The nervous system, responding to stimuli & reflexes

• how do animals increase their chances of survival ?

  responding to changes in their external enviroment
• What are examples of physiological factors that are controlled by homeostasis in mammals ?

  • Core body temperature
  • Metabolic waste (eg. carbon dioxide and urea)
  • Blood pH
  • Concentration of glucose in the blood
  • Water potential of the blood
  • Concentration of respiratory gases (carbon dioxide and oxygen) in the blood
• what are the 2 types of communication systems that that transfer information between different parts of the body ?

  • The nervous system
  • The endocrine system
• what is the scientific name of any change in the internal or external enviroment ?

  Stimulus
• what are the sense organs ?

  eyes, ears, nose, tongue, skin
• what are receptors ?

  groups of cells that detect external stimuli
• what do receptors detect ?

  stimuli
• what are effectors ?

  cells that bring about a response to stimuli
• how do receptors communicate with effectors ?

  the nervous system
• what are the 3 main types of neurones ?

  Sensory, motor, and relay
• what does the central nervous system only contain ?

  the brain and the spinal cord
• what is the job of the central nervous system ?

  To coordinate and control the body's activities and processes
• what happens when a receptor in a sense organ detects a stimulus ?

  they send electrical impulses along sensory neurones to the CNS
• what are 3 things coordinated responses always need ?

  a stimulus , a receptor and an effector
• why does the nervous system bring very rapid responses ?

  because neurones transmit information using high speed electrical impulses
• what is the scientific name of a connection between 2 neurones ?

  Synapse
• what is a sensory neurone ?

  A neurone conducting impulses from receptors to the brain or spinal cord
• what is a motor neurone ?

  A neurone transmitting impulses from the brain or spinal cord to a muscle or gland
• what is a relay neurone ?


  a type of neurone that transmits signals between sensory neurons and motor neurones in the central nervous system.
• the nerve signal is transferred by chemicals called neurotransmitters which diffuse across the gap, these chemicals then set off a new electrical signal in the next neurone
• what are the two systems that can be seperated for the nervous system ?

  Central nervous system and peripheral nervous system
• how many neurons approx in the human body ?

  100 billion
• label this neurone

  A) cell body

  B) schwann cells

  C) impulse jumping between gaps in myelin sheath

  D) axon

  E) direction of nerve impulse

  F) nerve ending

  G) axon terminal

  
• label these 3 different neurones

  A) sensory neurone

  B) myelin sheath

  C) receptor cell

  D) axon

  E) cell body

  F) relay neutrone

  G) dendrite

  H) cell body

  I) axon

  J) motor neutrone

  K) cell body

  L) nodes of ranvier

  M) schwann cells

  N) axon

  
• what are reflexes ?

  Automatic responses to stimuli.
• what do reflexes reduce ?

  chance of being injured
• what is released if you get a shock ?

  the hormones adrenaline
• label this reflex arfc

  A) spinal cord

  B) muscle (effector)

  C) leg

  D) receptor cell

  E) pin (stimulus)

  
• block diagram to represent a reflex arc ?

  stimulus - receptor - sensory neurone - CNS - motor neurone - effector - response