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					  Unit 10
Human Body



     Nervous System

             Chapter 35
I. Human Body Systems
    The eleven organ systems of the
     human body work together to
         maintain homeostasis
  1. Nervous system         7. Digestive
  2. Integumentary System   8. Excretory
  3. Skeletal               9. Endocrine
  4. Muscular               10. Reproductive
  5. Circulatory            11. Lymphatice
  6. Respiratory
         A. Nervous System
       Structures              Function
• Brain               Coordinates the body’s
• Spinal Cord          response to changes
• Peripheral Nerves    in its internal and
                       external
                       environments.
B. Four major types of tissues in
the human body?
         •   1. Muscle
         •   2.Epithelial
         •   3. Connective
         •   4. Nervous
1. What is Muscle Tissue?
• Most abundant tissue in most animals
• Filled with mitochondria
• Controls both external and internal
  functions.
2. What is Epithelial Tissue?
•   Covers the surface of the body
•   Closely packed cells
•   Lines the internal organs
•   Glands are made up of this tissue- saliva,
    sweat, or milk.
3. Connective Tissue
• Holds organs in place
• Binds different parts of the body together.
• Examples
  – Tendons: bones to muscle (TBM)
  – Ligaments: bones to bones (LBB)
          4. Nervous Tissue
• Receives messages from body’s external
  and internal environments
• Analyzes the data
• Directs the Response
• Example
  – Heart: controls the rate at which the heart
    beats.
C. How do you maintain
homeostasis?
• Through a process called feedback inhibition.
• Human Body Temperature 98.6 o F (37oC).
• Hypothalamus regulates homeostasis in the
  entire human body.
• Hypothalamus uses feedback inhibition to keep
  warm when your cold (by shivering) or to keep
  cool when your hot (by slowing down cell
  activity).
              Workbook
• Section 1
   Section 2

The Nervous System
II. What is the function of
the Nervous System?
• Controls and coordinates functions throughout
  the body and responds to internal and external
  stimuli.
• The messages carried by the nervous system
  are electrical signals called impulses.
• The cells the transmit these impulses are called
  neurons.
• Neurons have 3 categories
  – Motor
  – Sensory
  – Interneurons
A. Sensory Neurons
• Carry impulses from the sense organs to
  the spinal cord and brain
B. Motor Neurons
• Carry impulses from the brain and the
  spinal cord to muscles and glands.
C. Interneurons
• Connect sensory and motor neurons and
  carry impulses between them.
   Sensory Neurons


Spinal Cord
   Brain


                     Interneurons




                                    Motor Neurons


                                          Muscle
                                          Glands
D. Anatomy of a Neuron
• Cell Body                      • Axon Terminals
   – Nucleus                        – Series of small swellings .
   – Cytoplasm                      – Located some distance
   – Metabolic Activity               from the cell body.
• Dendrites                      • Myelin Sheath-
   – Carries impulses from the      – Some neurons
     environment or from other      – Surrounded by an
     neurons toward the cell          insulating membrane.
     body.                       • Nodes-
   – Numerous                       – are places along the axon
• Axon-                               where there is no myelin
   – Long fibers that carries         sheath
     impulses away from the         – Allows impulse (signal) to
     cell body.                       jump from node to node.
   – Only one axon
E. Nerve Impulses
• Is a result of the inside of the cell changing
  positive and negative charges.
• Four stages
  – 1. Resting Potential
  – 2. Moving Potential
  – 3. Action Potential
  – 4. Threshold
1. Resting Potential
• Voltage across its cell membrane of 70
  millivolts (mV).
• ATP is used to pump Sodium out and
  Potassium into the cell across the
  membrane.
• Potassium leaks out of the cell
• Results in a negative charge inside to the
  membrane.
      2. The Moving Impulse
• Begins when a neuron is stimulated by
  another neuron or by the environment
• Travels rapidly down the axon away from
  the cell body and toward the axon
  terminals.
• Sodium gates open allowing sodium to
  enter the cell and creates a positive
  internal environment.
            3. Action Potential
• The inside of the cell is now positively charged.
• Now the Potassium gates open allowing them to
  flow out of the cell
• This action restores the resting potential
  (creating a negative charge)
• Self Propagating nerve impulse- at any point of
  the membrane causes an impulse at the next
  point along the membrane (like dominos).

