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Biology 2312 > Chapter 46 > Flashcards

Chapter 46 Flashcards

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1
Q

What are the three main types of skeletal systems in animals?

A

hydrostatic skeletons; exoskeletons; endoskeletons

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2
Q

Where are hydrostatic skeletons found primarily? (3)

A

in soft-bodied terrestrial invertebrates; soft-bodied aquatic invertebrates; squids

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3
Q

Give two examples of soft-bodied terrestrial invertebrates.

A

earthworms; slugs

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4
Q

Give an example of a soft-bodied aquatic invertebrate.

A

jellyfish

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5
Q

The fluid-filled central cavity of animals bearing hydrostatic skeletons is supported by what two muscles?

A

circular muscles; longitudinal muscles

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6
Q

What are circular muscles?

A

muscles repeated in segments and run the length of the body

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7
Q

What are longitudinal muscles?

A

muscles that oppose the action of the circular muscles

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8
Q

Which muscles oppose the action of circular muscles?

A

longitudinal muscles

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9
Q

Describe the locomotion process in earthworms.

A

anterior circular muscles contract as locomotion begins; this presses on inner fluid; front of body is forced to become thin as the body wall extends forward

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10
Q

What are chaetae?

A

short, bristle-like structures found on the underside of a worm’s body

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11
Q

What happens to chaetae as circular muscles act?

A

as circular muscles act, the chaetae are pulled up close to the body and lose contact with the ground, which results in a backward wave of contraction

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12
Q

As the backward wave of contraction in worms continues, what happens?

A

anterior circular muscles relax and longitudinal muscles take over which allows chaetae to re-establish contact with the ground

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13
Q

Why is chaetae re-gaining contact with the ground important?

A

it prevents that body section from slipping backwards

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14
Q

In essence, in worms, what is the order of muscle contraction for body movement?

A

locomotion proceeds as waves of circular muscle contractions are followed by waves of longitudinal muscle effects

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15
Q

What are exoskeletons?

A

rigid, hard case that surrounds the body

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16
Q

Arthropod exoskeletons are made of

A

chitin

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17
Q

Other than in arthropod exoskeletons, where can chitin be found?

A

in the cell walls of fungi and protists

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18
Q

What acts as the skeletal framework for arthropod?

A

the chitinous exoskeleton

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19
Q

In order to grow, what must an arthropod do to its exoskeleton?

A

molt it periodically

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20
Q

Molting gives exoskeleton-bearing organisms the disadvantage of

A

being vulnerable whenever they molt their exoskeleton

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21
Q

What are limitations of exoskeletons? (3)

A

chitinous framework isn’t as strong as a bony one; ratio between SA of tubules and volume of body overwhelms respiratory system; muscles are confined in size/power

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22
Q

In what organisms are endoskeletons found? (2)

A

vertebrates; echinoderms

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23
Q

Give two examples of echinoderms.

A

sea urchins; sand dollars

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24
Q

Echinoderms have skeletons made of

A

calcite (crystalline form of calcium carbonate)

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25
Q

Give an example of an animal that has a totally cartilaginous skeleton.

A

sharks

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26
Q

Differentiate between chitin and bone/cartilage.

A

bone/cartilage are living tissues

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27
Q

T/F: Bone and cartilage can change and remodel themselves in response to injury or stress.

A

Yes, bone can do so, and to a lesser extent, so can cartilage

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28
Q

What is the main component in vertebrate skeletons?

A

bone

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29
Q

When did bone first appear?

A

520 million years ago

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30
Q

Bone is found in all vertebrates except

A

cartilaginous fishes

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31
Q

In intramembranous development, bones form

A

within a layer of connective tissue

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32
Q

Give examples of intramembranous mones in the human body. (2)

A

exterior of skull; jaw

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33
Q

During embryonic development, the dermis is formed largely of (2)

A

mesechyme; collagen fibers

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34
Q

What is mesenchyme?

