nervous system
complex
monitors conditions and takes corrective action, when necessary, to keep everything running smoothly
receives help from special senses
vital, hard to understand
brain and spinal cord
central nervous system, controls total nervous system
everything outside of brain and spinal cord is apart of PNS, peripheral nervous system.
input side of nervous system is sensory
output side is motor system
carries out orders and tells all three muscle types and body glands how to respond
somatic nervous system controls skeletal muscle and mostly voluntary mvmts
Motor system:
two branches
somatic: controls skeletal muscle and voluntary mvmts
autonomic: controls smooth and cardiac muscle in your organs and also several glands
voluntary
further divided into parasympathetic & sympathetic nervous systems
PARA: resting and digesting
sympathetic: fight or flight response
CNS sends directions to organs to gear up for action via autonomic NS
nervous tissue
neuroglia and neurons are two types of cells
glial: not capable of measuring environment, making decisions, sending orders
CNS has 4 types of glial cells:
astrocytes: metabolic and structural support cells that hold neurons and blood vessels close together
microglia: remove debris- microbes
ependymal: cover and line cavities of nervous system
oligodendrocytes: hold nerve fibers together and make lipid insulation- myelin
specialized cells in nervous system called neuroglia, or glial cells perform special functions
PNS has two types of glial cells:
schwann: make myelin
satellite: support
neurons: all of control functions of nervous system must be carried out by this group of cells, bizarre, many branches, a tail
each part of neuron has special function.
body- cell membrane
dendrites- receive info from the envrnmt
axon- generates and sends signals to other cells
axon terminal- where signal leaves cell
synapse- where axon terminal and receiving cell combine
neurons are classified by structure or function
neurons can have one axon and one dendrite: bipolar
one axon & many dendrites: multipolar
unipolar: neurons that have one process that splits into a central and a peripheral projection
interneurons/association neurons: neurons which carry info btwn neurons
excitable cells: if stimulated, can carry small electrical charge
a cell that is more positive: depolarized
cell that becomes more negative than resting: hyperpolarized
local potential- size or amount of stimulus determines excitement of cell
action potential- all or none
myelin- lipid insulation/ sheath formed by oligodendrocytes in cns & schwann cells in pns
MS:
myelin in cns is destroyed
autoimmune attack is cause
relapsing, chronic progressive
no cure, steroid meds, plasma exchange, immunosuppressing drugs
brain stem
receives sensory info and contains control systems for vital processes such as bp, heart rate, ventilation
peripheral neuropathy: damage to peripheral nerves
cranial nerves
31 pairs spinal
12 pairs cranial
diencephalon:
inferior to cerebrum
emotional state
divided into:
hypothalamus
pineal body
thalamus
pituitary gland
pineal body: responsible for melatonin
pituitary gland: secretes hormones
thalamus: relays and processes info going to cerebrum.
hypothalamus: regulates hormone levels, temp, h2o balance, thirst, appetite, pleasure, fear
sympathetic branch
controls fight or flight response.
HR, BP, sweating, dry mouth, dilation of pupils
ganglion
group of nerve cell bodies outside cns