synaptic transmision Flashcards
1
Q
what are the function of the nervous system
A
Receives, processes, encodes and rapidly transmits information about the internal and external environment from one part of body to another
Controls muscle movements and the secretions of many glands
Awareness, perception, memory, language, learning, thinking and behavior
2
Q
- “wired” system
- chemical messengers (neurotransmitters) usually diffuse a very SHORT distance (synaptic cleft)
- acts rapidly for a short period of time (msec, sec, min)
A
nervous system
3
Q
- “wireless” system
- chemical messengers (hormones) usually diffuse throughout the body (long distance, carried by the blood)
- acts SLOWLY (minutes to hours) for a long period of time (minutes, hours, days)
A
Endocrine system
4
Q
The central nervous system consist of the _______ and ______ ______
A
brain
spinal cord
5
Q
The peripheral nerves system consists of _________ nerves and _______ nerves
A
spinal nerves - carry info to from spinal cord
cranial nerves- carry info to from brain
6
Q
the peripheral nervous system (PNS) is divided into two divisions:
A
sensory division
motor division
7
Q
this PNS division is Afferent.
Conducts impulses from receptors to the CNS
– Informs the CNS of the state of the body interior and exterior
A
Sensory Division
8
Q
this PNS division is Efferent.
Conducts impulses from CNS to effectors
A
motor division
9
Q
the motor division is subdivided into :
A
somatic (voluntary) and autonomic (involuntary)
10
Q
Autonomic nervous system can be further divided into:
A
–Sympathetic Nervous System
•“Fight or Flight”
–Parasympathetic Nervous System
•“Rest and Digest”
11
Q
this system has as many neurons as the spinal cord.
it is regulated by the autonomic nervous system but cannot function on its own.
A
enteric nervous system
12
Q
dendrites
A
receive incoming information
13
Q
Axon
A
sends information to cell
14
Q
group or aggregation of neuron cell bodies in the central nervous system
A
Nucleus
15
Q
group or aggregation of neuron cell bodies in the peripheral nervous system
A
Ganglion
16
Q
bundle of axons (surrounded by glia & connective tissue) in the PNS
A
Nerve
17
Q
bundle of axons in the CNS (CNS has glia, but no connective tissue)
A
Tract/Pathway
18
Q
Two cell types in the nervous system:
A
neurons
supporting cells/neuroglia
19
Q
highly specialized,
excitable cells, generate action potential
A
Neurons
20
Q
do not initiate or conduct nerve impulses, important for viability of the neurons, support neurons physically and metabolically, actively modulate synaptic function
A
Supporting cells or Neuroglia
21
Q
4 types of glial cells in CNS
A
astrocytes
oligodendrocytes
microglia
ependymal cells
22
Q
2 types of glial cells in PNS
A
Schwann cells
satellite cells
23
Q
- Surround clusters of neuronal cell bodies in the PNS
* Unknown function
A
Satellite cells
24
Q
- Form myelin sheaths around the larger nerve fibers in the PNS
- Vital to neuronal regeneration
A
Schwann cells
25
________ _____ cover myelinated and unmyelinated axons in the PNS
Schwann cells
26
surrounded by Schwann cells that don’t form myelin
Unmyelinated axons
27
- composed primarily of
lipids
-protects, acts as insulator, increases conduction velocity
-Nodes of Ranvier
-conduct an action potential faster than unmyelinated axons
Myelinated axons
28
Form myelin sheaths around
axons
One for many axons
Oligodendrocytes
29
Immune defense cells of CNS
| act as specialized macrophages and antigen- presenting cells - release destructive chemicals
Microglia
30
Excessive release of chemicals form ______ is suspected to contribute to neuronal damage seen in stroke, Alzheimer’s disease, multiple sclerosis and other neurodegenerative diseases
microglia
31
Line the internal cavities of the CNS
cilia contributes to the flow of CFS
Stem cells
Ependymal Cells
32
Clear fluid fills the ventricles, central canal and the subarachnoid space
•CSF surrounds and cushions brain and spinal cord: CNS “floats” in CSF
cerebrospinal fluid
33
Imbalance between formation, circulation and absorption of CSF can cause accumulation of excess of CSF, this is called
hydrocephalus (“water in the brain”)
34
treatment of hydrocephalus (“water in the brain”) consists of ______ shunting the excess of CSF to veins elsewhere in the body
surgically
35
The most abundant glial cells, the main “glue” of CNS, hold neurons together in proper spatial relationship
Astrocytes
36
Important in the repair of brain injuries and in neural scar formation
Astrocytes
37
