Nervous System

nervous tissue

* found in brain, spinal cord + nerves
* produce action potentials
* nerve cells/ neurons

nerve cells

* neurons
* conduct nerve impulse

unipolar neurons

single short process, branches like T

bipolar neurons

two processes from cell body (axon+dendrite)

uncommon (olfactory)

multipolar neurons

many dendrites, single axon, most common

sensory neurons

(afferent) transmit nerve impulses from sensory receptors to CNS

most are unipolar (few bipolar)

motor neurons

(efferent) transmit nerve impulses fromCNS to muscles or glands

all mutlipolar

interneurons

association

entirely in CNS'

multipolar

communication between sensory + motor neurons

nerve impulse path

dendrite receives information, transfers it to cell body for processing, axon sends output to other cells

neuroglia (glial) cells

* support cells
* support neurons
* structurally, nutrients, oxygen, insulate, repair

Oligodendrite

CNS, many different axons portions

glial cell

Neuralemocite

* shwans cells
* PNS, many cells - one axon
* glial cell

myelination

speeds up nerve impulses around axon

Central nervous system

brain, spinal cord

Peripheral nervous system

* sensory receptor
* nerve
* ganglion
* plexus

sensory receptor

receptor for sensory information

* specialized cell + dendrite of neuron

nerve

axons from many neurons bundled, surrounded by connective

transmit nerve impulse

ganglion

collection of cell bodies of neurons

plexus

web like network of spinal nerves fusing + branching

Spinal cord

* located in vertebral canal
* regions (cervical, thoracic, lumbar, sacral)
* 31 pairs of spinal nerves, leave through intervertebral foramen

foramen magnum

brain + spinal cord continuous

tract

collection of axons in CNS, myelinated

form white matter

sensory PNS

information to CNS

Motor PNS

information away from CNS to organ

Somatic PNS

skeletal muscles, voluntary

autonomic NS

cardiac + smooth muscles + glands

involuntary

meninges

connective tissue membranes surrounding spinal cord + brain

additional protection , 3 layers

dura mater

outer most + thickest (dense irregular connective tissue)

\

arachnoid mater

much thinner

spider web

middle layer of meninges

pia mater

deepest, thin

attached to outside layer of spinal cord

epidural space

between dura mater + bone of vertebral column

anesthesia injected

subdural space

potential space, not normally present but something (like blood) could come between dura + arachnoid

subdural hematoma

subarachnoid space

cerebrospinal fluid

white matter

myelinated axons forming __**tracts**__

ascending tracts - info to brain (sensory)

descending - down spinal cord (motor)

three funiculi

* white matter
* columns
* posterior ,lateral + anterior

gray matter

neuron cell bodies, dendrites, axons (unmyelinated)

three horns

posterior, lateral, anterior

gray matter

posterior root gangelion

determine side of spinal cord

cervical plexus

C1-C4

Phrenic nerve

lateral side of neck into thoracic cavity to diaphragm (stimulates diaphragm to contract)

axons from C3-C5

brachial plexus

go into brachial region

C5 - T1

radial, ulnar, median

sciatic nerve

sacral plexus

posterior thigh, split at popliteal

2 nerves bundled (common fibular, tibial)

* common fibular - lateral + anterior leg muscles’
* tibial - hamstrings, calf muscles

Roots of spinal cord

sacral region of vertebral column

Nervous System Division

* Central Nervous System
* Peripheral Nervous System
* Sensory
* Motor
* Somatic
* Autonomic
* Sympathetic
* Parasympathetic

How many pairs of spinal cord nerves?

31

Meninges + Spaces superficial to deep

* epidural space
* dura mater
* subdural space
* arachnoid mater
* subarachnoid space
* pia mater

ascending tracts

info to brain, sensory

descending tracts

info down to spinal cord, motor

white matter