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OAT- Biology > Chapter 10 > Flashcards

Chapter 10 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Smooth Muscle

A

Found in the walls of all hollow organs (GI tract, the urinary system and the uterus)

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2
Q

What does skeletal muscles use for movement?

A

The framework of the bones of the skeleton

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3
Q

How are skeletal muscles attached?

A

Skeletal muscles attach at each end to two different bones

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4
Q

How are muscles attached?

A

Muscles are attached to bones by tendons

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5
Q

Tendons

A

Strong connective tissue formed primarily of collagen

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6
Q

Point of origin

A

Point where the muscle attaches on the bone closer to the center of the body Stays in place when contraction occurs

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7
Q

Point of insertion

A

Brought closer to the point of origin during contraction Point more distant from the center of the body

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8
Q

Why are different muscles needed to move a joint?

A

Muscles can only contract so different muscles are necessary for flexion and extension of a joint

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9
Q

Antagonistic

A

Muscles that are responsible for movement in opposite directions

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10
Q

Synergistic

A

Muscles that move a joint in the same direction

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11
Q

Myofibril that generate contractions

A

Polymerized actin and myosin

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12
Q

Actin polymerizes to form

A

Thin filaments

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13
Q

Thin filaments

A

Attach to eachZ line and overlap with thick filaments in the middle of each sacromere

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14
Q

Myosin polymerizes to from

A

Thick filaments

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15
Q

Thick filaments

A

Are not attached to the Z lines

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16
Q

When does contraction occur in the Myofiber?

A

When thin and thick filaments slide across each other

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17
Q

How is filament sliding powered?

A

ATP hydrolysis; myosin is an enzyme which uses energy of the ATP to create movement

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18
Q

Filament sliding step 1

A

(1) Binding of the myosin head to a myosin binding site on actin (cross bridge formation) Myosin has ADP and P1 bound

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19
Q

Filament sliding step 2

A

The power stroke; myosin head moves to a low-energy conformation, and pulls the actin chain toward the center of the sacromere. ADP is released

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20
Q

Filament sliding step 3

A

Binding of a new ATP molecule necessary for release of actin by the myosin head

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21
Q

Filament sliding step 4

A

ATP hydrolysis occurs immediately and the myosin head is cocked. Another cycle beings when the myosin head binds to a new binding site on the thin filament

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22
Q

Troponin-tropopomyosin complex

A

Prevents contraction when Ca2+is not present

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23
Q

Tropomyosin

A

A long fibrous protein that winds around the actin polymer, blocking all the myosin binding sites

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24
Q

Troop in

A

Globular protein bounds to tropomyosin that can bind Ca2+

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25
Q

How does the troponin-tropomyosin complex work?

A

When troponin binds Ca2+, troponin undergoes a conformational change that moves tropomyosin out of the wat, so that the myosin heads can attach to actin and filament sliding can occur

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26
Q

Neuromuscular Junction (NMJ)

A

The synpase between an axon terminus (synaptic knob) and a myofiber

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27
Q

How is the NMJ arranged?

A

Not a single point, but rather a long trough or invagination (infolding) of the cell membrane; the axon terminus is elongated to fill a long synaptic cleft

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28
Q

Why is the NMJ arranged the way it is?

A

To allow the neuron to depolarize a large region of the postsynaptic membrane at once

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29
Q

What’s the neurotransmitter at the NMJ?

A

ACh

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30
Q

What is ACh’s affect?

A

ACh is released and attaches to sodium channels, which release sodium and depolarize the cell. ACh stimulates until it is destroyed

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31
Q

How does contaction occur in the myofiber?

A

Summation is required to initiate an AP in the postsynaptic cell. When sufficient EPP occurs, threshold is reached and sodium channels open in the postsynaptic membrane.

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32
Q

How is the AP propagated in the myofiber?

A

By a continuing wave of voltage gated sodium channel opening

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33
Q

Transverse tubules (T-tubulues)

A

Since the myofiber is too thick for potentials to occur at the cell surface, action potentials must travel through T-tubules to depolarize the inside

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34
Q

Sacroplasmi Reticium (SR)

A

SR contains voltage-gated Ca2+ channels which allow Ca2+ to rush out of the SR into the sacroplasm upon depolarization. Increase in sacroplasmic Ca2+ causes troponin- tropomyosin to change confirmation, allowing myosin to bind actin –> actin and myosin slide across each other and muscle fibers contract

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35
Q

What happens to calcium upon repolirization?

A

Calcium is actively sequestered by the SR and contraction is ended

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36
Q

Twitch

A

Smallest measurable muscle contraction

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37
Q

Motor unit recruitment

A

A motor unit is a group of myofiber innervated by the branches of a single motor neuron’s axon. Activation of one motor neuron can then recruit more motor neurons to produce a large twitch

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38
Q

Frequency summation

A

If a second contraction occurs rapidly enough there is insufficient time for the Ca2+ to be sequestered by the SR, and the second contraction builds on the first

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39
Q

Tetanus

A

Strongest possible contraction

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40
Q

How does frequency summation occur?

