1. Nervous System at a Glance
Functions of Nervous System
Coordinates and controls body function
Receives sensory input
Makes decisions
Orders body responses
Organs of Nervous System
Nerves- transmits messages to & from the CNS
Spinal cord- transmits messages to & from the brain
Brain- coordinates all body functions

2. Medical Terminology: A Living Language, Fourth Edition
Bonnie F. Fremgen and Suzanne S. Frucht
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.

3. Anatomy and Physiology of Nervous System
Coordinates all activity of body
Receives information from both external and internal sensory receptors
Uses that information to adjust activity of muscles and glands to match needs of body
Nervous system is divided into:
Central nervous system (CNS)
BRAIN and SPINAL CORD
Peripheral nervous system (PNS)
CRANIAL NERVES and SPINAL NERVES

4. Nervous Tissue Nervous system composed of two types of cells Neurons
Neuroglial cells
Individual nerve cells
Conduct electrical impulses
Neurons have three basic parts:
Dendrites – highly branched projections that receive impulses
Nerve cell body – contains nucleus & organelles
Axon – conducts electrical impulse to destination

5. Figure 12.1A – The structure of a neuron.
Medical Terminology: A Living Language, Fourth Edition
Bonnie F. Fremgen and Suzanne S. Frucht
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 12.1A – The structure of a neuron.

6. Medical Terminology: A Living Language, Fourth Edition
Bonnie F. Fremgen and Suzanne S. Frucht
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 12.1B – Photomicrograph of typical neuron showing the nerve cell body, nucleus, and dendrites.

7. Nervous Tissue (Neuron cont.)
Synapse
Point where axon of one neuron meets dendrite of second neuron
Synaptic cleft
Gap between two neurons in a synapse
Electrical impulse cannot cross
Neurotransmitter
Chemical released by axon
Crosses gap to stimulate dendrite of second neuron

8. Nervous Tissue Neuroglial cells
Variety of cells found in nervous tissue
Each has different support function for neurons
Some neuroglial cells produce myelin, a fatty substance that acts as insulation for many axons
Neuroglial cells DO NOT conduct electrical impulses

9. Medical Terminology: A Living Language, Fourth Edition
Bonnie F. Fremgen and Suzanne S. Frucht
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Figure 12.2 – Electronmicrograph illustrating an axon (red) wrapped in its myelin sheath (blue).

10. Central Nervous System
Combination of the brain and spinal cord
Function
Receives impulses from all over body
Processes this information
Responds with action
Bundles of nerve fibers interconnecting different parts of CNS are called tracts

11. CNS Consists of both gray and white matter Gray matter
Comprised of unsheathed or uncovered cell bodies and dendrites
White matter
Myelinated nerve fibers

12. The Brain One of the largest organs in body It is center for: Thoughts
Memory
Judgment
Emotion

13. The Brain Four main sections: Cerebrum Cerebellum Diencephalon
Brain stem

14. Cerebrum Largest section Upper portion Processes: Thoughts Judgment
Memory
Association skills
Ability to discriminate between items

15. Cerebrum Cerebral cortex Gyri Sulci Outer layer of cerebrum
Composed of folds of gray matter
Gyri
Elevated portions of the cerebrum, or convolutions
Sulci
Fissures, or valleys, between gyri

16. Lobes of Cerebrum
Subdivided into left and right halves called cerebral hemispheres
Each hemisphere has four lobes:
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe

17. Lobes of Cerebrum Frontal lobe Parietal lobe Most anterior lobe
Controls motor function, personality, and speech
Parietal lobe
Most superior portion
Receives & interprets nerve impulses
Interprets language

18. Lobes of Cerebrum Occipital lobe Temporal lobe Most posterior
Controls vision
Temporal lobe
lateral portion
Controls hearing and smell

19. Diencephalon
Located inferior to cerebrum but superior & anterior to midbrain
Contains two of most critical areas of brain:
Thalamus
Hypothalamus

20. Diencephalon Thalamus Hypothalamus
Center for relaying impulses from eyes, ears, and skin to cerebrum
Controls perception of pain
Hypothalamus
Controls body temperature, appetite, sleep, sexual desire, and emotions
Controls autonomic nervous system, cardiovascular system, gastrointestinal system, and release of hormones from pituitary gland

21. Cerebellum Second largest portion of brain
Located beneath posterior part of cerebrum
Aids in:
Coordinating voluntary body movements - Refines muscular movements initiated in cerebrum
Maintaining balance and equilibrium

