Central Nervous System

CNS

consists of brain and spinal cord

includes neural tissue as well as blood vessels and connective tissues

responsible for integrating,processing and coordinating sensory data and motor commands

PNS

peripheral nervous system

includes all the neural tissue outside the CNS

can be divided into afferent and efferent divisions

delivers sensory info to the CNS and carries motor commands to peripheral tissues

cranial nerves connect to brain

spinal nerves attach to spinal cord

SNS

Somatic Nervous System

controls skeletal muscle contractions

voluntary contractions under conscious control

involuntary are automatic or beyond conscious awareness

reflex:automatic responce "touch hot stove"

afferent = to carry towards central area

carries sensory information TO the CNS from receptors in peripheral tissues and organs via receptors that either detect change in the environment or respond to a specific stimuli

efferent = to carry away from central area

carries motor commands from the CNS to muscles,glands and adipose tissue

effectors: target organs that respond to signals

Autonomic Nervous System

ANS

can't control

provides automatic regulation of smooth muscle, cardiac muscle and glandular secretions at the subconscious

has sympathetic and parasympathetic  divisions which are antagonistic. Ex: sympathetic will speed heart rate up and parasympathetic will slow it down

custodial cells of the nervous system

don't send message, they make sure the messages get delivered

6 types: 2 in PNS and 4 in CNS

In PNS: Satellite cells and Schwann cells

In CNS:

Oligodenrocytes

Astrocytes

Microglia

Ependymal cells

neuroglia in PNS

surrounds neuron cell bodies in ganglia

regulates O₂, CO₂, nutrient and neurotransmitter levels around neurons in ganglia

neuroglia in PNS

surround all axons in PNS

responsible for myelination of peripheral axons

participate in repair process after injury

"hot dog bun around axon"

gap btwn schwann cell called node of ranvier

neuroglia in CNS

myelinates CNS axons

myelin insulates axons increasing speed action potential travels along axon

"adipose blanket" around axons

provides structural framework

star-shaped neuroglia in the CNS

maintain the blood-brain barrier that isolates CNS from general circulation protecting it from harmful chemical and pathogens

provides structural support,regulate ion,nutrient, and dissolved gas concentrations;absorb and recycle neurotransmitters; form scar tissue after injury

least numerous and smallest neuroglia in the CNS

act as wandering janitorial service engulfing cellular debris, waste products and pathogens

neuroglia in CNS

ciliated cuboidal cells that line the ventricles of the brain and central canal of spinal cord that produce,circulate and monitor CSF

huge cell body

perikaryon:cytoplasm around nucleus

axon: tapering from cell body is long slender structure always Efferent taking the message away from cell body

dendites: little antenae around cell body bring messages TO cell body

axoplasm:cytoplasm of the axon

axolemma:specializd plasma membrane on axon

axon hillock: area where axon joins cell body

telodendria: fine extensions near end of axon

synaptic terminals: end of telodendria

based on relationship of dendrites to cell body and axon

anaxonic: dendrite and axons look the same,rare

bipolar:dendrite end,synaptic terminal w/ cell body in between. Occur in some sense organs

unipolar:. Most sensory sensory neurons

multipolar: 2 or more dendrite on cell body and single axon.  Most common in CNS and most motor neurons.

Sensory neurons are Afferent (sensory receptors)

Motor neurons are Efferent (SNS & ANS)

remember : SAME

outermost layer of connective tissue aroound entire peripheral nerve

equivalent to epimysium of muscles

dense collagen fibers that surround bundles of nerves called fascicles

equivalent to perimysium in muscles

delicate connective tissue, innermost layer,extend from perineurium and surround individual axons.

equivalent to endomysium

nerve impulse traveling in a wave

an electrical impulse that is propagated along the surface of an axon and does not diminish as it moves away from it's source

membrane channels that are always open

impt in establishing normal resting potential

RMP

resting membrane potential

Negative ions on the iNside : Cl-

pOsitve ion on the Outside : Na+

also called active channels

open and close in responce to specific stimuli

normal resting potential:gate closed

chemically gated:opens in responce to bound Ach

voltage-gate:opens if chg in transmembrane potential

any shift from resting potential toward a more positive potential

positive and negative poles are reversing...Na/Cl

the process of restoring the normal resting potential after depolarization

involves ion movement through membrane channels and ion pumps esp. sodium-potassium ion pump

mechanism in which UNmyelination axons propagate action potential.

signal has to travel the whole length of the axon by series of voltage-gated Na-channels

like ppl standing in a line..message conveyed person to person, one by one.

myelinated axons  carry impulses much faster

action potential jumps from node to node btwn schwann cells

a change in the environment that you respond to

ex: light for eyes,sound for ears

olfactory foramina in ethmoid bone for nose,taste bud on tongue