MCAT BIO CH. 11 PART 1 Flashcards
1
Q
What are the three types of muscle?
A
- Skeletal
- Cardiac
- Smooth
2
Q
What are tendons?
A
Connect muscles, strong connective tissue formed of collagen
3
Q
What are the four ways skeletal muscles can move?
A
- Flexing
- Extending
- Abducting
- Adducting
4
Q
What skeletal muscle movement is flexing?
A
Muscles can move a joint by flexing
5
Q
What skeletal muscle movement is extending?
A
Increasing the angle of the joint
6
Q
What skeletal muscle movement is abducting?
A
Moving away from the body’s midline
7
Q
What skeletal muscle movement is adducting?
A
Moving towards the body’s midline
8
Q
What is the only way for bones and joints to move?
A
By contracting skeletal muscles
9
Q
What does it mean when a skeletal muscle has an origin?
A
Point on this bone where the muscle attaches
10
Q
What does it mean when a skeletal muscle has a muscle insertion?
A
Point where the muscle attaches on the bone more distant from the center of the body
11
Q
What are muscles that are antagonistic?
A
Muscles that are responsible for movement in opposite direction
12
Q
What are muscles that are synergistic?
A
Muscles that move a joint in the same direction
13
Q
When antagonistic muscles receive stimulation by neurons, how do they differ between contraction and relaxation?
A
Difference in timing of the signal (frequency) and the amount of neurotransmitter released
14
Q
What are fascicles based on structure of skeletal muscle?
A
Connective tissue that holds the contractile tissue together in bundles to allow flexibility within the muscle
15
Q
What are muscle fibers?
A
Myofibers; single skeletal muscle cell
16
Q
Where are myofibers found?
A
Located within each fascicles bundle
17
Q
What is an important factor of the nucleus of skeletal muscle cells?
A
They are multinucleate syncytia
18
Q
How is the multinucleate syncytia formed in skeletal muscle cells?
A
By the fusion of individual cells during development
19
Q
What is sarcolemma?
A
The myofiber cell membrane
20
Q
What is the sarcolemma made out of?
A
Of plasma membrane and an additional layer of polysaccharide and collagen
21
Q
Why is it important for the myofiber to have sarcolemma?
A
Helps the cell to fuse with tendon fibers
22
Q
What are myofibrils?
A
Smaller myofiber units that generate contractile force of skeletal muscle
23
Q
What are the proteins in the myofibril that generate contraction?
A
Actin and myosin
24
Q
What is the difference between actin and myosin when they polymerize?
A
Actin polymerizes to form thin filaments, myosin forms thick filaments
25
What is the reason for the striated appearance of the skeletal muscle?
Due to the overlapping arrangement of bands of thick and thin filaments in sarcomeres
26
What are the sarcomeres bound by?
Z lines
27
How are the sarcomeres aligned and where are they located?
End to end, in myofibril
28
Thick filaments are also attached to the Z lines. T/F
False: they are not
29
Thin filaments attach to each Z line and overlap with ______ in the middle of each ______?
Thick filaments; sarcomere
30
What are I bands based on myofibril?
Regions of he sarcomere composed only of thin filaments
31
What are A band based on myofibril?
The full length of the thick filament represents the A band within each sarcomere
32
What is the H zone based on myofibril?
Region composed of only thick filaments
33
Where is contraction generated based on myofibril structure?
Overlapping regions of thick and thin filaments
34
Based on thick and thin filaments, when does contraction occur based on their structure?
When the thin and thick filaments slide across each other, drawing the Z lines of each sarcomere closer together
35
During muscle contraction, do thick and thin filaments shorten? What shortens?
No they slide across each other; the sarcomere sheens without them changing their lengths
36
Filament sliding requires....?
ATP hydrolysis
37
Which protein uses ATP to create movement?
Myosin - sometimes also named myosin ATPase
38
Each myosin monomer contains a ___ and a ____?
Head and tail
39
The head of the myosin monomer attaches to what?
The myosin binding site; a specific site on an actin molecule
40
When myosin and actin are connected, they're said to be connected by....
A crossbridge
41
Contraction occurs when what decreased, based on myosin and actin?
