B11 - Hormonal coordination

• Hormone


  Chemical secreted by endocrine glands directly into the bloodstream to produce an effect on target organs
• Endocrine gland


  Gland that secretes hormones directly into the bloodstream
• Endocrine system vs Nervous system

  • Endocrine effects are slower but longer lasting compared to the rapid but short-lived effects of the nervous system
• Pituitary gland


  Master gland that secretes hormones in response to changes in body conditions to coordinate other endocrine glands
• Pituitary gland does not produce enough growth hormone in a child


  Growth is stunted
• Pituitary gland continues to produce lots of growth hormone in an adult


  Excessive growth, leading to gigantism
• Insulin


  Hormone produced by the pancreas that allows glucose to move from the blood into cells and be stored as glycogen
• Glucagon


  Hormone produced by the pancreas that stimulates the liver to break down glycogen and release glucose into the blood
• Negative feedback control of blood glucose

  Insulin lowers high blood glucose, glucagon raises low blood glucose
• Type 1 diabetes


  Pancreas does not produce enough or any insulin, leading to uncontrolled high blood glucose
• Type 2 diabetes


  Body becomes resistant to insulin, leading to high blood glucose
• Treatment of type 1 diabetes involves regular insulin injections to control blood glucose levels
• Curing type 1 diabetes is difficult but scientists are exploring options like pancreas transplants and stem cell therapies
• Type 2 diabetes is linked to obesity and lack of exercise, and is treated with lifestyle changes and sometimes medication
• Genetic engineering


  1. Turned mouse pancreas cells that normally make enzymes into insulin-producing cells

  2. Using adult stem cells from patients with diabetes to try the same technique
• Scientists hope that eventually they will be able to genetically engineer faulty human pancreatic cells so that they work properly
• Scientists hope that they will be able to return the engineered cells to the patient with no rejection issues
• The easiest cure will be to use stem cells from human embryos that have been specially created for the process
• For some people, using stem cells from human embryos is not ethically acceptable
• Much more research is needed
• Scientists hope that type 1 diabetes will soon be an illness they can cure rather than just manage
• Type 2 diabetes


  Linked to obesity, lack of exercise, and old age
• If you develop type 2 diabetes, your body cells no longer respond to any insulin made by the pancreas
• Treating type 2 diabetes

  1. Eating a balanced diet with carefully controlled amounts of carbohydrates

  2. Losing weight

  3. Doing regular exercise
• If diet and exercise don't work for type 2 diabetes

  1. Taking drugs that help insulin work better on the body cells

  2. Taking drugs that help the pancreas make more insulin

  3. Taking drugs that reduce the amount of glucose absorbed from the gut
• If none of the treatments work for type 2 diabetes, you will probably need insulin injections
• Type 2 diabetes is becoming more common in young people who are very overweight
• Insulin injections cannot mimic natural control, but enable people with diabetes to live active lives
• Losing weight and taking exercise are simple ways to help overcome type 2 diabetes
• Ovulation


  1. Egg matures in ovary

  2. Egg is released from ovary
• Egg is not fertilised


  Lining of uterus and egg are shed from the body in the monthly period
• Hormones that control the menstrual cycle

  • FSH
  • LH
  • Oestrogen
  • Progesterone
• FSH


  Secreted by pituitary gland, makes eggs mature in ovaries, stimulates ovaries to produce oestrogen
• Oestrogen


  Made and secreted by ovaries, stimulates lining of uterus to grow, inhibits production of FSH, stimulates release of LH
• LH


  Secreted by pituitary gland, stimulates release of mature egg from ovary
• Progesterone


  Secreted by empty egg follicle in ovary after ovulation, helps maintain lining of uterus, inhibits FSH and LH
• The hormones produced by the pituitary gland and the ovary act together to control what happens in the menstrual cycle
• As the oestrogen levels rise, they inhibit the production of FSH and encourage the production of LH by the pituitary gland
• When LH levels reach a peak in the middle of the cycle, they stimulate the release of a mature egg
• FSH and LH are then suppressed and the body is kept ready for pregnancy until it becomes clear that the egg is not fertilised