248 terms

A&P2 Test 1:BOOK Chapter 12

Nervous system
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Terms in this set (...)

1. Which of the following is not a function of the nervous system?
a. Sensory function
b. Integrative function
c. Motor function
d. All are functions of the nervous system
d. All are functions of the nervous system
2. The peripheral nervous system can be divided into:
a. Somatic nervous system
b. Autonomic nervous system
c. Enteric nervous system
d. All of the above
d. All of the above
3. The motor portion of the autonomic nervous system can be divided into:
a. Somatic and sympathetic divisions
b. Somatic and parasympathetic divisions
c. Enteric and somatic divisions
d. Sympathetic and parasympathetic divisions.
e. Voluntary and involuntary divisions.
d. Sympathetic and parasympathetic divisions.
4. This has the property of electrical excitability.
a. Muscle cells
b. Neurons
c. All of the above
d. None of the above
c. All of the above
5. A site of protein synthesis in a neuron:
a. Mitochondria
b. Nucleus
c. Nissl body
d. Dendrite
e. Axon
c. Nissl body
6. Nerve fiber refers to:
a. Axon
b. Dendrites
c. Nissl body
d. Both a and b
e. All of the above
d. Both a and b
7. This type of neuron has one main dendrite and one main axon.
a. Multipolar neuron
b. Bipolar neuron
c. Unipolar neuron
d. Purkinje cell
e. Renshaw cell
b. Bipolar neuron
8. Myelin sheaths around axons are initially formed by Schwann's cells
a. When neurons are injured
b. During fetal development
c. After birth
d. Only in response to a disorder
e. During the early onset of Alzheimer's disease
b. During fetal development
9. This contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals and neuroglia.
a. Gray matter
b. White matter
c. Astrocytes
d. Satellite cells
e. Ependymal cells
a. Gray matter
10. Which of the following is not a type of channel used in production of electrical signals in neurons?
a. Leakage channel
b. Voltage-gated channel
c. Ligand-gated channel
d. Mechanically gated channel
e. Ion-gated channel
e. Ion-gated channel
11. The resting membrane potential in neurons ranges from:
a. +5 to 100 mV
b. -25 to -70 mV
c. -40 to -90 mV
d. -90 to 5 mV
e. None of the above
c. -40 to -90 mV
12. A polarized cell
a. Has a charge imbalance across its membrane
b. Includes most cells of the body
c. Exhibits a membrane potential
d. Both b and c
e. All of the above
e. All of the above
13. Na+/K+-ATPases are considered to be electrogenic pumps because
a. They contribute to the negativity of the resting membrane potential
b. Because the sodium ions a re negatively charged
c. Because they exhibit low permeability
d. Both a and b
e. All of the above
a. They contribute to the negativity of the resting membrane potential
14. A depolarizing graded potential
a. Makes the membrane more polarized
b. Makes the membrane less polarized
c. Is not considered a graded potential
d. Is the last part of an action potential
e. Is seen when the cell approaches threshold
b. Makes the membrane less polarized
15. When a depolarizing graded potential makes the axon membrane depolarize to threshold
a. Ligand-gated Ca+2 channels close rapidly
b. Voltage-gated Ca+2 channels open rapidly
c. Ligand-gated Na+ channels close rapidly
d. Voltage gated Na+ channels open rapidly
e. None of the above
d. Voltage gated Na+ channels open rapidly
16. During the resting state of a voltage-gated Na+ channel
a. The inactivation gate is open
b. The activation gate is closed
c. The channel is permeable to Na+
d. Both a and b
e. All of the above
d. Both a and b
17. During which period can a second action potential be initiated by a larger than normal stimulus?
a. Refractory period
b. Absolute refractory period
c. Relative refractory period
d. All of the above
e. None of the above
c. Relative refractory period
18. Saltatory conduction
a. Occurs through unmyelinated axons
b. Happens due to even distribution of voltage gated channels
