1. Essentials of Human Anatomy & Physiology
The Nervous System
Chapter 7

2. Nervous System Functions
1. Sensory input – gathered information
Allows you to monitor changes occurring in & outside of the body (changes = stimuli)
2. Integration
Process and interpret the sensory input and decide if action is needed
3. Motor output
A response to integrated stimuli activates muscles or glands

3. Structural Classification of the Nervous System
Central Nervous System (CNS)
Brain
Spinal cord
Peripheral Nervous System (PNS)
Nerves that extend from the brain and spinal cord

4. Functional Classification of the Peripheral Nervous System
Sensory (afferent) division
Nerve fibers that carry information to the central nervous system

5. Functional Classification of the Peripheral Nervous System
Motor (efferent) division
Nerve fibers that carry impulses away from the central nervous system

6. Functional Classification of the Peripheral Nervous System
Motor (efferent) division
Two subdivisions
Somatic nervous system = Voluntary
Autonomic nervous system = Involuntary
Sympathetic
Parasympathetic

7. Organization of the Nervous System

8. Nervous Tissue: Support Cells
Supporting Cells in the CNS
Lumped together as neuroglia (AKA- glia or glial cells)
“Nerve glue”
Includes many types of cells that support, insulate, & protect the delicate neurons
Each type has specific functions

9. Nervous Tissue: Neurons
Neurons = Nerve cells
Cells specialized to transmit messages
Nerve impulses
Major regions of Neurons
Cell body – Contains the nucleus and is the metabolic center of the cell
Processes – Fibers that extend from the cell body (dendrites and axons)

10. Neuron Anatomy
Cell body
Nucleus
Metabolic Center

11. Neuron Anatomy Extensions outside the cell body
Dendrites – Conduct impulses toward the cell body
Axons – Conduct impulses Away from the cell body

12. Axons and Nerve Impulses
Axons end in axonal terminals
Axon terminals contain vesicles that contain neurotransmitters
Axon terminals are separated from the next neuron by a gap
Synaptic cleft – just the space between adjacent neurons
Synapse – junction between neurons; including the membranes of both neurons & the space between them

15. Nerve Fiber Coverings Myelin
Covers nerve fibers
Whitish, fatty material
Waxy appearance
Protects & insulates the fibers
Increases the transmission rate of nerve impulses
Schwann cells – produce myelin sheaths in jelly-roll like fashion
Nodes of Ranvier – gaps in the myelin sheath along the axon

16. Application of Neurons
Multiple sclerosis (MS)
Chronic, potentially debilitating disease that affects the central nervous system, which is made up of the brain and spinal cord.
Myelin sheath is destroyed- It hardens to a tissue called the scleroses
Transmitted nerve impulses are short-circuited
Affected person loses control of his/her muscles and becomes increasingly more disabled
Autoimmune disease
Protein component of the sheath is attacked
No cure
Interferon injections
Hormone like substance released by some immune cells- provides relief
website

17. Multiple Sclerosis

18. Neuron Cell Body Location
Most neurons are found in the central nervous system
White matter- dense collections of myelinated fibers
Gray matter – unmyelinated fibers & cell bodies
Nuclei – clusters of cell bodies within the white matter of the central nervous system
Ganglia – collections of cell bodies outside the central nervous system (PNS)

19. Functional Classification of Neurons
Sensory (afferent) neurons
Carry impulses from the sensory receptors to the CNS
Cutaneous sense organs (Vision, hearing, equilibrium, taste & smell)
Proprioceptors – detect stretch or tension in skeletal muscles, tendons and joints
Pain receptors

20. Functional Classification of Neurons
Motor (efferent) neurons
Carry impulses from the central nervous system to the viscera and/or muscles and glands
Interneurons (association neurons)
Connect sensory and motor neurons in neural pathways

21. Neuron Classification