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Nervous System

Nervous System

Is the most complex organ system in the body.

It maintains homestatisis2 major divisions: A Central nervous system CNS and the B. Pheripheral nervous system

PNS

Nervous System

3 major Functions:1. Monitors the external and internal environments

2. Integrates sensory information 3. Coordinates voluntary and involuntary responses of many other organ systems

CNS

Includes the brain and spinal cord

Functions to integrate and coordinate sensory data and motor commands

It is the seat of higher functions such as intelligence and memory and emotions

PNS

Includes all neural tissue outside the CNS

It is divided into two divisions: A. the afferent division which brings sensory information to the CNS B. the efferent division which carries commands to muscles and glands

PNS

This efferent division is subdivided to the Somatic division which deals with control over skeletal muscles

Autonomic nervous system ANS or visceral motor system (VNS) which provides control of involuntary smooth muscles, cardiac and glandular secretions

ANS

Is subdivided into two systems:A. Sympathetic system or divisionB. Parasympathetic system they have opposite affects on objects in the body.

Cellular Organization of Neural tissue

Two types of cells are found here:A. NeuronsB. Neuralgia or sometimes called glial cells

Structure of Neurons

4 parts1. A cell body2. Several branching dendrites3. An elongate axon4. One or more synaptic terminals

Structural Classification of Neurons

3 typesA. Multipolar neuron- has multiple processes extending away from the cell body.

B. Unipolar neurons- the dendrites and the axons are continuous and the cell body is of to one side.

Structural Classification of Neurons

C. Bipolar neurons-have two processes , one dendrite and one axon with cell body between them.

Functional classification of Neurons

3 functioning groupsA. Sensory neurons-are part of the afferent division which convey information from both external and internal environments about 10 million

Functional classification of Neurons

B. Motor neurons- there are about ½ million and they belong to the efferent division and carry information from the CNS to the organs or organ systems.

C. Interneurons or association neurons- are located entirely within the brain and spinal cord

Glia cells

4 types found in the CNS1. Astrocytes2. Oligodendrocytes3. Microglia4. Ependymal

Glia cells

Most important Glia cell in the PNS

1. Schwann cell-cover every axon outside the CNS

Table 8.1 The sequence of events at a Synaspe

4 basic steps (need to know for test)

Spinal cord divisions

A. Cervical vertebrae- C1-C8B. Thoracic vertebrae- T1-T12C. Lumbar vertebrae-L1-L5D. Sacrum – s1-s5 nervesE. Coccygeal nerve

Figure 8-14

Cross section of vertebrae

Brainwaves

4 types1. alpha2. Beta3. Theta4. Delta

Memory

Fact memorySkill memoryShort termLong term

Table 8.2 Cranial nerves

Olfactory (N I)Optic (N II)Oculomotor (N III)Trochlear (N IV)Trigeminal (N V)Abducens (N VI)

Table 8-2 cont.

Facial nerves (N VII)Vestibulocholear nerves (N VIII)Glossopharyngeal nerves (N IX)Vagus nerves( N X)Accessory Nerves (N XI)Hypoglossal Nerves (N XII)

Figure 8-28

Components of a reflex ArcSteps 1-5

Table 8-4

Sensory and Motor pathways

Sympathetic Division

IncludesA. Preganglionic neuronsB. Ganglionic neuronsC. The Adrenial medullae

Parasympathetic division

1. Preganglionic neurons in the brain and in sacreal segments of spinal cord

2. Ganglionic neurons in peripheral ganglia within or adjacent to the target organs

Table 8.5

See handout