c. Encode only action potentials in response to pain
d. Both a and b
e. None of the above
e. None of the above
19. Which axons have the largest diameter?
a. A fibers
b. B fibers
c. C fibers
d. None of the above
a. A fibers
20. What phenomenon explains why a light touch feels different than a touch applied with more pressure?
a. Saltatory conduction
b. Continuous conduction
c. Frequency of impulses
d. Propagation
e. Refractory period
c. Frequency of impulses
21. Which of the following terms describes synapses?
a. Axodendritic
b. Axosomatic
c. Axoaxonic
d. None of the above
e. All of the above
e. All of the above
22. Faster communication and synchronization are two advantages of
a. Chemical synapses
b. Electrical synapses
c. Ligand gated channels
d. Voltage gated channels
e. Mechanically gated channels
b. Electrical synapses
23. If a neurotransmitter depolarizes the postsynaptic membrane it is referred to as:
a. Excitatory
b. Inhibitory
c. Spatial
d. Temporal
e. Summation
a. Excitatory
24. IPSP stands for:
a. Inhbitory presynaptic summation potential
b. Inhibitory postsynaptic summation potential
c. Inhibitory postsynaptic potential
d. Inhibitory presynaptic potential
e. None of the above
c. Inhibitory postsynaptic potential
25. Diffusion, enzymatic degradation, and uptake by cells are all ways to
a. Remove a neurotransmitter
b. Stop a spatial summation
c. Continue a temporal summation
d. Inhibit a presynaptic potential
e. Excite a presynaptic potential
a. Remove a neurotransmitter
26. When the summed total of postsynaptic potentials rises above threshold, creation of action potentials occurs:
a. In the synaptic cleft
b. In the dendrites
c. At the trigger zone
d. In the neuron nucleus
e. In the neuroplasm
c. At the trigger zone
27. A postsynaptic neuron responds to neurotransmitters released by a presynaptic neuron by creating:
a. EPSPs
b. Nerve impulses
c. IPSPs
d. Both a and c
e. All of the above
e. All of the above
28. Which of the following is not considered a small molecule neurotransmitter?
a. Acetylcholine
b. Biogenic amines
c. Purines
d. Endorphins
e. Serotonin
d. Endorphins
29. This neural circuit consists of a single presynaptic neuron synapsing with several postsynaptic neurons.
a. Diverging circuit
b. Converging circuit
c. Reverberating circuit
d. Parallel after-discharge circuit
e. Normal circuit
a. Diverging circuit
30. Plasticity means
a. The ability to regenerate
b. Sending a signal through a converging circuit
c. Signal transmission at a synapse
d. Capability to change based on experience
e. The ability to stretch without damage
d. Capability to change based on experience
31. What factors limit neurogensis?
Ans: Inhibitory influences from neuroglia, mainly from oligodendrites and the absence of growth stimulating cues present during fetal development.
Level: medium
Link: 12.8
32. Describe four ways drugs can modify the effects of neurotrasmitters.
Ans: Drugs can modify neurotransmitter effects by stimulating or inhibiting their synthesis, enhancing or blocking their release, activating or blocking their receptor, and stimulating or inhibiting their removal.
Level: hard
Link: 12.6
33. Describe the three ways neurotransmitters can be removed.
Ans: Neurotransmitters can be removed by diffusion, enzymatic degradation or uptake by cells.
Level: easy
Link: 12.6
34. Describe the two conditions that allow maintenance of the resting membrane potential in excitable cells.
Ans: Unequal distribution of ions across the plasma membrane and the relative permeability of the plasma membrane to Na+ and K+ help maintain the resting membrane potential.
Level: easy
Link: 12.4
35. Briefly describe what causes the depolarizing phase.
Ans: Voltage gated Na+ channels open rapidly then both the electrical and chemical gradients favor the inward movement of Na+. The inward rush of Na+ causes depolarization phase of the action potential.
Level: medium
Link: 12.4
Refer to image 1

