The document provides an overview of the anatomy and physiology of the nervous system, detailing the structure and classification of neurons, the central and peripheral nervous systems, and the functions of different types of nerves. It explains the processes of sensory input, motor output, and the role of neurotransmitters in nerve impulse transmission. Additionally, the document describes the regions of the brain, cranial and spinal nerves, and key functions related to the automatic nervous system.

1. The Nervous System
Anatomy & Physiology
Department of Allied
health Sciences
Module 9
The Nervous system
Neurons: Structure, types and properties
Central nervous system: neurons, neuralgia meninges.
Ventricles of brain, CSF
Brain, spinal cord: structures, functions, peripheral nervous system.
Spinal and cranial nerves: origin distribution and functions.
Automatic nervous system
Sympathetic and para sympathetic: origin distribution and function.
Common diseases of the system.
BCCTC102

2. Functions of the Nervous System
• Sensory input – gathering information
• To monitor changes occurring inside
and outside the body
• Integration - To process and interpret
sensory input and decide if action is
needed
• Motor output
•A response to stimuli
•Activates muscles or glands

3. Classification of the Nervous System
• Central nervous
system (CNS):
•Brain
•Spinal cord
• Peripheral nervous
system (PNS):
•Nerves outside the
brain and spinal cord

4. The Peripheral Nervous System
• Sensory (afferent) division - Nerve
fibers that carry information to the central
nervous system
• Motor (efferent) division - Nerve fibers
that carry impulses away from the central
nervous system.
• Somatic system:
voluntary
• Autonomic system:
involuntary

5. Autonomic Nervous System
• The involuntary branch of the nervous
system
• Consists of only motor
nerves
• Divided into two divisions
•Sympathetic division –
“fight or flight” response
•Parasympathetic division –
“housekeeping”

6. Nervous System Histology
Neurons = nerve cells
•Cells specialized to transmit
electrochemical messages
•Major regions of neurons
•Cell body – nucleus and
metabolic center of the
cell
•Processes – fibers that
extend from the cell body

7. Neuron Anatomy
• Dendrites – conduct impulses
toward the cell body
• Cell body (soma): contains
organelles & Nissl substance
(specialized rough ER)
• Axons – conduct impulses
away from the cell body
• Schwann cells – produce myelin
sheaths in jelly-roll like
fashion
• Nodes of Ranvier – gaps in
myelin sheath along the axon

8. Classification of Neurons
• Sensory (afferent) neurons
•Carry impulses from the sensory receptors
•Cutaneous sense organs
•Receptors – detect stretch or tension
• Interneurons (association): “connector”
• Motor (efferent) neurons
•Carry impulses from the central nervous
system

9. Neuron Classification
Figure 7.6

10. Electrochemical Nerve Impulses
• Dendrite depolarization
– a stimulus depolarizes
the dendrite’s membrane
• Sodium (Na+) flows
inside the membrane
with the help of Na+
pumps
• This exchange of ions
initiates an (+) action
potential in the neuron

11. The Action Potential
• If the action potential (nerve impulse)
starts, it is propagated to the end of the
axon
• Potassium (K+) ions rush out of the
neuron after sodium ions rush in, which
repolarizes the membrane
• The sodium-potassium pump restores
the original configuration - which is
resting potential (-)
*** This action requires ATP ***

12. Continuation of the Nerve
Impulse between Neurons
• Impulses are able to cross the synapse
to another neuron
•Neurotransmitter is released from a
neuron’s axon terminal
•The dendrite of the next neuron has
receptors that are stimulated by the
neurotransmitter
•An action potential is started in the dendrite

13. How Neurons Communicate at
Synapses
Figure 7.10

14. The Reflex Arc
• Reflex – rapid, predictable, and
involuntary responses to stimuli
• Reflex arc – direct route from a sensory
neuron, to an interneuron, to an effector

15. Regions of the Brain
• Cerebral
hemispheres
• Diencephalon
• Brain stem
• Cerebellum

16. Cerebral Hemispheres (Cerebrum)
• Paired (left and
right) superior
parts of the brain
• Include more
than half of the
brain mass
• The surface is
made of ridges
(gyri) and
grooves (sulci)

17. Specialized Area of the Cerebrum
Figure 7.13c

18. Specialized Areas of the Cerebrum
Figure 7.13c

19. Diencephalon
• Sits on top of the brain stem
• Enclosed by the cerebral hemispheres
• Three parts:
•Thalamus
•Hypothalamus
•Epithalamus

20. Brain Stem
• Attaches to the spinal cord
• Parts of the brain stem:
•Midbrain
•Pons
•Medulla
oblongata

21. Cerebellum
• Two hemispheres
with convoluted
surfaces
• Provides involuntary
coordination of body
movements
• “Arbor vitae” design
of white & grey
matter

22. • Extends from the
medulla oblongata to
the region of T12
• Below T12 is the cauda
equina (a collection of
spinal nerves)
• Carries sensory and
motor information
Figure 7.18
Spinal Cord Anatomy

23. Cranial Nerves
• 12 pairs of nerves
that mostly serve the
head and neck
• Numbered in order,
front to back
• Most are mixed
nerves, but three
are sensory only

24. Cranial Nerves
• I Olfactory nerve – sensory for smell
• II Optic nerve – sensory for vision
• III Oculomotor nerve – motor fibers to eye
muscles
• IV Trochlear – motor fiber to eye muscles
• V Trigeminal nerve – sensory for the face;
motor fibers to chewing muscles
• VI Abducens nerve – motor fibers to
eye muscles

25. Cranial Nerves
• VII Facial nerve – sensory for taste; motor
fibers to the face
• VIII Vestibulocochlear nerve –
sensory for balance and hearing
• IX Glossopharyngeal nerve – sensory for taste;
motor fibers to the pharynx
• X Vagus nerves – sensory and motor fibers for
pharynx, larynx, and viscera
• XI Accessory nerve – motor fibers to neck and
upper back
• XII Hypoglossal nerve – motor fibers to tongue

26. Spinal Nerves to know:
• Ulnar Nerve – Motor &
Sensory, “the funny bone”
• Radial Nerve – Motor &
Sensory
• Median Nerve – Motor &
Sensory
The Brachial Plexus (Arm)

27. The Lumbrosacral Plexus (Leg)
Spinal Nerves:
• Sciatic – M,S
• Femoral – M,S
• Obturator – M,S
• Tibial – M,S
• Common Fibular – M,S

28. “You just
nailed me in
the head!”
- Travis
Bogumill (21)
Eau Claire, WI
1998