When the angle between the head and the tail decreases
42
What is the first step of filament sliding in skeletal muscle?
Cross bridge formation; myosin has ADP and Pi bond
43
What is cross bridge formation?
Binding of the myosin head to a myosin binding site on actin
44
What is the second step of filament sliding in skeletal muscle?
Power stroke from myosin
45
What is the power stroke from myosin and when does it happen during filament sliding?
Myosin head moves to a low energy confirmation and pulls actin chain towards center of sarcomere; ADP is released and during 2nd step
46
What happens during step two then myosin head moves to a low energy confirmation?
They pull actin chain towards center of sarcomere
47
In which step of filament sliding does a new ATP molecule binds?
Step 3
48
What is the third step of filament sliding in skeletal muscle?
ATP binding necessary to release actin by the myosin head
49
What is the four step of filament sliding in skeletal muscle?
ATP hydrolysis, myosin head cocked formation
50
What does is mean when mentioned the myosin heads are cocked?
Set in a high-energy conformation
51
In the myofiber, contraction only occurs when...?
The cytoplasmic Ca2+ increases
52
Which molecule contains troponin-tropomyosin complex?
Thin filaments
53
What does troponin-tropomyosin complex?
Prevents contraction when Ca2+ is not present
54
What is tropomyosin?
A long fibrous protein that winds around the actin polymer, blocking all the myosin-binding sites
55
What is troponin?
A globular protein bound to the tropomyosin that can bind Ca2+
56
What happens to troponin when it binds to Ca2+?
It undergoes conformation change that moves tropomyosin out of the way so that myosin heads can attach to actin
57
What protein is responsible for ATP hydrolysis during muscle contraction?
Myosin protein with the ATPase activity
58
What is the neuromuscular junction?
The synapse between an axon terminus and a myofiber
59
The neuromuscular junction is a single point. T/F
False: A long invagination of the cell membrane - axon terminus is elongated to fill the long synaptic cleft
60
What is the purpose of the neuromuscular junction?
Allow the neuron to depolarize a large region of the postsynaptic membrane at once
61
What is the motor end plate?
The postsynaptic membrane of the neuromuscular junction
62
What is the neurotransmitter as the neuromuscular junction point?
ACh acetylcholne
63
During the impulse transmission at the NMJ, an action potential arrives at the axon terminus and triggers the opening of _______ channels?
voltage-gated Ca 2+ channels
64
During the impulse transmission at the NMJ, the resulting increase in ________ triggers the _______ of ACh?
Intracellular Ca 2+; release of vesicles of acetylcholine
65
What does the postsynaptic membrane contain to read ACh?
Contains ACh receptors which are ligand-gated Na+ channels
66
Based on impulse transmission in NMJ, how does ACh reach their receptors?
By diffusing across the synaptic cleft
67
What happens when ACh binds to the receptors of the postsynaptic membrane receptors?
A postsynaptic sodium influx, which depolarizes the postsynaptic membrane
68
What is the end late potential?
The depolarization of the postsynaptic membrane when ACh binds to the receptors of the postsynaptic membrane
69
What is the miniature EPP?
The smallest measurable AP dcaused by exocytosis of a single ACh vesicle
70
When does ACh stop stimulating postsynaptic receptors?
Until it is destroyed by acetylcholinesterase
71
What are T-tubules?
Transverse tubules; deep invaginations of the cell membrane which allow the AP to travel into the thick cell
72
What is the structure of the sarcoplasmic reticulum?
A huge, specialized smooth endoplasmic reticulum that enfolded each myofibril in the cell
73
What is the SR specialization?
Specialized to sequester and release Ca 2+
74
How is the calcium removed from the SR?
Active transporters remove calcium from the sarcoplasm
75
What is the sarcoplasm?
Myofiber cytoplasm
76
What happens when the AP travels down the T-tubular network?
It depolarizes the cell and the sarcoplasmic reticulum
77
The sarcoplasmic reticulum contains what? What does it allow?
Voltage-gated Ca 2+ channels, allows calcium to rush out of the SR into the sarcoplasm upon depolarization
78
When the cell myofiber repolarizes, what happens to the calcium?
It is actively sequestered by the SR and contracted is ended
79
The smallest measurable muscle contraction is know as....?
