Nervous Physiology (REYNOLDS) Flashcards
(84 cards)
1
Q
The transmembrane potential at which there is no net movement of a particular ion across the cell membrane is referred to as_______.
A. Resting potential
B. Equilibrium potential
C. Graded potential
D. Action potential
A
B. Equilibrium potential
2
Q
Transmembrane potential rises or falls in response to temporary changes in membrane permeability resulting from opening or closing specific membrane channels.
A. Resting potential
B. Equilibrium potential
C. Graded potential
D. Action potential
A
C. Graded potential
3
Q
A temporary, localized change in resting potential caused by a stimulus caused by a stimulus is referred to as _______.
A. Resting potential
B. Equilibrium potential
C. Graded potential
D. Action potential
A
C. Graded potential
4
Q
Which of the following is an electrical impulse that propagates along the surface of an axon to a synapse?
A. Resting potential
B. Equilibrium potential
C. Graded potential
D. Action potential
A
D. Action potential
5
Q
Which of the following will only occur at an axon hillock?
A. Resting potential
B. Equilibrium potential
C. Graded potential
D. Action potential
A
D. Action potential
6
Q
Explain how the Resting Potential is created and maintained:
A
Resting Potential
Summary: Resting potential is created by the movement of Na ions K ions and intracellular Cl ions and negative proteins. The Na+/K+ ATPase (exchange pump) is what maintains resting potential.
- Highly permeable to potassium ions which have a -90mV
- The electrochemical gradient for Na ions is very large, but the membrane’s permeability to the ions is very low
- Na+ has only a small effect on the normal resting potential, making it just slightly less negative than the equilibrium potential for K+
- The Na+/K+ ATPase is an exchange pump powered by ATP
- carries 3Na+ out and 2K+ in
- balances passive forces of diffusion
- maintains resting potential (70mV)
7
Q
Which of the following is initiated on Dendrites?
A. Resting potential
B. Equilibrium potential
C. Graded potential
D. Action potential
A
C. Graded potential
Graded potential = dendrites
Actions = Axon
8
Q
Which of the following is Resting Potential?
A. -90mV
B. -70mV
C. +66mV
D. -60mV
A
9
Q
Which of the following is true regarding Passive Channels (Leak Channels)?
A. Open and close in response to stimuli
B. Permeability changes w/ conditions
C. At resting potential, most gated channels are closed
D. All of the above
A
B. Permeability changes w/ conditions
Passive Channels (Leak Channels):
- are always open
- permeabilityu changes w/ conditions
Active Channels (Gated Channels):
- open and close in response to stimuli
- at resting potential, most gated channels are closed
10
Q
All of the following are true regarding Active Channels EXCEPT:
A. Open and close in response to stimuli
B. Are always open
C. At resting potential, most gated channels are closed
D. All of the above
A
B. Are always open
Passive Channels (Leak Channels):
- are always open
- permeabilityu changes w/ conditions
Active Channels (Gated Channels):
- open and close in response to stimuli
- at resting potential, most gated channels are closed
11
Q
Which of the following are Passive Channels?
A. Leak channels
B. Gated channels
C. Voltage gated channels
D. None of the above
A
A. Leak channels
Passive Channels = Leak Channels
Active Channels = Gated Channels
12
Q
Which of the following open in the presence of ACh?
A. Chemically gated channels
B. Voltage-gated channels
C. Mechanically gated channels
D. Leaky channels
A
A. Chemically gated channels
13
Q
Which of the following is found in sensory receptors and respond to membrane distortion?
A. Chemically gated channels
B. Voltage-gated channels
C. Mechanically gated channels
D. Leaky channels
A
C. Mechanically gated channels
14
Q
Which of the following is characteristic of excitable membrane?
A. Chemically gated channels
B. Voltage-gated channels
C. Mechanically gated channels
D. Leaky channels
A
B. Voltage-gated channels
Voltage-gated channels:
- Respond to changes in transmembrane potential
- have activation gates (open) and inactivation gates (close)
- Characteristic of excitable membrane
- Found in neuronal axons, skeletal muscle sarcolemma, and cardiac muscle
15
Q
Which of the following is the most common?
A. Chemically gated channels
B. Voltage-gated channels
C. Mechanically gated channels
D. Leaky channels
A
B. Voltage-gated channels
16
Q
Which of the following is found in the axon hillock?
