Exam 3 Flashcards
(140 cards)
1
Q
Negative ions are ______ and are found ______ the membrane potential
A
Anions inside
2
Q
Positive ions are ______ and are found ______ the membrane potential
A
Cations outside
3
Q
Two basic means by which membrane potential can develops
A
Active transport (ATP) Diffusion
(They both create charge imbalance)
4
Q
Membrane potential caused by active transport (the electrogenic pump)
A
3 Na+ out for every K+ in
5
Q
What is the nerst potential for K+
A
-94 mV
6
Q
What is the nerst potential for Na+
A
+61 mV
7
Q
How does a normal cell automatically develop a membrane potential
A
The sodium-potassium pump (3 sodiums out for every 2 potassiums in, leads to negative membrane potential)
8
Q
Resting nerve membrane is normally __________times more permeable to potassium as to sodium
A
50-100
9
Q
Inside the nerve fiber are more _______ that cannot diffuse out
A
Anions
10
Q
What if the sodium potassium pump doesn’t work but there are already a high concentration of K ions inside, and the membrane is highly permeable to K+ and poorly permeable to Na+
A
Diffusion happens and the negative membrane potential is reestablished
11
Q
How can an action potential be elicited in a nerve fiber
A
By almost any factor that suddenly increases the permeability of the membrane to sodium ions
12
Q
Two stages of action potential
A
Membrane depolarization
Membrane repolarization
13
Q
The sudden loss of normal negative potential inside the fiber
A
Membrane depolarization
14
Q
The positive potential that develops momentarily inside the fiber is called the
A
Reversal potential
15
Q
The excess positive charges inside the fiber are transferred back out of the fiber, and the normal negative resting membrane potential returns
A
Membrane repolarization
16
Q
At rest, __________ are almost completely closed (calcium ions close channels)
A
Sodium channels
17
Q
At rest, _______ are only partially closed (thus, 50-100x more permeable)
A
Potassium channels
18
Q
After potential: a brief _________ period following the action potential takes place due to the efflux of K+
A
Hyperpolarization
19
Q
The period of time of complete insensitivity to another stimulus
A
Absolute refractory period
20
Q
The period near the end of the repolarization phase where a greater than threshold strength stimulus can initiate another action potential
A
Relative refractory period
21
Q
What are the five characteristics of muscles
A
Excitability Conductivity Contractility Elasticity Extensibility
22
Q
The ability of muscle tissue to receive and respond to stimuli
A
Excitability
23
Q
The ability of muscle tissue to transport an action potential along the plasma membrane
A
Conductivity
24
Q
The ability to shorten and thicken when a sufficient stimulus is received
A
Contractility
25
The ability of a muscle to retract to its original shape after contraction or extension
Elasticity
26
The ability of muscle tissue to be stretched
Extensibility
27
3 functions of muscles
Motion
Posture
Heat production
28
3 types of muscles
Skeletal
Cardiac
Smooth
29
Long, cylindrical, voluntary movement, obvious striations, multinucleated cells
Skeletal muscle
30
Branching, involuntary movement, generally unnucleated, striated, intercalated discs
Cardiac
31
Involuntary, spindle shaped, unstriated, one nuclei, found in the walls of hollow organs
Smooth
32
Sheet or broad band of fibrous connective tissue beneath the skin or around muscles or other organs
Fascia
33
Two types of fascia
Superficial
| Deep
34
Immediately deep to the skin, found in the adipose tissue and loose connective tissue
Superficial fascia
35
Dense connective tissue that lines the body wall and extremities and holds muscle together, separating them into functioning groups
Deep fascia
36
Fascia around the entire muscle (dense irregular fibrous connective tissue)
Epimysium
37
Muscle bundles
Fascicles
38
Fascia around fascicles
Perimysium
39
Fascia around each muscle fiber (the sheath is areolar connective tissue with many reticular fibers)
Endomysium
40
Fibrous connective tissue that connects muscle fascia to the periosteum of bones
Tendons
41
Tubes of fibrous connective tissue that encloses certain tendons, especially those of the wrist and ankle
Tendon sheaths
42
The less movable end (generally proximal)
Origin
43
The more movable end (generally distal)
Insertion
44
What kind of nerve and blood supply penetrates skeletal muscle
