Transcript The Nervous System Introducion

The Nervous System
Introducion
Overview
• Functions
• Organization
• Protection
Functions
• Monitor activities of body parts sensory neurons
• Communicate between body parts associative neurons
• Command necessary action - motor
neurons
Functions
• The nervous system is a fast acting
control center; it gathers, integrates,
stores and recalls information, and acts
upon that information to ensure
survival.
Organization: Divisions of
the Nervous System
• Central Nervous System (CNS)
-brain
-spinal cord
Organization: Divisions of
the Nervous System
• Peripheral Nervous System (PNS)
-cranial nerves
-spinal nerves
• Has two subdivisions: somatic &
autonomic
Organization: Divisions of
the Nervous System - PNS
• Somatic nervous system - voluntary,
contains sensory & motor neurons;
stimulates skeletal muscle
Organization: Divisions of
the Nervous System - PNS
• Autonomic nervous system involuntary; controls action of cardiac
and smooth muscle as well as glands
• Two subdivisions: sympathetic &
parasympathetic
Organization: Divisions of the
Nervous System - PNS
• Sympathetic system = “fight or flight”
response activated during times of
stress = increased heart rate, blood
pressure, etc.
• Also referred to as the “E” system for
exercise, excitement, emergency, &
embarrassment
Organization: Divisions of the
Nervous System - PNS
• Parasympathetic system =
“housekeeping” in effect most of the
time; maintains homeostasis
• Also referred to as the “D” system for
digestion, defecation, and diuresis
(urination)
Protection of the Nervous
System
• Bones - skull protects brain; vertebrae
protect spinal cord
• Cerebrospinal Fluid (CSF) - watery fluid
formed from plasma that circulates
through the central nervous
system and function as a shock
absorber
Protection of the Nervous
System
• Blood-Brain Barrier - made of the least
permeable capillaries in the
body, keeps neurons
separated from many
substances in the body to
help prevent uncontrolled
neural activity
Protection of the Nervous
System
• Blood-Brain Barrier
- keeps out metabolic wastes such as
urea, toxins, proteins, and most drugs
-also keeps out nonessential amino
acids and potassium
-does allow essential amino acid, water
and glucose
Protection of the Nervous
System
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Protection of the Nervous
System
• Meninges - 3 layered connective tissue
membranes that cover &
protect the brain and spinal
cord
• Layers in order of outermost to
innermost: Dura mater, Arachnoid
membrane, and Pia mater
Meninges
• Dura mater = “tough mother”, leathery
and made up of two layers that forms
the outer covering of the brain as well
as the periosteum of the skull
Meninges
• Arachnoid membrane - middle layer
with threadlike extensions giving
a cobweb like appearance. Has
subarachnoid filled with CSF
Meninges
• Pia mater = “gentle mother”, innermost
layer, delicate and highly
vascularized (rich blood
supply)
The End!