36. Which part of the diagram is considered nerve fiber?

a. A
b. D
c. H
d. Both a and b
e. All of the above
e. All of the above
Refer to image 1

37. This part of the neuron contains the nucleu and Nissl bodies.
a. A
b. B
c. C
d. E
e. Both a and b
b. B
Refer to image 1

38. This part of a neuron contains cytoplasm and a myelin sheath wrapped around neurolemma.
a. C
b. D
c. E
d. F
e. G

Ans: C
Level: medium
Link: 12.2
c. E
Refer to image 1

39. In the diagram, where is the axon collateral?
a. C
b. D
c. F
d. H
e. I
a. C
Refer to image 1

40. In the diagram where are axon terminals?
a. F
b. G
c. H
d. I
e. None of the above
c. H
Refer to image 2

41. Which of the neurons is a touch receptor known as a Merkel disc?
a. A
b. B
c. C
d. D
b. B
Refer to image 2

42. Which of the neurons is the type used in detecting painful stimuli?
a. A
b. B
c. C
d. D
e. Both B and C
d. D
Refer to image 2

43. Which of the neurons is called a Meissner corpuscle or a corpuscle of touch?
a. A
b. B
c. C
d. D
e. Both A and D
a. A
Refer to image 3

44. This type of cell myelinates a single axon
a. A
b. B
c. C
d. D
e. E
a. A
Refer to image 3

45. This electrically insulates the axon of a neuron to increase the speed of nerve impulse conduction.
a. A
b. B
c. C
d. D
e. E
e. E
Refer to image 3

46. In the diagram where are the Nodes of Ranvier?
a. A
b. B
c. C
d. D
e. E
b. B
Refer to image 3

47. In the CNS, this is produced by oligodendrocytes.
a. A
b. B
c. C
d. D
e. E
e. E
Refer to image 4

48. Which of the following represents a ligand-gated channel?
a. A
b. B
c. C
d. D
b. B
Refer to image 4

49. Which of these types of channels is involved in leaking sodium and potassium ions across the membrane in order to establish the resting potential of a cell?
a. A
b. B
c. C
d. D
a. A
Refer to image 4

