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 of the Nervous System
Figure 7.2

5. 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)

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 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

8. 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.
Books says antagonistic, but they are more complimentary

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

11. 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

12. 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

13. Nervous Tissue: Neurons
Figure 7.4

14. 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

15. Nervous Tissue: Neurons
Myelin sheath—whitish, fatty material covering axons
Schwann cells—produce myelin sheaths in jelly roll–like fashion
Nodes of Ranvier—gaps in myelin sheath along the axon

16. Neurons
Figure 7.4

17. Functional Classification of Neurons
Sensory (afferent) neurons
Carry impulses from the sensory receptors to the CNS
Cutaneous sense organs
Heat, cold, pressure, pain
Proprioceptors—detect stretch or tension (found in muscles, tendons and joints)
Motor (efferent) neurons
Carry impulses from the central nervous system to viscera, muscles, or glands

18. 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)

19. Figure 7.6

20. 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)

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

22. 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

23. 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

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