One artery and 1 or 2 veins with each nerve, long and winding capillaries go within the endomysium, each skeletal muscle usually makes contact with a portion of a nerve cell called a synaptic end bulb
45
Cell membrane of muscle fiber
Sarcolemma
46
The cytoplasm of striated muscle fibers
Sarcoplasm
47
What is the sarcoplasmic reticulum
Comparable to the smooth endoplasmic reticulum
48
The original development of the membrane potential is by
Active transport
49
A negative membrane potential may be re-established by
Diffusion
50
What three ways may an action potential be elicited in a nerve fiber
Electrical stimulation
Mechanical compression
Application of chemicals to the membrane
51
What is the reversal potential
The positive potential that develops momentarily inside the fiber
52
The excess positive charges inside the fiber are transferred back out of the fiber and the normal negative resting membrane potential returns
Repolarization
53
What causes repolarization
Due to diffusion by the efflux is potassium
54
Light bands of only actin
I bands
55
Dark bands of both actin and myosin
A bands
56
In the middle of the I band, attaches myofibril with myofibril
Z disc
57
In the middle of the A band
H zone
58
In the center of the H zone
M line
59
When the sarcomere shortens, what happens to the I band, H zone, and A band
The I band shortens, the H zone shortens and disappears and the A band stays the same
60
Myosin heads contain what two things
An actin binding site and an ATP binding site
61
What are actin filaments composed of
Actin
Tropomyosin
Troponin
62
What are the two myosin binding sites
F-Actin (double stranded protein molecule)
| G-Actin (single molecule)
63
In resting state this covers the active sites on the actin strands
Tropomyosin
64
What three things does troponin have a high affinity for
Tropomyosin
Calcium
Actin
65
A neuron that stimulates muscle tissue
Motor neuron
66
What is a neruomuscular junction or motor end plate
Refers to the axon terminal of a motor neuron along with the portion of the sarcolemma that is close to the axon terminal
67
Three types of plasma membrane ion channels
Passive or leakage
Chemically gates (ligand gated)
Voltage gated
Mechanically gated channels
68
What channel is always open
Passive or leakage
69
What channel opens with the binding of a specific neurotransmitter
Chemically gated (ligand gated)
70
What channel opens and closes in response to a membrane potential
Voltage gated
71
What channel opens and closes in repose to physical deformation of receptors
Mechanically gated channels
72
During depolarization what channels are open
Sodium
73
During repolarization what channels are open
Potassium
74
What happens to the membrane potential during repolarization
The internal negativity is restored
75
What ions are moving in during repolarization
The k ions are moving out
76
What is an example of a voltage gated channel
An Na channel
77
What channels are closed when the intracellular environment is negative and open when it’s positive
Voltage gated channel (Na+)
78
These channels have receptors and respond to chemicals
Ligand gated channels (like Acetylcholine)
79
K channels stay open too long and the nerst potential is nearly reached
Hyperpolarization
80
The inside of the membrane becomes less negative
Depolarization
81
The membrane returns to its resting membrane potential
Repolarization
82
The inside of the membrane becomes more negative than the resting potential
Hyperpolarization
83
In what direction to action potentials travel
Down the membrane
84
Can action potentials travel in one direction or all directions
All directions
85
_______ cannot spread far from the area surrounding the site of stimulation
Local potentials
86
May result in a local potential
Subthreshold stimulus (Graded potential)
87
_________ results in an action potential
Threshold stimulus
88
Short lived, local changes in membrane potential that decrease in intensity with distance and their magnitude varies directly with the strength of the stimulus
Graded potentials
89
Can graded potentials imitate action potentials
If they’re sufficiently strong
90
An excitatory local potential, one that results in hypopolarization, is called an
Excitatory pre-synaptic potential (EPSP)
91
An inhibitory local potential, one that results in hyperpolarization, is called an
Inhibititory pre-synaptic potential (IPSP)
92
Action potential frequency is directly proportional to
