The nervous system is composed of the central nervous system (brain and spinal cord) and the peripheral nervous system. The central nervous system controls and coordinates essential body functions through sensory input, integration of sensory information, and motor output responses. The peripheral nervous system connects the central nervous system to the rest of the body and is divided into somatic, voluntary control, and autonomic, involuntary control systems. Within the central nervous system, the brain and spinal cord contain specialized cell types like neurons that communicate via electrical and chemical signals to regulate all body processes.

1. The Nervous System

2. The Nervous System
• The Nervous System is
the master controlling
and communicating
system of the body.
• The Nervous System
controls and coordinates
all essential functions of
the Human Body.

3. Functions of 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

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

5. 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

6. 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”

8. Central Nervous System
Neurons :
Neurons are
microscopic nerve cells
that make up the
brain, spinal cord, and
nerves
- 30,000 neurons can
fit on a pinhead

9. Anatomy of A Neuron
Each neuron contains:
• Cell body with
nucleus
• Dendrites : fibers
that receive
messages from
other neurons
• Axons : fibers that
send messages to
other neurons

10. Synapse
* Neurons do NOT
touch; there is a gap
between them called a
synapse
* The use of neurotransmitters
causes an electrical current
* Messages are sent
across the synapses by
special chemicals called
neurotransmitters

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

12. Central Nervous System
The central nervous system is composed of two major
interconnected organs:
• The brain
• The spinal cord
• These organs work together to integrate and coordinate
sensory and motor information for the purpose of
controlling the various tissues, organs, and organ
systems of the body.
• The central nervous system is responsible for higher
neural functions, such as memory, learning, and
emotion.

13. Central Nervous System
Brain:
• Weighs about 3 pounds in adults
• 75% water
• 20% of oxygen
• Contains over 100 billion neurons
• Controls bodily functions and interactions with the
outside world
Four Parts:
1. Cerebrum
2. Diencephalons
3. Brain stem
4. Cerebellum

14. Central Nervous System
Brain stem
Made up of the midbrain, pons and the medulla oblongata.
Midbrain : Involved with visual reflexes
Pons:
• Located between the midbrain and the medulla
oblongata
• Controls certain respiratory functions
Medulla Oblongata:
• Contains centers that regulate heart and lung
functioning, swallowing, coughing, vomiting and
sneezing

16. Central Nervous System
Cerebellum
• Area that coordinates musculoskeletal movement to
maintain posture, balance, and muscle tone.
• Inferior to the occipital lobes of the cerebrum.
• Posterior to the pons and medulla oblongata
Cerebrum
• Located above the cerebellum.
• Contains two hemispheres with an outer portion called
the cerebral cortex.
• The two hemispheres are connected by a bridge of
nerve fibers that relay information between the two
hemispheres called the corpus callosum.

18. • The left and right lobes are each divided into four lobes
or parts
• parietal lobe
• Frontal lobe
• Temporal lobe
• Occipital lobe
Diencephalon:
The deep portion of the brain containing:
• Thalamus
• Hypothalamus
• Epithalamus
• Ventral thalamus

19. Spinal Cord
• Extends from the medulla oblongata of the brain to the
area around the first lumbar vertebra in the lower back.
• Nerves from the peripheral nervous system extend out
from the spinal cord.
• Protected by:
*Vertebral column
*Cerebrospinal fluid (CSF) *Meninges
• Meninges are three layers of membranes that cover the
brain and spinal cord.

21. Layers of the meninges
1. Dura mater
• Outer tough fibrous membrane.
2. Arachnoid mater
• Middle web like membrane containing CSF.
3. Pia mater
• Innermost layer containing several blood vessels.