Exam 1 Flashcards
(128 cards)
1
Q
What is physiology?
A
The study of the functions of the body.
2
Q
What is anatomy?
A
The study of the structures of body.
3
Q
What is homeostasis?
A
Sensing internal and external changes, and responding to the changes by controlling the organ systems to maintain the composition of the internal environment.
4
Q
How does negative feedback help maintain homeostasis?
A
When an increase in the input of a system causes a decrease in the output of the system. The new output (decreased) becomes the new input and the system is kept within the range of regulation as defined by the setpoint.
5
Q
What are the components of a control system?
A
- Stimulus
- Sensor
- Afferent neurons
- Integrator
- Efferent neurons
- Effectors
- Response
6
Q
What is the role of the stimulus?
A
The change in the internal or external environment that triggers the need to maintain homeostasis.
7
Q
What is the role of sensor?
A
Acts as the receptor. Determines the presence or absence of some component in the internal or external environment, and transmit energy of stimuli to the afferent neurons.
8
Q
What is the role of afferent neurons?
A
Deliver information from the stimulus to the integrator.
9
Q
What is the role of integrator?
A
Receives information from the afferent neurons and analyzes to determine the appropriate output.
10
Q
What is the role of efferent neurons?
A
Deliver information from the integrator to the effectors.
11
Q
What is the role of effectors?
A
Receive information and elicit the response determined by the integrator.
12
Q
What is the role of the response?
A
To return the body to a state of homeostasis.
13
Q
What are the two types of effectors for the body’s control systems?
A
Muscles and glands.
14
Q
What are the three types of muscle used by the body as effectors?
A
Skeletal, smooth, and cardiac.
15
Q
What are the two major types of glands that can serve as effectors?
A
Endocrine and exocrine.
16
Q
What are an example of the types of glands that can serve as effectors?
A
Adrenal glands (endocrine) and sweat glands (exocrine).
17
Q
What is passive transport?
A
Energy not needed and movement down gradient.
18
Q
What is active transport?
A
Energy needed and movement against gradient.
19
Q
What is simple diffusion?
A
Energy not needed, movement against gradient, and carrier molecule not needed.
20
Q
What is facilitated diffusion?
A
Energy needed, movement against gradient, and carrier molecule needed.
21
Q
What are the factors involved in Fick’s law of diffusion?
A
Concentration gradient between Area A and Area B, temperature of diffusion molecules, solubility of substance, molecular weight of substance, area of membrane, and thickness of membrane.
22
Q
How does temperature affect rate of diffusion?
A
Directly
23
Q
How does solubility affect rate of diffusion?
A
Directly
24
Q
How does concentration gradient affect rate of diffusion?
A
Directly
25
How does molecular weight affect rate of diffusion?
Indirectly
26
How does area of membrane affect rate of diffusion?
Directly
27
How does membrane thickness affect rate of diffusion?
Indirectly
28
What is agar derived from?
Seaweed
29
What does agar serve as a model for?
Cytoplasm
30
What ion moves freely across the cell membrane in the development of the resting membrane potential?
Potassium
31
In a single neuron, a stimulus having a voltage greater than a threshold produces an action potential with what magnitude?
The same magnitude as the threshold.
32
During the absolute refractory period, what type of stimulus can elicit a response from a neuron?
No stimulus can elicit a response during the absolute refractory period.
33
A stimulus, which elicits the smallest response from a compound nerve is what?
Threshold stimulus.
34
The data in lab 2 represents the electrical recording of what type of action potential?
Compound nerve.
35
Amplitude of action potential is represented by what?
Milivolts.
36
An increase in stimulus strength will result in what in the amplitude of the recorded compound action potential?
An increase.
37
In the body, nerve transmission is a_____due to the presence of_____
One-way process; synapses
38
Changes in temperature can influence the conduction velocity by...
Reducing the movement of ions across the neuron's cell membrane.
39
Multiple motor unit summation occurs as a result of an increase in stimulus_____
Strength
40
Wave summation occurs as a result of increase in stimulus_____.
Frequency
41
Following muscle tetany, it should take_____ time for the muscle to recover due to the depletion of _____.
More; ATP.