50. This type of channel opens randomly.
a. A
b. B
c. C
d. D
e. All of the above
a. A
Refer to image 4

51. In the figure which one represents a converging circuit?
a. A
b. B
c. C
d. D
b. B
The following statements regarding action potentials are true....
1. chemical-gated NA channels opening causes depolarization
2. refractory period is the time when the neuron cannot generate another action potential
3. threshold level is the same as refractory period
4. all of the above
2. refractory period is the time when the neuron cannot generate another action potential
The brain stem consists of the medula, pons and midbrain?
True/False?
true
The type of neuoglia cell which is responsible for myelinization in the central nervous system is the....
1. ependymal cell
2. oligondendrocyte
3. astrocyte
4. microglial cell
2. oligondendrocyte
factors which increase the speed of propgation of the action potential include...
1. larger diameter of axon
2. myelination
3. increased level of neurotransmitters
4. 1,2 are correct
5. 1,2,3 are correct
4. 1,2 are correct
which of the following are NOT part of the spinal reflex arc?
1. cerebellum
2. sensory neuron
3. integrating center
4. motor neuron
5. effector
1. cerebellum
the nervous system.....
1. works with the endocrine system to maintain homeostasis
2. communicated with the body via action potentials
3. is responsible for thoughts and behaviors
4. initiates voluntary movements
5. all above are correct
5. all above are correct
differences between graded potentials and action potentials include all of the following EXCEPT.....
1, AP is all-or-none, GP is not
2. GP can lead to AP
3. GP tends to be localized
4. there may be hyperpolarization or depolarizing AP
4. there may be hyperpolarization or depolarizing AP
release of the neurotransmitter from a synaptic end bulb is dependent on the opening of ________________gated channels in the presynaptic neuron.
1. voltage-gated calcium ions
2. chemical gated sodium channels
3. potassium leakage channels
4. chemical gated potassium channels
1. voltage-gated calcium ions
_____________gated channels participate in the generation and conduction of action potentials
1. thermal
2. mechanical
3. chemical(ligand)
4. voltage
voltage
what two cells are there in the nervous system?
neurons and neuroglia cells
the __________nervous system consists of the brain and spinal cord
central nervous system
most signals that stimulate muscles to contract and glands to secrete originate in the _________nervous system
CNS
what part of the nervous system deals with incoming sensory information and is the source of thoughts, emotions, and memories.
CNS
What are the two main subdivisions of the nervous system?
central and peripheral
the ________nervous system consists of all tissue outside the CNS
peripheral
components of the PNS consist of ___________, ________, ________, and _________.
nerves, ganglia, enteric plexuses, and sensory receptors
a __________ is a bundle of hundreds to thousands of axons plus associated CT and blood vessels that lies outside the brain and spinal cord
nerve
there are _______pairs of cranial nerves,and _______pairs of spinal nerves
12, 31
_______are small masses of nervous tissue, consisting primarily of neuron cell bodies that are located outside the brain and spinal cord
ganglia
_______is closely associated with cranial and spinal nerves
ganglia
What three categories is the PNS divided into?
somatic nervous system(SNS) and autonomic nervous system(ANS) and enteric nervous system(ENS)
the somatic nervous system consists of ______that convey info from somatic receptors in the head to the CNS, and_____________that conduct impulses from the CNS to skeletal muscle only
sensory neuorns
motor neurons
the SNS is voluntary/involuntary?
voluntary
the branch of medical science that deals with the normal functioning and disorders of the nervous system is called ____________.
neurology
name the 3 types of neurons
1. sensory neurons
2. motor neurons
3. associative neurons
The ANS conduct sensory neurons and motor neurons from the CNS to ________,______, and ________.
smooth muscle, cardiac muscle, glands
the ANS is voluntary/involuntary?
involuntary
The motor part of the ANS consists of what two branches?
sympathetic division
parasympathetic division
___________division increases heartrate, fight or flight response while _________division slows down heart rate and rest and digest activities.
sympathetic division
parasympathetic division
the _____nervous system is considered the brain of the gut, mainly in the GI tract
enteric
the ENS is voluntary/involunatry?
involunatry
what are the three main functions of the nervous system?
sensory function
integrative function
motor function
the _________ is the functional unit of the nervous system
neuron
a _______or nerve impulse is an electrical signal that propagates along the surface of the membrane of a neuron
action potential
neurons make up 50% mass of nervous system and ______ make up 50% of mass of nervous system but are smaller in size then.
neurons
neuroglia
a __________ is any change in the environment that is strong enough to initiate an action potential.
stimulus
name the 3 parts of a neuron
cell body
axon
dendtrites
________ are the location of protein synthesis in a neuron
nissl bodies
a single axon of a neuron propagates nerve impusles toward _________,_______, or_________.
another neuron
muscle fiber
gland cell
in most neurons, nerve impusles arise at the _______and the _______, an area called the trigger zone.
