Chapter 10

• What is


  the regulation of the conditions inside your body to maintain a stable internal environment, in response to changes in both internal and external conditions
• Why does the body need to maintain optimal conditions?

  For optimal enzyme activity and cell function
• What are examples of internal conditions?

  Blood PH and blood concentration
• What are examples of external conditions?

  the amount of fluids you drink and room temperature
• What is a stimulis?

  A change in the internal or external environment
• What does the receptor do?

  the receptor detects change in the internal or external environment
• What does the coordination centre do?

  The coordination centre interprets changes and organises a response. They are located in the brain and spinal cord
• What do effectors do?

  Effectors carry out the change. The two types of effector are muscles and glands. Muscles contract when stimulated whilst glands release hormones.
• What is negative feedback?

  Homeostasis relies on negative feedback, meaning whenever the levels of something get too high, they're brought back down and whenever the levels of something gets too low, they're brought back up.

  
  

  Negative feedback- any change in a system causes and action that reverses the change
• How are messages transferred across the synapse?


  -the electrical impulse reaches the end of the neurone

  -This triggers the release of chemicals called neurotransmitters

  -The neurotransmitters diffuse across the gap between the neurones

  -The neurotransmitters bind to receptors on the next neurone

  -The presence of the neurotransmitter causes the production of a new electrical impulse in the next neurone
• What is the central nervous system? What happens there?

  The CNS is where all the information from the receptors is sent and where the reflexes and actions are coordinated. The Brain and the spinal cord are parts of the central nervous system.
• What is the role of the sensory neurone?

  the role of the sensory neurone is to transfer a signal from a receptor to the CNS
• What is the role of the motor neurone?

  the role of the motor neurone is to transfer a signal from the CNS to an effector
• What is the role of the relay neurone?

  The role of the relay neurone is to transfer a signal from a sensory neurone to a motor neurone
• What is a reflex?

  A reflex is an automatic response to a stimulus that protects us from harm
• How do you get from the stimulus to the response?

  stimulus -> receptor -> sensory neurone -> relay neurone -> motor neurone-> effector -> response
• Describe the brain

  
• What is the function of the cerebral cortex?


  Controls consciousness, intelligence, memory and language
• What is the function of the hypothalamus?

  Regulates balance and body temperature
• What is the function of the medulla?

  controls unconscious activities, breathing and heart rate
• What is the function of the cerebellum?


  Balance and muscle coordination
• How can matching specific regions of the brain with specific functions be done?

  -studying people with brain damage

  -electrically stimulate different parts of the brain

  -scan the brain using CT, PET, MRI or fMRI scanners
• Why is studying the brain very difficult?

  -there is a huge range of things that can go wrong

  -It is encased in the skull, so is hard to access.

  -It is very complicated, so it is hard to target with medications
• Describe the eye

  
• What is the sclera?


  The tough supporting wall of the eye
• What is the cornea?

  the transparent layer forming the front of the eye. It refracts light into the eye
• What is the pupil?


  The hole in the centre of the eye, through which light enters
• What is the Iris?


  Contains muscles that allow it to control the diameter of the pupil and therefore how much light enters the eye
• What is the retina?

  The layer at the back of the eye that contains two tyoes of light receptor cells
• What is the lens?

  focuses light into the retina
• What are the ciliary muscles and suspensory ligaments?

  Control the shape of the lens
• What is the optic nerve?

  Carries impulses from the receptors on the retina to the brain
• What are cone cells?

  Cone cells are light-sensitive cells in the retina which enable you to see colour.
• What are rod cells?


  Rod cells are light-sensitive cells in the retina which enable you to see in the dark
• What muscles make up the iris?

  circular and radial muscles
• What happens when the eye is exposed to bright light?

  The pupil will constrict. When the pupil constricts the circular muscle contract and the radial muscle relaxes
• What happens when the eye is exposed to dim light/no light?

  The pupil will dilate. When the pupils dilates the circular muscle relaxes and the radial muscle contracts.
• What is accommodation?


  Accommodation is the alteration of the lens' shape in order to focus on near or distant objects.
• What does the eye do when looking at near objects?

  -the ciliary muscles contract, slackening the suspensory ligaments

  -the lens become more fat (more curved)

  -This increases the amount by which it refracts light
• What does the eye do when looking at distant objects?

  -The ciliary muscles relax, which allows the suspensory ligaments to pull tight

  -this makes the lens go thin (less curved)

  -so it refracts light by a smaller amount