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Chapter 12 Neural Tissue
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Anatomy
Undergraduate 1
05/05/2009

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Term

Central Nervous System

 

CNS

Definition

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

Term

PNS

 

peripheral nervous system

Definition

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

 

Term

SNS

 

Somatic Nervous System

Definition

controls skeletal muscle contractions

 

voluntary contractions under conscious control

 

involuntary are automatic or beyond conscious awareness

 

reflex:automatic responce "touch hot stove"

 

Term
Afferent
Definition
Term
Afferent divison of PNS
Definition

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

Term
Efferent division of the PNS
Definition

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

Term

Autonomic Nervous System

 

ANS

Definition

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

 

Term
Neuroglia
Definition

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

Term
6 types of Neuroglia
Definition

In PNS: Satellite cells and Schwann cells

 

In CNS:

Oligodenrocytes

Astrocytes

Microglia

Ependymal cells

Term
Satellite cell
Definition

neuroglia in PNS

 

surrounds neuron cell bodies in ganglia

 

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

Term
Schwann cells
Definition

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

 

Term
oligodendrocyte
Definition

neuroglia in CNS

 

myelinates CNS axons

 

myelin insulates axons increasing speed action potential travels along axon

 

"adipose blanket" around axons

 

provides structural framework

Term
astrocyte
Definition

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

Term
Microglia
Definition

 

least numerous and smallest neuroglia in the CNS

 

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

Term
ependymal cells
Definition

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

Term
Neuron structure
Definition

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

 

Term
Structural classification of neurons
Definition

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.

Term
Functional classification of neurons
Definition

Sensory neurons are Afferent (sensory receptors)

 

Motor neurons are Efferent (SNS & ANS)

 

remember : SAME

Term
Epineurium
Definition

outermost layer of connective tissue aroound entire peripheral nerve

 

equivalent to epimysium of muscles

Term
perineurium
Definition

dense collagen fibers that surround bundles of nerves called fascicles

 

equivalent to perimysium in muscles

Term
endoneurium
Definition

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

 

equivalent to endomysium

Term
impulse conduction
Definition
??
Term
action potential
Definition

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

Term
leak channels
Definition

membrane channels that are always open

 

impt in establishing normal resting potential

Term

RMP

 

resting membrane potential

Definition

Negative ions on the iNside : Cl-

 

pOsitve ion on the Outside : Na+

Term
gated channels
Definition

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

Term
depolarization
Definition

any shift from resting potential toward a more positive potential

 

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

Term
repolarization
Definition

the process of restoring the normal resting potential after depolarization

 

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

Term
continuous propagation (conduction)
Definition

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.

Term
saltatory propagation
Definition

myelinated axons  carry impulses much faster

 

action potential jumps from node to node btwn schwann cells

Term
stimulus
Definition

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

 

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