The Nervous System - SchoolWorld by yurtgc548


									The Nervous System
 n … the body’s mission control         
 n … keep the life-support systems 
   functioning together
Cells of the Nervous System

n Neurons – the basic unit (cell) of the 
 nervous system.  Neurons bundled 
 together are called NERVES.
  n Cell

  n Dendrites

  n Axon
n Cell Body – Contains nucleus & other cell parts
n Dendrites –conducts an impulse toward the cell
n Axon – conducts impulses away from the cell
   n Schwann cells – a series of enclosed cells that
     make up the axon. Collectively, these Schwann
     cells are called the Myelin Sheath. The gap
     between nerve cells is the synapse.
Stimulus à Response

  Stimulus             Response
   Information         A reaction to a
received from the      condition or a
  nervous system      STIMULUS! To
     about the           survive an
condition inside &     organism must
 outside the body.   respond to stimuli.
  How the Nervous System
      works together
              What is it?         Their Job?
             Sense organ or    To receive a nerve
             any other organ   impulse and send it
Receptors    sensitive to a    through a conductor to
             stimulus          the interpretor.

                                 Carries a nerve
             The axon of the     impulse from the
             nerve cell          receptors to the
   How the Nervous System
       works together
             What is it?         Their Job?
                              Takes incoming
Inter-                        messages & makes a
              The Brain
pretor                        decision and sends out
                              a message.

                              Receives information
                              coming from the brain
Effectors   Organ or Tissue
                              & responds to a
  The Reflex Arc
n Reflexes   are automatic, involuntary
n A reflex arc involves the following
  n Sensory  receptors generate an
   impulse in a sensory neuron that
   moves along sensory axons toward
   spinal cord.
The Reflex Arc
n Sensory  neurons enter the spinal cord and
  pass signals to interneurons.
n Impulses travel along motor axons to an
  effector, which brings about response to
  the stimulus.
n The immediate response is that muscles
  contract to withdraw from source of pain;
  the brain does not integrate the sensory
  & motor activities
Reflex Arc Animations
 Animation #1
 Animation #2
 Animation #3
The Reflex Arc
Chapter 40 Bookwork
n Read   Chapter 40 (Pg. 939-960)
n Answer the following questions
  n Pg. 943 #1-2
  n Pg. 949 #1-5
  n Pg. 954 #1-5
  n Pg. 961 #1-6

n Be sure to write out QUESTION & 
    2 Basic Parts of the
  Human Nervous System
n Central   Nervous System (CNS)
  n Made up of the brain & spinal cord.  The 
   control center; coordinates body activity.
n Peripheral   Nervous System (PNS)
  n Made up of the nerves that carry 
   messages to and from the central nervous 
Peripheral Nervous System
n Somatic  Nervous System – voluntary 
  responses (ex. Walking, running).
n Autonomic Nervous System – 
  involuntary responses (ex. Glands in 
  stomach produce enzymes to break 
  down protein).
  n Sympathetic Nervous System
  n Parasympathetic Nervous System
Autonomic Nervous System

n Sympathetic    Nervous System – 
  controls internal functions during 
  times of stress. “Fight or Flight”
n Parasympathetic Nervous
  System – controls internal 
  functions of the body at rest.   
  “Rest & Digest”
Central Nervous System
n Cerebrum – 
 conscious activity; 
 memory, language 
 and the senses.
The Lobes of the Cerebrum
Lobes of the Cerebrum
n   Frontal Lobe - Speech 
    production, the elaboration of 
    thought and emotion, and 
    skilled movements are 
    controlled by neurons found 
    in this part of the brain.
n   Temporal Lobe – Hearing & 
    Tte recognition of specific 
    tones and loudness takes place 
    here. This area also plays a 
    role in memory storage.
Lobes of the Cerebrum
n   Parietal Lobe - A variety 
    of bodily sensations such 
    as touch, pressure, pain 
    and temperature are all 
    perceived and interpreted 
n   Occipital Lobe - The 
    neurons in the occipital 
    lobe interpret nerve 
    impulses from the eyes.
 Central    Nervous System
n Cerebellum – 
 balance, posture & 
n Thalamus – 
 receives and sends 
 sensory signals to 
 the cerebrum.
Central Nervous System
n   Hypothalamus – regulation 
  of heart rate, blood pressure, 
  body temperature, water 
  balance; hunger, thirst and 
  sleep; serves as a link between 
  the nervous and endocrine 
n Medulla Oblongata – 
  controls involuntary activities 
  such as breathing, heartbeat, 
  swallowing & sneezing.
            The Eye
n 90% of our information comes
 through the sense of sight. The eye
 is made up of 3 layers:
  n Outer Layer – Sclera

  n Middle Layer – Choroid

 n Inner   Layer - Retina
The outer layer of the Eye -

 n Cornea:  The transparent area
  of the sclera located at the
  front of the eye. 
The middle layer of the Eye
n Iris: regulates the amount of light
  entering the eye. It is pigmented and
  surrounds the pupil which is a hole.
n Lens: A transparent protein disc that is
  used to focus light onto the retina. Its
  shape is controlled by…
n Ciliary muscles: Controls the shape of
  the lens.
The inner layer of the Eye
 The Retina is the inner most layer of the
   eyeball. It contains photoreceptor cells
   that transmit signals to the optic nerve.
 n Rods and Cones: Rods are sensitive to
   light but do not distinguish colors, where
   as cones are responsible for daytime color
The inner layer of the Eye 
n Fovea: Area of the retina that contains
  the highest concentration of cones. Does
  not contain any rods. This is where an
  object comes into focus.
n Optic nerve: Nerve that connects the eye
  to the brain.
n Blind spot: Area of the eye that does not
  contain any rod or cones. It is here that
  the eye is attached to the optic nerve.
The Fluids of the Eye
n Aqueous   Humor: fluid behind the 
  cornea and in front of the lens. Helps 
  focus light onto the retina. 
n Vitreous Humor: fluid that fills the 
  large central chamber of the eye. It 
  helps focus light onto the retina. 
The Ear
n     The ear 
    maintains both 
    hearing and 
    balance. The 
    structures for 
    these sensory 
    functions are 
    located in 
    separate areas of 
    the inner ear. 
The Outer Ear
n The Pinna, which 
  is the visible part of 
  the outer ear, 
  funnels sound 
  waves into the 
  outer ear canal.
n The waves travel to 
  the eardrum and 
  cause it to vibrate. 
The Middle Ear
n This air-filled portion 
  of the temporal bone 
  lies between the 
  eardrum and the  
  inner ear. 
n The malleus, incus 
  and stapes are bones 
  that transfer sound 
  vibrations from the 
  eardrum to the inner 
The Inner Ear
n   The inner ear consists of 
    a complex system of 
    membranous canals. 
n   The hearing organ is 
    located in the snail-like 
n   The sense of balance 
    operates from the 
    structures in the 
    vestibule and 
    semicircular canals. 

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