Homeostasis and response

• What organ does the hormone that controls water and ion content act on?

  Kidney
• Veins contain valves
• Glandular tissue produces digestive juices in the stomach
• A mechanical heart can keep patients alive whilst waiting for a heart transplant.
• True or false? During exercise, an increase in breathing rate causes an increase in heart rate.

  False
• Deamination - removal of excess amino acids in the kidneys
• Selective reabsorption is when kidneys filters out substances that are uneeded. All glucose, some water and no urea is reabsorbed.
• Each kidney contains millions of tiny units called nephrons
• Blood goes in to the kidneys through the renal arteries, and out through the renal veins.
• Blood is filtered in the glomerulus to the bowman's capsule.
• Only 20% of the plasma in the blood is filtered into the Bowman's capsule
• Water, ions and urea are lost from the skin as we sweat
• Deamination happens in the liver
• Blood is at pH 6
• The cerebellum coordinates muscular activity
• Oestrogen is made in the ovaries.
• The medulla oblongata controls unconscious activities such as breathing and heart rate
• The cerebral cortex is the outer layer of neural tissue, responsible for consciousness, memory and language
• ADH (anti-diuretic hormone) from the pituitary gland causes tubules in kidneys to reabsorb more water into the bloodstream
• Reflex action:

  stimulus → receptor → coordinator → effector → response
• The eye accommodates to focus on near or distant objects
• The pituitary gland is the "master gland" responsible for regulating body functions, and controlling the activity of many other glands.
• Adaptation is when the eye adjusts to dim light
• Myopia is short-sightedness
• Hyperopia is long-sightedness
• To focus on a near object:

  • Ciliary muscles contract
  • Suspensory ligaments loose
  • The lens is thicker and refracts light strongly
• To focus on a distant object:

  • Ciliary muscles relax
  • Suspensory ligaments pulled taut
  • Lens is pulled thin and only slightly refracts light
• Laser eye surgery can change the shape of the cornea
• If blood glucose concentration is too high, the pancreas produces insulin, causing glucose to move from the blood into cells. In liver and muscle cells, excess glucose is converted to glycogen for storage.
• If blood glucose concentration is too low, the pancreas produces glucagon, causing glycogen to be converted into glucose and released into the blood.
• In Type 1 diabetes the pancreas fails to produce sufficient insulin. It is characterised by uncontrolled high blood glucose levels and is normally treated with insulin injections.
• In Type 2 diabetes body cells don't respond to insulin produced by the pancreas. A carbohydrate controlled diet and an exercise regime are common treatments. Obesity is a risk factor for Type 2 diabetes
• Ammonia is toxic and so it is immediately converted to urea for safe excretion.
• The kidneys produce urine by filtration of the blood and selective reabsorption of useful substances such as glucose, some ions and water.
• In females, an egg is released every 28 days.
• Follicle stimulating hormone (FSH) causes maturation of an egg in the ovary.
• Luteinising hormone (LH) stimulates the release of the egg.
• Oestrogen and progesterone are involved in maintaining the uterus lining.
• IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs.
• Disadvantages of IVF:

  • emotionally and physically stressful
  • success rates low
  • can lead to multiple births, risking mother and child