axon hillock, and initial segment
the site of communication between two neurons, or between a neuron and an effector is called the ____________.
synapse
synaptic end bulbs contain many tiny membrane enclose sacs called __________ that store a chemical called _______
synaptic vesicles
neurotransmitter
___________axonal transport carries axoplasm in one direction only-from the cell body toward axon terminals.
slow
____________axonal transport moves materials in both directins-away and toward the cell body.
fast
_________axonal transport supplies new axoplasm to developing or regenerating axons and replenishes axoplasm in growing and mature axons.
slow
_________axonal transport uses proteins that function as motors to move materials along the surfaces of microtubules of the neurons cytoskeleton.
fast
________neruons usually have several dendrites and one axon. Most neurons in the brain and spinal cord are this type.
multipolar neurons
______neurons have one main dendrite and one axon. They are found in the retna of the eye, the ear, and olfactory area of the brain
bipolar neurons
_________have dendrites and one axon that are fused together to form a continuous process that emerges from the cell body.
unipolar neurons
What are the 3 functional classifications of neurons?
sensory neurons
motor neurons
interneurons or association neurons
________neurons convey action potentials away from the CNS to effectors in the PNS through cranial and spinal nerves.
motor
__________neurons convey action potentials from the axon into the CNS through cranial and spinal nerves.
sensory
_______neurons are mainly located within the CNS between sensory and motor neurons. they integrate incoming sensory information from sensory neurons and elecit a motor response.
interneuorns or association neurons
most sensory neurons are _______in structure
unipolar
motor neurons are _____in structure
multipolar
most association neurons are ________in structure
multipolar
________do not generate or propogate action potentials
neuroglia
________can multiply and divide in the mature nervous system
neuroglia
name the 4 neuroglia cells found in the CNS
1. astrocytes
2. oligodendrocytes
3. microglia
4. epemdymal
name the 2 neuroglia cells found in the PNS
schwann and satellite cells
____________cells are the largest and most numberous neuroglia cells.
astrocytes
__________neuroglia cells deal with the blood brain barrier
astrocytes
______________neuroglia cells are responsible for maintaining myelin sheath around CNS axons.
oligodendrocytes
_______neuroglia cells function as phagocytes
microglia
________neuroglia cells produce CSF
ependymal
______neuroglia cells encircle PNS axons; form myelin sheath.
schwann
______neuroglia cells surround cell bodies of neurons in the PNS ganglia and regulate intersitial fluid
satellite
axon surrpunded by a multilayered ______ and __________covering is called the myelin sheath
lipid and protein
What is the purpose of the myelin sheath?
electrically insulates the axon of a neuron and increases speed of nerve impusle conduction.
what two types of neuroglia cells produce myelin sheath?
schwann(PNS) and oligodendrocytes(CNS)
________cells begin to form myelin sheaths around axons during fetal development
schwann
_______are clusters of neuronal cell bodies in the PNS. __________ is a cluster of neuronal cell bodies located in the PNS
gangliaon
nucleus
a _______is a bundle of axons in the PNS. A ______ is a bundle of axons that is located in the CNS.
nerve
tract
_______interconnect neurons in the spinal cord and brain
tract
_________mater is composed primarily of myelinated axons.
white
__________mater contains neuronla cells bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia.
gray
True/Fasle Blood vessels are found in both white and gray matter?
true
what two types of electrical signals do neurons communicate with?
graded potentials and action potentials
_________potentials are used for short distance, while __________potentials are long distance.
graded potentials
action potentials
As you touch a pen, a_________ potential develops in a sensory receptor in the skin and fingers. The graded potential then triggers the axon of the sensory neuron to form a nerve ______potential, which travels along the axon into the ________nervous system and ultimatly causes release of __________ at the ________. The neurotransmitter stimulates the interneuron to form a ________potential in its ______ and _________.
graded
action
CNS
neurotransmitter
synapse
graded
dendrites
cell body
the production of graded potentials and action potentials depends on two basic features. Name them.
1. existence of resting membrane potential
2. presence of specific types of ion channels
name the 4 types of ion channels
1. voltage gated channels
2.leak channels
3. ligand-gated channels
4. mechanically gated channels
typically, plasma membranes have many more ________leak channels then _________leak channels.
potassium ion
sodium ion
a wide variety of chamical ligands such as ______,________, and__________ can open or closeligand-gated channels.
neurotransmitter
hormones
particular ions
_______gated channels opens in response to a change in membrane potential (voltage)
voltage gated
__________ are gated channels that randomly open and close
leak channels
Why does the resting membrane exist?
a small buildup of negative ions in the cytosol along the inside of the membrnae and an equal buildup of positive ions in the extracellular fluid along the surface of the membrane.