A

loose tissue consisting of undifferentiated mesenchyme cells + other related cells

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35
Q

Undifferentiated mesenchyme cells differentiate to become (in the context of bone development)

A

osteoblasts

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36
Q

Osteoblasts are derived from

A

undifferentiated mesenchyme cells

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37
Q

How do osteoblasts arrange themselves?

A

arrange themselves along collagenous fibers and begin to secrete the enzyme alkaline phosphatase

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38
Q

What is hydroxyapatite?

A

a crystalline configuration of calcium phosphate salts resulting from the secretion of alkaline phosphatase

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39
Q

What does the enzyme alkaline phosphatase do?

A

promotes the creation of hydroxyapatite

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40
Q

Undifferentiated mesenchyme cells can differentiate to become what three types of cells?

A

fibroblasts; chondroblasts; osteoblasts

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41
Q

Fibroblasts differentiate to become

A

collagen (fibrous tissue)

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42
Q

Chondroblasts differentiate to become

A

chondrocytes

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43
Q

Osteoblasts differentiate to become

A

osteocytes

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44
Q

Osteocytes differentiate to become

A

osteoclasts

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45
Q

What are chondrocytes?

A

cartilage cells

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46
Q

When does an osteoblast become an osteocyte?

A

if it becomes trapped in the bone matrix it is constructing, it becomes an osteocyte (bone cell)

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47
Q

Osteocytes reside in spaces called

A

lacunae

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48
Q

What are osteoclasts?

A

bone-removing cells

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49
Q

Where are osteoclasts derived from?

A

fusion of monocytes (white blood cells)

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50
Q

Describe the relative amounts of collagen and hydroxyapatite in bone.

A

bone contains roughly equal volumes of collagen and hydroxyapatite

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51
Q

What percentage of bone weight is made up of hydroxyapatite?

A

about 65%

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52
Q

What are canaliculi?

A

canals extending from lacunae

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53
Q

What cells live in lacunae?

A

osteocytes

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54
Q

What is the purpose of canaliculi?

A

promote intercellular communication because the starburst-like extensions of each osteocyte contact their neighbors

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55
Q

T/F: osteoclasts are mononucleate cells.

A

FALSE, osteoclasts are multi-nucleate cells

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56
Q

Where can endochondrally-developed bones be found in the body?

A

found deeper in the body because they form the body’s architectural framework

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57
Q

Give examples of endochondrally-developed bones. (6)

A

vertebrae; ribs; shoulder bones; pelvis bones; long bones of limbs; internal skull bones

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58
Q

Endochondral bones begin as

A

tiny, cartilaginous models that have the rough shape of bones

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59
Q

Bone added to the outside of the model is produced

A

in the fibrous sheath that envelopes the cartilage

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60
Q

Describe the fibrous sheath that envelopes the cartilage and adds bone to the outside of the model. (3)

A

tough; made of collagen fibers; contains undifferentiated mesenchyme cells

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61
Q

What do osteoblasts do in the fibrous sheath that envelopes the cartilage and adds bone to the outside of the model? (2)

A

osteoblasts arise from the undifferentiated mesenchyme and sort themselves along the fibers in the deepest part of the sheath; bone forms between sheath and cartilaginous matrix

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62
Q

As outer bone is formed, what happens to interior cartilage?

A

interior cartilage begins to calcify

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63
Q

What is the calcium source for the calcification of interior cartilage as outer bone forms?

A

the calcium source is the cartilage cells themselves because the cartilaginous tissue breaks down

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64
Q

What is the periosteum?

A

blood vessels from the sheath

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65
Q

How does growth in bone thickness occur?

A

by adding additional bone layers just beneath the periosteum

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66
Q

The mammalian humerus is formed of

A

a slender shaft with widened ends, called epiphyses

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67
Q

What are epiphyses?

A

widened ends found on bones like the mammalian humerus

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68
Q

What are found within the epiphyses?

