Chapter 8: Nervous system Flashcards
Axon
long cell process that moves the signal away from the cell body
neuron
receive stimuli, conduct action potentials, and transmit signals to other neurons or effector organs
myelin sheath
fatty covering that protects and speeds up the signal in the axon
nodes of ranvier
gaps in the myelin sheaths where the signal from the axon skips
saltatory conduction
when the signal in the axon jumps through the nodes of ranvier, skipping parts of the axon
unipolar/pseudo unipolar
has a single process extending from the cell body
bipolar neurons
has one dendrite and one axon extending from the cell body
multipolar neurons
have many dendriites, and a single axon
astrocyte
the major supporting tissue in the CNS; also forms the blood-brain barrier between the blood and the CNS
ependymal cells
line the fluid-filled cavities within the CNS. some produce CSF while others move CSF.
microglia
act as the immune cells of the CNS. they remove bacteria and debris
oligodendrocytes
provide myelin sheaths in the CNS. covers many cells
schwann cells
provides myelin sheaths to individual cells in the PNS
differences between CNS and PNS
CNS : uses oligodendrocytes, a collection of axons is called a nerve tract, and cells of cell bodies are called nuclei
PNS : uses schwann cells, a collection of axons are called peripheral nerves, and cells of cell bodies are called ganglion
neurotransmitters
chemical substances that send messages to other parts of the body
aceytlcholine
a neurotransmitter found usually in the neuromuscular junction
norepinephrine
excitatory; cocaine and amphetamines increase the release of norepinephrine and blocks the reuptake of them, causing overstimulation
serotonin
generally inhibitory, involved with mood, anxiety, and sleep. drugs such as prozac block serotonin transporters, treating anxiety and depression
dopamine
excitatory or inhibitory; parkinsons comes as a result of destruction of dopamine secreting neurons
Gamma-aminobutyric acid (GABA)
inhibitory; drugs that increase GABA function have been used to treat epilepsy, which is an excessive release of neurons
glycine
inhibitory; can lead to tetanus of repiratory muscles if strychnine is involved
endorphins
inhibitory; makes you feel good
converging neural pathway
two or more neurons go to one neuron
diverging neural pathway
one neuron divides to 2 neurons
meningitis
infections of meninges ( wrapping arpund brain and spinal cord)