Nervous System - Nervous Cells, Synapses, Neurotransmitters Flashcards
1
Q
main cells of the nervous system (2)
A
- neuron (nerve cell)
2. glial cell (neuroglia)
2
Q
neuron (nerve cell) vs glial cel (neuroglia)
A
- nervous cell vs supporting cell
- conductive cell vs non-conductive cell
- structural/ functional unit vs major part of nervous system
3
Q
where does information converge on the neuron
A
soma
4
Q
“all or none”
A
action potential will either fire or not :0
5
Q
soma
A
cell body
6
Q
dendrites
A
processes that gather sensory information
7
Q
axon
A
- process that conveys excitation to other neurones or effector cells
- often branch at end, causing a divergence of output
8
Q
axon hillock
A
region where action potential is generated
9
Q
Nodes of Ranvier
A
facilitate the rapid conduction of nerve impulses
10
Q
myelin sheath
A
protect and insulate axons and enhance transmission of electrical impulses
11
Q
structural criteria of neurons
A
look at photos!
12
Q
functional criteria of neurons
A
- afferent (sensory)
- association (interneurons)
- efferent (motor)
13
Q
afferent structure and function
A
- dendrites and cell body within the PNS, axons extend into CNS
- transmit impulses from peripheral sense receptors to CNS
14
Q
association structure and function
A
- located entirely within CNS
- sensory-motor integration
15
Q
efferent structure and function
A
- dendrites and cell body within CNS, axons extend to PNS
- transmit impulses from CNS to effectors in periphery
16
Q
glial cells (neuroglia)
A
- don’t conduct nerve impulses
- support, nourish, and protect neurons
- outnumber nerve cells (10x)
- capable of mitosis (cell division)
17
Q
glial derived from what?!
A
Greek word “glia” (“glue”)
18
Q
glial cells in CNS (4)
A
- ependymal
- oligodendroglial
- astrocyte
- microglia
19
Q
ependymal cells
A
- line surface of ventricles and produce/circulate CSF
20
Q
oligodendroglial cells
A
- form myelin sheath in the CNS
- usually each cell forms sheath of several axons
21
Q
astrocytes
A
- bind blood vessels to nerves
- help form the blood-brain barrier: take up ions and neurotransmitters
22
Q
microglia
A
- originate in the blood
- enter the brain and become phagocytic in response to inflammation
23
Q
blood-csf barrier
A
- “barrier that separates blood from CSF and CSF from brain tissue”
- choroid plexuses produce CSF
- choroid plexuses consist of ependymal cells
- CSF contains less protein and different ion concentrations than plasma (almost cell free)
24
Q
function of myelin? how is it produced?
A
- insulates the axon and increases action potential conduction velocity
- formed by Schwann cells
25
where are Schwann cells located
PNS!
26
motor neurons disease
Amyotrophic Lateral Sclerosis
27
disease associated with atrophy of basal ganglia (caudate and putamen)
Huntington's Disease
28
disease associated with axon demyelination in brain and spinal cord
Multiple Sclerosis
29
disease associated with atrophy of frontal and temporal cortex
Alzheimer's Disease
30
disease associated with decreased number of dopaminergic neurons in basal ganglia
Parkinson's Disease
31
main functions of neuron (2)
1. excitability
| 2. conductivity
32
excitability
- respond to a stimulus
| - produce an electrical signal (action potential)
33
conductivity
- provide a fast way for an impulse to travel from one point to another
- conduct an electrical signal (action potential)
34
action potential
- pulse-like change in membrane potential
- moves along surface of excitable cells
- fastest way to convey a signal in the body
35
generation of an action potential
see graph image
36
absolute refractory period
impossible to send another action potential
37
relative refractory period
hard to send action potential
38
synapses
- communication between two cells
| - apposing the axonal end feet of one cell to the membrane of another cell
39
pre-synaptic cell
cell sending message
40
post-synaptic cell
cell receiving the message
41
types of synapses
1. chemical synapses
| 2. electrical synapses
42
chemical synapse vs electrical synapse
1. gap between pre-synaptic and post-synaptic membranes vs appear to be fused
2. transmission is unidirectional vs bidirectional
43
chemical synapse components
1. presynaptic knob: contains neurotransmitter vesicles
2. synaptic cleft: gap between cells
3. postsynaptic knob: contains receptors
44
mechanism of neurotransmission
1. action potential enters the presynaptic terminal, depolarization opens voltage gated Ca2+ channels, entry of Ca2+ causes synaptic vesicles to fuse with the presynaptic terminal
2. Ca2+ binds to synaptotagmin causing opening of fusion pore, chemical neurotransmitter is rebased into the synoptic cleft
3. neurotransmitters bind to postsynaptic receptors, signal is initiated in the postsynaptic cell
45
mechanism for shut off of neurotransmission
1. destruction of the NT by degradative enzymes
2. diffusion of the NT away from the post-synaptic receptors
3. re-uptake of the NT either by the presynaptic terminal or by other cells
46
mechanism of vesicle recycling
1. kiss and run
| 2. full-collapse fusion
47
classification of neurotransmitters (4)
1. amino acids
2. monoamines
3. neuropeptides
4. choline esters
48
amino acids
gamma-aminobutyric acid (GABA), glutamate, glycine
49
monoamines
dopamine, norepinephrine, epinephrine, histamine, serotonin
50
neuropeptides
opioids (endorphins), hypothalamic peptides
51
chlorine esters
acetylcholine (Ach)
52
membrane receptors
1. ionotropic
| 2. metabotropic
53
ionotropic receptors
- ligand-gated ion channels
- open/close gated ion-channels
- short latency and rapid responses
54
metabotropic receptors
- G-protein-coupled receptors
- indirectly linked with ion channels
- act on G protein coupled receptors
- second messenger involvement (cAMP, IP3)
- longer latency and slow response
55
acetylcholine receptors
1. nicotinic receptors: ionotropic
2. muscarinic receptors: metabotropic
3. neurotransmitter: acetylcholine
56
adrenergic receptors
1. alpha (a1, a2) receptors: metabotropic
2. beta (B1, B2) receptors: metabotropic
3. neurotransmitter: norepinephrine/ epinephrine
