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Chapter 2
Nerve Cells and Muscles
43
Anatomy
Graduate
09/22/2009

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Term

Axons

&

Dendrites

Definition
long; narrow extensions, increase the cells surface area
Term
The Cell body can also be called...
Definition

soma

or

perikaryon

are alternate names for..

 

Term
Collateral
Definition
branc of an axon
Term
Nissal Substance
Definition
rough endoplasmic reticulum which synthesizes proteins; very dominant in neurons
Term
Axon Hillock
Definition
single axon in a multi polar neuron which extends from a small area of the cell body
Term
Terminal bouton
Definition
contains a few mirochondria and the distal ends of the axon's cytoskeleton; a swellin @ the end of telodendron
Term
What forms a synapse...
Definition

the terminal bouton

&

postsynaptic membrane

Term
Irritability
Definition
characteristic that is well developed & specalized in neurons, allowing a cell to react to its environment
Term
Resting potential
Definition

when the cell's cytosol is electrically negative relative to the extracellular fluid around

-70mV "polarized"

Term
At rest a neuron is..
Definition
when a neuron is polarized it is...
Term
Action potential
Definition
when there is a depolarization of about 15 to 30 mV at the axon hillock
Term
Depolorization
Definition
when the resting potential becomes less than -70mV, becoming more positive
Term
Nerve impulses
Definition
wave of negativity in which there is a sudden opening of ion channels and a rapid flow of    (+)sodium
Term
"All or non phenomenon"
Definition
an action potential exists or it does NOT; there is NO inbetween
Term
Repolarization
Definition
a decrease in membrane potential towards the resting state
Term
Hyperpolarization
Definition

if the restinf potential becomes greater then  -70 mV

(more negative)

ex/ -90mV

Term

Sodium

Potassium

Pump

Definition

maintains a chemical as well as an electrical gradient

-the resting membrane potential is re-established

Term
Satellite cells
Definition

glial cells in CNS

schwann cells in PNS

 

-facilitate the activity of the neurons

Term
"Principle cell"
Definition
neuron
Term
Oligoenrocytes
Definition
produce myelin in CNS cells & cover multiple processes around different axons
Term
Astrocytes
Definition
role in maintaining nerve signals, protective role in blood brain barrier (BBB), repair andscarrin in the NS and secrete neurotophic growth factors
Term
Microglia
Definition
the phagocytes of the NS
Term
Schwann cells
Definition
produce myelin in PNS & cover a single axon, in a "jelly roll" fashion
Term
Ependymal cells
Definition
line the ventricle & central canal of the spinal cord & are associted w/ choraic plexus/cerebral spinal fluid(CSF) & helps to form a blood (CSF)barrier
Term

Chorioid

Plexuses

Definition
responsible for the production of cerebral spinal fluid (CSF)
Term

Myelination -->

axon's myelin sheath

Definition
when a layer wraps around an axon, multiple times
Term
Node of Ranvier
Definition
axon is NOT covered by myelin; tiny space between one satellite cell and another
Term
Saltotorial conduction
Definition
when action potentials are not propagated continuously along a myelinated axon, instead jump from the sodium channels @ 1 node of ranevier to another
Term

Gogli Type I

(projection neurons)

Definition
large neurons w/ long axons that project to distant portions od the nervous sytem
Term

Gogli Type II

(local circut neurons)

Definition
small neurons in the CNS w/ short axons; do NOT extend to other parts of the NS
Term
Multipolar neurons
Definition

the most numerous of neurons; belongs to two types :

Gogli type I

Gogli type II

ex/ motor neurons

Term
Unipolar neurons
Definition

a nerve cell w/ a single process

ex/ sensory neurons

Term
Bipolar neurons
Definition

dendrite & axon arise from opposite end of the cell body

(two processes)

1.extend towards CNS

2. extend towards PNS

Term
Skeletal muscles
Definition

more portions of the skeleton & usually under voluntary control

(striated)

Term
Smooth muscle
Definition

found in walls or hollow contracting organs

-non voluntary

-non striated

-single nucleus

Term
Cardiac muscle
Definition

found only in the heart

-non voluntary

-striated

-single nucleus

-intercaleted disks

Term

Upper Motor Neuron

(UMN)

Definition
w/i the CNS, their cell bodies lie higher in the CNS center & their axons go to lower motor neurons
Term

Lower Motor Neuron

(LMN)

 

Definition

cell body in spinal cord or brain stem

-goes to organ, gland or muscle

(2 types)

1. alpha motor neurons

2.gamma motor neurons

Term
Alpha motor neurons
Definition
skeletal muscle cells are innervated by large multi-polar neurons
Term
Sense organs send 3 messages to the CNS..
Definition

1. degree of stretch of muscle

2. tension on each muscle

3.position of each joint

are the 3 messages this organ sends to the CNS

Term
Interneurons
Definition
w/i the spinal cord; help to regulate background excitation & spinal level reflexes
Term
Motor unit
Definition
formed by single alpha motor neurons & the muscle cells
Term
Proprioception
Definition
sense organs w/i the muscles, tendons and joints
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