thick filaments to actin in the thin filaments

88

A bands are

Dark bands, contain entire thick filament

89

I bands are

Light region, contain thin filaments (no thick). Also contain protein filaments called titin

90

Titin found in the I band of a sarcomere plays a role in...

Muscle elasticity & control of thick filament assembly, & passive stiffness generated in the muscle

91

What are the 3 types of skeletal muscle fiber

1) Slow (Type I slow oxidative)
2) Intermediate (type II-A, fast aerobic)
3) Fast (Type I-B, fast anaerobic)

92

The epineurium is

A thick, dense irregular connective tissue layer enclosing the nerve

93

Has nuclei for CN III & CN IV

Mesencephalon

94

Autonomic centers for heart rate & respiration

Medulla oblongata

95

Dura mater fold between cerebral hemispheres

Falx cerebri

96

Innervates most thoracic/abdominal organs

Vagus nerve

97

Contains the motor speech area

Frontal lobe

98

Contains the primary auditory cortex

Temporal lobe

99

Innervates lateral rectus

Abducens nerve

100

Responsible for involuntary arm swinging

Cerebral nuclei

101

Visual reflex centers

Superior colliculi

102

Sensory information relay center

Thalamus