A

epiphyseal growth plates, which separate the epiphyses from the shaft itself

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69
Q

As long as the bone is growing, epiphyseal growth plates are composed of

A

cartilage

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70
Q

How are epiphyseal growth plates involved in bone elongation? (3)

A

during growth of long bone, cartilage of growth plates actively grows in lengthwise direction to thicken plate; growth pushes epiphyses farther away from shaft; cartilage calcification encroaches onto growth plate so that bony portion of shaft elongates

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71
Q

Growth in bone length in humans usually ceases by

A

late adolescence

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72
Q

T/F: growth in bone width is ceased after puberty.

A

False, growth in width still occurs by bone addition beneath the periosteum

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73
Q

What are vascular bones?

A

endochondral bones that retain internal blood vessels after completing development

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74
Q

Vascular bone is found in what non-mammalian species? (2)

A

reptiles; amphibians

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75
Q

Cellular bones contain

A

osteocytes

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76
Q

T/F: cellular bones can also be vascular.

A

true, cellular bones can be vascular

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77
Q

T/F: cellular bones are metabolically inactive

A

false, cellular bones are metabolically active

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78
Q

Avascular bones are found in what species? (2)

A

fish; birds

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79
Q

Describe avascular bone. (3)

A

does not contain osteocytes; fairly inert; surface periosteum can repair bone with mesenchyme cells

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80
Q

What is another name for avascular bone?

A

acellular bone

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81
Q

Bones like the endochondral long bones contain a cavity called

A

the medullary cavity

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82
Q

Where is the medullary cavity found?

A

bones like the endochondral long bones

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83
Q

In many vertebrates, the medullary cavity contains

A

bone marrow, which is important for manufacturing red and white blood cells

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84
Q

If the medullary cavity contains red/white blood cells, it is called the

A

marrow cavity

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85
Q

Give an example of species whose medullary cavity does not contain marrow.

A

Light-boned birds

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86
Q

T/F: all medullary cavities contain marrow.

A

False, not all medullary cavities contain marrow

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87
Q

How do birds produce red blood cells if their medullary cavities don’t contain marrow?

A

they depend on stem cells to produce RBCs

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88
Q

Bone falls into what three categories?

A

compact bone; medullary bone; spongy bone

89
Q

Where is compact bone found?

A

outer surface

90
Q

Where is medullary bone found?

A

medullary cavities

91
Q

Describe spongy bone.

A

honeycomb structure; typically forms the epiphyses inside a thick shell of compact bone

92
Q

Which two types of bone contribute to bone strength?

A

compact and spongy bone

93
Q

Medullary cavities are lined with thin tissues called

A

the endosteum

94
Q

What is the endosteum?

A

thin tissue that lines the medullary cavities that doesn’t contain collagen fibers but does contain other stuff like mesenchyme cells

95
Q

Vascular bone has a special internal organization called

A

the Haversian system

96
Q

Endochondral bone is constructed of concentric layers called

A

Haversian lamellae

97
Q

Where are Haversian lamellae found?

A

beneath the outer basic layers

98
Q

What are Haversian canals?

A

narrow channels that contain concentric tubes

99
Q

Haversian canals may contain

A

nerve fibers

100
Q

Haversian canals always contain

A

blood vessels that keep osteocytes alive even though they’re stuck in the bony matrix

101
Q

What kind of blood vessels can be found in the Haversian canals? (3)

A

arterioles; venules; capillaries

102
Q

What are Sharpey’s fibers?

A

collagen fibers that connect periosteum to bone

103
Q

T/F: exercise and frequent muscle use can not only alter muscles, but can alter blood vessels, strengthen skeletal frame, etc.

A

true

104
Q

T/F: remodeling occurs only in some bones

A

false, remodeling is known for all bones

105
Q

Bone remodeling can be considered as what kind of feedback system, and why?

A

negative feedback system, because stress promotes thicker bones, which reduce the amount of stress that can affect itself, which reduces the need for thickness

106
Q

What are the effects of osteoporosis?

