10 - Human Nervous System

• Homeostasis - the regulation of the internal conditions of a cell to maintain optimum conditions for a function in response to internal and external changes.
• Nervous System: A network of neurons that transmits information from one part of the body to another.
• Stimulus - a change either internal or external which lead to a response
• Receptor - cells that detect the change to the environment
• Sensory Neurone - carries impulses from the receptors to the CNS
• Relay Neurone - relays the impulse from sensory neurone to a motor neurone
• Motor Neurone - carries impulse from CNS to an effector
• Effector - muscle or gland that produces a response to a detected stimulus
• Response - change as result from the detection of a stimulus
• CNS involves brain and spinal cord
• Co-ordinator - area that receives and processes the info normally the brain
• Reflex arc - an automatic response that does not involve the conscious part of the brain to help us avoid danger.
• In the reflex arc, the coordinator is a relay neurone not the brain.
• Reflex arc:

  A) Stimulus

  B) Receptor

  C) Sensory Neurone

  D) Relay Neurone

  E) Motor Neurone

  F) Effector

  G) Response

  
• Normal Response

  A) Stimulus

  B) Receptor

  C) Sensory Neurone

  D) Co-ordinator

  E) Motor Neutrone

  F) Effector

  G) Response

  
• Synapse - a junction between 2 neurones
• Parts of the brain:

  • cerebral cortex
  • cerebellum
  • medulla
  • hypothalamus
• Cerebral cortex - high level function
• Cerebellum - controls movement and balance
• Medulla - unconscious control
• Hypothalamus - homeostasis
• The brain:

  A) Cerebral Cortex

  B) Cerebellum

  C) Medulla

  D) Hypothalamus

  
• Eye - sense organ that contains many receptors that are sensitive to light and colour
• the receptor in the eye is the retina where it converts light into electrical impulses
• • Sclera - white outer layer of the eye
  • strong so eye is not easily damaged
• Sclera - white outer layer of the eye. Strong to prevent damage
• Cornea - transparent area at the front of the eye that refracts light into the eye so focuses on retina
• Iris - muscle that controls size of the pupil
• Pupil - hole which light enters the eye
• Len - clear disk that fine tunes focusing of light. It help in place by suspensory ligament and ciliary muscle
• The eye

  A) Suspensory Ligament

  B) Cornea

  C) Iris

  D) Pupil

  E) Ciliary Muscle

  F) Lens

  G) Sclera

  H) Retina

  I) Optic Nerve

  
• 2 common eye problems - myopia and hyperopia
• Myopia:

  • see close objects in clear focus, but distant objects as blurry
  • light is focused in front of the retina
  • happen because lens in too curved or eyeball is long
  • uses concave lens
• Hyperopia:

  • see distance objects in clear focus but close objects are blurry
  • light is focused behind the retina
  • may happen because lens is too flat or short eyeball
  • uses convex lens
• Pupil Size

  A) Contracts

  B) relaxes

  C) wide

  D) more

  
• Near Objects:

  A) Ciliary

  B) Contracts

  C) Suspensory

  D) Loosen

  E) Low

  F) Thicker

  G) strongly