Muscle twitch
80
What are the two ways the nervous system can increase the force of contraction?
1. Motor unit recruitment
| 2. Frequency summation
81
What is a motor unit?
A group of myofibers innervated by the branches of a single motor neuron's axon
82
What does a muscle twitch result from?
The activation of one motor neuron and a larger twitch can be obtained by activating more motor neurons
83
What is a motor unit recruitment?
Activating or recruiting more motor neurons and thus more myofibers
84
When does each contraction ends?
When the SR returns calcium to low resting levels
85
What is tetanus?
Rapidly repeating series of stimulation resulting in the strongest contraction possible
86
The skeletal muscle does not have a refractory period.T/F
False: it does
87
What is frequency summation?
The second contraction builds on the first as there's no time for calcium to become sequestered
88
When does frequency summation over through refractory period?
Successive stimulation must be greater than the duration of the refractory period
89
What is the length-tension relationship?
A muscle contracts more forcefully at an optimum length
90
What is the length of a sarcomere at the muscle contracting at optimum length?
2.2 microns
91
What happens at 2.2 microns in sarcomere length based on contraction?
A maximum degree of overlap between thick and thin filaments
92
Why is greater sarcomere length favorable compared to shorter length?
A shorter length causes filaments to obstruct each other's movement by bumping together
93
What molecule is used for intermediate-term energy storage in the myofiber?
Creatine phosphate
94
What is myoglobin? What is its role?
A globular protein; provide an oxygen reserve by taking O2 rom hemoglobin and then releasing it as needed
95
What happens when the supply of oxygen runs low in the myofiber?
Metabolism becomes anaerobic and lactic acid is produced
96
When lactic acid is produced, how does it cause a pH drop in the blood?
Because it moves into th bloodstream
97
What happens to the lactic acid that infiltrates our blood, how is it removed?
The liver picks up this lactate and converts it into pyruvate
98
What is rigor mortis?
Rigidity of skeletal muscles which occurs soon after death due to complete ATP exhaustion
99
Skeletal muscle fibers fall into two categories:....
Slow twitch fibers and fast twitch fibers
100
What are type I slow twitch fibers known as?
Red slow twitch or red oxidative
101
Why are they called red oxidative or red slow twitch fibers?
Because of their high myoglobin content
102
Why do red oxidative have much better blood supply than fast twitch fibers?
Extensive surrounding capillary network
103
What allows slow twitch fibers to maintain contraction for extended periods of time?
Good oxygen delivery and ability to store oxygen in myoglobin
104
Why does Type IIA fast twitch fibers has more fatigue resistant than Type II B?
Have more mitochondria
105
What are Type IIA known as?
Fast twitch oxidative fibers
106
What type of force does Type IIB fast twitch fibers provide?
Explosive force needed
107
What is different between the skeletal muscle maximum length and the cardiac muscle maximum length?
Cardiac muscle has no such limitations
108
What is different between the structure of skeletal and cardiac muscle?
Skeletal muscles are syncytial and cardiacs are not, they each only have one nucleus
109
All the muscle cells in the cardiac muscle are interconnected with what?
By gap junctions known as intercalated disks
110
What do the intercalated disks in the cardiac muscle allow?
Allow AP to propagate throughout the entire heart without allowing nuclei and cytoplasmic contents to be shared
111
What is heart muscle called based on the function of their intercalated discs?
Functional syncytium
112
What is different between the calcium content between skeletal and cardiac muscle?
Skeletal muscle calcium comes for SR intracellular structure, cardiac muscle requires some from extracellular environment
113
If neurons don't trigger cardiac contraction, what does?
Pacing by the sinoatrial node
114
Which muscle does not depend on stimulation by motor neurons?
Cardiac muscles
115
The vagus nerve release ACH for heart muscle at chemical synapses with the heart is....?
Inhibitory
116
What type of channels is the AP in cardiac muscles dependent on?
Na and Ca channels
117
What are sodium channels in the cardiac muscles called? What about calcium channels?
Sodium: fast channels Calcium: slow channels
118
Why are calcium channels in cardiac muscles called slow channels?
They respond more slowly to threshold depolarization
119
What does the voltage-gated calcium channel in cardiac muscle cause the cardiac AP to have?