the separation of negative and positive charge during resting membrane potential creates _______energy.
potential
inneurons, the resting membrane potenital ranges from _____ to _____ mV
-40 to -90
what does the minus sign in -70mV mean?
the inside of the cell is negative relative to the outside
a cell that exibits a resting membrane potential is said to be ___________.
polarized
Name the 3 major factors in which resting membrane potentials arise.
1. unequal distribution of ions in the EFC and cytosol
2. inability of most anions to leave the cell
3. electrogenic nature of the Na+/K+ ATPases-membrane permeability to NA+ is very low because there are only a few sodium leak channels.
a _______________ is a small deviation from the membrane potential that makes the membrane either more polarized or less polarized.
graded potential
what does hyperpolarizing mean?
making the membrane more polarized (inside more negative)
what does depolarizing mean?
makeing the membrane less polarized (inside less negative)
what is the typical value for the resting membrane potential of a neuron?
-70mV
graded potentials deal with ________gated channels
ligand or chemically
action potentials deal with _______gated channels
voltage
the amplitude of graded potentials vary depending on what?
strength of the stimuli
according to the all or none principle, if a stimulus is strong enough to generate an action potential, the impulse generated is a ______size.
constant
True/Fasle A stronger stimulous generates a larger action potential?
false
The grater the stimulus strength above threshold, the ________the frequency of the action potentials.
greater
during an action potential, voltage gated ______ and _______channels open and close in sequence.
Na+
K+
during the first part of the refractory period, another impulse can/can not be generated?
cannot
when another impulse can not be generated is considered ________. when another impulse can be generated, but only by a larger then normal stimulus is _________.
absolute RP
relative RP
nerve impulse propagation in which impulse "leaps" from one node of Ranvier to the next along a myelinated axon is called ______________.
saltatory conduction
__________conduction is faster then _________ conduction
saltatory conduction
continuous conduction
True/False Axons with larger diameters conduct impulses at higher speeds than do axons with smaller diameters.
True
what does graded mean?
varying in amplitude (size)
what determines the amplitude of a graded potential?
depends on how many ligand gated channels have opened (or closed) and how long each remains open.
_________is the process by which graded potentials add together
summation
a ________ or impulse is a sequence of rapidly occurring events that decrease and reverse the membrane potential and then eventually restore it to the resting state.
action potential
what two main phases does and action potential have?
repolarizing state
depolarizing phase
What occurs during the depolarizing phase of an action potential?
the negative membrane potential becomes less negative, reaches 0, then becomes more positive
What occurs during the repolarization phase of an action potential?
the membrane potential temporarily becomes more negative then the resting level.
what two types of voltage gated channels open and close during an action potential?
open-voltage gated Na+ channels allow Na+ to rush into the cell which causes depolarization.
open-voltage gated K+ channels allow K+ to flow out which produces the repolarizing phase.
what creates the depolarization in an action potential?
open-voltage gated Na+ channels allow Na+ to rush into the cell which causes depolarization.
what creates the repolarization in an action potential?
open-voltage gated K+ channels allow K+ to flow out which produces the repolarizing phase.
the __________phase occurs when the voltage gated k+ channels remain open after the repolarizing phase
after-hyperpolarizing
an action potential occurs in the membrane of an axon of a neuron when depolarization reaches a certian level termed ____________.
threshold
what is threshold for an action potential?
-55mV
a ___________stimulus does not cause an action potential because it does not bring the membrane to threshold.
subthreshold
an action potential will occur in response to a __________
threshold stimulus
describe the all or none principle for an action potential.
an action potential either occurs or it doesnt.
ex:dominoes all fall or they dont
during the depolarizing phase, voltage gated Na+ channels ______rapidly. The inflow of Na+ changes membrane potential from -55mV to _______
open
+30mV
each voltage gated Na+ channel has two separate gates, ___________and _____________. In the resting state of a voltage gated Na+ channel, the inactivation gate is ________, and the activation gate is ________.
activation gate
inactivation gate
open
closed
during repolarizing phase, activation gates of voltage gated Na+ channels _______ and the inactivation gates ______.
open
close
the period of time after an action potential begins during which an excitable cell cannot generate another action potential in response to a normal threshold stimulus is called the _________.
refractory period
the _______is the period of time during which a second action potential can be initiated, but only by a larger then normal stimulus.
relative refractory period
