Nervous System Flashcards
nervous system
CNS + PNS
CNS
brain + spinal cord
brain
forebrain
midbrain
hindbrain
PNS
cranial nerves
spinal nerves
peripheral ganglia
somatic + autonomic
SNS
motor + sensory
control of body wall + upper/lower extremities
ANS
visceral
motor + sensory
motor → symp. + parasymp
cells in NS
neurons: nerve cells that conduct signals
neuroglia: support cells for neurons
neuron
~ 100 billion neurons (10^11)
each one has ~ 100 000 connections with other neurons
cell body = nucleus, nucleolus, dendrites, mitochondria, Nissl bodies
1 axon leaves cell body
synapse
connections between neurons
10^15 in CNS
nerve cell bodies
nucleus: collection in CNS
ganglia: collection in PNS
Nissl bodies
specialized ribosomal bodies
specific to nerve cells
neurofibrils
intermediate filament proteins
provide support within axon hillock
axon hillock
initial segment
summation of excitatory + inhibitory input
if threshold potential is reached = fires
bipolar neuron
2 appendages = 1 dendrite + 1 axon
senses = vision, taste, olfaction
unipolar neuron
1 appendage
somatosensation (afferents)
multipolar neuron
many dendrites, one axon
efferents (motor)
pyramidal, purkinje, stellate, granule, basket cells → found in brain = different dendrite branching
satellite cells
neuroglia that surround cell bodies in ganglia (PNS)
regulate O2, CO2, nutrient, + NT levels around neurons
Schwann cells
neuroglia that surround axons in PNS
one cell wraps one section of axon + produces myelin sheath = participate in repair process after injury
oligodendrocytes
neuroglia that myelinate CNS axons
have appendages = one cell myelinates many whole axons
provides structural framework
astrocytes
neuroglia in CNS
provide structural support; regulate ion, nutrient, + dissolved gas concentrations; absorb + recycle NT; form scar tissue after injury
some maintain blood-brain barrier
ependymal cells
neuroglia in CNS
line ventricles + spinal cavity
assist in producing, circulating, and monitoring of CSF
microglia
neuroglia in CNS
circulate to remove cell debris, wasts, and pathogens by phagocytosis (substitute for blood = limited by BBB)
meninges
membranes covering CNS structures = protection
- dura mater: tough outer layer; protect from external force
- arachnoid mater: secretes CSF into subarachnoid space; covers cranial blood vessels
- pia mater: delicate covering of brain
cerebrum
higher cognitive functions
language + speech
somatic motor + sensory function
regulates emotional aspects of behaviour