TOPIC 5

• What is homeostasis?

  Homeostasis is the regulation of the internal conditions of a cell or organism in response to internal or external changes to the enviroment.
• Why is homeostasis important?

  Because it keeps conditions constant for enzyme action and cell functions.
• What does homeostasis include the control of? [3]

  - Blood glucose concentration - Body temperature - Water and ion levels
• What may control systems involve? [2]

  - Responses using nerves - Chemical responses using hormones
• What is a receptor cell?

  It detects a stimuli
• What is a stimuli?


  A change to the enviroment
• Give examples of coordination centres? [3]

  - Brain - Spinal cord - Pancreas
• What do coordination centres do?

  Receive and process information from the receptors
• What do effectors do?

  They bring about responses that restore optimum levels
• What are examples of effectors? [2]

  - Muscles - Glands
• What happens in negative feedback? [3]

  - A receptor detects a change in a stimulus - The coordinating centre commpares the stimulus to a set point - An effector then produces a response to correct any difference from the set point
• What does the nervous system enable humans to do?

  Enables them to react to their surroundings and coordinate their behaviour
• Where does information from the receptors pass to?

  Passes to the central nervous system.
• What does the CNS coordinate?

  It coordinates the response of effectors.
• What are reflex actions like?

  Automatic and rapid so they can protect the body
• Explain the nervous system

  Stimula --> Receptor --> Sensory Neurones --> Relay Neurones --> CNS --> Relay Neurones --> Moto Neurones --> Effector --> Response
• How do neurones communicate with each other?

  Via synapses
• What is the electrical impulse name that when it reaches the synapse and has to diffuse across the gap to the other synapse?

  Neurotransmitters
• What is the endocrine system?

  It is made up of glands that secrete hormones directly into the bloodstream.
• What are hormones?

  Hormones are chemical messengers that are carried in the blood to a target organ or tissue.
• Compared with the effects of the nervous system, are the effect of hormones longer?

  Yes, they are also slower.
• What is the pituitary gland?

  It is the 'master gland'. - It secretes several hormones in response to body conditions.
• Where is adrenaline produced?

  In the adrenal glands
• What does adrenaline do to your body?

  It increases heart rate, boosting the delivery of oxygen and glucose to the brain and muscles.
• What does adrenaline prepare your body or?

  Flight or fight
• Where is Thyroxine produced?

  In the Thyroid gland
• What does Thyroxine regulate? [3]

  - Rate of metabolism - Heart rate - Temperature
• Where is testosterone produced?

  Testes
• What does testosterone do?


  Controls puberty and sperm production in males.
• Where is oestrogen produced?

  In the ovaries
• What does oestrogen do?


  It is involved in the menstrual cycle
• What monitors and control the blood glucose concentration?

  Pancreas
• What happens if the blood glucose is too high? [3]

  - Pancreas releases more of the hormone insulin - Insulin is transported to the liver, where it binds with liver cells and causes the glucose to move into the liver cells. - Excess glucose is converted into glycogen for storage
• What hormone is secreted by the pancreas if the blood glucose concentration is too high?

  Insulin
• What hormone is secreted by the pancreas if the blood glucose concentration is too low?

  Glucagon
• What happens if the blood glucose concentration is too low? [2]

  - Pancreas releases glucagon - Glucagon stimulates glycogen to be converted into glucose and released into the blood
• What is Type 1 diabetes caused?

  - It is caused by the pancreas failing to produce enough insulin
• What does Type 1 diabetes result in?

  High blood glucose levels
• How is type 1 diabetes treated?

  By insulin injections
• What is Type 2 diabetes caused by?

  It is caused by the body cells no longer responding to insulin