how does local anesthetics work?
they block the voltage gated Na+ channels, and action potentials can not propagate so pain does not reach the CNS
name the two types of propagation
saltatory conduction and continuous conduction
________conduction requires step by step depolarization and repolarization of each adjacent segment in the plasma membrane
continuous conduction
___________, the special mode of action potential propagation that occurs along myelinated axons, occurs because of the uneven distribution of voltage gated channels.
saltatory conduction
name 3 factors that affect propagation
1. amount of myelination-more myelin the faster it is
2. axon diamter-larger diameter are faster due to their large surfaces
3. temperature-faster when warmer, slower when cool
Axons can be classified into 3 major groups based on amount of myelination, their diameters, and their propagation speeds. Name them.
1. A fibers-largert diameter, myelinated, somatic sensory & motor to skeletal muscle
2. B fibers-medium diamtere, myelinated, visceral sensory autonomic preganglinic
3. C fibers-smallest diamter-unmyeliated, sensory & autonomic motor
Name 7 differences between graded potentials and action potentials
1. GP arise mainly in dendrites and cell body, while AP arise at trigger zone
2. GP use ligand gated ion channels, AP use voltage gated channels for Na+ and K+
3. GP decremental(not propogated); short distance, while AP propagate and long distance
4. GP depends on strength of stimulus, AP is all or none
5. GP is longer, AP is shorter
6. GP may be hyperpolarizing or depolarizing, AP always consists of depolarizing followed by repolarizing phase and return to resting membrane potential
7. GP has no refractory period and summation can occur, AP has refractory period and summation cannot occur
________is a region where communication occurs between two neurons or between a neuron and an effector cell.
synapse
______refers to a nerve cell that carries a nerve impulse toward a synapse. It is the cell that sends signals
presynaptic neuron
_____________is the cell that receives a signal
psotsynaptic cell
______means from axon to dendrite. ________means from axon to cell body. _______means from axon to axon
axodendritic
axosomatic
axoaxonioc
at _________synapse, AP conduct directly between plasma membranes of adjacent neurons through structures called __________.
electrical synapse
gap junction
name the two main advantages of electrical synapses.
faster communication and synchronzation
in a chemical synapse plasma membranes are separated by the ____________
synaptic cleft
____________gated channels are used in chemical synapses
voltage gated Ca+
what type of synapse are the plasma membranes of a presynaptic and postsynaptic neurons?
chemical and electrical synapse
after neurotransmitter diffuses and binds to the receptors in the plasma membrane of the postsynaptic neurons, the postsynaptic neuron recieves an electrical/chemical signal and turns it into a ________________, a type of graded potential.
chemical
postsynaptic potential
the presynaptic neuron converts a ____________signal(nerve impulse) into a ________signal (relaesed neurotransmitter)
electrical
chemical
The postsynatic neuron recieves a ________signal and in turn generates a ___________signal (postsynaptic potential)
chemical
electrical
describe the 7 steps of a typical chemical synapse
refer to book page 474
A nerve impulse arrives at the ____________ of a presynaptic neuron. The depolarizing phase of the nerve impulse opens ____________channels which are present in the membrane of synaptic end bulbs. Because calcium ions are more concentrated in the extracellular fluid, _____flows _________through open channels. An increase in Ca2+ inside the presynaptic neuron serves as a signal that triggers _______of the synaptic vesicles. As vesicle membranes merge with the plasma membrane, ______________molecules within the vesicles are released into the synaptic cleft. The neurotransmitter molecules ____across the synaptic cleft and bind to _____________ in the postsnaptic neurons plasma membrane. Binding of neurotransmitter molecules to their receptors on _________gated channels opens the channels and allows particular ions to flow across the membrane. As ions flow through the open channels, the _______across the membrane changes. This change is called a ____________. Depending on which ions the channels admit, the postsynaptic potential may be a ___________ (excitation), or a ____________(inhibition). When a depolarization postsynaptic potential reaches ________, it triggers an ____________ in the axon of the postsynaptic neuron.
synaptic end bulb
voltage gated Ca2+ channels
Ca2+
inward
exocitosis
neurotransmitter
neurotransmitter receptors
ligand gated channels
voltage
postsynaptic potential
depolarization
hyperpolarization
threshold
action potential
at most chemical synapses only _________information transfer can occur.-from a presynaptic neuron to a potsynaptic neuron or a effector, such as a muscle fiber or gland cell.
one way
Action potentials move in only one/multiple directions
only one-from presynaptic neuron to postsynaptic neuron
a neurotransmitter can either cause a _________or _______graded potential.
excitatory
inhibitory
a neurotransmitter that causes depolarization is excitatory/inhibitory because it brings the membrane closer to threshold
excitatory
a depolarizing post synaptic potential is called a ________________
excitatory postsynaptic potential (EPSP)
