A&P Chapter 12

116 cards

Nervous Tissue. For test #3.


 
  
Created Mar 5, 2009
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slvp

 

 
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1
What is the nervous system
 
About 3% of total body weight, one of the smallest but most complex systems.
2
What are some structures of the nervous system?
 
Brain, cranial nerves and their branches, ganglia, enteric plexuses, sensory receptors.
3
The brain is...
 
enclosed by the skull, contains 100 billion neurons, and 12 pairs (rgt and lft) of cranial...
4
What is a nerve?
 
A bundle of hundreds to thousands of axons w/ associated tissue and blood vessels that lies...
5
What is the function of the spinal cord?
 
Connects the brain through the foramen magnum of the skull and is encircled by the bones of...
6
Spinal nerves
 
31 prs, that emerge from the spinal cord, each serving a specific region on the right and left...
7
ganglia
 
small masses of nervous tissue, consisting mostly of neuron cell bodies, located outside of...
8
enteric plexuses
 
extensive neurons that help regulate the digestive system
9
sensory receptor
 
used to refer to dendrites of sensory neurons as well as separate, specialized cells that monitor...
10
Function of the nervous system
 
carries out a complex array of tasks, grouped into 3 basic functions: sensory, integrative,...
11
Sensory function
 
detect internal stimuli. Info carried to brain/spinal cord through spinal & cranial nerves
12
Integrative function
 
nervous system integrates information by analyzing & storing. Connects Sensory and motor functions.Important...
13
Perception
 
the conscious awareness of sensory stimuli
14
Motor function
 
activates effectors (muscles and glands) through cranial and spinal nerves. Stimulation of...
15
What are the two subdivisions of the nervous system?
 
Central nervous system (CNS), Peripheral nervous sytem (PNS).
16
CNS consists of...
 
brain and spinal cord
17
PNS includes...
 
all nevous tissue outside of the CNS
18
What are neurons
 
also known as nerve cells, possess electrical excitability.
19
Electrical excitability
 
the ability to respond to a stimulus and convert it into AP
20
Stimulus
 
any change in the environment that is strong enough to initiate an AP
21
An AP or nerve impulse is a....
 
electrical signal that propagates (travels) along the surface of the membrane neuron, it begins...
22
In what manner does the electrical signal travel?
 
once begun they travel at a rapid and constant strength
23
What are the three parts of a neuron
 
cell body, dendrites, and axons
24
cell body
 
known as the periaryon or soma, contains nucleus and cytoplasm with organelles.
25
What are the three unique features of the cell body
 
-there are nissil bodies located in the rough ER -hypofusion/lipofuscion the yellow pigment -neurofibrils...
26
Dendrites
 
structures that receive stimulus and send info to cell body, tree-shaped
27
Axon
 
takes all info from cell body and it is a strong enough stimulus it will send out information,...
28
Where are the places an Axon will send a stimulus?
 
Towards/Away from: neuron along the path, the brain, the spinal cord, glands, muscles, cells,...
29
Parts of an Axon:
 
Hillock, initial segment, trigger zone, axon collateral, axolemma, axoplasm, axon terminal,...
30
Hillock
 
cone-shaped, cell body of axon
31
Initial segment
 
first part of the axon closest to the axon hillock
32
Trigger Zone
 
junction of hillock and initial segment
33
axolemma
 
plasma membrane of the axon
34
asoplasm
 
cytoplasm of the axon
35
axon terminal
 
the many fine processes at the end of the axon
36
myelin sheath
 
only on myelinated axons/ Ex: PNS
37
NTS
 
stands for neurotransmitters
38
What are neurolgia and how large is it?
 
also known as glial, smaller than neurons, 5 to 50X more, take up 1/2 volume of CNS
39
What do neurolgia do?
 
They do not generate AP's, can divide, nourish/insulate/support/protect neurons
40
How many types or neurolgia are there?
 
6 types. 4 in CNS, 2 in PNS
41
4 types of neurolgia in CNS
 
Astrocytes, Oligodendrocytes,Microbial cells, ependymal cells
42
astrocytes
 
takes up the excess NTS's and maintains the K+ balance, star shaped cells, largest and most...
43
oligondendrocytes
 
produces and secretes myelin, which increases the speed of AP's
44
microbial/ microglia
 
small phagocytic with spinelike projections, eats microbes and cell debris
45
ependymal cells
 
possess cilia and microvilli, lines the surface, secretes CSF (cerebrealspinal fluid)
46
2 types of neurolgia
 
schwann cells and satellite cells
47
schwann cells
 
myelin sheath (speeds up AP)
48
satellite cells
 
supports neuron cell bodies in the ganglion
49
Nerve Repair
 
-occurs only in PNS -neurolemma repairs damadged axon (schwann cells)
50
nodes of ranvier
 
"sausages" gaps in the myelin sheath, appear in intervals along the axon
51
RMP
 
resting membrane potential
52
electrochemical gradient
 
a concentration (chemical) difference plus an electrical difference
53
what happens when ion channels open?
 
they allow specific ions to move across the plasma membrane
54
how to ions move
 
from a higher concentration to a lower concentration, postively charged cations move toward...
55
ion charges open and close due to...
 
gates/channels
56
leakage channels
 
randomly alternate b/w open and closed. Permeabililty to K+ much higher than to NA+
57
ligand-gated channel
 
opens and closes in response to a specific chemical stimulus, a wide variety of chemical ligands...
58
What are some examples of chemical ligands
 
neurotransmitters and hormones
59
What does the neurotransmitter acetylcholine do?
 