A

The amount of time between successive stimulations must be greater than the duration of the refractory period, but brief enough so that the sacroplasmic Ca2+ has not been returned to its low resting level

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41
Q

Length-tension relationship

A

A muscle contracts most forcefully at an optimum length (2.2 microns). This is where there is maximum degree of overlap between thick and thin filaments.

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42
Q

Intermediate term energy storage molecule

A

Creating phosphate; during contraction its hydrolysis drives the regeneration of ATP from ADP+P

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43
Q

What is the role of Myoglobin?

A

Muscle is highly aerobic tissue. The role of myoglobin is to provide an oxygen reserve by taking O2 from hemoglobin and then releasing it as needed.

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44
Q

What happens during prolonged contractions?

A

The supply of oxygen runs low, and metabolism becomes anaerobic. Lactic acid is produced and moves into the blood stream, causing a drop in pH.

45
Q

Rigor Morris

A

Rigidity of skeletal muscles which occurs soon after death. Occurs after ATP exhaustion. Without ATP, myosin heads cannot release actin and the muscle can neither contract nor relax.

46
Q

How are cardiac muscles the same as skeletal muscles

A

(1) thick and thin filaments are organized into sarcomeres (2) T-tubules are present (3) Tropononin-tropomyosin regulates contraction (4) Length-tension relationship works the same way and is more significant in cardiac muscle

47
Q

How are cardiac different from skeletal muscles?

A

(1) They each have only one nucleus (2) Cardiac muscle cells are each connected to several neighbors by intercalated disks (3) Cardiac muscle contractions do not depend on stimulation by motor neurons (4)AP in cardiac muscle depends not only on voltage-gated sodium channels but also on voltage-gated calcium channels

48
Q

What is the most important nerve in a cardiac muscle?

A

Vagus nerve (a parasympathetic nerve) synapses with the sinoatrial node, where it releases ACh to inhibit spontaneous depolarization resulting in a slower heart rate

49
Q

What is the significance of a plateau phase?

A

(1) Longer duration of contraction facilitates ventricular emptying (better ejection fraction) (2) a longer refractory period helps prevent disorganized transmission of impulses through the heart and makes summation and tetanus impossible

50
Q

What kind of AP do skeletal muscles cells exhibit?

A

A steeply-spiking AP

51
Q

What type of AP do smooth and cardiac muscle cells exhibit?

A

A spike and a plateau

52
Q

Smooth muscles compared to skeletal muscles 1-4

A

(1) Smooth muscle cells are much narrower and shorter than skeletal muscle cells (2) T-tubules are not present in smooth muscle cells (3) each cell has only one nucleus and is connected to its neighbors by gap junctions (4) Thick and thin filaments are not organized into sacromere in smooth muscle

53
Q

Smooth muscles compared to skeletal muscles 5-8

A

(5) Troponin-tropomyosin complex is not present (6) SR in smooth muscles are poorly developed. SR stores very little Ca2+, most rely on extra cellular Ca (7) AP is determined by slow channels only, it takes ten to twenty times as long as skeletal muscle action potential (8) Smooth muscles that must sustain prolonged contractions have action potentials similar to those of cardiac muscles

54
Q

Smooth muscles compared to skeletal muscles 9-10

A

(9) Smooth muscles have a constantly fluctuating resting potential (10) Smooth muscle cells are innervated by motor neurons. Smooth muscle cells are autonomic motor neurons instead of somatic motor neurons

55
Q

What roles does the vertebrae skeletal system serve?

A

(1) Support the body (2) Provide the framework for movement (3) Protect vital organs (brain, heart, etc.) (4) Store calcium (5) Synthesize the formed elements of the blood.

56
Q

Hematopoisis

A

When synthesis of the formed elements occurs in the marrow of flat bones

57
Q

Axial skeleton

A

Consists of the skull, the vertebral column, and the rib cage

58
Q

The appendicular skeleton

A

All other bones in the body that are not the axial skeleton

59
Q

Connective tissue

A

Bone; consists of cells and the materials they secrete

60
Q

Where does all connective tissue cells derived from?

A

Fibroblast

61
Q

Elastin

A

Gives tissue the ability to stretch and regain its shape

62
Q

What cells are derived from fibroblast

A

Adipocytes, chondrocytes and osteocytes

63
Q

Loose connective tissue

A

Includes adipose tissue and material located between cells throughout the body, known as the extra cellular matrix

64
Q

Basement membrane

A

Sheet of collagen that supports cell layers

65
Q

Dense connective tissue

A

Refers to tissues that contain large amounts of collagen, such as bones, cartilage, tendons and ligaments

66
Q

Compact bone

A

Hard and dense while spongy bone is porous.

