1. NERVOUS SYSTEM

2. Structure & Function The function of the nervous system is:
To sense, interpret, and respond to internal and external environmental changes to maintain a steady state in the body (homeostasis)
The nervous system is divided into two major structures:
Central nervous system (CNS)
Peripheral nervous system (PNS)

4. Central Nervous System
Central nervous systems includes:
Brain
Spinal cord
*Coordinates body’s full nervous system
*Contains nerves that control connections between impulses coming to and from the brain and the rest of the body

5. CentRAL NERVOUS SYSTEM
Nervous tissues are surrounded by 3 tough membranes (Meninges) because they are extremely delicate & easily damaged
Pia mater (inner)
Arachnoid (middle)
Dura mater (outer)
The nervous tissue & meninges are further protected by bones (vertebrae & cranium)

7. PERIPHERAL NERVOUS SYSTEM
Peripheral nervous system consists of:
12 pairs of cranial nerves
-Originate in the brain
31 pairs of spinal nerves
-Act independently from the
brain in some reflex reactions

9. PERIPHERAL NERVOUS SYSTEM
Organs of the peripheral nervous system contains:
Afferent (sensory) neurons
*Carry messages from the sensory cell of the
body to the brain
Efferent (motor) neurons
*Carry messages from the brain to the body organs or parts
*Classified as somatic (voluntary) or autonomic
(involuntary)
Interneurons
*Connecting nerves
*Carry messages from afferent to efferent nerves

10. PERIPHERAL NERVOUS SYSTEM
Autonomic nervous system is a part of the peripheral nervous system and has two parts: Sympathetic * Stimulated in situations that require action * Example: “fight or flight” reaction Parasympathetic * Functions in response to normal, everyday situations * Example: Digestion of food

11. UNITS OF THE NERVOUS SYSTEM

12. Nerves system is the nerve, which is a bundle of
* The basic structural unit of the nervous
system is the nerve, which is a bundle of
fibers that carries impulses
* Nerve fibers consist of neuron cells

13. NEURONS *Neuron cells are the functional unit of the nervous system
* Three main types of neuron cells:
afferent, efferent, & interneuron
(each carry messages, or impulses, to & from the body’s organs)
* Parts of Neuron:
Dendrite
Cell body
Axon

14. Dendrites: receive impulses & transmit them to the cell body Cell body: contains nucleus, transmits impulse to axon Axon: transmits impulse away from cell body to dendrite of next neuron

15. NEURONS * Impulse transmissions can travel more than 130
meters per second or 300 miles per hour
* Myelin (white matter)
- White, fatty substance covering the axon (outside CNS)
- Arranged in bundles called Schwann cells
- Has protective membrane called neurilemma which enables
axons to repair & regenerate themselves
* Gray Matter
- Axons IN the CNS
- Unable to repair or regenerate themselves
due to NO neurilemma

16. NEUROGLIA (glia) * Special nervous tissue cells that act as “glue”
to support, bind, repair, & protect neurons
* Three major types:
Astrocyte cells
Oligodendroglia
Microglia

17. SYNAPSE across the synapse to another neuron by a
* Space between two neurons
* Impulses from one neuron are transmitted
across the synapse to another neuron by a
chemical called a neurotransmitter
* Two most common neurotransmitters:
Acetylcholine
Norepinephrine

18. GANGLIA of the Central Nervous System
* Groups of nerve tissue located outside
of the Central Nervous System
* Increased ability to transmit impulses
because they are clustered together in
the ganglion

19. PLEXUS & DERMATOME Plexus * Four major networks of interwoven
spinal nerves
(cervical, brachial, lumbar, and sacral)
* Provide impulses to specific regions of
the body
Dermatomes
* Spinal nerves that control sensations on
the skin surface

20. BRAIN * Largest structure of the nervous system and
one of the largest organs of the body
* Brain weighs about 2 to 3 pounds
* The brain is covered by three layers of
membranes called meninges:
- Dura mater
- Arachnoid
- Pia mater

21. BRAIN
* Brain cells can only survive 4-6 min without oxygen and glucose from the blood * Four major areas of the brain: - Cerebrum - Diencephalon - Cerebellum - Brain Stem