       Negative                      Positive
              4. Threshold
• The minimum level of a stimulus that is
  required to activate a neuron.
• A stimulus that is stronger than the
  threshold will produce an impulse
• A stimulus that is weaker than the
  threshold will produce no impulse.
• Follows the all or none principal: either the
  stimulus will produce an impulse, or it
  won’t produce an impulse.
F. Synapse
• The location at which a neuron can
  transfer an impulse to another cell.
• Neurotransmitters-
  – are located in the synapse
  – Chemicals used by a neuron to transmit an
    impulse across a synapse to another cell.
  – These chemical molecules diffuse across the
    gap and attach themselves to receptors on
    the membrane of the neighboring cell.
             Section 2
• Workbook
         Section 3

Divisions of the Nervous System
III. The Central Nervous System
A. Function
• Relays messages
• Processes information
• Analyzes information
B. Parts
• Brain
• Spinal Fluid
C. Tissues in the brain and
spinal chord
  • Three layers of
    connective tissues
    called the meninges.      Meninges
  • Cereberal Spinal
                             Spinal Fluid
    fluid lies between the
    spaces of the             Meninges
    meninges.                Spinal Fluid

                              Meninges
D. Brain
1. Parts
               Part         Funciton
• Cerebrum
• Cerebellum
               Cerebrum
• Brain stem

               Cerebellum

               Brain Stem
E. The Spinal Cord
• The main communications link between
  the brain and the rest of the body.
• 31 pairs of spinal nerves branch out from
  the spinal cord which connects the brain to
  the body.
• Reflexes are processed directly in the
  spinal cord.
  – Examples : blinking, sneezing
F. Peripheral Nervous System
(PNS)
• Transmits impulses from sense organs to the CNS and
  back to the muscles’
• Include
   – Spinal nerves
   – Ganglia- nerve cell bodies
   – Cranial nerves that control the head and neck.
• Divided into two divisions
       • 1. Sensory
       • 2. Motor
• Somatic Nervous System
• Autonomic Nervous System
             PNS- divisions
     1. SENSORY                2. MOTOR
• Transmits impulses     • Transmits impulses
  from sense organs to     from the CNS to the
  the CNS                  muscles or glands.
PNS
1. Somatic Nervous System      2. Autonomic Nervous
                                  System
• Regulates activities that
  are under conscious          • Regulates activities that
  control                        are automatic, or
                                 involuntary.
   – Ex: movement of the
     skeletal muscles.            – Ex: Heartbeat, digestive
                                    system.
      • Wiggle your toes
      • Lift your finger       • 2 parts
                                  – A. Sympathetic nervous
• Regulates activities              system
  without conscious control.      – B. Parasympathetic
   – Ex: stepping on a tack         nervous system
 PNS- Autonomic Nervous system
These two systems have opposite effects
 on the same organ. Two different sets of
 neurons and can quickly make
 adjustments.
  – Parasympathetic
  – Sympathetic Nervous System

    • Ex: Heart Rate
       – Increased: Sympathetic Nervous System
       – Decreased: Parasympathetic Nervous System
             Section 3
• Workbook
Section 4 (IV)

  The Senses
A. Sensory Receptors
•    5 General Categories of Sensory
     Receptors
    1.   Pain
    2.   Thermoreceptors
    3.   Mechanoreceptors
    4.   Chemoreceptors
    5.   Photoreceptors
         1. Pain Receptors
• Located throughout the body except in the
  brain.
• Respond to chemicals released by
  damaged cells.
        2. Thermoreceptors
• Located in the skin, body core, and
  hypothalumus.
• They detect variations in temperature.
       3. Mechanoreceptors
• Located in the skin, skeletal muscles, and
  inner ear.
• They are sensitive to touch, pressure,
  stretching of muscles, sound, and motion.
         4. Chemoreceptors
• Located in the nose and taste buds, are
  sensitive to chemicals in the external
  environments.
          5. Photorecpetors
• Found in the eyes, are sensitive to light
B. Senses
•   Vision
•   Hearing and Balance
•   Smell and Taste
•   Touch and Related Senses


                      Project
                      Page 906
V. Drugs and the Nervous System
• Drugs that affect the synapse:
  – 1. Stimulants
  – 2. Cocaine
  – 3. Opiates
  – 4. Marijuana
  – 5. Alcohol
        Section 5

Drugs and the Nervous System
A. Stimulants
•   Increase heart rate
•   Increase blood pressure
•   Increase breathing rate
•   Increase the release of neurotransmitter at some
    synapses in the brain.

• When stimulants wear off- the user falls into
  fatigue and depression.
• Long Term use can lead to circulatory problems,
  hallucinations, and pyschological depression.
B. Depressants
• Slow down
  – Heart rate
  – Breathing rate
  – Lower blood pressure
• Relax Muscles
• Relieve Tension
C. Cocaine

				
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