42
What are skeletal muscles innervated by?
Somatic motor neurons.
43
In skeletal muscles, the release of calcium from the_____ initiates the contractile process in the sarcomere.
Sacroplasmic reticulum.
44
In skeletal muscle, ATP initially binds with...
Myosin
45
What is a motor unit?
A single neuron and the muscle fiber it innervates.
46
What is the result of increasing the frequency of stimulation?
Wave summation.
47
What agents will increase smooth muscle contractions?
Acetylcholine and pilocarpine.
48
What is plasticity?
The ability of smooth muscle to reform actin-myosin cross-bridges after being stretched and reduce the amount of tension the muscle is under.
49
What input is no longer present when isolated tissue is prepared?
Autonomic nervous system and enteric nervous system.
50
What is one of the pharmacological agents in an adrenergic agent?
Epinephrine
51
What is an antagonist?
A substance that binds to receptor and blocks the effect of neurotransmitters, hormones, or drugs.
52
Which nervous system has a short pre-ganglionic neuron and a long post-ganglionic neuron?
Sympathetic nervous system.
53
What do cholinergic drugs mimic?
Parasympathetic activity
54
What do pacemaker cells control?
Inherent rhythmicity.
55
What does the enteric nervous system control?
Coordinated contractions.
56
What does the autonomic nervous system control?
Does not control, modifies movements only.
57
What is not controlled by the autonomic nervous system?
Skeletal muscle
58
How does resting cell membrane potential develop?
K+ diffuses out of the cell. Anions cannot follow. Na+ attempts to diffuse into the cell but cannot because the membrane is not a permeable to Na+. Excess positive charge builds up on the outside of the cell and excess negative charges build up along the inside of the cell. Na+/K+ pump maintains gradient.
59
What type of cells develop resting membrane potentials?
All living cells.
60
What is an action potential?
Progression of an abrupt change in membrane potential?
61
What happens to the action potential when it reaches the synapse?
It is transmitted to the next neuron or to an effector via the release of a neurotransmitter. Synapses result in unidirectional movement of action potential in the nervous system.
62
What type of cells can generate action potential?
Only excitable tissues. (Nerve and muscle)
63
What happens during depolarization?
Stimulus on membrane causes an increase in permeability to Na+, which then move into the cell along concentration gradient. Inside of the cell becomes more positive with respect to the outside.
64
What happens during repolarization?
Membrane permeability to Na+ decreases, while permeability to K+ increases. K+ moves out of the cell along concentration gradient, making the outside positive with respect to the inside. Na+/K+ pump moves K+ back in and Na+ moves back out.
65
What is a compound nerve action potential?
Graded action potential measured from nerve made up of several neurons.
66
How is compound nerve action potential measured?
1. Extracellular electrodes are placed on the compound nerve.
2. Oscilloscope used to monitor difference in electrical potential between the two electrodes.
3. In polarized resting state, no difference is recorded between two electrodes.
4. As an action potential passes the first electrode, the outside of the membrane is negative with respect to the membrane inside of the second electrode (seen as positive).
5. As the action potential reaches the second electrode, there is no potential difference between the electrodes.
6. As the membrane repolarizes beneath the first electrode, it is positive with respect to the second electrode. (Shown as negative)
7. As the membrane completely repolarizes, no difference exists between the electrodes again.
67
What is latent period?
Period between introduction of a stimulus and the actual start of action potential as noted by a change in membrane potential.
68
What is refractory period?
Period of non-responsiveness following an action potential, during which the membrane is repolarizing back to the resting membrane potential.
69
What is velocity?
Rate at which something travels. Distance over time.
70
What is recruitment?
Depolarization of more than one neuron in a compound nerve as the stimulus intensity increases.
71
How does the All or None law apply to a single axon?
Demonstrates maximal response whenever a threshold stimulus is used and larger stimulus voltages have no additional impact.
72
How does the All or None law apply to a compound nerve?
Each neuron obeys the All or None law, but the threshold for each neuron probably varies.
73
How does threshold stimulus apply to a single axon?
Causes maximal response.
74
How does threshold stimulus apply to a compound nerve?
Causes most excitable neurons to depolarize.
