Response and Regulation

• What are sense organs made of?

  Groups of receptor cells that respond to specific stimuli and send electrical impulses to the CNS.
• Which stimuli do the main sense organs detect?

  Light (eye), sound and balance (ear), touch/temperature/pain (skin), chemicals (nose and tongue).
• What is the CNS made up of?

  The brain and spinal cord.
• What does the nervous system include?

  Brain, spinal cord, and nerves.
• What are the key properties of reflex actions?

  Fast, automatic, and protective.
• Give examples of reflex actions.

  Withdrawal reflex, blinking, and pupil size adjustment.
• What are the components of a reflex arc?

  Stimulus, receptor, sensory neurone, relay neurone, motor neurone, effector.
• What are synapses?

  Junctions between neurones where impulses are chemically transmitted.
• What is the function of the sclera?

  Tough outer layer that protects the eye.
• What is the role of the cornea?

  Transparent front part that refracts light.
• What is the pupil?

  An opening that allows light into the eye.
• What does the iris do?

  Controls the size of the pupil.
• What is the function of the lens?

  Focuses light onto the retina.
• What is the choroid?

  Pigmented layer that prevents light reflection inside the eye.
• What does the retina do?

  Contains light-sensitive cells (rods and cones) to detect light.
• What is the blind spot?

  Area with no light-sensitive cells where the optic nerve exits.
• What is the optic nerve?

  Carries impulses from the eye to the brain.
• What is homeostasis?

  The maintenance of a stable internal environment.
• Why is homeostasis important?

  To ensure optimal conditions for enzyme and cell function.
• What are hormones?

  Chemical messengers carried in the blood to target organs.
• What happens when blood glucose levels rise?

  The pancreas releases insulin, converting glucose to glycogen in the liver.
• What is glycogen?

  An insoluble storage form of glucose.
• What causes type 1 diabetes?

  The pancreas does not produce insulin.
• What causes type 2 diabetes?

  The body's cells do not respond properly to insulin.
• How is type 1 diabetes treated?

  With insulin injections and a controlled diet.
• How is type 2 diabetes managed?

  With diet, exercise, and sometimes medication.
• Name structures in the skin involved in temperature regulation.

  Hair, erector muscle, sweat gland, sweat duct, sweat pore, blood vessels.
• What is vasodilation?

  Widening of blood vessels to release heat.
• What is vasoconstriction?

  Narrowing of blood vessels to retain heat.
• How does sweating help regulate temperature?

  Evaporation of sweat cools the body.
• Why do hairs stand on end when cold?

  To trap air and insulate the body.
• What is shivering?

  Rapid muscle contractions to generate heat.
• What is negative feedback?

  A response that counteracts a change to maintain balance.
• Give an example of negative feedback.

  Blood glucose control by insulin and glucagon.
• How do lifestyle choices affect health?

  Poor diet and inactivity can increase the risk of type 2 diabetes.
• What is phototropism?

  Growth of plant shoots towards light.
• What is gravitropism?

  Growth of plant roots in the direction of gravity.
• What hormone controls phototropism?

  Auxin, which promotes cell elongation on the shaded side of shoots.