functions of nervous system 

regulatory and coordinating all bodies system

1. central NS- brian and spinal cord

2. Peripheral NS(PNS)- sensory receptors , nerves, ganglia, and plexuses

::sensort receptors-endings of nerve cell or specialized cells that detect light, temp, pain, sound , pressure

:nerve-connect CNS to sensory receptors

::ganglion- collection of neuron bodies located outside the CNS

::plexus- extensive network of axons and neurons bodies outside CNS

sensory

-transmit action potential fom sensory receptors to CNS

motor

- transmit action potentails from CNS to organs or musckes

PNS

motor 2 divisions

somatic nrevous system - transmitss action potential to skeletal muscles

:voluntary control (SKELETAL )

autonomic NS- involuntary control (cardiac, smooth0
:sympathetic division - prepares body for physical activity

:Parasympathetic divisions- regulate resting functions

Made of of neurons adn neuroglia cells

-neurons

::dendrites-short, branched cytoplasmic ectensions, input part of neuron

::axon- signle, export part of neuron, forms branches

-neuroglia 

::more numerous than neurons, major supporting cells of CNS

6 types of nueroglia AkA CNS

1-4 in brain

5-6 outside

1. astrocytes- star shapes adn used to spread over

::blood vessels and neurons

::extensive sytoskelten extensive cytoskeleton, used fo rsupporting 

::helps blood (barrier)

2. ependymal cells

::line ventricles of brian and central canal of spinal cord

::form choroid plexus

3. Microglia

::mobile and phagocytic cells that destroy dead brain cells

4. oligodendrocytes

::cells that surround axons

::form myelin sheath

5. Shwann cells

:wrap around axon of PNS

6. Satellite cells

::surround neurons bodies for support and nutrient supply

extension from schwann cells or oligodendrocytes that surround axon 

::phospholipids adn appear white 

::nodes of ranvier

::protects and electrically insulates
::faster than unmyelinated 

organization of nervous tissue

-bundles of parallel axons with myelin sheaths are white, called white matter (FASTER)

-neuronal bodies adn unmyelinated bodies called grey matter (SLOWER)

-white matter makes nerve tracts

-gray matter performs integration and relay function

spinal cord

define

extensions?

communication link between brain and PNS

-extends from foramen magnum to second Lumbar vertebrare

-31 pairs of spinal nerves

-conus medullaries - conelike region where spinal cord terminates (inferior)

-cauda equina- formation of nerves that leave cornus medullaris

connective tissue 

-superficial and thickest is DURA MATER

-EPIDERAL SPACE-between vertebral canal and outside of dura mater

-Subdural space_located insdie dura mater , has fluid

-arachnoid mater- thin, cobweb like layer

_piamater- bound to surface of spinal cord

smallest , simplest part of NS capable of recieving stimuli, producing a responce

w/o conscious thought

-function

::move body from painful stimuli

::keep body from falling b/c of external stimuli

----blood pressure, water intake

stretch reflex

-muscle will contract in responce to a stretch 

-once muscle is stretched, sensory neurons fire to spinal cord

-sensory neurons connect with alpha motor neurons , which contract the muscle , stopping the stech

BRAIN 

brianstem

-most inferior part of brian stem

---continuous with spinal cord

::involved in regualtion of heart rate, blood vessel diameter, swallowing, vomiting, hiccupnig, couching, adn sneezing

Two enlargments called PYRIMDS

- descending nerve tracts used in conscous control of skeletal muscle 

-near inferior portion of nerve tracts switch sies (DECUSSATE)

-each half of brain controls opposite side of body

-two olives of medulla

--olives are nuclei which control balance, coordinaton and sound from inner ear

pons

superior to medulla

--contains assending and descending nere tracts

---conains pontine b=nuclei---relays information fom cerebrum to cerebellum, 

---includes pontine sleep center adn respiratory center, helps control respiratory movements