human anatomy and phaysiolgy is nervous system fo cranial nerevs, Study notes of Human Physiology

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Organization of

Nervous System

Have you heard the expression

“Information is power?”

Nowhere is this truer than in

the human body. Without

information, we could not

survive.

Neurons within our nervous system must take in sensory information from the outside world and then decide what to do with the information.

The Nervous System is the body’s main

processing system for information.

This consists of structures and organs that

facilitate electrical and chemical

communication in the body

Functions of the Nervous System

1. Sensory input – gathering information

• To monitor changes occurring inside and outside the body
• Changes = are called stimuli

2. Integration

• N.S. is able to integrate this information
• Process and interpret sensory input and decide if action is needed

The Nervous System

• Components
  • Brain, spinal cord, nerves, sensory receptors
• Responsible for
  • Sensory perceptions, mental activities, stimulating muscle movements, secretions of many glands
• Subdivisions
  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)

Central Nervous System

• Consists of
  • Brain
    • Located in cranial vault of skull
  • Spinal cord
    • Located in vertebral canal
• Brain and spinal cord - Continuous with each other at foramen magnum

Peripheral Nervous System

• Two subcategories
  • Sensory or afferent
  • Motor or efferent
    • Divisions
      • Somatic nervous system
      • Autonomic nervous system (ANS) » Sympathetic » Parasympathetic » Enteric

Nervous System Organization

Figure 7. Functional Classification of the PNS

• Motor (efferent) division
  • Nerve fibers that carry impulses away from the central nervous system
  • Activate (effect) muscles or glands to bring about a response.

Functional Classification of the PNS

• Motor (efferent) = 2 division
  • Somatic nervous system = voluntary (skeletal muscles)
  • Autonomic nervous system = involuntary (smooth and cardiac muscles, glands)

Nervous Tissue

• Comprise of 2 types of cells
  • Neuroglia = supporting cells
    • The insulators, adhesive, protectors and nourishers
  • Neurons = nerve cells that transmit impulses

11 - 17 Cells of Nervous System

• Neurons or nerve cells - Receive stimuli and transmit action potentials - Organization - Cell body or soma - Dendrites: Input - Axons: Output
• Neuroglia or glial cells - Support and protect neurons

Nervous Tissue: Support Cells

• Microglia
  • Spider-like phagocytes
  • Dispose of debris
• Ependymal cells
  • Line cavities of the brain and spinal cord
  • Circulate cerebrospinal fluid

Nervous Tissue: Support Cells

• Oligodendrocytes
  • Produce myelin sheath around nerve fibers in the central nervous system