1. CHAPTER 19 NERVOUS SYSTEM

2. Learning Objectives
Define at least six (6) terms relating to the nervous system
Describe the function of the nervous system
Identify at least 10 structures of the nervous system
Describe at least five (5) disorders of the nervous system

3. Vocabulary (p. 225) Cerebrospinal Fluid Dementia Epilepsy Intracranial
Ischemia
Meninges
Neurotransmitter
Reflex
Senile
YOU HAVE 15 minutes TO FINISH

4. Structure and Function
The nervous system is divided into two major structures:
Central nervous system (CNS)
Peripheral nervous system (PNS)
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’s homeostasis

5. Figure 19-1A & B Divisions of the Nervous System

6. 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

7. Figure 19-1A Central Nervous System (Continued)

8. 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. Figure 19-1B Peripheral Nervous System (Continued)

10. Table 19-1 Functions of the Peripheral Nervous System

11. Organs of the Peripheral Nervous System
Organs of the peripheral nervous system 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)

12. Figure 19-2 The Spinal Reflex Arc

13. The Autonomic Nervous System
Sympathetic system
The sympathetic nerves are stimulated in situations that require action such as the fight-or-flight reaction
Parasympathetic system
The parasympathetic nervous system functions in response to normal, everyday situations

14. Divisions of the Nervous System Figure 19-3

15. Neurons Basic structural unit of the nervous system is the nerve.
Nerve is bundle of fibers that carries impulses
Nerve fibers consist of neuron cells
Three main types of neurons:
Afferent
Efferent
Interneuron
Each carries messages, or impulses, to and from the body’s organs

16. Neurons (Continued) Important parts of a neuron Dendrites
Receive impulses and transmit them to cell body
Cell body transmits impulses to the axon
Axon transmits impulse away from cell body to dendrite of next neuron
Myelin (white matter)
White, fatty substance covering the axon
Arranged in bundles called Schwann cells

17. Figure 19-4 Neuron

18. Neuroglia (Glia)
Special nervous tissue cells that act as “glue” to support, bind, repair, and protect neurons

19. Synapse 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 (helps transmit nerve impulses)
Norepinephrine (vasoconstrictor)

20. Ganglia Groups of nerve tissue
Increased ability to transmit impulses because they are clustered together in the ganglion

21. Plexus and Dermatome Plexus Dermatomes
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

22. 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

23. Figure 19-5 The Brain

24. Lobes of the Brain Frontal: Parietal: Temporal: Occipital:
personality, behavior, memory, reasoning, and emotion
Parietal:
Understanding speech or choosing words
Temporal:
Hearing & understanding speech and printed words; memory of music & visual scenes
Occipital:
vision

25. Lobes of the Brain

26. Parts of the Brain Cerebrum: Cerebellum: Brainstem:
Largest area; divided into two hemispheres
Reasoning & senses
Cerebellum:
Directs coordination, muscle tone, and equilibrium
Brainstem:
Heartbeat, respiration, and blood pressure
Pons, medulla, midbrain

27. Parts of the Brain Hypothalamus Thalamus
Regulates & coordinates activity of the ANS
Controls hormone secretion & appetite
Thalamus
Sensory

28. Figure 19-6 The Parts of the Brain

29. Parts of the Brain

30. Table 19-2 Functions of the Brain

31. Assessment Techniques
Electroencephalography (EEG)
Lumbar puncture
Myelography
Nerve conduction velocity
Computed tomography (CT)
Positron emission tomography (PET)
Magnetic resonance imaging (MRI)

32. Assessment Techniques

33. Disorders of the Nervous System
Alzheimer’s
A form of senile dementia
Cerebrovascular accident
Commonly called a stroke or CVA,
Down syndrome
A genetic disorder caused by the presence of an extra chromosome

34. Disorders of the Nervous System (Continued)
Encephalitis
An inflammation of the brain caused by a virus, bacteria, or chemical agent
Guillain-Barré syndrome
Progressive muscular weakness that may lead to paralysis; it may appear shortly after a viral immunization or infection
Headache
The muscles around the occipital area of the brain constrict the blood flow to the area

35. Disorders of the Nervous System (Continued)
Migraine headaches
Vascular headaches of unknown cause; the pain results from the narrowing of blood vessels in the brain
Sinus headaches
From the swelling of the membranes that line the sinus cavities

36. Disorders of the Nervous System (Continued)
Intracranial tumors
Usually involve neuroglia, blood vessels, or membranes rather than neurons
Meningitis
A serious inflammation of the meninges caused by a bacterium, virus, or fungus

37. Disorders of the Nervous System (Continued)
Meningocele
A birth defect that occurs when the membranes covering the brain or spinal cord protrude through a congenital defect in the skull or spinal column
Multiple sclerosis
From a defect in electrical transmission of the neurons caused by degeneration of the myelin sheath

38. Disorders of the Nervous System (Continued)
Parkinson’s disease
Results from degeneration of certain brain cells
Sciatica
Pressure on the sciatic nerve or other nerves in to your leg; Cause is usually a rupture of an intervertebral disk
Spina bifida
A birth defect involving a malformed spinal column resulting from neural tube defects

39. Disorders of the Nervous System (Continued)

40. Disorders of the Nervous System (Continued)
Seizure
Result from injury, infection, or epilepsy
Over 40 different types
Petit mal
Lapse of consciousness for several seconds
Grand mal
Series of distinctive tonic & clonic spasms that last several minutes
Tonic: muscles contracted rigidly
Clonic: involuntary muscle movements