Introduction To Nervous System Flashcards
(74 cards)
1
Q
CNS
A
- central nervous system
- brain- in skull
- spinal chord- vertebral canal
- connect at foramen magnum
2
Q
PNS
A
- peripheral nervous system
- made if nervous tissue, with sensory receptors, ganglia, plexuses, nerves
- external to CNS
- sensory and motor division
3
Q
Sensory division
A
Ending of neurons that detect, heat, pain, light
•sensory receptors
•transmits action potential from receptors to CNS
4
Q
Motor division
A
Efferent way •response transmits action potential from CNS to effector organs •ex: muscle glands Subdivisions: Somatic and autonomic
5
Q
Somatic (motor division, PNS)
A
Conscious control movement
•cell bodies in CNS,axons extend to skeletal muscles
6
Q
Autonomic (PNS, motor division)
A
•transmits action potential from CNS to specific sites
•out put, in voluntary
•two sub divisions:
Sympathetic and parasympathetic
7
Q
Sympathetic (PNS, motor division, autonomic subdivision)
A
Most active during physical activity
•fight or flight
8
Q
Parasympathetic (PNS, motor division, autonomic subdivision)
A
•regulates resting functions
Ex: digesting food, emptying bladder
•rest and relax
9
Q
Neurons
A
Receive stimuli
•transmits action potentials to other neurons or effector glands
•3 parts:
Cell body, axon and dendrites
10
Q
Cell body
A
- aka soma
* source of info for protein synthesis
11
Q
Dendrites
A
Inputs
•different neurons have different amount if dendrites
12
Q
Multipolar neuron
A
Has multiple dendrites and an axon
•most common neuron
•most neurons in the CNS and motor neurons
•axon conducts action potential to CNS
13
Q
Bipolar neuron
A
Has a dendrite and an axon
•dendrite is specialized to receive stimuli
•axon conducts action potentials to the CNS
•sensory organs: eyes nose ears
14
Q
Pseudo-unipolar neuron
A
An axon
No dendrites
•sensory receptor to CNS
•mostly sensory neurons
15
Q
Axon
A
Nerve fivers
•most have straight alignment and uniform diameter
16
Q
Trigger zone
A
Made of:
Axon hillock
Initial segment
17
Q
Axon hillock
A
Where action potential starts
18
Q
Initial segment
A
Beginning of axon
19
Q
Presynaptic terminals
A
Output
•enlarged ends branching out from axons
•contain neurotransmitters in small vesicles
20
Q
Sensory neurons conduct towards:
A
CNS
21
Q
Motor neurons conduct away from:
A
CNS and towards muscles or glands
22
Q
Interneurons
A
Conduct action potential from one neuron to another
23
Q
Neuroglia
A
•supporting cells •help form a permeability barriers between blood and neurons •produce cerebral fluid 3 types Astrocytes, choroid plexus, microglia
24
Q
Astrocytes
A
Star shaped neuroglia
•cytoplasmic processes extend from cell body
•cover surfaces: blood vessels, pia matter, neurons
•with foot processes
•blood-brain barrier
•regulate extra extracellular composition of brain fluid
25
Blood-brain barrier
Astrocytes Creates a water tight junction between endothelial cells
•determines what passes from the blood to nervous tissue of the brain or spinal chord
26
Ependymal cells
* produce cerebrospinal fluid
* line ventricles of brain and central canal of spinal chord
* bear patches of cilia that help move cerebrospinal fluid
27
Choroid plexuses (CNS neuroglia)
* specialized ependymal cells and blood vessels
* central regions of ventricles
* secrete spinal fluid
28
Cerebrospinal fluid (CNS)
* secreted by choroid plexus
* moved through out brain cavities on patches of cilia
* cilia helping with movement
29
Microglia (CNS)
Neuroglia in CNS
•free swimming
•phagocytic in response to stimulation
•move to areas of stroke, trauma, infection, perform phagocytosis
30
Oligodendrocytes CNS
Have cytoplasmic extensions that can surround axons
•if wrapped many times, forms a myelin sheath
•can for myelin sheaths around portions of several axons
31
Peripheral nervous system
* Schwann cells
| * satellite cells
32
Schwann cells PNS
Neuroglia in PNS
•wrap around axons
•wrap many times creates myelin sheath
•only wrap around a portion of one axon
33
Satellite cells PNS
•surround neuron cell bodies in sensory ganglia
•provide nutrients and support to neuron cell bodies
•protect neurons from heavy metal poisons
- absorbs and reduces access to neuron cell bodies
34
Myelinated
* Schwann cells or oligodendrocytes wrap repeatedly around axon
* makes action potential faster
* wrapped membranes rich in phospholipids
* cytoplasm sandwich between layers
35
Unmyelinated
* rest in invaginations of Schwann or oligodendrocytes
* surrounds but does not wrap
* able to surround many cells at once
* nucleus in center of surrounding axons, in cytoplasm
36
Gray matter
* groups of neurch cell bodies and dendrites
| * little myelin
37
White matter
Myelinated areas
38
CNS gray matter
* cortex: grey matter on the surface of the brain
| * clusters of grey matter located deeply in the brain are called NUCLEI
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PNS gray and white matter
Ganglia: gray matter, clusters if neuron cell bodies
Nerves: white matter
Bundles if axons with connective tissue and sheathes
40
Leak ion channel
Non gated
# of each leak ion channel in membrane determines its permeability characteristics of plasma to different ions
• permeable to k+ and cl-
•less permeable to na+ due to lack of channels
41
Ligand gated ion channels
* has an extracellular receptor site and membrane spanning part, forms ion channel
* Ligand Neurotransmitter that binds to receptor to open or close
* in nervous and muscle tissues as well as glands
42
Ganglion
Cluster of cell bodies in PNS
43
Nerve tracts are formed by what?