A. Chemically gated channels
B. Voltage-gated channels
C. Mechanically gated channels
D. Leaky channels
A
B. Voltage-gated channels
17
Q
A shift in transmembrane potential toward 0mV (neutrality):
A. Equilibrium potential
B. Depolarization
C. Repolarization
D. Hyperpolarization
A
B. Depolarization
18
Q
Increasing the negativity of the resting potential:
A. Equilibrium potential
B. Depolarization
C. Repolarization
D. Hyperpolarization
A
D. Hyperpolarization
19
Q
When the stimulus is removed, transmembrane potential returns to normal and potassium leaves the cell:
A. Equilibrium potential
B. Depolarization
C. Repolarization
D. Hyperpolarization
A
C. Repolarization
20
Q
Which of the following produces a local current?
A. Equilibrium potential
B. Depolarization
C. Repolarization
D. Hyperpolarization
A
B. Depolarization
21
Q
What are four basic characteristics of Graded Potentials?
A
Graded Potential
- effect decreases w/ distance
- the effect spreads passively, due to local currents
- depolarization or hyperpolarization
- the stronger the stimulus, the greater the change in the transmembrane potential and the larger the area affected
22
Q
Which of the following is true regarding action potentials?
A. is an electrical impulse
B. Produced by graded potentials
C. propagates along surface of axon to synapse
D. All of the above
A
D. All of the above
23
Q
Discuss the initiation of an action potential:
A
Initial stimulus:
- a graded depolarization of axon hillock large enough to change resting potential to threshold level of voltage-gated sodium channels
24
Q
Discuss the All-or-none principle of action potential:
A
Action Potential
- All-or-none principle
- If a stimulus exceeds threshold amount
- the action potential is the same
- no matter how large the stimulus
- If a stimulus exceeds threshold amount
- Action potential is either triggered or not
25
What are the 4 steps in an Action Potential?
1. **Depolarization to threshold**
2. **Activation of voltage gated Na channels**
* Rapid depolarization
* Na+ ions rush into cytoplasm
* Inner membrane changes from negative to positive
3. **Inactivation of Na channels and activation of voltage gated K channels**
* At +30mV
* Inactivation gates close (Na channel inactivation)
* K channels open
* Repolarization begins
4. **Return to normal permeability**
* K+ channels begin to close when membrane reaches normal resting potential
* K+ channels finish closing
* membrane is hyperpolarized to -90mV
* transmembrane potential returns to resting level
* Action potential is over
26
All of the following are true regarding the activation of voltage-gated Na channels EXCEPT:
A. Rapid depolarization
B. Na+ ions rush into cytoplasm
C. Inner membrane changes from negative to positive
D. Repolarization begins
E. All of the above are true
D. Repolarization begins
note: repolarization begins in step 3 of an action potential where Na channels are inactivated and K+ channels are open
27
Discuss the Sodium-Potassium Exchane Pump:
Requires energy in the form of ATP. Without ATP, neurons stop functioning and you die.
* This pump is involved in action potentials and functions to maintain concentrations of Na+ and K+ over time
28
Discuss the Refractory Period of an action potential:
Refractory period
* The time period
* From beginning of action potential
* To return to resting state
* **During which membrane will not respond normally to additional stimuli**
**Absolute Refractory period:**
* sodium channels open or inactivated
* **no action potential possible**
**Relative Refractory Period:**
* membrane potential almost normal
* **very large stimulus can initiate action potential**
29
Discuss the propagation of action potentials:
* Continuous propagation
* Saltatory propagation
Propagation
* Moves action potentials generated in axon hillock along entire length of axon
Continous propagation = unmyelinated axons
Saltatory propagation = myelinated axons
30
Which of the following is associated w/ myelinated axons?
A. Continuous propagation
B. Saltatory propagation
B. Saltatory propagation
31
How does axon diameter and myelination affect propagation speed?
The larger the diameter of the axon the faster the propagation speed
Myelinated axons are faster than unmyelinated axons
32
Which of the following is myelinated and contains a medium diameter?
A. Type A fibers
B. Type B fibers
C. Type C fibers
D. All of the above
B. Type B fibers
33
Which of the following is myelinated and contains a large diameter?
A. Type A fibers
B. Type B fibers
C. Type C fibers
D. All of the above
A. Type A fibers
34
Which of the following is the fasted (most rapid)?
A. Type A fibers
B. Type B fibers
C. Type C fibers
D. All of the above
A. Type A fibers
35
Which of the following is responsible for position, balance, touch and motor impulses?
