5.2 - The Endocrine System

• What is the function of the pituitary gland?

  The pituitary gland is responsible for producing and releasing hormones that regulate various bodily functions, including growth, reproduction, and metabolism.
• What is the function of the pancreas?

  To produce insulin, which regulates blood glucose levels.
• What is the function of the thyroid?

  Produces thyroxine, which regulates things like, metabolism, heart rate and temperature.
• What is the purpose of the adrenal glands?

  Produces adrenalin, which is used to prepare the body for a 'fight or flight' response.
• Nerves are fast action, short-term and act on a precise area.
• Hormones are slow action, long-term, and act in a more general way.
• When the glucose level rises, the pancreas detects it and produces insulin. The insulin is secreted into the blood causing body cells to take up more glucose and store it as glycogen. Causing the blood glucose levels to fall.
• When the blood glucose levels fall, the pancreas detects it and produces glucagon . That is secreted into the blood and stores in the muscles and liver as glycogen. Glucagon causes glycogen to be converted to glucose (which enters the blood). Causing the blood glucose levels to rise.
• Ways to control type 1 diabetes:

  Insulin therapy, regular exercise and limiting the intake of foods rich in simple carbs.
• Ways to control type 2 diabetes:

  Regular exercise and eating a carbohydrate-controlled diet.
• What is a modern treatment option for diabetes?

  Pancreas transplant or an artificial pancreas.
• What is the role of the kidneys?

  They filter urine by taking waste products out of the blood. The process is called filtration.
• What substances are filtered and by how much?

  Glucose is filtered out of the blood and then completely absorbed back into the blood. Ions (salts) are filtered out then only partially re-absorbed. Lastly, urea is completely filtered out of the blood and not re-absorbed.
• Proteins can't be stored in the body, so are broken down into amino acids, any excess amino acids are converted into fats and carbs which can be stored. This happens in the liver and is called deamination. The waste product of this is ammonia.
• Ammonia is toxic so it is converted to urea in the liver, then transported to the kidneys.
• What happens when dehydrated?

  A receptor in the brain detects the low water levels. The pituitary gland releases more ADH. This causes the kidney tubules become more permeable and so more water is reabsorbed from the kidney tubules.
• What happens when over-hydrated?

  A receptor in the brain detects the high water levels. The pituitary gland releases less ADH. This causes the kidney tubules becomes less permeable and so less water is reabsorbed from the kidney tubules.
• What are the treatments for kidney failure?

  Dialysis treatment (machines doing the job of the kidneys) and kidney transplant.
• How does a dialysis machine work?

  Blood flows alongside a permeable membrane and surrounded by dialysis fluid. The permeable membrane doesn't allows dissolved ions and glucose to be lost. Only waste substances to be filtered out (urea).
• Problems with dialysis:

  Not a nice experience for patients; can lead to infections and blood clots; patients have to have a careful diet; limited fluid intake; expensive.
• Why can kidney transepts be rejected?

  Antigens on the donor kidney aren't recognised as being part of the patient's body by the white blood cells. So the white blood cells produce antibodies to attack the donor cells.
• How do you prevent rejection?

  Find a donor with a similar tissue-type to the recipient or treat the recipient with drugs.
• What are other problems with kidney transplants?

  Long waiting lists; possibility of rejection; drugs make vulnerable immune system; transplant is risky.