Stimulus strength
93
Step one of contracting a muscle
An impulse arrives at the synapse (presynaptic terminal) between the motor neuron and the muscle fiber (postsynaptic terminal)
94
Step two of contracting a muscle
The transmitter substance, usually acetylcholine, diffuses across the synaptic cleft at the neuromuscular junction
95
Step three of contracting a muscle
Permeability of the muscle plasma membrane is altered, sodium channels open causing an action potential
96
Step four of muscle contraction
An action potential travels along membrane of the muscle cell and moves deep into the muscle cell by the T tubules
97
Step five of muscle contraction
The sarcoplasmic reticulum becomes more permeable to calcium ions and calcium ions are released
98
Step six of muscle contraction
Calcium ions diffuse into the sarcoplasm
99
Step seven of muscle contraction
Calcium ions bind to the troponin
100
Step eight of muscle contraction
The troponin-tropomyosin complex moves away from the active sites on the G actin
101
Step 9 of muscle contraction
Myosin cross bridges that have hydrolyzed ATP prior to this event bind to the actin
102
Step ten of muscle contraction
The power stroke occurs and ADP and pi are released (myosin and actin are still attached)
103
Step 11 of muscle contraction
New ATP binds to the myosin head
104
Step 12 of muscle contraction
Cross bridges are released from the actin
105
Step 13 of muscle contraction
ATP is hydrolyzed to ADP and Pi (recocking the myosin head)
106
Step 14 of muscle contraction
Steps 9-13 continue
107
Step 15 of muscle contraction
The sarcomere shortens
108
Step 16 of muscle contraction
Calcium ions return to the sarcoplasmic reticulum (returning the troponin-tropomyosin complex over the active sites on the G-actin) and the muscle relaxes
109
Binds with ACh and breaks ACh down into acetic acid and choline
AChE
110
The motor unit and all the muscle fibers that it stimulates
Motor unit
111
Means the adding together of individual muscle twitches to make strong and concerted muscle movement
Summation
112
Contraction with partial relaxation
Incomplete tetanus
113
Sustained contraction with no relaxation
Complete (fused) tetanus
114
A condition in which skeleton muscle contracts more forcefully in response to the same strength of stimulus after it has contracted several times
Treppe
115
What are the two ways summation occurs
Multiple motor unit summation
| Wave summation
116
Increasing the number of motor units contracting simultaneously within one muscle; spatial
Multiple motor unit summation
117
Wave summation is also known as
Temporal summation
118
When the muscle does not shorten during the contraction
Isometric
119
When the muscle shortens, but the tension on the muscle remains constant
Isotonic
120
Muscle shortens and does work
Concentric contractions
121
Muscle contracts as it lengthens; this is about 50% more forceful than the other type of contractions at the same load
Eccentric contractions
122
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Slow oxidative fibers
High myoglobin content
Smaller diameter
More mitochondria
More blood capillaries
Relatively slow
```
Red muscle fibers
123
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Fast glycolic fibers
Lower myoglobin
Larger in diameter
Fewer mitochondria
Fewer blood capillaries
Fast muscles
More extensive sarcoplasmic reticulum
```
White muscle fibers
124
Without oxygen
Anaerobic respiration
125
With oxygen
Aerobic respiration
126
What is the function of the sarcoplasmic reticulum
Calcium storage/regulation
127
Portion of the sarcoplasmic reticulum that deals extensively with calcium going in and out
Terminal cisternae
128
Myofilament is smaller than a
Myofibril
129
Calcium binds to
Troponin ( a protein)
130
Myosin heads attach to actin due to
Phosphorylation of ATP
131
Energy is stored in _______ in ADP
Phosphates
132
Is acetylcholine excitatory or inhibitory
Both
133
Are all motor units the same size?
No
134
Is treppe spatial
Yes, it allows for relaxation
135
Is temporal spatial
No it does not allow for relaxation
136
Concentric involves _____
Shortening
137
Eccentric involves
Lengthening
138
Can muscle fibers partially contract
No
139
What do the arrows look like on spatial summation
They increase in size (increase in stimulus strength)
140
What do the arrows look like on temporal (wave) summation
They’re closer together (increase in stimulus frequency)