## Footnote
A. Type A fibers
B. Type B fibers
C. Type C fibers
D. All of the above
A. Type A fibers
Type A fibers = position, balance, touch and motor impulses
Type B fibers = sensory information and peripheral effectors
Type C fibers = involuntary muscle and gland controls
36
Which of the following is unmyelinated w/ a small diameter and is the slowest?
A. Type A fibers
B. Type B fibers
C. Type C fibers
D. All of the above
C. Type C fibers
37
Which of the following is responsible for sensory information and peripheral effectors?
A. Type A fibers
B. Type B fibers
C. Type C fibers
D. All of the above
B. Type B fibers
Type A fibers = position, balance, touch and motor impulses
Type B fibers = sensory information and peripheral effectors
Type C fibers = involuntary muscle and gland controls
38
Which of the following is responsible for involuntary muscles and controls glands?
A. Type A fibers
B. Type B fibers
C. Type C fibers
D. All of the above
C. Type C fibers
Type A fibers = position, balance, touch and motor impulses
Type B fibers = sensory information and peripheral effectors
Type C fibers = involuntary muscle and gland controls
39
Discuss Synapses:
* How are action potentials transmitted?
* Electrical synapses
* Chemical synapses
* What are the two classes of neurotransmitters?
* which one promotes action potential?
* Which of the following does the postsynaptic membrane depend on?
* A. depends on the receptor
* B. depends on the neurotransmitter
* What does Ach promote and what does it inhibit?
**_Synapses_**
* Action potentials (nerve impulses) are transmitted from presynaptic neuron to postsynaptic neuron across a synapse
**Electrical synapses** (less common): _direct physical_ contact between cells
**Chemical synapses**: signal transmitted across a gap by chemical neurotransmitters
**Excitatory neurotransmitters:**
* cause depolarization of post synapic membranes
* promote action potentials
**Inhibitory neurotransmitters:**
* cause hyperpolarization of postsynaptic membranes
* suppress action postentials
Which of the following does the postsynaptic membrane depend on?
**A. depends on the receptor**
B. depends on the neurotransmitter
**ACh** usually promotes action potentials but inhibits cardiac neuromuscular junctions
40
Discuss the events in the functioning of a cholinergic synapse:
1. An action potential arrives and depolarizes the synaptic terminal
2. Extracellular Ca2+ enters the synaptic terminal, triggering the exocytosis of ACh
3. ACh binds to receptors and depolarizes the postsynaptic membrane
* initiation of action potential if threshold is reached at the initial segment
4. ACh is removed by AChE
* propagation of action potential
41
Discuss Synaptic delay:
Synaptic delay
* Synaptic delay occurs between:
* arrival of action potential at synaptic terminal
* and effect on postsynaptic membrane
* Fewer synapses mean faster response
* Reflexes may involve only one synapse
42
\_\_\_\_\_\_\_\_ occurs when neurotransmitter cannot recycle fast enough to meet demands of intense stimuli. Synapse inactive until ACh is replenished.
Synaptic fatigue
"AChE is doing its job and we need some time enzymatically to replenish ACh, which is why there is synaptic fatigue
43
What is the purpose of a Synaptic Delay?
"Synaptic Delay bc all those steps need to occur in sequence, there is a bit of delay from when an action potential arises at the end of a synaptic bulb until it activates an action potential on the target tissue." - Reynolds
The fewer synapses that you have the faster the response and the shorter the synaptic delay
44
All of the following are Neurotransmitters EXCEPT:
A. Dopamine
B. Gamma aminobutyric acid (GABA)
C. Serotonin
D. Norepinephrine
E. All of the above are neurotransmitters
E. All of the above are neurotransmitters
45
All of the following are characteristics of neuromodulators EXCEPT:
A. Effects are short term, quick to appear
B. Responses involve multiple steps, intermediary compounds
C. Affect presynaptic membrane, postsynaptic membrane or both
D. Released alone or with a neurotransmitter
E. All of the above are true regarding neuromodulators
A. Effects are short term, quick to appear
correct statement: effects are long term and slow to appear
46
How do Neurotransmitters and Neuromodulators work?
