Chap 9 nervous

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Chap 9 nervous

  1. 1. CHAPTER 9Nervous Tissue
  2. 2. NERVOUS TISSUE Nervous tissue is found in the brain, spinal cord, and nerves. It is responsible for coordinating and controlling many body activities. It stimulates muscle contraction, creates an awareness of the environment, and plays a major role in emotions, memory, and reasoning. To do all these things, cells in nervous tissue need to be able to communicate with each other by way of electrical nerve impulses.
  3. 3. NERVOUS TISSUE Nervous tissue is responsible for sensing "stimuli" and transmitting "signals" to and from different parts of the body. Neurons are the basic unit of nervous tissue.
  4. 4. A NEURON CONSISTS OFTWO MAJOR PARTS: 1. Cell Body - contains the neurons nucleus and associated cytoplasm/organelles.  Also known as soma, cyton or perikaryon 2. Nerve Processes - are "finger-like" projections from the cell body that are able to conduct and transmit signals.  There are two types: 1. Axons: typically carry signals away from the cell body. 2. Dendrites: typically carry signals toward the cell body.
  5. 5. NEUROGLIA Supporting tissue intermingled with the essential elements of nervous tissue especially in the brain, spinal cord, and ganglia. Functions include  providing support for the brain,  assisting in nervous system repair and maintenance,  assisting in the development of the nervous system and  providing metabolic functions for neurons.
  6. 6. THERE ARE SEVERAL TYPES OF GLIAPRESENT IN THE NERVOUS SYSTEM OFHUMANS: Astrocytes are found in the brains capillaries and form the blood-brain barrier that restricts what substances can enter the brain. Microglia are extremely small cells of the central nervous system that remove cellular waste and protect against microorganisms. Oligodendrocytes are central nervous system structures that wrap some neuronal axons to form an insulating coat known as the myelin sheath. Schwann Cells are peripheral nervous system structures that wrap some neuronal axons to form an insulating coat known as the myelin sheath.
  7. 7. CLASSIFICATION OF NEURONSACCORDING TO THEIRSTRUCTURE, 1. Unipolar Neurons. have only a single process or fibre which divides close to the cell body into two main branches (axon and dendrite). Because of their structure they are often referred to as unipolar neurons. 2. Multipolar Neurons, which have numerous cell processes (an axon and many dendrites) are often referred to as multipolar neurons. 3. Bipolar Neurons. are spindle-shaped, with a dendrite at one end and an axon at the other . An example can be found in the light-sensitive retina of the eye.
  8. 8. THERE ARE THREE MAIN TYPES OFNEURONS, CLASSIFIED ACCORDINGTHEIR FUNCTION Sensory Neurons move from the receptor to the Central Nervous System. Afferent neuron. Motor Neurons move from the Central Nervous System to the effector muscle. Interneurons (also known as connector neurons or association neurons) are those that connect sensory neurons to motor neurons.
  9. 9.  End of Presentation EXAM, EXAM, EXAM

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