1. CHAPTER 19 NERVOUS SYSTEM Lesson 1
Cerebrospinal fluid
Dementia
Epilepsy
Impulse
Intracranial
Ischemia
Meninges
Myelography
Neurotransmitter
Polyneuritis
Reflex
Regenerate
Senile
Journal question: What are the functions of the nervous system?

2. Chapter 19 Learning Objectives
Define at least 10 terms relating to the nervous system.
Describe the function of the nervous system.
Identify at least 10 structures of the nervous system.
Remind students that the learning objectives are the goals of the chapter – what the student is expected to know or learn from the chapter. Turning each objective into a question will help the student better understand the objective.
As a pre-test, challenge the class to give possible answers to these learning objectives. Ask the students to write their answers on a sheet of paper. When the chapter is completed, have the students go back and re-visit their initial answers to these questions.

3. Structure and Function
The nervous system is divided into two major parts:
Central nervous system (CNS)
Peripheral nervous system (PNS)
The nervous system senses, interprets, and responds to internal and external environmental changes to maintain the body’s homeostasis.
The nervous system transmits messages to the brain at 180 miles per hour.
How does the nervous system help maintain homeostasis in the human body?

4. Central Nervous System
Parts of the CNS
Brain
Spinal cord
Coordinates body’s full nervous system
Contains nerves that control connections between impulses to and from the brain and the rest of the body
The human brain is very soft, like butter.
The human spinal cord is about 17 to 18 inches long and is longer in men than in women.

5. Central Nervous System
The CNS plays a critical role in maintaining a healthy, normally functioning body.
Meninges (tough membranes) protect the nervous tissues.
Surrounding the human brain is a liquid that helps cushion it as we move our heads.

6. Central Nervous System
Human brains require a continuous supply of oxygen to survive and sugar in the form of glucose for the neurons to function.
FIGURE 19-1 Divisions of the nervous system. A, The central nervous system. (From Sorrentino SA: Mosby’s textbook for nursing assistants, ed 7, St. Louis, 2008, Mosby.)

7. Peripheral Nervous System
The PNS contains
12 pairs of cranial nerves
Originate in the brain
31 pairs of spinal nerves
Act independently from the brain in some reflex reactions
Refer to Slide 9 for the location of the cranial and spinal nerves or Figure 19-1B in the students’ textbook and to Slide 10 (Table 19-1 in students’ textbook) for the functions.

8. Peripheral Nervous System
FIGURE 19-1 Divisions of the nervous system. B, The peripheral nervous system. (From Sorrentino SA: Mosby’s textbook for nursing assistants, ed 7, St. Louis, 2008, Mosby.)

9. Functions of the Peripheral Nervous System

10. Organs of the Peripheral Nervous System
PNS organs contain
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 automatic (involuntary)
There are about 13,500 neurons in the human spinal cord.

11. Divisions of the Nervous System
FIGURE 19-5 The nervous system may be divided into parts on the basis of their functions.

12. Spinal Reflex Arc
The most sensitive nerves are found at the base of the spinal cord.
FIGURE 19-3 The spinal reflex arc. The motor response to injury is a reflex action controlled by the spinal nerves.

13. Neurons The basic structural unit of the nervous system is the nerve.
A nerve is a bundle of fibers that carries impulses (messages) to and from the body’s organs.
Nerve fibers consist of neurons (cells).
Three main types of neurons
Afferent (sensory)
Efferent (motor)
Interneuron
Interneurons connect sensory impulses to motor impulses.

14. Autonomic Nervous System
Sympathetic system
Sympathetic nerves are stimulated in situations that require action (e.g., fight-or-flight reaction).
Parasympathetic system
Parasympathetic nerves respond to normal, everyday situations.

15. Neurons Important parts of a neuron Dendrites Cell body Axon
Receive impulses and transmits them to the cell body
Cell body
Transmits impulses to the axon
Axon
Transmits impulse away from the cell body to the dendrite of the next neuron
Myelin (white matter)
White, fatty substance covering the axon
Arranged in bundles called Schwann cells
The term dendrites is from the Greek word meaning “tree.” Dendrites are the branched projections of a neuron.
Myelin is referred to as white matter because of the color of its fatty substance.
Schwann cells are named after the German physiologist, Theodor Schwann. Schwann cells keep peripheral nerve fibers alive.

16. Neurons
FIGURE 19-6 Neuron.

17. Glia
Special nervous tissue cells that act as “glue” to support, bind, repair, and protect neurons
Five major types
Astrocyte cells
Oligodendroglia
Microglia
Ependymal cells
Neuroglia

18. Synapse Space between two neurons
Impulses from one neuron are transmitted across the synapse to another neuron by a chemical called a neurotransmitter.
Most common neurotransmitters
Acetylcholine
Norepinephrine
Neurons may be as close as one millionth of an inch to each other but still not touch.
More than 100 chemical messengers used by the nervous system have been identified.

19. Ganglia Groups of nerve cell bodies Located outside of the CNS
Increased ability to transmit impulses because they are clustered in the ganglion
Ganglia means “glue” in the Greek language.

20. Plexus and Dermatome Plexus Dermatomes
Four major networks of interwoven spinal nerves
Cervical
Brachial
Lumbar
Sacral
Provides impulses to specific regions of the body
Dermatomes
Spinal nerves that control sensations on the skin surface

21. Brain
Largest structure of the nervous system and one of the largest organs of the body
Weighs 2 to 3 pounds
Covered by three layers of membranes called meninges
Dura mater
Arachnoid
Pia mater
Only 4% of the brain cells work, and the remaining cells are kept in reserve.
Any damage to brain cells cannot be repaired completely.
The human body can function without a brain.

22. The Brain
The human brain is made of 60% white matter and 40% gray matter.
It is estimated that there are more than one hundred quadrillion connections in the human brain.
Men listen with the left side of their brain, and women use both sides of the brain.
FIGURE 19-8 The parts of the brain. (From Patton KT, Thibodeau GA: Anatomy & physiology, ed 7, St. Louis, 2010, Mosby.)

23. Parts of the Brain
Your brain is about 2% of your total body weight but uses 20% of your body's energy.
The energy used by the brain is enough to light a 25-watt bulb.
FIGURE 19-8 The parts of the brain. (From Patton KT, Thibodeau GA: Anatomy & physiology, ed 7, St. Louis, 2010, Mosby.)

24. Functions of the Brain

25. Summary
The function of the nervous system is to sense, interpret, and respond to internal and external environmental changes to maintain homeostasis.
Structures of the nervous system include the CNS and PNS and their parts.

26. Review
The term cerebrospinal, with regard to the nervous system, pertains to:
a. Inflammation of the meninges
b. An incision into the skull
c. Study of the nerve
d. The brain and spine
e. A small brain

27. Review
The term cerebrospinal, with regard to the nervous system, pertains to:
a. Inflammation of the meninges
b. An incision into the skull
c. Study of the nerve
d. The brain and spine
e. A small brain