A

loss of bone mineral density

107
Q

Osteoporosis primarily affects

A

postmenopausal women

108
Q

What is a treatment for osteoporosis?

A

weight-lifting, which stimulates bone deposition

109
Q

What is another name for joints?

A

articulations

110
Q

What is another name for articulations?

A

joints

111
Q

What are the four basic joint movement patterns?

A

ball-and-socket; hinge; gliding; combination

112
Q

Give an example of a ball-and-socket joint.

A

the hip: the upper leg bone forms the ball and the pelvis is the socket

113
Q

Describe the movement of the ball-and-socket joint.

A

can perform universal movement in all directions, plus twisting of the ball

114
Q

What is the simplest type of joint?

A

hinge joint

115
Q

Give an example of a hinge joint.

A

knee

116
Q

The knee is what kind of joint?

A

hinge joint

117
Q

Describe the movement of the hinge joint.

A

restricted to rotate forward or backward, but not side-to-side

118
Q

Where can gliding joints be found? (2)

A

found in skulls of some nonmammalian vertebrates; found in lateral vertebral projections of vertebrates including mammals

119
Q

Describe the gliding joint in vertebral projections.

A

the projections can slip along the undersurface of the posterior projection, which gives stability and flexibility to the vertebral column

120
Q

What are combination joints?

A

joints that have characteristics of two or more joint types

121
Q

Give an example of a mammalian combination joint.

A

the mammalian jaw, which allows both rotation and side-to-side sliding

122
Q

What are the two means of bone attachment?

A

muscle fibers may connect directly to the periosteum; sheets of muscle may be connected to bone by a tendon

123
Q

What is a tendon?

A

dense connective tissue cord that attaches to the periosteum

124
Q

The origin of muscle attachment remains

A

relatively stationary during a contraction

125
Q

What is the opposite end of the origin of muscle attachment?

A

insertion

126
Q

The quadriceps muscles counter the movement of which muscles?

A

leg flexor muscles (hamstrings)

127
Q

Each muscle contains a bundle

A

of 4 to 20 elongated structures called myofibrils

128
Q

Each myofibril contains

A

thick and thin myofilaments

129
Q

Describe the hierarchy of muscle structures.

A

skeletal muscle > muscle fibers > muscle fiber cell > myofibril > myofilaments

130
Q

Describe the appearance of myofilaments under a microscope.

A

they have alternating light and dark bands

131
Q

What gives skeletal muscle fibers their striped appearance?

A

the alternating light and dark bands of myofibrils

132
Q

What are A bands?

A

thick myofilaments stacked together that produce the dark bands

133
Q

Thick myofilaments stack together to produce

A

dark bands called A bands

134
Q

Thin filaments are found in

A

the light bands called I bands

135
Q

I bands contain

A

thin filaments

136
Q

Each I band in a myofibril is divided

A

in half by a protein disk called the Z lin

137
Q

What is the Z line?

A

protein disk that divides the I band in myofibrils in half

138
Q

What is anchored to Z lines?

A

thin filaments

139
Q

What is a sarcomere?

A

the repeating unit from Z line to Z line

140
Q

What is the smallest unit of muscle contraction?

A

the sarcomere

141
Q

The sarcomere is the smallest

A

unit of muscle contraction

142
Q

What is the name for the center of the A band?

A

the H band

143
Q

What is the H band?

A

the center of the A band

144
Q

Draw out the structure of a repeating sarcomere in relaxed and contracted muscles.

A

pg. 970 in book

145
Q

Describe the placement of the thick/thin filaments relative to the A band in relaxed and contracted muscles.

A

in a relaxed muscle, the thick and thin filaments are on either side of the A band but don’t extend all the way to the center; in a contracted muscle, the thick and thin filaments overlap on each side of the A band

146
Q

Describe the color of the H band.

A

lighter than the areas on each side of the A band

147
Q

T/F: myofilaments shorten during contraction.