opens cation channels that allow Na+ and Ca+ to diffuse inward and K+ to diffuse outward
60
Mechanically gated channels
 
open or close in response to mechanical stimulation in the form of vibration, touch, pressure...
61
voltage gated channels
 
opens in response to a change in membrane potential (voltage)
62
how does resting membrane potential exist
 
because of a small buildup of -ions in the cytosol along the inside of the membrane and equal...
63
potential energy is measured in...
 
millivolts (mv)
64
what is potential energy
 
a separation of positive and negative electrical charges
65
what is true about the difference in charge across the membrane
 
the greater the difference the larger the membrane potential (voltage)
66
what is graded potential
 
a small deviation from the membrane potential that makes the membrane more polarized or less...
67
more polarized
 
the inside is more negative
68
less polarized
 
the inside is less negative
69
hyperpolarizing
 
when the response makes the membrane more polarized
70
depolarizing graded potential
 
when the response makes the membrane less polarized
71
decremental conduction
 
the mode of travel by which graded potentials die out as they spread along the membrane
72
summation
 
the process by which graded potentials add together
73
propagagtion
 
the AP keeps its strength as it spreads along the membrane
74
continous conduction
 
involves step by step depolarization and repolarization of each adjacent segment of the plasma...
75
salatory conduction
 
the special mode of AP propagation that occurs along myelinated axons, occurs b/c of uneven...
76
nodes of Ranvier (no myelin sheath)
 
the axolemma has many voltage-gated channels
77
what are the two consequences of a current crossing the membrane
 
AP appears to leap from node to node as each nodal area depolarized to threshold=saltatory,...
78
what three things effect the speed of propagation of an AP
 
amount of myelination, axon diameter, and temperature
79
amount of myelination
 
AP propagates more rapidly along myelinated axons than along unmyelinated axons
80
axon diameter
 
larger-diameter axons propagate AP faster than smaller ones due to their larger surface areas
81
temperature
 
axons propagate AP's at lower speeds when cooled
82
presynaptic neuron
 
the synapse b/w neurons, it is the neuron sending the signal
83
postsynaptic neuron
 
neuron receiving the message
84
axodendritic
 
from axon to dendrite
85
axoaxonic
 
from axon to axon
86
What are the two types of synapses
 
electrical and chemical
87
what are synapses essential for
 
homeostasis b/c they allow info to be filtered and integrated
88
what can come from the disruptions of synaptic communication
 
diseases and neurological disorders
89
electrical synapse
 
AP's conduct directly b/w adjacent cells through structures called gap junctions
90
where are gap junctions common
 
visceral smooth muscle, cardiac muscle, developing embryo, CNS
91
What are two main advantages to electrical synapses
 
Faster communication and Synchronization
92
Faster communication
 
faster communication, b/c AP conduct directly through gap junctions, they are faster
93
Synchronization
 
coordination of the activity of a group of neurons or muscle fibers, can produce AP's in unison...
94
Chemical synapses
 
plasma membranes of presynaptic and postsynaptic neurons that are close but do not touch
95
postsynaptic potential
 
type of grade potential caused when postsynaptic neuron recieves chemical signal
96
epsp
 
excitatory and inhibitory posysynaptic potential (neurotransmitter deploarizes the postsynaptic...
97
Inhibitory postsynaptic potential
 
IPSP, neurotransmitter that causes hyperpolarization, membrane potential becomes more negative...
98
iontropic receptor
 
a type of neurotransmitter receptor that contains a NT binding site and an ion channel, are...
99
what kind of channel is an iontropic receptor
 
ligand-gated channels
100
when does ESPS or IPSP occur in the postsynaptic cell
 
w/out the ligand, the ion channel component of ionotropic receptor is closed, when correct...
101
what do epsp's result in
 
opening of cation channels and allow K+, Na+, and Ca+ through the cell membrane
102
what do ipsp's result from
 
opening Cl channels, when these open chloride ions diffuse inward
103
spatial summation...
 
is the summation of postsynaptic potentials in response to stimuli that occur at different...
104
temporal summation
 
summation of postsynaptic potentials in response to stimuli that occur at the same location...
105
acetylcholine (ACh)
 
released by many PNS neurons and by some CNS neurons, when binding occurs w/ ionotropic receptors...
106
Glutamate
 
glutamic acids (amino acid) powerful excitatory affect
107
asparate
 
aspartic acid (amino acid) powerful excitatory affect
108
gamma aminobutyric acid and glycine
 
GABA and glycine are important inhibitory neurotransmitters, opens Cl channels
109
norepinephrine (NE)
 
plays roles in arousal (awakening from deep sleep), dreaming, regulating mood, serves as hormones
110
epinephrine
 
neurotransmitter, serves as hormones
111
dopamine
 
are active during emotional responses, addictive behavior and pleasurable experiences, help...
112
serotonin
 
concentrated in the neurons in a part of the brain, involved in sensory perception, temp regulation,...
113
nitric oxide
 
important w/ widespread effects throughout the body
114
neuropeptides
 
numerous and widespread in both CNS and PNS, bind to metabotropic receptors, have excitatory...
115
enkephalins
 
200x stronger than morphine
116
endorphins and dynorphins
 
bodies natural painkillers


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