Chapter 12 [ EXAM #1 ] Flashcards
define innervation
nerve supply (motor and sensory)
what is the CNS composed of?
brain and spinal cord
what is the PNS composed of?
nervous tissue
nerve fibers
peripheral nerves:
- spinal
- cranial
what is the job of the CNS?
integrating, processing and coordinating sensory data and motor commands
how is the CNS organized?
nuclei (cell bodies)
tracts (axons)
what is the job of the PNS?
delivers sensory info into the CNS
carries motor commands out from the CNS
what is the PNS composed of?
nerves (axons)
ganglia (nervous tissue, cell bodies)
what is afferent division integration
processes sensory info, analyzes, makes decisions
what is efferent division?
produces appropriate motor response by activating effectors (e.g. muscles, glands)
somatic nervous system
voluntary: conscious skeletal muscle contraction
reflexes:
involuntary contractions
autonomic nervous system
visceral motor
involuntary, unconscious
cardiac muscle, smooth muscle, glands
sympathetic and parasympathetic
parasympathetic nervous system
“rest of digest”
conserves energy
promotes house-keeping functions during rest
sympathetic nervous system
“fight or flight”
mobilizes body systems during activity
visceral sensory
unconscious
organs
somatic sensory
conscious
skin, skeletal muscles
nervous tissue
very cellular
neurons: excitable nerve cells, functional units
neuroglia: supporting (glue) cells
neurons
variable sizes
long-lived and amitotic
high metabolic rate (glucose and O2)
electrically excitable (respond to stimuli, produce action potential)
action potential
electrical signal that moves along neuron membrane
neurofibrils
facilitate shape
neurotubules
facilitates motility (ribosome transport down axon)
dendrite spine
increase SA:V of dendrites
neuron plasma membrane components
axoplasm and axolemma
axon collateral
branches off the axon into more terminals
presynaptic cell
sends neurotransmitters
postsynaptic cell
receives neurotransmitters
neurotransmitters
released from synaptic vesicles in synaptic (axon) terminal
diffuse through synaptic cleft, bind to postsynaptic cell receptors
axoplasmic transport
movement between cell body and synaptic terminal
monorail system, neurotubules
anterograde axoplasmic transport
cell body to axon terminals, replenish neurotransmitters
retrograde axoplasmic transport
axon terminal to cell body (growth factor, rabies)
interneurons
association neurons
in brain and spinal cord
more interneurons = more complex respons (learning, memory)
neuroglia
supporting cells
in CNS: astrocytes microglia ependymal cells oligodendrocytes
in PNS:
satellite cells
Schwann cells
myelination
axons surrounded by multi-layered myelin sheath
electricity insulates, increases nerve impulse speed
nodes on Ranvier
gaps between internodes
gray vs white matter
white: mainly myelinated axons
gray: dense neuronal cell bodies, dendrites, unmyelinated axons
transmembrane potential
pos. and neg. ions held apart by selectively permeable membrane
varies with cell activity
determined by activity of passive and active forces
resting membrane potential
transmembrane potential at res (~70mV)
current
ion flow
resistance
interferes with ion current
chemical gradient
difference in concentration
K+ moves out
Na+ moves in
electrical gradiant
difference in charge
neg. insides, pos. outside
Na+ moves in
electrochemical gradient
difference in concentration of chemicals and electric charge
influences movement and establishes resting membrane potential
membrane very permeable to K+, K+ moves out
membrane somewhat permeable to Na+
leak (passive) channels
always open, differ between ions; establish resting membrane potential
gated (active) channels
closed at resting membrane potential, open/close in response to stimuli
chemically (ligand) gated channels
present in dendrites and neuron cell bodies
open/close when bind to specific chemical
voltage gated channels
present in unipolar and multipolar neuron axons
in excitable membrane (that generate AP)
open/close to change membrane potential
activation and inactivation gates
mechanically gated channels
present in dendrites and neuron cell bodies
not present in axons
in response to physical distortion of membrane: touch, stretch, vibration
depolarization
less neg. and more pos. resting membrane potential
repolarization
removal of stimulus, returns to resting membrane potential after depolarization
more neg. and less pos.
hyperpolarization
membrane more neg. than resting potential
graded potential
local changes in transmembrane potential
ratio of Na : K gates
3 Na : 2 K
