NervousSystemNotes by HC111111055312


									Nervous System
•       Nervous Coordination and Regulation
•       The Neuron
•       The Human Nervous System

•       Nervous Coordination and Regulation
    •     Functions of the Nervous System
    •     Stimulus, Receptor, Impulse, Effector
    •     Role of the Nervous System in Homeostasis

•       The Neuron
    •     Types of Neurons
    •     Structure and Function of the Parts of the Neuron
    •     Transmission of a Nerve Impulse
    •     The Synapse
    •     Human Reflexes and Reaction Time

•       The Nervous System
    •     Structure and Function of the Central Nervous System
    •     Anatomy of the Brain
    •     Somatic vs. Autonomic Nervous System - Sympathetic and Parasympathetic Nervous Systems

1. Nervous Coordination and Regulation
•       Functions of the Nervous System
     central nervous system = the brain and spinal cord
    •     also includes interneurons and the cell bodies of most motor neurons
     peripheral nervous system = a vast network of nerves that conducts impulses between the central
      nervous system and the receptors and effectors of the body
    •     includes sensory neurons, their cell bodies, and the axons of the motor neurons
     the CNS controls most of the activities of the body
     information from the sense receptors about conditions inside and outside the body is brought to the
      CNS by the PNS, and
     responses are carried from the CNS by the PNS to muscles and glands

b) Stimulus, Receptor, Impulse, Effector
 stimulus = something that causes a receptor to trigger impulses in a nerve pathway
 receptor = a sense organ responding to a particular type of stimulus
 impulse = message carried by the nerve cells
 effector = a muscle or gland that responds to a particular stimulus

c) Role of the Nervous System in Homeostasis
 Describe 3 ways that you know that the body reacts to changes in its internal and
   external environment.
Explain how the Nervous System would be involved. Use terms like stimulus, receptor,
   impulse, effector in your answer. (Hint think about specific body systems or sense
2. The Neuron
•         Types of Neurons
sensory neurons = nerve cells that carry impulses from receptors toward the spinal
    cord and brain
motor neurons = neurons that carry responses from the brain and/or spinal cord to the
    effectors (muscles or glands)
interneurons = the neurons that relay impulses from one neuron to the next in the brain
    and spinal column
(nerves are bundles of axons or dendrites that are bound together by connective tissues)

b) Structure and Function of the Parts of the Neuron
  • neurons carry nerve impulses
  • processes (extensions) on a neuron are dendrites and axons
  • dendrites pick up impulses sent by other neurons
  • axons pass impulses on to other neurons through their synaptic terminals

      •   Using page 85 and 86 in your textbook draw a neuron and label the dendrites, cell
          body, nucleus, axon, myelin sheath, and synaptic terminals. Indicate the direction
          that a nerve impulse would travel.

    c) Transmission of a Nerve Impulse
Using page 86 and 87 of your textbook, answer the following questions:
•    What causes the initiation of a nerve impulse?
•    What controls the ability of an impulse to begin at a particular neuron?
•    How does the nerve cell membrane function when at rest?
•    What happens to the membrane at the point where an impulse is passing?
•    Draw a simple diagram showing the movement of sodium and potassium ions across the cell
     membrane. Why is the overall charge on the inside of the cell negative except where the impulse is

d) The Synapse
•   What happens at the end of the axon of the stimulated nerve cell?
•   How is the impulse able to cross the gap between one neuron and the next?
•   What is the type of chemical that breaks down the acetylcholine? What is it made of?
•   Draw a simple diagram of a synapse between 2 neurons. Label the receiving and
    transmitting structures. Identify the synaptic gap and name the chemical involved.

e) Human Reflexes and Reaction Time
The Reflex Arc
 consists of: receptor, sensory neuron, interneuron, motor neuron, effector
 a typical relflex arc is the response to pain
 it involves only 3 neurons
3. The Nervous System
•    Structure and function of the Central Nervous System
    The CNS is made up of the brain and spinal cord
    both are protected by bone (skull and spinal column)
    both are protected by 3 tough membranes called the meninges
    cerebrospinal fluid (CSF) fills the space b/w the inner and middle membrane and cushions both the
     brain and spinal cord
    concussions occur when the brain is severely shaken causing it to contact the the skull
    4 spaces in the brain contain the CSF and are called ventricles
    ventricles connect with the spaces b/w the meninges and with the central canal of the spinal cord

b) Anatomy of the Brain
   is the major user of glucose in the body
   major parts are the cerebrum, cerebellum, medulla oblongata
   other parts are the thalamus, hypothalamus, and pons
   the forebrain is the cerebrum, thalamus, and hypothalamus
   the midbrain is a small area at the top of the medulla oblongata
   the hindbrain is the name for the brainstem and the cerebellum
   the brainstem is a name given to the pons, medulla oblongata, and the midbrain

 largest part of the human brain
 divided into 2 hemispheres (right and left)
 a deep groove or fissure divides the 2 hemispheres
 a bridge-like connection of nerve fibres b/w the 2 hemispheres that connects to the rest
  of the NS is called the corpus callosum
 the outer layer of the cerebrum is called the cerebral cortex = gray matter = no myelin
 the many folds on the surface of the cortex greatly increases the surface are of the gray

Functions of the cerebrum = sensory, motor, and associative

 receive and interpret impulses from the sense receptors (eyes, ears, taste buds, nose,
  also touch, pain, pressure, heat)

 start impulses for all voluntary movements and ford the position of the moveable parts
  of the body

 memory, learning, and thought
The two hemispheres do not function equally – one side may be more mathematical, the
  other may be artistic and musical
   below the gray matter is the white matter = myelinated fibres
   corpus callosum is here connecting the right and left hemispheres
   other bundles of fibres connect the cortex to other parts of the nervous system
   the left cerebral hemisphere controls the right side of the body, the right hemisphere
    controls the left side of the body

The Cerebellum
 below the rear part of the cerebrum
 also has 2 hemispheres, white and gray matter
 controls all voluntary movements and some involuntary movements
 provides information b/w motor and sensory pathways about muscle positions, rate of
  contractions, etc. to produce smooth, orderly voluntary movements
 also works with inner ear to maintain balance (equilibrium)
 maintenance of muscle tone by keeping muscles slightly tensed
 staggering and loss of coordination result from impairment of cerebellar function (drinking

Medulla Oblongata
 lowest part of the brain
 connected to the spinal cord
 white matter is outer layer, gray matter is inner
 mainly made of nerve fibres that connect the spinal cord to other parts of the brain
 nerve centers here control many involuntary activities like breathing, heartbeat, blood flow,
  and coughing

the Spinal Cord
 extends from the opening at the base of the skull, through the vertebral canal, to the lower
 conducts messages b/w the brain and peripheral nerves (sensory and motor)
 controls reflex actions that do not require supervision by higher centres in the brain

c) Somatic and Autonomic Nervous Systems
Somatic Nervous System
 contains both sensory and motor neurons that connect the
  central nervous system to skeletal muscles, the skin, and the
  sense organs
 is responsible for body movements over which the individual has
  conscious awareness or voluntary control

Autonomic Nervous System
 made   up of motor fibres from the brain and spinal cord that serve
  the internal organs of the body
 usually has no voluntary control
 controls functions like rate of heartbeat, blood flow through
  arteries, breathing movements, movements of the digestive
  system, and secretions of certain glands
 is made up of 2 systems: parasympathetic and sympathetic
 these work in opposite ways to counteract each other
 parasympathetic functions to return to normal operations of the
  body that were shut down or slowed down by the sympathetic
  system in an emergency or stressful situation

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