exam 2 nervous system Flashcards
central nervous system
brain and spinal cord
“control center”
peripheral nervous system
cranial nerves, spinal nerves, and ganglion
define ganglion
group of neuron cell bodies located outside the CNS
sensory division
- receives info from body and transmits it to the CNS for processing
- has both CNS and PNS
somatic sensory component:
receives sensory info from skin, joints, muscle, special senses
visceral sensory component:
receives sensory info from blood vessels and viscera (organs)
motor division
transmits info from the CNS to muscles and glands
somatic motor component:
innervates skeletal muscle involuntary
nervous tissue cells are composed of
neurons and glial cells
neurons
respond to stimuli and conduct nerve impulses–primarily amitotic
glial cells function
- support and protect neurons
- many more glial cells than neurons, they divide by mitosis
cell body
neuron’s control center or “head”
chromatophilic substances
rough ER
- function: protein synthesis
- look like darkened “clumps’ within cytoplasm
- not found in axon hillock
dendrites
short nerve cell processes
- receive input and send nerve impulses to cell body.
- neuron can have 1 or man dendrites
axon
long nerve cell process
-send output
axon hillock
cone-shaped portion of cell body from where axon originates
what are the glial cells found in the PNS
satellite cells
neurolemmocytes
what are the glial cells found in the CNS
astrocytes
oligodendrocytes
microglia
ependymal cells
Satellite cells
surround neuron cells in spinal ganglia
-protect cell bodies and regulate nutrient exchange and waste removal
neurolemmocyte
- myelinated axons on PNS
- can help regenerate damaged PNS axons
What is mylin
- protective covering around axon
- it insulated axon and helps produce faster nerve impulses
- not all axons are myelinated
astrocytes
- regulates transfer of materials from blood to the brain (blood brain barrier)
- helps name blood vessels less leaky
multipolar neuron
one axon and many dendrites
- most common
- EX: Motor neurons, interneurons
bipolar neuron
2 processes– 1 axon and 1 dendrite, limited in location
EX: retina of eye, olfactory neurons in nose
unipolar neuron
single process comes off of the cell body and divides into 2 branches
- common
- EXs: most sensory neurons
sensory neuron
brings info to the CNS
-they are either unipolar or bipolar neurons
motor (efferent) neurons
takes info from CNS to other parts of the body
-all are multipolar
interneuron
helps coordinate and integrates info between sensory and motor neurons
- located solely in CNS
- “translator”
- multipolar
in the CNS, myelin sheath is formed by:
oligodendrocytes
in the PNS, myelin sheath is formed by:
neurolemmocytes
myelination procedure in PNS
1) Neurolemmocytes wrap around a 1mm portion of an axon successfully
2) Cytoplasm and nucleus of neurolemmocyte gets “squeezed” to the outside
3) inner successive layers of the cell membrane make up the myelin sheath
neurofibril nodes
- “gaps” between 2 adjacent neurolemmocytes
- axon unmyelinated
- its at nodes that a nerve impulse is generated
myelinated procedure in CNS
similar to process in PNS, but
- oligodendrocytes myelinate CNS axons
- one oligodendrrocytes myelinated 1mm portions of many axons
how does an impulse travel on an unmyelinated axon
spread along entire length
how does an impulse travel on a myelinated axon
nerve impulse jumps from node to node
