1. Nervous System

2. 3 Functions of the Nervous System (SIM)
1. Sensory input—gathering information
monitor changes inside and outside the body
changes = stimuli
sensory receptors responsible for input
2. Integration
decide if and what action is needed
3. Motor Output
a response
activates muscles or glands (effectors)

3. Functions of the Nervous System
Figure 7.1

4. Organization and Structural Classification of the Nervous System
2 Main Divisions
Central nervous system (CNS)
Brain
Spinal cord
2. Peripheral nervous system (PNS)
Spinal nerves (to and from spinal cord)
Cranial nerves (to and from brain)

5. Organization of the Nervous System

6. Functional Classification of the Peripheral Nervous System
Sensory (afferent) division
carry information to the central nervous system
Keep the body informed of internal and external environment
Motor (efferent) division
carry impulses away from the central nervous system
Cause some sort of effect

7. Functional Classification of Neurons
Interneurons (association neurons)
Found in neural pathways in the central nervous system
Connect sensory and motor neurons
Receptors
Specialized dendritic endings
Simple: cutaneous receptors (pain, touch)
Complex: special sense organs (eye, nose)

8. Functional Classification of the Peripheral Nervous System
Two Subdivisions of the Motor (Efferent) Division
Somatic nervous system = voluntary
Skeletal muscles (except reflexes)
Autonomic nervous system = involuntary
smooth muscle, cardiac muscle, glands

9. Functional Classification of the Peripheral Nervous System
Two subdivisions of the Autonomic nervous system
1. Sympathetic
Concerned with processes involving expending energy.
Active during times of extreme stress, emotion, and exercise.
Parasympathetic
Concerned with conservation of energy
Can dominate sympathetic system.

11. Nervous Tissue:
2 Main Types of Cells 1. Neurons carry messages (impulses) 2. Supporting cells or neuroglia

12. Nervous Tissue Neurons: specialized to transmit messages -structures may differ, but all neurons have:
PARTS:
1. Cell body
contains transparent nucleus
large conspicuous nucleolus
metabolic center of the cell

13. Nervous Tissue: Neurons
Figure 7.4

14. Nervous Tissue Neurons 2 Types of Processes
fibers that extend from the cell body
Dendrites—conduct impulses toward the cell body
Axons—conduct impulses away from the cell body

15. Myelin: whitish, fatty material that covers nerve fibers to speed up nerve impulses
Schwann cells: surround axons and form myelin sheath
Myelin sheath: tight coil of wrapped membranes
Nodes of Ranvier: gaps between Schwann cells

16. Axon Terminals- axon ends
contain vesicles with neurotransmitters
do not touch dendrite of next neuron OR muscle
Synaptic cleft—gap between adjacent neurons
Synapse—junction between nerves

17. Neurons Figure 7.4 Site of protein synthesis
Provides support and shape
Figure 7.4

18. Figure 7.6

19. 6 Types of Support Cells 1. Astrocytes (CNS) star-shaped cells
Most abundant of the glial cells
Mainly function between neurons and capillaries
Bridging the two
Communication between the two
Barrier between the two
Control the chemical environment of the brain (taking in extra K+ or neurotransmitters)

20. Nervous Tissue: Support Cells
2. Microglia (CNS)
Spiderlike phagocytes (phago- eat)
Dispose of debris
(dead brain cells and bacteria)

21. Nervous Tissue: Support Cells
3. Ependymal cells (CNS)
Line cavities of the brain and spinal cord
Ciliated cuboidal epithelial cells
Circulate cerebrospinal fluid
Help in production of cerebrospinal fluid

22. Nervous Tissue: Support Cells
4. Oligodendrocytes (CNS)
Wrap around nerve fibers in the central nervous system
Produce myelin sheaths in CNS
5. Schwann cells (PNS)
Form myelin sheath in the PNS

23. Nervous Tissue: Support Cells
6. Satellite cells (PNS)
Protect neuron cell bodies by providing cushion

24. Regions of a Typical Neuron

25. Vocabulary
Tract- bundles of nerve fibers running through the CNS. Nerves-bundles of nerve fibers running through the PNS White matter- Consists of dense collections of myelinated fibers Gray matter- Consists of mostly unmyelinated fibers and cell bodies