75
How does maximal stimulus apply to a single axon?
Same as the threshold stimulus, the response is all or none once threshold is reached.
76
How does maximal stimulus apply to a compound nerve?
Is reached when all neurons in the nerve have been recruited.
77
What is resting membrane potential?
An imbalance of charged particles between the extracellular and intracellular surfaces of the membranes.
78
How does the Na+/K+ pump affect membrane potential?
Transports Na+ to the outside and K+ to the inside (3 Na+ out for every 2 K+ in). More positive ions are moved out of the cell and the potential gradually becomes more negative on the inside.
79
What type of transport is the Na+/K+ pump?
Active transport.
80
What are the two distinctive properties of nerve and muscle cells?
Excitability (ability to generate an action potential) and conductivity (ability to propagate an action potential).
81
What are the steps leading to action potential?
1. An adequate stimulus (chemical, electrical, mechanical) if the membrane occurs at some point, altering the membrane potential via graded potential.
2. Voltage gated Na+ channels open up, creating increased membrane permeability for Na+.
3. Na+ diffuse inward.
4. Transmembrane potential reaches 0.
5. Na+ continue to diffuse inward and inside membrane becomes positively charged relative to the outside.
6. Depolarization at the original site causes a local current that acts as stimulus to the adjacent region.
7. At original site, Na+ gated channels are inactivated so the permeability to Na+ decreases.
8. Voltage gated K+ channels open, increasing permeability to N+.
9. K+ ions diffuse outward, returning membrane to 0.
10. After the action potential, the membrane potential becomes more negative as a result of more K+ moving out of the cell.
11. Repeats relative to the advanced site along the axonal membrane.
12. After action potential, Na+/K+ pump transports Na+ out and K+ in.
82
What is absolute refractory period?
Interval during which the cell membrane will not respond to stimulus. The Na+ channels are inactivated and cannot be opened.
83
What is relative refractory period?
Period of less than normal responsiveness and results partially because the membrane in hyperpolarized.
84
What is conduction velocity?
The speed at which axons of nerve cells conduct impulses.
85
What factors affect conduction velocity?
Diameter of conducting fiber, temperature of cell, presence of myelin sheath, and pharmacologic agents.
86
How does diameter of conducting fiber impact conduction velocity?
Conduction velocity is directly proportional to fiber diameter. Larger fibers conduct action potential faster.
87
How does temperature of the cell impact conduction velocity?
Warmer nerve fibers conduct action potentials at higher speeds.
88
How does presence of myelin sheath impact conduction velocity?
Myelinated fibers conduct impulses faster. Action potentials are generated only at nodes of Ranvier, giving the appearance of jumping (saltatory conduction).
89
How do pharmacological agents impact conduction velocity?
Some drugs affect the stability of the nerve cell membrane.
90
What is a compound nerve?
A nerve made up of several populations of axons rather than a single
91
What is a compound nerve action potential?
Action potentials recorded from whole nerves and represent the sum of electrical activity occurring at any given time in the compound nerve.
92
Why is the compound nerve capable of recruitment or a "graded" response while a single neuron's response is All or None?
The compound nerve is most likely composed of axons with different thresholds. This means that it will take different amounts of stimulus to recruit each axon. As the stimulus increases in strength, more axons will be recruited, resulting in a graded response. In a single neuron, the threshold stimulus activates the nerve and no increase in stimulus strength will increase the amount generated.
93
Why does temperature alter conduction velocity?
In Fick's law, temperature has a direct impact on the rate of diffusion. Since conduction uses the movement of ions across the plasma membrane to generate the action potential, changes in the rate of diffusion would impact the conduction velocity.
94
What is a motor unit?
Single motor neuron and all the muscle fibers it innervates.
95
What effect does a sub-threshold stimulus have on the motor units in a muscle?
No response
96
What effect does a threshold stimulus have on the motor units in a muscle?
At least one motor neuron depolarizes, action potential, and contraction of fibers in that motor unit.
97
What effect does a maximal stimulus have on the motor units in a muscle?
All motor units are recruited, leading to a maximal force of contraction.
98
What effect does a supra-maximal stimulus have on the motor units in a muscle?