A

FALSE, they don’t shorten, the thick and thin filaments slide relative to each other

148
Q

What happens to the H band during maximal contraction?

A

the H band disappears entirely

149
Q

What happens to the I bands during contraction?

A

I bands become narrower

150
Q

What happens to the Z line during contraction?

A

Z lines are brought closer together

151
Q

Each thick filament is composed of

A

many subunits of myosin packed together

152
Q

The myosin protein is composed of

A

two subunits, each shaped like a golf club that twist around each other

153
Q

Each thin filament is composed of

A

actin proteins arranged into two fibers twisted into a double helix

154
Q

Myosin is a member of what class of protein?

A

motor proteins

155
Q

What do motor proteins do?

A

convert chemical energy in ATP into mechanical energy

156
Q

What cycle converts chemical energy in ATP into mechanical energy?

A

the cross-bridge cycle

157
Q

What is an individual cross-bridge?

A

link between a myosin head and an actin molecule

158
Q

Describe the cross-bridge cycle. (6)

A

myosin hydrolyzes ATP into ADP+Pi; ADP+Pi remain bound to myosin head which is now energized; myosin binds to actin to form cross-bridge and releases Pi; myosin pulls thin filament towards center of sarcomere in the power stroke; ADP is lost; myosin binds to a new molecule of ATP and is displaced from actin

159
Q

What is the power-stroke? (2)

A

when the myosin head pulls the thin filament towards the center of the sarcomere; also when it returns to its original conformation and releases Pi+ADP

160
Q

What happens in rigor mortis?

A

the cell can’t produce any ATP and therefore the cross-bridge cycle isn’t broken, which causes muscle stiffness

161
Q

Describe a relaxed muscle in the context of myosin, ADP, and Pi.

A

the myosin heads are in the activated conformation bound to ADP and Pi but are unable to bind to actin because the binding site is blocked

162
Q

What blocks the myosin-actin binding site on the actin molecule?

A

tropomyosin

163
Q

Tropomyosin is what type of filament?

A

thin filament

164
Q

What is troponin?

A

a regulatory protein complex that holds tropomyosin and actin together

165
Q

What does tropomyosin do?

A

blocks the myosin-actin binding site

166
Q

The regulatory interactions between troponin and tropomyosin are controlled by

A

Ca2+ concentrations in the muscle fiber cytoplasm

167
Q

Describe tropomyosin when Ca2+ levels are low.

A

When Ca2+ levels are low, tropomyosin inhibits cross-bridge formation

168
Q

Describe tropomyosin when Ca2+ levels are high.

A

Ca2+ binds to troponin, which alters its conformation and moves the troponin-tropomyosin complex, which exposes the myosin-actin binding site

169
Q

Where do muscle fibers store Ca2+?

A

sarcoplasmic reticulum

170
Q

What is the sarcoplasmic reticulum?

A

a modified endoplasmic reticulum that stores Ca2+ in muscle fibers

171
Q

What happens to a muscle fiber membrane when the muscle fiber is stimulated to contract?

A

the muscle fiber membrane becomes depolarized

172
Q

What are transverse tubules?

A

invaginations of the cell membrane that transmit muscle fiber depolarizations to the SR

173
Q

Depolarization of the T tubules causes

A

the SR to release Ca2+, which diffuses into the myofibrils and binds to troponin, allowing contraction

174
Q

The involvement of Ca2+ in muscle contraction is called

A

excitation-contraction coupling

175
Q

Motor neurons that stimulate skeletal muscles are called

A

somatic motor neurons

176
Q

The synapses between neurons and muscle cells are called

A

neuromuscular junctions

177
Q

T/F: each human muscle fiber has only a single synapse with a branch of an axon.

A

true

178
Q

What is the neurotransmitter used for muscle contraction?

A

acetylcholine

179
Q

How does the Ca2+ return to the SR?