Play a role in neurotransmitter activity: take up glutamate and GABA neurotransmitters bringing their actions to a halt
Astrocytes
38
responsible for establishing the blood-brain barrier (BBB
Astrocytes
39
brain capillaries the cells are joined by
tight junctions
40
signal the cells forming the brain capillaries to “get tight”
astrocytes
41
pathways of the BBB (5)
- paracellular- water soluble agents
- lipohilic- lipid soluble
- transport protein
- receptor mediated trancytosis
- adsorptive transcytosis
42
negative side to BBB
limits use of drug for treatment of CNS disorders
43
astrocytes are capable of releasing chemicals similar to neurons (gliotransmitters) , this synapse is called
Tripartite synapse
44
functions of astrocytes (5)
```
provide substrates for ATP production
Forms BBB
secretes neurotrophic factors
take up k, water, neurotransmitters
source of neural stem cells
```
45
2 functions of ependymal
create barrier between compartments
| another source of neural stem cells
46
oligodendrocytes forms
myelin sheaths
47
Cell body is called
soma
48
Cell processes that extend from the soma and receive input
dendrites
49
Cell processes that extend from the soma and primarily transmit action potentials (output)
axon
50
Axon originates from a special region of the cell body called
axon hillock
51
The myelin sheath is made by ________ in the CNS and by _________ in the PNS
oligodendrocytes
| scwhann
52
Interspersed along the axon are gaps where there is no myelin
nodes of Ranvier
53
Highly abundant rough ER (site of protein synthesis)
Nissl bodies
54
______ increase the surface area of a neuron, allowing it to communicate with multiple other neurons.
Dendrites
55
A dendrite’s surface area can be expanded even more by the presence of _______
dendritic spines
56
dendritic spines provide membrane space to form as many synapsis as possible - found in the ______
cerebellum
57
The movement of material is driven by motor proteins:
kinesin (anterograde transport)
| dyein (retrograde transport)
58
anterograde transport
from cell body to axon terminal
59
retrograde transport
axon terminal to the cell body
60
Many infectious agents such as the herpes virus utilize ______ transport
to reach their site of action.
axonal
61
Functional classification of neurons (3)
sensory (afferent)
motor (efferent)
internuerons
62
conduct action
| potentials toward the CNS (coming)
Sensory or afferent
63
conduct action potentials away from the CNS (going)
Motor or efferent
64
within CNS from one neuron to another
Interneurons or association neurons
65
Structural classification of neurons (3)
Multipolar, bipolar, unipolar
66
Specific location, function, and/or neurotransmitter of neurons (5 hint: ergic)
```
cholinergic
adrenergic
serotonergic
GABAergic
glutaminergic
```
67
a change in membrane potential that occurs when voltage-gated ion channels in the membrane open, increasing the cell’s permeability first to Na+ and then to K+.
Action potential (AP)
68
So long as threshold is surpassed, additional increases in stimulus strength do not lead to increases in the amplitude of the AP - this is referred to as the:
“all-or-none law” (refers to the fact that there is no "in-between“ AP).
69
In the membrane of dendrites and cell body (soma) of the neuron, the voltage gated Na+ channels are sparse. These areas generate
local (graded) potentials
70
result from ligand binding to receptor, mechanical stimulation, temperature changes, spontaneous change in permeability
local (graded) potentials
71
a touch-pressure receptor in the skin, where mechanical energy is converted into electric signals.
Pacinian corpuscle
72
Graded potentials vary in ________ (the larger the stimulus [stretch or pressure], the larger the depolarization).When the depolarization reaches the threshold, AP is generated in the sensory nerve.
amplitude
73
Degree of depolarization caused by the graded potential decreases with ______ from the _______: “ripples created by a stone tossed into a pond”
distance
| origin
74
Once an AP is initiated no further triggering event is required to activate the rest of the nerve fiber. The impulse is automatically conducted throughout the neuron without further stimulation by one of two methods of propagation:
unmyelinated nerve axon
| myelinated nerve axon
75
if amplitude is always the same, how do neurons encode for stimuli strength?
by frequent # of AP per second
76
has after rate of AP conduction
myelinated
77
the axon with the largest diameter is conduct a faster or slower AP?