Same as maximal, all motor units are already recruited, therefore increasing the voltage has no additional effect.
99
What is summation?
Adding of individual responses from motor units to make strong, useful muscle contractions.
100
What is multiple motor unit summation?
Increased force of contraction as increasing number of motor units are recruited by increased voltage of stimuli.
101
What is wave summation?
Increased force of contraction as elasticity is taken up and not allowed to slacken before the next stimulus occurs. Contraction is smooth and sustained because there is not enough time for relaxation between stimuli.
102
What type of stimulus is needed for multiple motor unit summation?
Single stimuli of increasing strength or voltages.
103
What type of stimulus is needed for wave summation?
Maximal stimulus with increasing frequency.
104
What events are occurring in the muscle fiber during the latent period?
Fiber stimulated by Ach from neuron. Action potential travels along sarcolemma. Ca++ released from sarcoplasmic reticulum. Ca++ binds to troponin and contraction begins.
105
What is muscle tone?
A continuous level of partial muscle contraction.
106
What is asynchronous firing of motor units and its role in maintaining muscle tone?
A few motor units fire while the muscle fibers associated with other motor units are relaxed. Then the motor unit that was firing relaxes, while fibers in a different motor unit contract. The process continues so that at least some motor units are firing at all times, but alternate with other motor units so that fatigue does not occur.
107
What efferent branch of the peripheral nervous system innervates skeletal muscle?
Somatic
108
What neurotransmitter is released from the motor neuron synapsing with the muscle fiber at the neuromuscular junction?
Acetylcholine
109
What type of channels open when acetylcholine binds to the sarcolemma?
Chemically gated channels.
110
What type of channel must open before the action potential can be generated and propagated along the sarcolemma?
Na+ voltage gated channels
111
What structure of skeletal muscle facilitates rapid and efficient propagation of the action potential from the sarcolemma to the sarcoplasmic reticulum?
T-tubules
112
What ion is released from the sarcoplasmic reticulum once the wave of depolarization reaches it?
Ca++
113
Is the movement of Ca++ from the sarcoplasmic reticulum into sarcoplasm active transport or diffusion?
Diffusion
114
Is the concentration of Ca++ greater in the sarcoplasmic reticulum or the sarcoplasm?
Greater in the sarcoplasmic reticulum.
115
What are the three molecules that make up the actin myofibril?
Actin, troponin, and tropomyosin.
116
What molecule does Ca++ bind to?
Troponin
117
What molecule moves when Ca++ binds to expose an active myosin binding site on the actin myofilament?
Tropomyosin
118
What step is necessary to convert myosin to its high energy state so that it can attach to the myosin binding site on the actin molecule?
ATPase on the myosin head hydrolyzes the ATP on the myosin head.
119
What event must occur before the myosin head detaches from the actin binding site during relaxation?
ATP binds to myosin.
120
What process transports Ca++ from the sarcoplasm back into the sarcoplasmic reticulum following contraction?
Active transport
121
Why does rigor mortis occur?
Without ATP, myosin heads cannot be released from actin binding sites and calcium ions bound to actin cannot be removed. Therefore, relaxation cannot occur.
122
What is the latent period?
The time between the application of the stimulus and before the muscle begins to contract.
123
What type of muscles have more muscle fibers per motor unit, fine motor or gross muscle?
Gross contractions
124
What is a myogram?
The electrical and mechanical response of a skeletal muscle fiber to a single maximal stimulus. Electrical events in mV, mechanical events in g, and time in msec.
125
What causes the increasing force of contraction seen with wave summation?
If the second stimulus is applied before the muscle has time to fully relax, it will find the muscle already partially contracted and the new twitch summates with the first twitch.
126
What is the difference between wave summation and tetanus?
Wave summation allows some relaxation between contractions. Tetanus does not allow any relaxation between contractions and is just a smooth sustained contraction.
127
What is the role of the refractory period in allowing tetanus to occur?
The short refractory period of skeletal muscle allows the skeletal muscle to respond to a second stimulus before relaxation is complete.
128
Why does it take a fatigued muscle longer to relax than a rested muscle?
The inability of the muscle to generate energy in the form of ATP, due to the depletion of metabolic reserves.