A

via a membrane protein using energy from ATP hydrolysis in active transport fashion

180
Q

What is a motor unit?

A

set of muscle fibers innervated by all the axonal branches of a motor neuron, including the motor neuron itself

181
Q

Why is the division of muscle into motor units advantageous?

A

allows a finer degree of control

182
Q

What is recruitment?

A

cumulative increase of numbers and sizes of motor units to produce a stronger contraction

183
Q

What is summation?

A

cumulative response of an electric shock after another electric shock of a muscle

184
Q

What is tetanus?

A

sustained contraction

185
Q

Skeletal muscle fibers can be divided on the basis of their contraction speed into

A

slow-twitch and fast-twitch fibers

186
Q

Give an example of a human fast-twitch fiber.

A

muscles in the eye

187
Q

Give an example of a human slow-twitch fiber.

A

soleus muscle in the leg

188
Q

Describe slow-twitch fibers. (4)

A

rich capillary supply; numerous mitochondria; numerous aerobic respiratory enzymes; high concentration of myoglobin

189
Q

Which protein is abundant in slow-twitch fibers?

A

myoglobin

190
Q

Myoglobin is abundant in which fiber?

A

slow-twitch fibers

191
Q

What is the color of myoglobin?

A

red

192
Q

What is another name for slow-twitch fibers

A

red fibers

193
Q

Which fiber can sustain action of a long period of time without fatigue?

A

slow-twitch fibers

194
Q

Describe fast-twitch fibers. (5)

A

fewer capillaries; fewer mitochondria; not much myoglobin; high glycogen content; many glycolytic enzymes

195
Q

What is another name for fast-twitch fibers?

A

white fibers

196
Q

How do fast-twitch fibers respire?

A

anaerobically

197
Q

Skeletal muscles at rest obtain most of their energy from

A

the aerobic respiration of fatty acids

198
Q

In what time period to skeletal muscles respire anaerobically?

A

for the first 45 to 90 seconds of moderate-to-heavy exercise

199
Q

What is aerobic capacity?

A

maximum rate of oxygen consumption in the body

200
Q

What is muscle fatigue?

A

use-dependent decrease in the ability of a muscle to generate force

201
Q

Short-term fatigue has been shown to occur because of

A

a buildup of Pi from the breakdown of creatine phosphate

202
Q

Long-term fatigue has been shown to occur because of

A

depletion of glycogen

203
Q

What adaptation improves physical endurance?

A

any adaptation that spares the use of muscle glycogen

204
Q

Does endurance training increase muscle size?

A

no, endurance training does not increase muscle size

205
Q

When is muscle enlargement produced?

A

by frequent periods of high-intensity exercise like weight-lifting

206
Q

What is another name for type I muscle fibers?

A

slow-twitch fibers

207
Q

What is another name for type II muscle fibers?

A

fast-twitch fibers

208
Q

What is hypertrophy?

A

increased cell size

209
Q

Resistance training increases

A

the thickness of fast-twitch fibers (muscles don’t grow by cell division)

210
Q

Locomotion requires what two mechanisms?

A

propulsive mechanism and control mechanism

211
Q

What is appendicular locomotion?

A

locomotion that is produced by appendages that oscillate

212
Q

What is axial locomotion?

A

bodies that undulate, pulse, or undergo peristaltic waves

213
Q

Large animals undergo what two types of locomotion?

A

appendicular or axial locomotion

214
Q

How does aquatic mammal locomotion differ from fish locomotion?

A

waves pass from top to bottom instead of side to side

215
Q

What is another name for top-to-bottom flexing?

A

dorsoventral flexing

216
Q

How do mollusks locomote?

A

by secreting a mucus that they glide along using a muscular foot

217
Q

How many times has convergent evolution of flying occurred?

A

4 times - 1 in insects, 3 in vertebrates

218
Q

Describe air pressure around a wing.

A

top of the wing has lower pressure, bottom of the wing has higher pressure

Biology 2312 (11 decks)

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