Plateau
120
What is the significance of the plateau phase in cardiac muscle?
1. Longer duration of contraction
| 2. Longer refractory period to prevent disorganized impulses
121
Smooth muscles have T-tubules. T/F
False: they're too small
122
Smooth muscles are narrower and shorter than skeletal muscles. T/F
True
123
How many nucleus do smooth muscle cells have? How is it connected to its neighbors?
One nucleus; by gap junctions
124
Why does the cell appear smooth and not striated in smooth muscle cells?
Thick and thin filaments not organized into sarcomeres in smooth muscle
125
What molecules control contraction in smooth muscle cells?
Calmodulin and myosin light-chain kinase
126
What does calmodulin do and what does myosin light-chain kinase do?
Binds Ca 2+ and activates MLCK, MLCK then phosphorylates a portion of the myosin molecule
127
What is different with the calcium storage of smooth and skeletal muscle?
Smooth muscle also relies on extracellular calcium
128
What does the smooth muscle cell action potential vary on?
Depending on the location of the smooth muscles
129
How do smooth muscles cells sometimes sustain prolonged contractions?
Has action potentials similar to those of cardiac muscle, although with a less sharp spike
130
How are the resting potentials of smooth muscle cells?
Fluctuating
131
The fluctuations in resting potentials are called what and due to what?
Called slow waves; ion pass through the gap junctions between neighboring cells, causing the changes in resting potential to propagate like waves
132
What are slow waves necessary for based on smooth muscle cells?
Coordinate the action potentials
133
How are the amplitudes of slow waves passing through smooth muscle cells altered?
Increased by ACh, decreased by NE
134
How do the motor neurons differ between smooth muscle cells and skeletal muscle cells?
Smooth: autonomic motor neurons while skeletal have somatic motor neurons
135
How does the action potential differ between smooth, skeletal and cardiac?
Skeletal: Each AP limited to one large myofiber
Cardiac: One large function syncytium
Smooth: Spreads from cell to cell; shares features of bot
136
What does the skeletal system synthesize and what is it called?
The elements ht blood; hematopoiesis
137
What are the axial components of the skeleton? What are the appendicular?
Axial: Skull, vertebral column and rib cage
Appendicular: all other bones
138
What are connective tissues derived from?
Fibroblast, progenitor
139
What are two important fibrous protein?
Collage, elastin
140
What are three important fibroblast cells?
Adipocytes (fat cells), Chondrocytes (Cartilage cells), Osteocytes (Bone cells)
141
Why does connective tissue differ from other tissue types in the body?
Primarily extracellular material wit few cells scattered in it
142
What is the matrix based on connective tissue?
Extracellular material
143
What are ground substance based on connective tissue?
Fibers in connective tissue, thick viscous material
144
What are the main ingredients of the ground substance in connective tissue?
Proteoglycans
145
What are proteoglycans?
Large macropolymers consisting of protein core with many attached carbohydrate chains in connective tissue
146
What are glycosaminoglycans?
Carbohydrate chains that attach proteoglycans in connective tissue
147
What gives connective tissues their thickness and firmness?
The carbohydrate chains of the connective tissue are hydrophilic
148
What are the two types of connective tissue?
1. Loose
| 2. Dense
149
What is loose connective tissue?
Packing tissues including areolar tissue and adipose tissue
150
What is areolar tissue and what is adipose tissue?
Areolar: Soft material between cells Adipose: Fat tissue
151
What is dense connective tissue?
Tissues that contain large amounts of fibers
152
What are the two types of bone shapes?
Flat and long
153
What are flat bones mostly used for?
Protection of organs
154
What are long bones used for?
Support and movement
155
What is a diaphysis? What about. an epiphysis?
Main shaft of a long bone; flared end
156
What are the two general structures of a bone?
Compact or spongy
157
How are compact bones based on structure? What about spongy?
Compact: hard and dense
Spongy: Porous
158
Where are spongy bones always found?
Surrounded by a layer of compact bone
159
What are the three different types of marrows?
1. Bone marrows
2. Yellow marrow
3. Red marrow
160
What is bone marrow?
Non-bony material found int he shafts of long bones and pores of spongy bones
161
What is red marrow?
