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What is the function of the CNS?
- Sensory input
- integration of the info
- Motor out put
What is the function of the PERIPHERAL nervous system (PNS)
The PNS nevers extend from the brain to the spine cord
Function - serve as communication lines among the sensory organs
The PNS is apart of the outside nervous system
•Sensory (afferent)(TOWARDS) division–Nerve fibers that carry information to the central nervous system
•Motor (Efferent) (exit) division–Nerve fibers that carry impulses away from the central nervous system organs
The Motor or EFFERENT division breaks down into which 2 sub division?
a. Voluntary and Involuntary
b. Somatic and Autonomic
c. CNS and PNS
d. All of the above
b. Somatic and Autonomic!!!
•Somatic nervous system = voluntary
•Autonomic nervous system = involuntary
What are the FOUR types of nervous tissue?
- Ependymal cells
What is the function of an Astrocytes
* Star shaped cell the count for nearly HALF neural tissue.
*they have swollen ends that cling to neurons that anchor them to the blood capillaries.
* they help to protect neurons from harmful substances in the blood
* help to control the chemical environment in the brain by mopping up leaked potassium ions
what is the function of the Microglia?
the shape is spider like
they are phagocytes that monitor neurons and dispose of debri
(For example - Dead brain cells and bacteria
What is the function of Ependymal cells?
* The Ependymal cells line the central cavity of the brain & spinal cord
* The beating of the cilia help circulate cerebrospinal fluid
What is the function of the Oligodendrocytes?
they wrap their flat extentions around nerve fibers producing fatty insulin called myelin sheaths
What is the function of –Dendrites?
DEndrites convey incoming electrical messages toward the cell body
What is the function of the Axons?
Axons generate nerve impulses and conduct them AWAY from the cell body
what is another name for neurons?
transmit messages from one part of the body to the other
What and where is grey matter?
Grey matter contains mostly un-myelinated fibers & cell bodies
What is WHITE matter?
White matter consists of thick myelinated fibers (tracks)
What do you call the bundles of nerve fibers running in the CNS?
What do you call the bundles of nerve fibers running in the PNS?
Sensory (afferent) (towards) neurons do what?
•detect stimuli such as light, heat, pressure; •transmit information about stimuli to CNS;
Motor (efferent) neurons do what?
• Carry impulses from the central nervous system to viscera, muscles, or glands
what are the two Functional Properties of Neurons
•Irritability = –respond to a stimulus and convert it to a nerve impulse
•Conductivity = –transmit the impulse to other neurons, muscles, or glands
What does it mean when the neuron is polarized?
it means there are LESS positive ions sitting on the inner face of the neuron than there are on the outside
True or false?
As long as the inside of the cell remains more negative than the outside, the neuron will stay active
The inside of the cell must always be more NEGATIVE
What is an action potential?
The action potential is an explosion of electrical activity that is created by a depolarizing current. (A LONG DISTANCE SIGNAL)
What is another name for action potential?
What is a resting membrane potential is?
Resting membrane of a neuron is about -70 mV.
This means that the inside of the neuron is -70 mV
At rest, there are more sodium ions outside the neuron
More potassium ions inside that neuron.
Is sodium more positive outside the cell or inside the cell?
Na+ is the major positive ion outside the cell
–The plasma membrane at rest is polarized
–As long as inside is more negative than outside, the cell stays at rest
What does a resting neuron have to be at rest?
A. more negative inside
B. more negative outside?
A. more negative inside
Action potential initiation and generation:
A stimulus depolarizes the neuron’s membrane
The membrane is now permeable to sodium as sodium channels open
A depolarized membrane allows sodium (Na+) to flow inside the membrane