* Direct vs indirect effects
Direct effects on membrane channels:
* eg. ACh, glycine, aspartate
Indirect effects via G proteins:
* eg. Epi, norepinephrine, dopamine, histamine and GABA
Indirect effects via intracellular enzymes:
* eg. lipid-soluble gases (NO,CO)
47
All of the following have indirect effects on **G proteins** EXCEPT:
A. Epinephrine
B. Norepinephrine
C. Dopamine
D. Acetylcholine
E. GABA
D. Acetylcholine
Direct effects: ACh, glycine, aspartate
Indirect effects: Epi, norepinephrine, dopamine, GABA, histamine
48
Discuss the indirect effects of G proteins:
**_G Proteins_**
* work through second messengers
* enzyme complex that binds GTP
* link between neurotransmitter (first messenger) and second messenger
* Activate enyme **adenylate cyclase**
* which produces **cAMP**
49
Discuss Postsynaptic potential:
* Excitatory postsynaptic potential (EPSP)
* Inhibitory post synaptic potential (IPSP)
Excitatory postsynaptic potential (EPSP):
* Graded depolarization of postsynaptic membrane
Inhibitory postsynaptic potential (IPSP):
* Graded hyperpolarization of postsynaptic membrane
50
Which of the following is depolarization of postsynaptic membrane?
A. EPSP
B. IPSP
A. EPSP
EPSP = depolarization
IPSP = repolarization
51
A neuron that receives many ______ is **inhibited** from producing an action potential.
IPSPs
52
Discuss Summation:
Summation
* To trigger an action potential
* one EPSP is not enough
* EPSPs (and IPSPs) combine through summation
**Temporal Summation:**
* Multiple times
* Rapid repeating stimuli at one synapse
**Spatial Summation:**
* Multiple locations
* Many stimuli, arrive at multiple synapses
53
Rapid, repeated stimulation at one synapse:
A. Temporal summation
B. Spatial summation
A. Temporal summation
54
Many stimuli, arrive at multiples synapses:
A. Temporal summation
B. Spatial summation
B. Spatial summation
**Temporal summation** = rapid, repeated stimuli at **one synapse**
**Spatial summation** = many stimuli, arrive at **multiple synapses**
55
Discuss Temporal Summation:
Temporal summation occurs on a membrane that receives two depolarizing stimuli from the same source in rapid succession. The effects of the second stimulus are added to those of the first. If it is enough, an action potential will occur.
56
Discuss Spatial Summation:
Spatial summation occurs when sources of stimulation arrive simultaneously, but at different locations. Local currents spread the depolarizing effects, and areas of overlap experience the combined effects.
57
\_\_\_\_\_\_ and ______ can change membrane sensitivity to neurotransmitters shifting balance between EPSPs and IPSPs.
Neuromodulators and hormones
58
Which of the following is IPSP?
A. GABA release
B. Serotonin release
A. GABA release
GABA = IPSP
Serotonin = EPSP
59
Which of the following is EPSP?
A. GABA release
B. Serotonin release
B. Serotonin release
GABA release causes an inactivation of calcium channels which reduces the effect on postsynaptic membrane
Serotonin release activates calcium channels to increase thus increasing the effect on the postsynaptic membrane
60
All of the following are true regarding Sympathetic division EXCEPT:
A. "Fight-or-flight" response
B. uses Norepinephrine
C. contains a long preganglionic fiber
D. All of the above
E. None of the above
C. contains a long preganglionic fiber
Sympathetic = short preganglion
Parasympathetic = long preganglion
61
All of the following are responses to increased sympathetic activity EXCEPT:
A. Increased metabolic rate
B. Increased heart rate and blood pressure
C. Sweat glands activated
D. Increased secretion by salivary and digestive glands
E. Reduced digestive and urinary functions
D. Increased secretion by salivary and digestive glands
Sympathetic sys:
* heightened mental alertness
* increased metabolic rate
* reduced digestive and urinary functions
* energy reserves activated
* increased respiratory rate and respiratory passageways dilate
* increased heart rate and blood pressure
* sweat glands activated
62
All of the following is true regarding parasympathetic stimulation EXCEPT:
A. Decreased metabolic rate
B. Increased motility and blood flow in digestive tract
C. Urination and defecation stimulation
D. Increased secretion by salivary and digestive glands
E. Reduced digestive and urinary functions
E. Reduced digestive and urinary functions
Parasympathetic:
* Decreased metabolic rate
* Increased motility and blood flow in digestive tract
* Urination and defecation stimulation
* Increased secretion by salivary and digestive glands
* Decreased heart rate and BP
63
All of the following are true regarding the parasympathetic division EXCEPT:
A. Pre-ganglionic neuron is myelinated
B. Both pre-ganglionic and postganlionic neurons are unbranched
C. Preganglionic neuron contains extensive branching but postganglionic neuron does not
D. Contains a long preganglion
C. Preganglionic neuron contains extensive branching but postganglionic neuron does not
64
Which of the following is true regarding the **Sympathetic** division of the ANS?
