Test 4 Flashcards
Central Nervous System (CNS)
Consists of brain and spinal cord(part that does integration)
Peripheral Nervous System (PNS)
the wire service between the body and CNS
Cranial Nerves
12 Pairs
Spinal Nerves
31 Pairs
- 8 cervicals
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
Somatic Nervous System
To and from body
Autonomic nervous system
Sympathetic: Fight or flight
Parasympathetic: rest and digest
Enteric Nervous System
Intestinal tract system
Sensory function
Afferent-arriving
brings in info from internal and external environment
Integrative function
analyzes the information that is gathered
Motor function
Efferent-exiting
acts on the analyzed information
Nervous tissue
2 types of cells
Neuron has 3 main parts
Cell body
Dendrites
Axons
Cell body
where the nucleus is located
Dendrites
small short extensions, bring action potential towards the cell body
Axons
one long/ very long extensions takes action potential away
Unmediated
uncoated
no special covering by cells
Myelinated
Coated
wrapped by a special covering made up of individual cells
wrapped by neuroglia cells called Oligodendrocytes
CNS
wrapped by Schwann cells
PNS
Node of Ranvier
gap on axon where no cell (between wrapping cells)
Myelin gap
where one cell ends and the next begin its wrap
Design of Nerve cells
classified by number of extensions to cell body
Multipolar cells
multiple dendrites
one axon
Bipolar Cells
one main dendrite
one axon
Unipolar cells
one fused extension, dendrite end and axon end
Neuron
used to integrate and transmit information
Gray matter
cell bodies and unmyelinated axons
white matter
myelinated axons
Neuroglia
structural support to the nervous system
Oligodendrocyte
Myelinating cell in CNS
Astrocyte
supporting cell for Neurons
Microglia
phagocyte in CNS
Ependymal
makes and helps circulate CSF (cerebral spinal fluid)
Schwann Cells
Myelinating cell in PNS
Satellite Cells
structural support
Neurons Pathway
Dendrite>Cell body>Axon>another cell
2 unique abilities of neurons
respond: mechanical, chemical, or electrical stimuli
transfer stimuli to other cells
Leakage gate channel
channel leaks allowing ions to slowly pass
Voltage gated channel
open when triggered by electrical changes
Ligand gated channel
opens when a molecule binds to a receptor
Mechanical gated channel
open in response to mechanical stimuli
pressure, vibration, stretch, etc
Action potential
all or nothing change in membrane
-stimuli either causes complete change in potential or nothing at all
Graded potential
change in membrane potential is NOT enough to reach threshold
-No action potential is generated
Depolarization
stimuli threshold is reached
-causing the opening of Na+ ion channels
Repolarization
K+ gates open, K+ moves out of cell down its conc gradient
Hyperpolarization
overshoots 70 mv usually down towards -90 mv
Continuous conduction
every part of the axon must depolarize and repolarize the entire length of the axon
Saltatory conduction
depolarization of action potential jumps between Myelin sheath gaps, traveling much faster
A fibers
Motor, Joint sensory
fastest
largest
most myelinated
B fibers
Autonomic
Slightly slower
-myelinated
-smaller
C fibers
Sensory
Slower
-unmyelinated
-smallest
Intensity of nerve input into system
- frequency of impulses
- number neurons sending
Acetylcholine
cholinergic sites, nerve to muscle, parasympathetic
-can be excitatory or inhibitory
Amino acids
Excitatory-Glutamate
Biogenic Amines
Norepinephrine/Epinephrine-energy and pleasure
Dopamine-energy and pleasure
Neuropeptides
excitatory and inhibitory proteins
Nitric Oxide
vasodilator (viagra works by enhancing NO effect)
Nerve
100’s-1000’s of axons
- blood vessels
- connective tissue component to hold it together
Nerve circuits
SImple Diverging Converging Reverberating Parallel
Simple (Nerve circuit)
one axon to one dendrite
Diverging
one axon to two different cell’s dendrites
Converging (Nerve Circuit)
several different cell axons to one cell’s dendrites
Reverberating
collaterals: branches of an axon, stimulate dendrites of cells that extend their axons back into the direction of the stimuli to the original cell
Parallel
Collateral axons: stimulate dendrites of different cells, that in turn stimulate the same cell’s dendrites
Excitatory
make membranes less negative, easier to depolarize
Inhibitory
make membrane more negative, harder to depolarize
Electrical communication
Cell membranes almost touch with gap cell junctions between cells that touch
Synaptic transmit ion (communication)
Axons of nerves do not touch dendrites of next nerve
Spinal cord anatomy
- from base of the brain to the end of the vertebral column
- exits skull through foramen magnum
- runs down the vertebral column in the vertebral foramen
What is the spinal cord protected by?
Meninges
Fat
Meninges
3 connective tissue layered, fluid filled bag that protects and anchors the spinal cord
- Pia mater
- Arachnoid
- Dura mater
Nerve tracts
bundles of axons, some cell bodies, that pass impulses to and from the brain
Pia mater
inner most layer on cord, anchors cord within vertebral column
Denticulate ligaments
anchor cord to column laterally
Filium terminale
anchors cord at the base of the column, coccyx
Arachnoid
has space between it and pia mater is filled with cerebral spinal fluid
Dura mater
outer layer of spinal cord
Cervical enlargement
C4-T1
-thicker, nerves to and from upper extremity
Lumbar enlargement
T9-T12
-thicker, nerves to and from lower extremity
Conus medullaris
point at L1-L2 position
Cauda equina
numerous nerves are what is left of below level of L2 area
Dorsal root
sensory axons coming into cord
Ventral root
motor axons leaving the cord
Cross-sectional anatomy of cord
looks like a gray butterfly in a white oval dish
Gray butterfly
is made up of cell bodies
White dish
made of myelinated axons
Thalamus
cerebral cortex’ executive secretary
all sensory axons end, sends axons to cortex
Hypothalamus
controls the autonomic nervous system, hormones
Epithalamus
contains pineal gland, which secretes melatonin
-promotes sleep
Medulla Oblongota
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