Biology GCSE

• Hormones are chemical messengers which travel in the blood to activate target cells
• Hormones are produced in and secreted by endocrine glands, which make up the endocrine system
• The endocrine system uses hormones to react to changes in the environment or changes inside the body
• Pituitary gland-produces hormones that regulate body conditions. Called the master gland, as these hormones act on other glands
• Pancreas-produces insulin, which is used to regulate the blood glucose level
• thyroid- produces thyroxine, involved in regulating metabolism, heart rate and temperature
• adrenal glands- produces adrenaline, used to prepare the body for a 'fight or flight' response
• ovaries- produces oestrogen, for menstrual cycle
• testes- produces testosterone, controls puberty and sperm production
• Nerves -fast action, act for a short time, acts on a very precise area
• Hormones- slower action, act for a long time, acts in a more general way
• The level of glucose in the blood must be kept steady. Changes in the blood glucose level are monitored by the pancreas
• Insulin-

  1)After a meal containing carbohydrate, a person's glucose levels rise. This is detected by the pancreas

  2)The pancreas responds by producing insulin, which is secreted into the blood

  3)Insulin causes body cells to take up more glucose from the blood. Cells in the liver and muscles take up glucose and convert it into glycogen

  4)This causes the blood glucose level to fall
• Glucagon-

  1)If a person's blood glucose level decreases, the fall is detected by the pancreas

  2)the pancreas responds by producing glucagon, which is secreted into the blood

  3)Glucose can be stored as glycogen, which can be broken down by glucagon, allowing glucose into the blood

  4)this causes the blood glucose level to rise
• Type 1 diabetes is a condition where the pancreas produces little or no insulin. This can result in a person's blood glucose rising to a level that can kill them
• What is the primary treatment for people with Type 1 diabetes?

  Insulin therapy
• Why do people with Type 1 diabetes need several injections of insulin throughout the day?

  To ensure glucose is removed from the blood quickly after food digestion
• How does insulin therapy help manage blood glucose levels in Type 1 diabetes?

  It prevents blood glucose levels from getting too high
• What factors determine the amount of insulin injected by a person with Type 1 diabetes?


  The person's diet and level of physical activity
• What type of carbohydrates should people with Type 1 diabetes limit in their diet?

  Foods rich in simple carbohydrates
• What dietary strategy is advised for people with Type 1 diabetes regarding starchy carbohydrates?

  To spread their intake throughout the day and choose varieties that are absorbed more slowly
• How does regular exercise benefit individuals with Type 1 diabetes?

  It helps lower blood glucose levels by increasing metabolism
• What is the relationship between exercise and blood glucose levels in people with Type 1 diabetes?

  Increased metabolism during exercise removes more glucose from the blood
• Why is regular monitoring of blood glucose levels crucial for individuals with Type 1 diabetes?

  To ensure that blood glucose levels remain within a safe range
• What role does glucagon play in blood glucose regulation?

  It raises blood glucose levels when they are too low
• Type 2 diabetes is a condition where a person becomes resistant to their own insulin. Being overweight can increase your chance of developing type 2 diabetes
• Controlling type 2 diabetes-

  -eating a carbohydrate controlled diet - to avoid sudden rises in glucose

  -regular exercise - helps to lower the blood glucose level
• Type 1

  -autoimmune disease

  -develops rapidly

  often diagnosed in young children or teenagers

  -no insulin produced

  -can't be reversed

  -can't be prevented
• Type 2

  -not an autoimmune disease

  -develops slowly

  -often diagnosed in adults

  -some insulin produced

  -can be reversed with early diagnosis

  -can be prevented through lifestyle changes
• modern treatment options for type 1-

  -Diabetics can have a pancreas transplant. However, the body can reject the tissue. If this happens you have to take costly immunosuppressive drugs, which often have serious side effects
• -When the level of thyroxine in the blood is higher than normal, the secretion of TSH is inhibited. This reduces the amount of thyroxine released from the thyroid gland, so the level in the blood falls back to normal
• -When the level of thyroxine in the blood is lower than normal, the secretions of TSH from the pituitary gland is stimulated again. This increases the amount of thyroxine released from the thyroid gland, so the level in the blood rises back towards normal
• Thyroxine regulates the basal metabolic rate, stimulates protein synthesis for growth and development
• Adrenaline gets the body ready for 'fight or flight' response by triggering mechanisms that increase the supply of oxygen and glucose to cells in the brain and muscles #
• 1)Day 1 is when menstruation starts. The uterus lining breaks down for about four days

  2) The lining of the uterus builds up again, from day 14, into a thick spongy layer full of blood vessels, ready to receive a fertilised egg

  3) An egg is released from the ovary at day 14. This is called ovulation

  4) The wall is maintained for 2 weeks. If no fertilised egg has landed on the uterus wall the spongy lining starts to break down.

  
• FSH is produced in the pituitary gland and causes an egg to mature in an ovary. It also stimulates the ovaries to produce oestrogen

  pituitary gland -> FSH -> ovary -> oestrogen
• Oestrogen is produced in the ovaries and causes the lining of the uterus to grow. It also stimulates the release of LH (which causes the release of an egg) and inhibits the release of FSH

  ovary -> oestrogen -> pituitary gland -> LH
• LH is produced by the pituitary gland and stimulates the release of an egg at day 14

  pituitary gland -> LH -> ovary
• Progesterone is produced in the ovaries by the remains of the follicle after ovulation. It maintains the lining of the uterus during the second half of the cycle. When the level of progesterone falls, the lining breaks down. Progesterone also inhibits the release of LH and FSH
• Hormones involved