bio p2

• What is homeostasis?


  The regulation of the internal conditions in a cell or organism to maintain optimum conditions for function in response to internal and external changes
• What key three factors does homeostasis in human control?

  Blood glucose concentration, body temperature, water levels
• What does the nervous system do in humans?

  Enable humans to react to their surroundings and to coordinate their behaviour
• What is the Central Nervous System?

  The brain and spinal cord
• What does the Central Nervous System do?

  Coordinates the response of effectors which may be muscles or gland secreting hormones
• What is the Central Nervous System sequence?

  Stimulus --> Receptor --> Coordinator --> Effector --> Response
• What is the brain?

  Billions of interconnected neurones that control complex behaviour using different regions that carry out different functions
• What is the function of the cerebral cortex?

  It controls intelligence, personality, conscious thought and high-level functions, such as language and verbal memory
• What is the function of the cerebellum?

  It controls balance, co-ordination of movement and muscular activity
• What is the function of the medulla?

  It controls unconscious activities such as heart rate and breathing rate
• In the eye what is accommodation?

  The process of changing the shape of the lens to focus on near or distant objects
• How does the eye focus on a near object?

  The ciliary muscles contract, the suspensory ligaments loosen, the lens is then thicker and refracts light rays strongly
• How does the eye focus on a distant object?

  The ciliary muscles relax, the suspensory ligaments are pulled tight, the lens is then pulled thin and only slightly refracts light rays
• What is short-sightedness or myopia?

  Where near objects are seen clearly but the eye cannot focus on distant objects
• What is a long sightedness or hyperopia?

  Where distant objects are seen clearly but the eye cannot focus on nearby objects
• What does the thermoregulatory centre in the brain do?

  Monitor and control body temperature
• What happens when body temperature is too high?

  Blood vessels to dilate (vasodilation) and sweat is produced from the sweat glands
• What happens in the body temperature is too low?

  Blood vessels constrict (vasoconstriction), sweating stops and skeletal muscles contract (shiver)
• What is the endocrine system?

  A system composed of glands which secret chemicals called hormones directly into the bloodstream
• What is the pituitary gland?

  The 'master gland' in the brain which secretes hormones into the blood in response to body conditions
• What does the pancreas do?

  Monitor and control blood glucose concentration
• What happens when the blood glucose concentration is too high?

  The pancreas produces the hormone insulin that causes glucose to move from the blood into the cells
• What happens when the blood glucose concentration is too low?

  The pancreas produces the hormone glucagon that causes glycogen to be converted into glucose and release into the blood
• What is glucose converted to in liver and muscle cells?

  Glycogen
• What is Type 1 diabetes?

  A disorder where the pancreas fails to produce sufficient insulin
• What is Type 2 diabetes?

  Where body cells no longer respond to insulin produced by the pancreas
• How do you treat Type 1 diabetes?

  Through insulin injections
• How do you treat Type 2 diabetes?

  Through a carbohydrate-controlled diet and exercise regime
• How does water leave the body via the lungs?


  By exhalation
• What two other substances are lost from the skin in sweat in addition to water?

  Ions and urea
• What is removed via the kidneys in urine?

  Water, ions and urea
• How does the liver remove amino acids?

  By deamination to form ammonia
• How does the kidney produce urine?


  By filtration of the blood and selective reabsorption of useful substances such as glucose, some ions and water
• How is the water level in the body controlled?

  By the hormone ADH which acts on the kidney tubules
• Where is ADH released from?

  From the pituitary gland when blood is too concentrated
• What does the hormone ADH do?

  Causes more water to be reabsorbed back into the blood from the kidney tubules; controlled by negative feedback
• What is oestrogen?


  The main female reproductive hormone produced in the ovary
• What is ovulation?


  Where a mature egg is released
• What is testosterone?


  The main male reproductive hormone produced by the testes and it stimulates sperm production
• Name the hormones involved in the menstrual cycle

  Follicle stimulating hormone (FSH), Luteinising hormone (LH), Oestrogen, Progesterone