Found in spongy bone within flat bones and is the site of hematopoiesis
162
What is yellow marrow?
Found in the shafts of long bones filled with fat and is inactive
163
Bones are composed of two principal ingredients, what are they?
1. Collagen
| 2. Hydroxyapatite
164
What is hydroxyapatite?
Solid material consisting of calcium phosphate crystals
165
What characteristic does hydroxyapatite provide for bone structures?
strength and inflexibility
166
What are spicules or trabeculae?
Spikes of bone in spongy
167
What is an osteon?
The basic unit of compact bone structure
168
What is the osteon sometimes referred to?
Haversian system
169
What is the central canal of the osteon?
A hole which contains blood, lymph vessels and nerves
170
What are lamellae in compact bones?
Surrounding the cancel, concentric rings of bone
171
What is the canaliculi of compact bones? What about the lacunae?
Tiny channels; spaces
172
Where are osteocytes located and what are they?
In each lacuna; mature bone cell
173
Why do osteocytes have long processes that extend down the canaliculi?
To contact other osteocytes through gap junctions allowing cells to exchange nutrients and waste
174
What are perforating or volkmann's canals?
Channels that run perpendicular to central canals to connect osteons
175
What is cartilage?
A strong, flexible extrcellular tissue
176
What is cartilage secrete by?
Chondrocytes
177
What are the three types of cartilage?
Hyaline, elastic and fibrous
178
What is hyaline cartilage and found where?
Strong and somewhat flexible; found in larynx and trachea
179
What is elastic cartilage?
Contains elastin; found in areas that require support and more flexibility - outer ear and epiglottis
180
What is articular cartilage?
Joints lined by hyaline cartilage
181
What is fibrous cartilage?
Rigid and found in places where very wrong support is needed
182
What does avascular mean? Which component the body is that?
No blood vessels; cartilage
183
How does cartilage receive nutrition and immunity since its avascular?
From surrounding fluid
184
What is the difference between ligaments and tendons?
Ligaments connect bones to other bones, tendons connect bones to muscles
185
What are synarthroses joints?
Immovable joints
186
What are amphiarthroses joints?
Slightly movable joints
187
Wha are diarthroses joints?
Freely movable joints
188
What are Immovable joints called?
synarthroses
189
What are Slightly movable joints called?
amphiarthroses
190
What are Freely movable joints called?
diarthroses
191
What is synovial fluid?
Lubricate movable joints, kept within the synovial capsule
192
What does arthritis damage?
Destruction of articular cartilage
193
Bone growth occurs by what?
Endochondral ossification - hyaline cartilage is produced and replaced by bone
194
What is intramembranous ossification?
Synthesis of bone from an embryonic tissue called mesenchyme
195
What does intramembranous ossification result in?
Flat bones
196
What is the epiphyseal plate?
A disk of hyaline cartilage that is actively being produced by chondrocytes
197
Where is the epiphyseal plate found?
Between the diaphysis and epiphysis
198
What is the epiphyseal line?
The fusion point where the diaphysis and epiphysis have fused together
199
What is the bone process called remodeling?
Bones are degraded and remade
200
What are osteoblasts?
Cells that make bone by laying down collage and hydroxyapatite
201
What do osteoclasts do?
Dissolve hydroxyapatite crystals
202
Which hormones control the activity of osteoclasts and osteoblasts?
Parathyroid hormone, calcitonin and calcitriol
203
What is calcitriol derived from?
Kidney from vitamin D
204
Which hormones controlling the osteoclast to osteoblast activity reduces it?
Calcitonin
205
Which hormones controlling the osteoclast to osteoblast activity increases it?
PTH and calcitriol
206
What is the effect of parathyroid hormone on the kidney?
Increases absorption of calcium
207
What is the effect of parathyroid hormone on the intestines?
Increases intestinal calcium absorption
208
What is the effect of calcitriol on the intestines?
Increases intestinal calcium absorption
209
What is the effect of calcitriol on the kidneys?
Increases reabsorption's of phosphorus
210
What is the effect of calcitonin on the kidneys?
Decreases reabsorption of calcium
211
What is the effect of calcitonin on the intestines?
Doesn't have any