White matter of the CNS
| •propagate APs from one area of the CNS to another
44
Voltage gated ion channels
* open and close in response to small voltage across plasma membrane
* measured in millivolts
* Na+ K+: electrically excited tissue
* Ca+ : smooth muscle and cardiac muscle fibers
45
Plasma membrane of voltage gated channels
* millivolts measured by charge difference, due to neg charge inside plasma membrane relative to outside
* stimulated cell changes permeability of membrane due to open gates
* movement if ions into or out of cell changes charge difference across the plasma membrane
46
Resting membrane potential
* in stimulated, is potential difference
* intercellular fluid neutral (cations and anions)
* extracellular fluid also neutral
47
Polarized
Due to changes across membrane
| •inside negative outside positive
48
Potential difference
Electrical charge difference across membrane
49
Depolarization
* decrease in the membrane potential
* caused by decrease in charge difference (polarity) across plasma membrane
* inside becomes more positive
50
Hyperpolarization
* increase in membrane potential
* caused by increase of charge difference across plasma membrane
* inside becomes more negative
51
Grades potential
* chance in membrane potential that is localized to one area of the plasma membrane
* potential change can vary from small to large
52
Nerve fiber types are classified by what
Size and myelination
| •structure reflects function
53
Nerve fiber types
1- large and myelinated, 15-20 mls
• motor neurons supporting skeletal muscles, most sensory neurons
2-lightly myelinated medium sized 3-15 mls
3- small and unmyelinated
54
Type 2 and 3 nerve fiber types are mostly:
* part of the ANS, stimulates internal organs ( stomach heart intestines)
* responses necessary to maintain internal homeostasis
* don't need to be as rapid as responses to external environment
55
Synapsis
Junction between two cells
| •where communication takes place
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Presynaptic cell (terminal)
•transmits a signal towards the synapse
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Postsynaptic cell (membrane)
•cell that receives the signal from presynaptic terminal
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Postsynaptic membrane
Membrane of post synaptic cell
| •usually neurons, muscle cells or glands
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Neurotransmitter
* in chemical synapse
* action potentials do not pass directly from the presynaptic terminal to postsynaptic membrane
* instead, AP causes the release of neurotransmitters from terminals
60
Synaptic vesicles
* contains neurotransmitters
| * are membrane bound
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How action potential travels
* AP arrives at presynaptic terminal
* initiate a series of specific events
* = the release of neurotransmitters
* voltage gate Ca2+ channels open
* Ca2+ diffuse into presynaptic terminals
* ions cause synaptic vesicles to fuse with presynaptic membrane
* release neurotransmitter by exocytosis into synaptic cleft
62
Presynaptic terminals job:
•produce and release neurotransmitters
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Exocytosis
Elimination of material from a cell through the formation of vacuoles
64
Post synaptic potentials
When Hyperpolarization occurs in post synaptic membrane
65
Excitatory postsynaptic potential
* when depolarization occurs
* the response is stimulatory
* graded potential is called "EPSP"
66
Excitatory postsynaptic potential "EPSP"
* important because depolarization might reach threshold and fire off action potential
* excitatory neurons: release neurons that cause EPSP
67
Inhibitory postsynaptic potential
* when neurotransmitter and receptor result in Hyperpolarization
* "IPSP"
68
Inhibitory postsynaptic potential "IPSP"
* important because they reduce the likelihood of producing action potential
* movement and potential farther from threshold
69
Inhibitory neurons
* release neurotransmitter substances that cause IPSP
| * results from increase if permeability of the plasma membrane to Cl- or K+
70
Axoaxon synapse (CNS)
•the axon of one neuron synapses with the presynaptic terminal if another
71
Presynaptic inhibition
The amount of neurotransmitter release from the presynaptic terminal decreases
•ex: endorphins can reduce or eliminate pain by inhibiting the release of neurotransmitter from presynaptic terminals
72
Presynaptic facilitation
The amount if neurotransmitter release from presynaptic terminal increases
Ex: serotonin, release in certain axoaxonic synapses, function as neuromodulator that increase release of neurotransmitters from the presynaptic terminal, opening voltage gated Ca2+ channels
73
Spatial summation
* occurs when multiple action potentials arrive at two presynaptic terminals
* that synapse with same post synaptic neuron
74
Temporal summation
Two or more action potentials arrive in very close succession @ single presynaptic terminal
•combine where IPSP and EPSP summate to reach threshold