faster
78
Continuous conduction occurs in:
unmyelinated axons
79
Saltatory conduction
•Occurs in myelinated axons
When AP occurs at one node, opposite charges attract from the adjacent inactive node, bringing potential to threshold so that it undergoes an AP, and so on
80
schwanncells are in the _______ system
PNS
81
oligodenrocytes are in the ______ system
CNS
82
autoimmune disease in which the body defense system erroneously attacks the myelin sheath surrounding the nerve fibers. Leads to myelin damage blocking AP propagation
Multiple Sclerosis (MS)
83
what are symptoms of MS
visual problems, tingling and numbness, muscle weakness, impaired coordination and gradual paralysis
84
during this, the portion of the membrane that has just undergone an action potential cannot be restimulated.
corresponds to the time during which Na+-channel gates are not in their resting confirmation.
absolute refractory period
85
during this, AP can be generated, but it will require considerably stronger stimulation than usually necessary. It happens because fewer than normal voltage-gated Na+-channels are in a resting position and K+ is still leaving
relative refractory period
86
The ensures the one-way propagation of the action potential down the axon away from the initial site of activation.
refractory period
87
Junction between two neurons
The Synapse
88
two types of junctions between synapse
– Presynapticneuron
| – Postsynapticneuron
89
two types of synapse
1. Electrical Synapses (pass electrical signals)
| 2. ChemicalSynapses (use neurotransmitters)
90
* Found in cardiac & smooth muscle and some neurons & glia
* Allows the action potential of the presynaptic cell to be propagated to the postsynaptic cell
* Bidirectional (two-way), very fast
Electrical Synapses
91
Synaptic vesicles contain chemical messenger neurotransmitter (NT)
presynaptic terminal
92
– Space between presynaptic cell
and postsynaptic cell
– Neurotransmitterdiffusion
Synaptic cleft
93
where Neurotransmitter receptors are found
Postsynaptic membrane
94
chemical synapse
Monodirectional (one-way)
pre/postsynaptic
synaptic cleft
95
Events at the Synapse and Exocytosis
| (5 steps)
1 AP depolarizes axon terminal
2 voltage gated Ca open and Ca enters cell
3 Ca triggers exocytosis of synaptic content
4 neurotransmitter diffuses across synaptic cleft and binds to receptor in post synaptic cell
5 neurotransmitter binding initiates response in postsynaptic cell
96
Some NTs increase permeability of Na+ channels, which results in a
graded depolarization
97
graded depolarization is often referred to
EPSP - excitatory postsynaptic potential
98
Some NTs increase permeability for K+ or Cl-, which results in a graded
hyper-polarization
99
Graded hyperpolarizations will bring theneuronalVM fartherawayfrom the threshold. This is often referred to
inhibitory postsynaptic potential or IPSP
100
Individual EPSPs can combine
| through ______
summation
101
Two types of summation:
Temporal summation
| Spatial summation
102
the same presynaptic neuron stimulates the postsynaptic neuron multiple times in a brief period
Temporal summation
103
multiple neurons all stimulate a postsynaptic neuron resulting in a combination of EPSPs which may yield an AP
Spatial summation
104
some chemicals released by neurons have little or no direct effects on their own but can modify the effects of neurotransmitters. These chemicals are called
neuromodulators.
105
neurotransmitter that are both excitatory and inhibitory (3)
acetylcholine
norepinephrine
dopamine
106
neurotransmitter that are generally excitatory (3)
glutamate
aspartate
nitric oxide
107
neurotransmitter that are generally inhibitory
| 7
```
GABA
glycine
serotonin
histamine
substance P
endorphin
enkephalin
```
108
Ionotropic receptors
- Fast transmission
| - Effect is very brief (a few ms to tens of ms)
109
Metabotropic receptors
second-messenger mediated
110
_______ is the major inhibitory mediator in the brain
GABA
111
The _____ receptors are Na+ channels, _____ receptor channel is permeable to Ca2+ and Na+
AMPA
| NMDA
112
Barbiturates and benzodiazepines
used to manage the seizures and also as sedatives and anesthetics
113
Many drugs used to treat depression either block NT reuptake or inhibit NT enzymatic break down, these types of drugs are
anti-depressants
114
this drug increases levels of DA and NE primarily by blocking their reuptake or promoting their release.
•Amphetamine
