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ANATOMY AND
PHYSIOLOGY
Chapter 8
The Nervous
System
The Nervous System
The Nervous
System is the
major
controlling and
communicating
system in the
body
The Nervous System
The means of
communication is
Electrical impulses
Which causes
immediate
responses
3 major Functions of the
Nervous System
Monitor
changes
occurring
inside and
outside the
body
These changes are
called stimuli and the
gathered info is called
sensory input
3 major Functions of the
Nervous System
Process and
interpret
sensory input
and make
decisions about
what should be
done.
This is called
integration
3 major Functions of the
Nervous System
Effect a
response by
activating
muscles or
glands.
The response is called
motor output
3 major Functions of the
Nervous System
So……
sensory input
integration
motor output
Works along with the
endocrine system
The Nervous System
2
Classifications:
CNS
Central Nervous
System
Made of brain and
spinal cord
The Nervous System
2 Classifications:
PNS
Peripheral Nervous
System
Made of nerves (spinal
and cranial)
Nerve Tissue
2 kinds:
1. Supporting
Cells
Nerve Tissue
2 kinds:
2. Neurons
Nerve Tissue
Neuroglia
Supporting cells in the CNS
Support, insulate, and
protect neurons
Not able to transmit impulses
Never lose ability to divide
so most brain tumors are gliomas.
Tumors are formed by neuroglia
Nerve Tissue
Neuroglia
1. Astrocytes
Star shaped
Cling to neurons
Form a barrier btw neurons and capillaries
Protect neurons from harmful substances in
the blood
Pick up excess ions and neurotransmitters
Nerve Tissue
Neuroglia
2. Microglia
Phagocytes
that dispose of
dead brain cells
and bacteria
Nerve Tissue
Neuroglia
3. Oligodendrocytes
Produce
insulating
covering called
myelin sheath
Nerve Tissue
Supporting
cells in the
PNS
• Schwann
cells
Form the myelin sheath
around nerve fibers in the
PNS
Nerve Tissue
Supporting
cells in the
PNS
2. Satellite
cells
Protective, cushioning cells
NEURONS
Nerve Cells
Transmit nerve
impulses
(messages)
Made of:
Cell body
Axon
Dendrite
NEURONS
Nerve Cells
Cell body Center of cell.
Contains the
nucleus
Process or fibers
extend from the cell
body
NEURONS
Nerve Cells
Axon conducts impulse
away from the cell
body
Only one per
neuron
NEURONS
Nerve Cells
Dendrite conducts impulse
toward the cell body
100s per neuron
1. dendrites
2. nucleus
3. Cell body
4. Myelin
5.
axon
sheath
NEURONS
Nerve Cells
Synapse
junction
between 2
neurons.
The 2 neurons
never actually
touch
NEURONS
Nerve Cells
Myelin
white fatty covering
on the axon.
They protect and
insulate
Also increase the
rate of nerve impulse
transmission
NEURONS
Nerve Cells
Myelin
if the myelin sheath
is destroyed as in
multiple sclerosis,
the person loses
the ability to control
their muscles.
NEURONS
Nerve Cells
Myelin of the CNS
White matter
myelinated fibers
Gray matter
unmyelinated fibers
NEURONS
Classification
Functional
classification
groups are
according to the
direction the
nerve impulse is
traveling
Afferent
or
Efferent
NEURONS
Classification
Afferent
Sensory. Carries
impulse from organs to
CNS
Efferent
Motor. Carries impulse
from CNS to muscles,
glands.
Properties of Nerve Impulses
Irritability
Ability to respond
to a stimuli
Conductivity
Ability to transmit
impulses to other
neurons, muscles, glands
Properties of Nerve Impulses
Electro-chemical
event.
Na ion enters cell
K ion leaves the cell
causing a resting
state.
NA K pump
depolarization
repolarization
Properties of Nerve Impulses
Neurons release
neurotransmitters
to influence other
neurons.
This opens a
specific ion channel
Neurotransmitter?
acetycholine
NA K pump
Active transport
Reflex
A reflex is a
rapid predictable
response to a
stimulus
Autonomic
Somatic
Regulates activities of smooth
muscles, the heart and glands.
Stimulates skeletal muscles
Reflex
Autonomic
Salivary reflex
Pupillary reflex
Somatic
Patellar reflex
Sucking reflex
Reflex
Normal reflexes
indicate normal
nervous system
functions
Plantar reflex (Babinski) The
normal reflex is toe flexion. If
the toes extend and separate, this
is an abnormal finding called a
positive Babinski's sign.
Central Nervous System CNS
Neural
Tube
How nervous system 1st
appears in embryo
Ventricles
Chambers. We have 4
Neural Tube
Deficiency of Folic acid =
neural tube birth defects
Folic Acid
Also called
B9
Leafy vegetables such as spinach and turnip greens
dried beans and peas, fortified cereal products,sunflower
seeds and certain other fruits and vegatables are rich
sources of folate. Some breakfast cereals are fortified
with 25% to 100% of the recommended dietary allowance
(RDA) for folic acid.