22. Brain Stem
Has three components:
Midbrain
Pons
Medulla oblongata

23. Brain Stem Midbrain Pons Medulla oblongata
Acts as pathway for impulses between brain and spinal cord
Pons
Means bridge
Connects cerebellum to rest of brain
Medulla oblongata
Most inferior portion of brain
Connects brain to spinal cord

24. Brain Ventricles Cavities containing cerebrospinal fluid (CSF)
Watery, clear fluid
Provides shock protection for CNS
Locations:
One in each cerebral hemisphere
One in thalamus
One in front of cerebellum

25. Spinal Cord Extends from medulla oblongata to second lumbar vertebra
Within vertebral column
33 vertebrae of back bone line up to form spinal cavity or vertebral canal

26. Spinal Cord Protected by cerebrospinal fluid
Flows through central canal down through spinal cord
Outer portion of spinal cord is myelinated white matter
Ascending tracts carry sensory information up to brain
Descending tracts carry motor commands down from brain to peripheral nerves

27. Medical Terminology: A Living Language, Fourth Edition
Bonnie F. Fremgen and Suzanne S. Frucht
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.

28. Meninges Protective membrane sac that encases entire CNS
Consists of three layers:
Dura mater
Arachnoid layer
Pia mater

29. Meninges Dura mater Means tough mother
Outermost, tough, fibrous sac around CNS
Subdural space
Empty space between dura mater and arachnoid layer

30. Meninges Arachnoid layer Means spider-like
Thin, delicate layer attached to pia mater by web-like filaments
Subarachnoid space
Between arachnoid layer and pia mater
Contains cerebrospinal fluid

31. Meninges Pia mater Means soft mother Innermost membrane layer
Applied directly to surface of brain

32. Peripheral Nervous System (PNS)
Consists of:
12 pairs of cranial nerves
31 pairs of spinal nerves
Cranial nerves
Arise from brain
Spinal nerves
Split off from spinal cord
One pair (left and right) exit between each pair of vertebrae

33. Nerves Nerve root A nerve: Point where nerve is attached to CNS
Is a bundle of axon fibers located outside CNS
Carries messages between CNS and various parts of body
Nerve root
Point where nerve is attached to CNS
Names of most nerves reflect:
Organ the nerve serves &/OR
Portion of body the nerve is traveling through

34. Table 12.1 Cranial Nerves I Olfactory II Optic Oculomotor IV Trochlear
sense of smell II
Optic
sense of sight
Oculomotor
controls eye muscles and pupil of eye IV
Trochlear
controls oblique muscles of eye V
Trigeminal
facial sensation and controls muscles for chewing VI
Abducens
controls eyeball muscles to turn eye to side

35. Table 12.1 Cranial Nerves VII Facial VIII Vestibulocochlear IX
controls facial muscles for expression, salivation, and taste on two-thirds of tongue (anterior)
VIII
Vestibulocochlear
sense of equilibrium and hearing IX
Glossopharyngeal
sensation from pharynx and taste on one-third of tongue X
Vagus
supplies most organs in abdominal and thoracic cavities XI
Accessory
controls neck and shoulder muscles
XII
Hypoglossal
controls tongue muscles

36. Neurons Each nerve can carry information both to and from CNS
But any individual neuron can carry information in only one direction
Either an:
Afferent neuron
Efferent neuron

37. Neurons Afferent neurons Efferent neurons Also called sensory neurons
Carry sensory information from sensory receptor to CNS
Efferent neurons
Also called motor neurons
Carry activity instructions from CNS to muscles or glands

38. Divisions of PNS Nerves of PNS are subdivided into two divisions
Autonomic nervous system (ANS)
Somatic nerves
Each division serves different area of body

39. 1. Autonomic Nervous System (ANS)
Control of involuntary or unconscious bodily functions
It may increase or decrease the activity of:
Smooth muscle found in viscera and blood vessels
Cardiac muscle of heart
Glands
ANS divided into 2 branches:
Sympathetic branch
Parasympathetic branch

40. Parasympathetic branch
Stimulates body in times of stress and crisis
Increases heart rate, dilates airways, increases blood pressure, inhibits digestion, and stimulates production of adrenaline
Parasympathetic branch
Serves as counterbalance for sympathetic nerves
Causes heart rate to slow down, lowers blood pressure, and stimulates digestion

41. 2. Somatic Nerves
Mainly involved with conscious and voluntary activities of body
Serve skin and skeletal muscles
Carry information from sensory receptors of skin
Such as touch, temperature, pressure, and pain
Carry motor commands to skeletal muscles