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”
7.
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
15.
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.
17.
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.
20.
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.
