Nervous System Flashcards
General Functions
Sensation
motor
intergration
CNS
Central nervous system
brain
spinal cord
PNS
Peripheral nervous system
everywhere else in the body
Afferent
Relays sensory information TOWARD the CNS
Efferent
Relays motor information AWAY from the CNS
Somatic
Innervates voluntary muscle
Automatic
Innervates involuntary muscle and glands
Parasympathetics
“Rest and digest”
Sympathetics
“Fight or flight”
Nervous tissue characteristics
Irratibility - responds to stimulus
conductivity
secretion of neurotransmitters or hormones
Nervous tissue cells
Glial Cells - Supporting Cells
Neurons- Functional cells
Glial cells in the CNS
ependymal cells
microglia
oligodendrocytes
astrocytes
Ependymal cells functions
Lines the spaces
produces cerebral spinal fluid
Microglia cells functions
Phagocytes
move around the CNS
Oligodendrocytes
Produce myelin
Astrocytes
Provide physical support for neurons and their processes
maintains optimal external environment for neurons
guides neurons for their development
forms the blood brain barrier
Glial Cells in the PNS
Satellite cells
shwann cells
Satellite cells functions
Provides physical support for neurons
Schwann cells functions
Makes myelin
guides neurons during development and their processes
guides for regeneration
Soma
Neurons Cell body
contains major organelles
no centrioles
Dendrites
Processes attached to the soma
main receivers of nuerons
contain mitochondria and cytoskeleton proteins
Axon
Process attached to the soma at the axon hillock
helps movement
maintains shape
contain mitochondria and cytoskeleton proteins
Types of axons
Unmyelinated
myelinated
Node of ranvier
Where axon is exposed from myelin
Axolemma
Axons membrane
Types of transportation along the axoplasm
Axoplasmic flow
axonal transport
Axoplasm
Axons cytoplasm
Axoplasmic flow
Passive process
TRANSPORTS:
mitochondria
cytoskeleton proteins
Axonal transport
Active transports
uses cytoskeleton proteins
Types of axonal transport
Anterograde
retrogrde
Anterograde axonal transport
Soma»_space;>axon terminal
TRANSPORTS:
Neurotransmitters
Retrograde axonal transport
Axon terminal»_space;> soma
TRANSPORTS:
VIRUSES
HEAVY METALS
Neurons based on structure
psuedounipolar
bipolar
multipolar
Neurons based on function
Afferent
efferent
interneurons
Interneurons
Connects afferent and efferent
Ionic channels
Leak channels
gated channels
Leak channels
ALWAYS OPEN
NA+ LEak channels
K+ leak channels
Gated channels
OPEN &. CLOSE
Chemically gated channels
voltage gated channels
Chemically gated channels
Opens when a chemical attaches to the proteins
Closez when a chemical is not attached to the proteins
Voltage Gated channels
Open & Close at different membrane voltages
Voltage gated NA+ channels
voltage gated K+ channels
Membrane Potential
a barrier between electrical charges
Resting membrane potential
in a stimulated neuron
USES
NA+ & K+ leak channels
NA+- K+ ATP Pumps
Anionic proteins
Graded Potential
in a stimulated neuron
USES
chemically gated NA+ channels
Anionic protein charge
negative
ATP PUMP
for every 3NA+ out 2K+ in
Local current
diffusion of NA+ underneath adjacent pieces of membrane
Action Potential
generated at the axon hillock
USES
local current from a graded potential
NA+ & K+ voltage gated channels
Action potential steps
starts at RMP
Local current diffuses along axon hillock
depolarizes to threshold
voltage gated NA+ channels open’
NA+ rushes into axon hillcok
depolarizes the membrane
VOltage gated NA+ channels close
Voltage K+ channels open
K+ rushes out of axon hillock
Repolarizes
VOltage gated channels become active
voltage gated channels start closing
hyperpolarization
voltage gated K+ channels finally close
Returns to RMP
RMP =
-70mv
Threshold =
-55mv
repolarization
membrane voltages move back to negative
hyperpolarization
membrane voltage drops lower than RMP
REfractory periods
Starts at threshold ends when returned to RMP
absolute refractory period
starts at threshold ends at -55mv during repolarization
reflective Refractory period
starts at -55mv during the repolarization
ends when returned to resting membrane potential
Threshold Stimuli
generates enough local current to depolarize the axon hillock to threshold
subthreshold stimuli
does NOT generate enough local current to depolarize the axon hillock to threshold
Summaation
can add effects of stimuli together
temporal summation
apply 1 subthreshold over a short period of time
spatial summation
apply multiple subthreshold stimuli sumutaniously
Continuous Propogation conduction
occurs along an unmyelinated axon
individual electrical currents
each piece of axolemma is depolarized to threshold generating an action potentiaal
Saltatory Conduction
occurs along a myelinated axon
generates action potentials at succesive nodes of ranvier
voltage gated channels only are found at the nodes of ranvier
factors that affect the rate of conduction
presence of myelin
diameter of axon
temperature
presence of myelin means
electrical activity is faster in a myelinated axon
diameter of axon means
larger = faster
smaller= more resistance slower (typically unmyelinated)
temperate effects
rates of diffusion
effects local current
effects Action potential
synapse
where axon terminal communicates with a postsynaptic cleft
If a neurotransmitter receptor is a … chemically gated NA+ channel
NA+ diffuses into the postsynaptic cleft
causes depolarization
produces EPSP
If a neurotransmitter receptor is a … chemically gated K+ channel
K+ diffuses out of post synaptic cleft
causes hyperpolarization
produces IPSP
If a neurotransmitter receptor is a … chemically gated CL- channel
CL- diffuses into post synaptic cleft
produces IPSP
ISPS
inhibitory postsynaptic potential
ESPS
excitatory postsnaptic potential
cholinergic synapse
releases ACh
ACh production
OCCURS
in the axon terminal
USES
choline= amino acid
ACellCOA= BYproduct of ATP
ACh breakdown
ACh turns into choline and acetyle
Cholinergic synapse locations
neurotransmitter junctions
ALL neuron- neuron synapse in PNS
Most neuron- neuron synapse in CNS
between parasympathetic neuron & its effector orgin
Alzheimer’s disease
progressive degeneration of cholinergic neurons
Cells die Stops transferring information
LOW PH on neutral activity
decreases neuron excitability by decreasing the RMP volatage
HIGH PH neutral activity
increases neuron excitability by increasing the RMP voltage
Reflexes
rapid automatic response to a stimulus (external or internal)
steps of reflex arc
apply stimulus to activate a sensory receptor
activate a afferent neuron
CNS processing
activate efferent neuron
response of effector organ
site of CNS processing
Cranial- ALL in brain
Spinal - ALL in soinal
monosynaptic reflex
1 synapse
polysynaptic reflex
2+ synapses