a neurotransmitter that causes hyperpolarization of the postsynaptic membrane is ___________.
inhibitory
a hyperpolarizing postsynaptic potential is called a________________
inhibitory postsynaptic potential (IPSP)
during hyperpolarization, generation of an action potential is harder because....?
the membrane potential becomes inside more negative and thus farther from threshold then in its resting state.
since each specific neurotransmitters has different binding sites, when a neurotransmitter binds to the correct receptor, a ________opens and a postsynaptic potential forms in the membrane of the _____________.
ion channel
postsynaptic cell
what are the two types of postsynaptic potentials?
EPSP-excitatory
IPSP-inhibitory
neurotransmitter receptors are classified as either _____________receptors or ___________receptors based on whether the the neurotransmitter beinding site and the ion channel are components of the same proteins or are components of different proteins.
ionotropic
metabotropic
an ionotropic receptor when a neurotransmitter binding site and the ion channel are components of the same/different protein.
the same
an ionotropic receptor is a type of __________gated channel
ligand
when the correct neurotransmitter binds to an ionotropic receptor, the ion channel opens/closes and an EPSP or IPSP occurs in the postsynaptic cell.
opens
a metabotropic receptor is a type of neurotransmitter receptor, but lacks ____________.
ion channels
a metabotropic receptor is coupled to a seperate ion channel by a type of membrane protein called a _________.
G protein
a metabotropic receptor differs from ionotrophic receptors because the neurotransmitter binding site and ion channel are components of the same/different proteins
different
the greater the summation of EPSP, the greater/lesser the chance that threshold will be reached.
greater
name the 2 types of summation
spatial and temporal
___________summation is summation of postsynaptic potentials in response to stimuli that occur in at different locations in the membrane of a postsynaptic cell at the same time
spatial summation
spatial summation results from the buildup of neurotransmitter released simutaneoulsy by one/many presynaptic end bulbs.
many
________summation is summation of postsynaptic potentials in response to stimuli that iccur at the same location in the membrane of a postsynaptic cell but at different times.
temporal
temporal summationresults from buildup of neurotransmitter released by single/many presynaptic endbulb two or more times in rapid succession.
single
____________summation of effect of neurotransmitters released from 2 or more firing of the same end bulb in rapid succession onto a second neuron.
temporal
_____________summation of effects of neurotransmitters released from several end bulbs onto one neuron
spatial
nae the two categories of neurotransmitters
small-molecule neurotransmitters
neuropeptides
name the 6 types of small-molecule neurotransmitters
acetycholine
amino acids
biogenic amines
ATP and other purines
nitric oxide
carbon dioxide
__________neurotransmtter is released by many PNS neurons and by some CNS neurons
acetylcholine
________neurotransmitter is excitatory on NMJ but inhibitory at others
acetylcholine
_________neurotransmitter is inactivated by the enzyme acetycholinesterase
acetylcholine
___________ is an amino acid released by nearly all excitatory neurons in the brain-inactivated by glutamate specific transporters
glutamate
________ is in contrast to N20(laughing gas)smooth muscle relaxant
nitric oxide
____________is inhibitory neurotransmitter for 1/3 of all brain synapses (Valium is a GABA agonist—enhancing its inhibitory effect)
GABA
Name 4 amino acid neurotransmitters
glutamate
aspartate
GABA
glycine
name 4 important biogenic amino acids
norepinepherine
epinephrine
dopamine
serotonin
the neurotransmitter receptors can be acitvated or blocked. An agent that binds to receptors and enhances or mimics the effect of a natural neurotransmitter is called an ________. An agent that binds to block neurotransmitter receptors is called an ___________.
agonist
antagonist
throught your life, your nervous system exhibits _________, the capability to change based on experience
plasticity
__________ cells are able to reproduce, but __________ are not
neuoglia
neurons
how are individual nerves maintained throughout life? name 3 ways.
sprouting new dendrites
synthesis of new proteins
changes in synaptic contacts with neurons
_______ is the capability to replicate or repair themselves
regeneration
the __________nervous system may repair itself, while the __________nervous system has little to no repair.
PNS
CNS
_______is the birth of new neurons from undifferentiated stem cells.
neurogenisis
axons and dendrites that are associated with the neurolemma may be repaired if...name 3 ways.
-neuron cell body remains intact
-schwann cells remain active and form a tube
-scar tissue does not form too rapidly(3-5 days)
degeneration of the distal potrion of the axon and myelin sheath is called ____________
wallerian degeneration
what are neuropeptides composed of?
3-40 amino acids
what 3 ways is a neurotransmitter removed from the synaptic cleft?
1. diffusion
2. enzymatic degradation
3. uptake by cells (neurons, neuroglia)
at a chemical synapse between two neurons, the neuron receiving the signal is the ______________neuron, and the neuron sending the signal is celled the _______neuron
postsynaptic
presynaptic