Download The Central Nervous System

The Central Nervous
System
Advanced Biology
2002-2003
Spinal Cord: Protection
and Coverings
• Located in the spinal
canal.
• Surrounded by three
membranes.
• Cushioned by fluids.
• Protected by
ligaments.
Tortora
Pages 219 - 22
Spinal Cord: Protection
and Coverings
•Surrounded by
spinal meninges
–Dura mater
–Arachnoid mater
–Pia mater
Spinal Cord: Protection
and Coverings
•Epidural space:
between the dura
mater and the spinal
column
–Fat and connective tissue.
–Epidural block: anesthesic
causes a temporary loss of
sensation (childbirth)
Spinal Cord: Protection
and Coverings
• Subarachnoid space:
• Between the arachnoid
mater and the pia
mater
– Cerebrospinal fluid
circulates
• Spinal Tap:
– Spinal cord ends at L2
vertebra.
- Cerebrospinal fluid can be
withdrawn from
subarachnoid space.
Cauda equina
• The spinal cord is
shorter than the
vertebral column.
• Below the spinal
cord, nerves branch
out in the shape of
a horse’s tail
Structure of Nerve
Cord in Cross Section
• Cord is divided into
two halves
– Anterior median
fissure
– Posterior median
fissure.
Tortora
245
Posterior Median Fissure
Anterior Median Fissure
Structure of Nerve
Cord in Cross Section
• Cord contains
Whiter matter
– “H” shaped gray matter
– Gray matter is
surrounded by white
matter.
– Central canal in gray
matter contains
cerebrospinal fluid
Gray matter
Central canal
Structure of Nerve Cord in
Cross Section
• Cord contains
– The sides of the cord are
divided into horns.
– Anterior = front
– Lateral = side
– Posterior = back
Posterior Horn
Lateral Horn
Anterior Horn
Structure of Nerve Cord
in Cross Section
• Gray matter
contains mostly
association
neurons.
• White matter is
arranged into
columns.
• Columns contain
tracts
Function of Nerve
Cord
• White
matter
tracts serve
as highways
for impulse
conduction.
• Gray matter
integrates
incoming and
outgoing
information
Malformation of Spinal Cord
- Spina bifida-
Function of
Nerve Cord
• Motor tract
– Composed of just
three neurons.
– Fibers cross over in
the medulla.
– Pyramids
Tortora
Pages 370 - 375
Relex arc
•A reflex
arc is an
example of
a pathway.
Purpose is
to help
maintain
homeostasis
Tortora
Pages 370 - 375
Reflex Arc
Composed of 5
structures:
Tortora
Pages 370 - 375
Relex Arc
Receptor
Sensory neuron
Integrating Center
Motor neuron
Effector
Tortora
Pages 370 - 375
Spinal
Nerves
Spinal nerves are
paired.
31 pairs of spinal
nerves.
Tortora
Pages 370 - 375
Structure of the Brain
• Principal Parts
• Brain
is
divided into
four principle
parts.
•
Brain Stem
•
Diencephalon
•
Cerebrum
•
Cerebellum
Structure of the Brain
• Protection of
the Brain
• 3 cranial
meninges
•
Dura Mater
•
Arachnoid
mater
•
Pia mater
Structure of the Brain
• Cerebral Spinal
Fluid
•
Circulates through
the sub-arachnoid
space & ventricles
•
2 lateral
ventricles
•
3rd ventricle
•
4th ventricle
Human Vs Sheep Brain Cerebrum
Autonomic N.S.
• Regulates
•
Smooth Muscle
•
Cardiac Muscle
•
Glands
•
Hypothalamus is major
control area for ANS.
•
ANS is composed of
motor fibers.
•
Divided into two parts:
•
Sympathetic
•
Parasympathetic
Tortora
Pages 250-256
Autonomic N.S.
•
Organs have dual
innervation.
(Somatic is only
excitatory)
Tortora
Pages 250-256
Fight or Flight
Response
•
Pupils of eye dialate
•
Heart rate
increases
•
Blood pressure
increases.
•
Constriction of
blood vessels in non
essential organs.
•
Essential organ
blood vessels
dialate.
Tortora
Pages 250-256
Fight or Flight
Response
•
Bronchioles dialate.
•
Blood sugar level
rises. (glycogen
released.
•
Adrenal glands
secrete
epinephrine.
•
Non-essential
activities slow or
stop.
Tortora
Pages 250-256