Control%20and%20Coordination

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Chapter 21

• Control and Coordination

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Ch 21.1 The Nervous System

• A. Your nervous system helps your body make
  adjustments to changes in your environment
• 1. Stimulus any change inside or outside the
  body that brings about a response
• 2. Homeostasis the regulation of steady
  internal conditions inside an organism

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• B. Neurons (nerve cells) made up of a cell body
  and branches to transmit signals

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• 1. Dendrites branches that receive messages and
  send to the cell body
• 2. Axons branches that carry messages away from
  the cell body to the next neuron

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• 3. Messages carried by nerve cells are called
  impulses

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• 4. There are 3 kinds of nerve cells
• a) Sensory receive information and send
  impulses to brain or spinal cord
• b) Interneuron interpret impulse and relay to
  next cell type
• c) Motor conduct impulses from brain to
  muscles or glands to bring about response

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Reflex Arc
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• 5. Nerve cells do not touch each other, yet
  impulses still pass from one to the next
• a) Synapse the space b/w nerve cells
• b) When an impulse reaches the end of an axon it
  releases chemicals (Sodium Potassium)
• c) The chemical flows across the synapse to
  relay the impulse to the next dendrite

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• C. Central Nervous System (CNS) made of brain
  spinal cord
• 1. Brain - coordinates ALL body activities
• a) Cerebrum largest part interprets impulses
  from senses, stores memory, controls movements
  and has outer covering called cortex that allows
  thinking to take place

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Cerebrum
(Tactile Senses)
(Imagination)
(Memory)
(Emotions, Judgment)
(Memory)
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• b) Cerebellum located behind under cerebrum
  coordinates voluntary muscle movement and
  maintains muscle tone balance

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• c) Brain Stem part of brain that extends from
  cerebrum to the spinal cord made of 3 parts
• 1) Midbrain Pons pathways that pass
  signals b/w different parts of brain
• 2) Medulla controls involuntary actions such
  as heartbeat, breathing BP

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Brain Stem
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• 2. Spinal Cord made of bundles of nerve cells
  that carry impulses to and from the brain

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• D. Peripheral Nervous System (PNS) made of all
  the nerves that extend from spinal cord to rest
  of body
• 1. Somatic division controls voluntary actions
• 2. Autonomic division controls involuntary
  actions

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• E. Any injury to the brain or spinal cord can be
  serious
• 1. Injury to the spinal cord may result in
  paralysis
• 2. Injury to brain may result in a concussion,
  permanent brain damage or even coma
• 3. Safety gear in cars and sports is an
  important preventative measure

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• E. Reflex any involuntary, automatic response
  to a stimulus controlled by brain and spinal cord

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• G. Drugs have effects on nervous system
• 1. Alcohol slows down activities of CNS
• 2. Caffeine speeds up activities of CNS

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Ch 21.2 - Senses

• A. Light rays, sound waves, heat, chemicals or
  pressure that come into your personal territory
  stimulate your sense organs
• B. Your body has 5 senses

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• 1. Vision
• a) Light enters eye though cornea and pupil and
  the lens focuses it on the back wall of the eye
  called the retina

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• b) The light stimulates rods and cones (cells) on
  the retina and sends impulses over the optic
  nerve to the visual area of brain
• c) The visual area of the cortex interprets the
  image you see

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• d) Nearsightedness occurs when light focuses in
  front of retina corrected with concave lens

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• e) Farsightedness occurs when light focuses
  behind the retina corrected with convex lenses

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• 2. Hearing
• a) When objects vibrate they create waves
• b) These sound waves are caught by in outer ear
  and funneled down the ear canal

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• c) Middle Ear at end of canal sound waves
  strike the ear drum and sends the vibrations
  through 3 tiny bones hammer, anvil, stirrup

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• d) Inner Ear the vibrations pass through a
  fluid in the cochlea which send nerve impulses to
  the brain where sound is interpreted

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• e) Fluid of the cristae ampullaris and maculae of
  the middle ear help control balance

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• 3. Smell
• a) Food and other objects give off molecules
  into the air
• b) These molecules stimulate nerve cells called
  olfactory cells in the nasal passage
• c) These cells send impulses through olfactory
  nerve to bran where they are interpreted

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• 4. Taste
• a) Taste buds (about 10,000) in mouth are the
  major sensory receptors for taste
• b) When a solution of saliva and food washes
  over the taste buds impulses are sent to the brain

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• 5. Touch
• a) Sensory receptors on nerve cells in the skin
  and internal organs
• b) They pick up changes in touch, pressure, pain
  and temperature and send impulses to brain