67
Q

Spongy Bone

A

Always surrounded by a layer of compact bone

68
Q

Bone marrow

A

Non bony material found in the shafts of long bones and in the pores of spongy bones

69
Q

Red marrow

A

Found in spongy bone within flat bones. Activity increases in response to erythropoietin (hormone made by the kidneys)

70
Q

Yellow marrow

A

Found in the shafts of long bones, filled with fat and is inactive

71
Q

Tow principal ingredients of bone

A

Collagen and hydroxyapatite

72
Q

Osteoblasts

A

Basic unit of compact bone structure. Sometimes referred to as the Haversian system

73
Q

In the center of the osteon is a hole called

A

The central (or Haversian) canal which contains blood, lymph vessels and nerves

74
Q

Osteocytes

A

Mature bone cell. Allows cells to exchange nutrients and waste through an otherwise impermeable membrane

75
Q

Cartilage

A

Strong but very flexible extracellular tissue secreted by cells called chondrocytes

76
Q

Hyaline Cartilage

A

Strong and somewhat flexible (larynx & trachea)

77
Q

Elastic Cartilage

A

Found in structures that require support and more flexibility than hyaline cartilage can provide (outer ear & epiglottis)

78
Q

Fibrous Cartilage

A

Very rigid and is found in places where very strong support is needed (pelvis & spinal chord)

79
Q

Cartilage is avascular

A

Cartilage is not innervated and does not contain blood vessels. Cartilage receives nutrition and immune protection from the surrounding fluid

80
Q

Ligaments

A

Connect bones to other bones

81
Q

Tendons

A

Connect bones to muscles

82
Q

Synarthroses

A

Immovable joints. Points where two bones are fused together.

83
Q

Amphiarthoses

A

Slightly movable joints. Provides both movability and a great deal of support

84
Q

Diarthroses

A

Freely movable joints (most of the joints of in the body)

85
Q

What lubricates movable joints?

A

Synovial fluid; kept within the joint by the synovial capsule

86
Q

How are bones connected?

A

The surface of two bones that contact each other are perfectly smooth because they are lined by articulate cartilage

87
Q

How does most bone growth occur?

A

By endochondral ossification

88
Q

endochondral ossification

A

Hyaline cartilage is produced and then replace by bone

89
Q

Intramembranous ossification

A

Refers to the synthesis of bone from an embryonic tissue called mesenchyme

90
Q

Epiphyseal plate

A

Seen between the diaphysis and the epiphysis

91
Q

What happens when the chondrocytes divide?

A

The epiphysis and diaphysis are forced apart. Cartilage is then replaced by bone (ossified)

92
Q

Epiphyseal line

A

The fusion point in adults

93
Q

Osteoclasts

A

Continually destroy bone by dissolving the hydroxyapatite crystals

94
Q

PTH’s effects on bones

A

Stimulates osteoclasts activity

95
Q

PTH effects on kidneys

A

Increases reabsorption of calcium, stimulates conversation of vitamin D into calcitriol

96
Q

PTH effect on intestines

A

Indirectly (via calcitriol) increases intestinal calcium absorption

97
Q

Calcitriol effect on bones

A

may stimulate osteoclasts activity, but has a minor effect

98
Q

Calcitriol effect on kidneys

A

Increases reabsoprtion of phosphorous

99
Q

Calcitriol on intestines

A

Increases intestinal absorption of calcium

100
Q

Calcitonin effects on bones

A

Inhibits osteoclasts activity

101
Q

Calcitonin effect on kidneys

A

Decreases reabsoprtion of calcium

102
Q

Calcitonin on intestines

A

N/A

103
Q

What is the epidermis composed of?

A

Stratified (many layers of) squamous epithelial cells

104
Q

Squamous cells of the epidermis are keratinized

A

As they die, they become filled with a thick coating of the though, hydrophobic protein keratin

105
Q

Melanin

A

Brown pigment, produced by specialized cells in the epidermis termed melanocytes which help absorb the ultraviolet light of the sun to prevent damage to underlying tissues

106
Q

Dermis

A

Consists of various cell-types embedded in a connective tissue matrix. Also contains sensory receptors and sudoriferous (sweat) glands, sebaceous (oil) glands and hair follicles

107
Q

How do we cope with cold weather?

A

(1) Contraction of skeletal muscles produce heat (2) the skin insulates us so that we conserve heat generated by the metabolism (3) Heat loss is minimized by constriction of blood vessels in the dermis (cutaneous vasoconstriction) (4) Clothing & blankets

108
Q

Mechanisms for dissipation of excessive heat

A

(1) Sweating, which allows heat loss by evaporation (2) Dilation of blood vessels in the dermis results in heat loss by conduction

OAT- Biology (10 decks)

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