A. Pre-ganglionic neuron is myelinated
B. Both pre-ganglionic and postganlionic neurons are unbranched
C. Preganglionic neuron contains extensive branching but postganglionic neuron does not
D. Contains a long preganglion
C. Preganglionic neuron contains extensive branching but postganglionic neuron does not
65
(T/F)
Both the sympathetic and parasympathetic sys contain myelination of the post-ganglionic neuron.
False
Both the sympathetic and parasympathetic sys contain myelination of the **pre-ganglionic** neuron.
note: Both of them have postganglion that are NOT myelinated
66
Which of the following adrenergic receptors causes smooth muscle relaxation and heart muscle contraction?
A. alpha receptors
B. beta receptors
B. beta receptors
67
Norepinephrine is more potent in which of the following adrenergic receptors?
A. alpha receptors
B. beta receptors
A. alpha receptors
68
Which of the following adrenergic receptors causes smooth muscle contraction?
A. alpha receptors
B. beta receptors
A. alpha receptors
69
Which of the following is the more common sype of alpha receptor?
A. alpha1 receptors
B. alpha2 receptors
A. alpha1 receptors
70
Which of the following adrenergic receptors lowers cAMP and has inhibitory effects on the cell (negative feedback)?
A. alpha1 receptors
B. alpha2 receptors
C. beta1 receptors
D. beta2 receptors
E. beta3 receptors
B. alpha2 receptors
71
Which of the following adrenergic receptors causes a release in intracellular Ca2+ ions from reserves in the ER?
A. alpha1 receptors
B. alpha2 receptors
C. beta1 receptors
D. beta2 receptors
E. beta3 receptors
A. alpha1 receptors
72
Which of the following type of adrenergic receptors causes an increase in cAMP?
A. alpha receptors
B. beta receptors
B. beta receptors
note: alpha2 receptors cause a decrease in cAMP
73
Which of the following increases metabolic activity, heart rate?
A. alpha1 receptors
B. alpha2 receptors
C. beta1 receptors
D. beta2 receptors
E. beta3 receptors
C. beta1 receptors
74
Which of the following triggers relaxation of smooth muscles along respiratory tract?
A. alpha1 receptors
B. alpha2 receptors
C. beta1 receptors
D. beta2 receptors
E. beta3 receptors
D. beta2 receptors
75
Which of the following causes vasodilation to heart and skeletal muscles?
A. alpha1 receptors
B. alpha2 receptors
C. beta1 receptors
D. beta2 receptors
E. beta3 receptors
D. beta2 receptors
76
Which of the following leads to lipolysis, the breakdown of triglycerides in adipocytes?
A. alpha1 receptors
B. alpha2 receptors
C. beta1 receptors
D. beta2 receptors
E. beta3 receptors
E. beta3 receptors
77
Discuss Cholinergic (ACh) sympathetic terminals:
* What do they innervate?
* What does it stimulate?
78
Discuss Nitroxidergic synapses:
* What does it release as a neurotransmitter?
* What does it innervate?
* What does it stimulate?
79
The only neurotransmitter that is released via parasympathetic system is \_\_\_\_\_\_\_.
Acetylcholine
80
Discuss Nicotinic receptors:
* What are these receptors on the surface of?
* What neurotransmitter is used and what does it do?
81
What is different about the adrenal medulla in regards to the parasympathetic system?
The main neurotransmitter of the sympathetic system is norepinephrine in postganglion. The postganglion of the adrenal medulla is sensitive to Epinephrine (exception to the rule)
82
Discuss Muscarinic receptors:
* Where are they located in the parasympathetic system?
* Where are they located in the sympathetic system
* What effect do the G proteins have?
83
Which of the following initiate cell signaling cascades and contain several of subtypes?
A. Nicotinic receptors
B. Muscarinic receptors
C. alpha adrenergic receptors
D. beta adrenergic receptors
B. Muscarinic receptors
84
Which of the following receptors open cation channels?
A. Nicotinic receptors
B. Muscarinic receptors
C. alpha adrenergic receptors
D. beta adrenergic receptors
A. Nicotinic receptors
