Chapter 12 Flashcards
Whats CNS stand for?
Central Nervous System
What does the CNS contain?
The brain and the spinal cord
What does it do?
Integrates snsory information, evaluates it, and initiates an outgoing response.
What is the CNS?
Structual and functional centre of the entire nervous system
What does PNS stand for?
Peripheral Nervous System
white matter
PNS: myelinated nerve
CNS: myelinated tracts
Gray matter
composed of cell bodies an unmyelinated fibers
CNS: referred to as nuclei
PNS: referred to as ganglia
Where does repair of neurons happen
in the PNS because of shawann cells neurolemma,
mature neurons cant be repaired because they are incapable of cell division
what is membrane potential
outside more positive
inside more negative
sign is relative to the inside
what is resting membrane potential
selective permiabile membrane helps maintain slight excess of positive ions on the outer surface of the membrane
at rest more potassium on the inside
not many sodium channels open at rest
-70mv (polarized)
Start to depolarize if doesnt reach threshold nothing will happen
what is local potential
excitation: opening of additional Na+ channels, allowing membrane potential to move toward zero (depolarization). inside will be positive when sodium channels open
Inhibition: triggers the opening of additional K+ channels, increasing the membrane potential (hyperpolarization). inside more negative when potassium channels open
Action Potential
the membrane potential of a neuron conducting an impules
also known as a nerve impulse
Threshold- -59mv NEED TO KNOW
never moves backwards
Saltatory
when you have myelin sheath
Absolute refractory period
cant have another action potential gonna occur
Relative refractory period
only have another stimulus if its big enough
What are the types of synapes
electrical and chemical
What is an electrical synapes
occurs where cells are joined by gap junctions allow an action potential to simply continue along postsynaptic membrane
What is a chemical synapes
occur where presynaptic cells release chemical transmitters (neurotransmitters) across a tiny gap to the postsynaptic cell, possibly inducing an action potential
What is a synaptic knob?
a tiny bulge at the end of a terminal branch of a presynaptic neuron axon that contains vesicles housing neurotransmitters
What is synaptic cleft?
space between a synaptic knob and the plasma membrane of a postsynaptic knob
what is the arrangements of the synapes?
Axondendritic: axon signals postsynaptic dendrite
axosomatic: axon signals postsynaptic soma
axoaxonic: axon signals postsynaptic axon; may regulate action potential of postsynaptic axon
sodium and chloride can never go together
potassium and sodium always do
what is spatial summation?
adding together the effects of several knobs being activated stimulaneously and stimulating different locations on the postsynaptic membrane, producing an action potential
What is temporal summation
when a synaptic knobs stimulate a postsynaptic neuron in rapid succession, their effects can summate over a brief period to produce an action potential
what does neurotransmitters mean
means by which neurons communicate with one another; more than 30 compunds are known to be neurotransmitters, and dozens of others are suspected
neurotransmitters relleased into the bloodstream are called hormones
what is the sympathetic system do
fight or fight prepares body to deal with immediate threats to the internal environment
what is the parasympathetic system do
coordinates the bodys normal resting activities; sometimes called the rest-and-repair division
what does the afferent divison consist of
consists of incoming sensory pathways
what does efferent divisons consist of
consists of all outgoing motor pathways
what does the somatic nervous system do
somatic motor divisoncarries information to the somatic effectors ( skeletal muscles)
somatic sensory carries feedback information to somatic integration centers in the CNS
what does the autonomic nervous system do
efferent divisons carries info to the autonomic or visceral effectors (smooth and cardiac muscles and glands)
visceral sensory carries feedback information to autonomic integrating centers in the CNS
What are the 5 major types of glia
astrocytes CNs microgilliaCNS ependymalCNS oligodendrocytesCNS schwann cells in the PNs
What are astrocytes
largest glia,
transfer nutrients from the blood to the neurons
form tight sheaths around brain capillaries, which , with tight junctions between capillary endothelial cells, constitute the blood-brain barrier
what are microglia
small, usually stationary cells
carry on phagocytosis
engolf anything that shouldnt be in there
what are ependymal cells
resemble epithelial cells and form thins sheets that line fluid filled cavities in the CNS
some produce fluid others aid in circulation of fluid
what are oligodendrocytes
hold nerves together
produce myelin sheath
what are schwann cells
only in perhipheral neruons
support nerve fibers and perform myelin sheaths
neurilemma is formed by cytoplasm of schwann cells myelin sheath gaps are often called node of ranvier
satellite cells are schwann cells that cover and support cell bodies in the pns
what are neurons
excitable cells that initiate and conduct impulses
what are the different components of a neuron
cell body
dendrites
axon
cytoskeleton
what does the cell body consist of
what does it do
ribosome, rough endoplasmic reticulum, golgi apparatus
provide proteins for maintaining and regenerating nerve fibers
mitochondria provide energy
what does the dendrites do
conduct nerve signals to the cells body of the neuron
each neuron has one or more dendrites, which branch from the cell body
what does the axon do
conducts nerve impulses away from the cell body of the neuron
pushes out the info
what does the cytoskeleton do
motor molecules shuttle organelles to and from the far ends of a neuron
what are the functional regions of the neuron
input zone: dendrites and cell body
summation zone: axon hillock
conduction zone: axon
output zone: telodendria and synaptic knobs of axon
what are the classification of the neurons
multipolar
bipolar
unipolar
what is multipolar
on axon and several dendrites
what is bipolar
only one axon and one dendrite; least numerous kind of neuron
what is unipolar
one process comes off nurson cell body but divides almost immediately into two fibers: central fiber abd peripheral fiber
whats an afferent (sensory) neurons
conduct impulses to spinal cord or brain
whats an efferent (motor) neuron
conduct impulses away from spinal cord or brain toward muscles or glandular tissues
what are interneurons
in between efferent and affernt
what is the reflex arc
a signal conduction with the electrical signal
beginning receptors and ending ineffectors
what are bundles of nerves called in the PNS
they are called bundles of nerve fibers
what are bundles of nerves called in the CNS
bundles of nerve fibers are called tracts rather than nerves
what are nerves
bundles of peripheral nerve fibers held together by several layers of connective tissue
what are the differnt layers
Endonerurium endo- inside
perineurium
epinerurium epi- outside
what is the endoneurium
delicate layer of fibrous connective tissue surrounding each nerve fiber
what is the perineruium layer
connective tissue holding together fasciles (bundles of fibers)
what is the epineurium layer
fiborous coat surrounding numerous fascicles and blood vessels to form a complete nerve.
