Animal coordination, control, and homeostasis

• Hormones


  Hormones are chemical messenger sent in the blood to other parts of the body to target organs. They control things in organs and cells that need constant readjustment. They are produced by various glands called endrocrine glands, which make up the endocrine system
• Endocrine Glands

  • Pituitary gland- produces many hormones that regulate body conditions
  • Thyroid gland- produces thyroxine which is involved in metabolism rates
  • Adrenal glands- produce adrenaline used to prepare the body for a fight or flight response
  • Pancreas- produce insulin used to regulate blood sugar levels
  • Testes- produce testosterone (controls puberty and sperm production)
  • Ovaries- produce oestrogen involved in the menstrual cycle
• How are hormones transported?

  Hormones are released into the bloodstream and are transported in the blood plasma  to target body tissues where they bind to cells to produce a response.
• How does adrenaline work

  Adrenaline is released by adrenal glands, it prepares the body for a fight or flight response. It does this by activating processes that increases supply of oxygen and glucose to cells such as:

  • Binding to receptors in the heart causing it to contract quicker and harder causing heart rate and blood pressure to increase
  • Increasing blood flow to muscles for increased respiration
  • Binding to receptors in the liver to break down its glycogen stores for more glucose in the blood to be transported to cells as energy
• How does thyroxine work?

  Thyroxine is released by thyroid glands to control metabolic rate. It works in a negative feedback system: If there is not enough thyroxine, TRH is released by the hypothalamus. This causes the anterior pituitary to release TSH, which in turn causes the thyroid glands to release thyroxine. If there in too much thyroxine, the hypothalamus stops releasing TRH and shuts the system down. This negative feedback system is used to regulate thyroxine levels.
• Menstrual cycle stages.


  Day 1-5: Uterus lining is shed. FSH is released from the pituitary gland and travels to the ovaries causing a follicle to mature.

  Day 5-14: Ovary releases oestrogen, which causes the lining of the uterus to thicken in preparation for a fertilised egg. In high levels oestrogen causes the release of LH from the pituitary gland

  Day 14: A surge in LH causes the release of the mature egg from ovary.

  Day 14-28: Corpus luteum releases progesterone (maintains the lining of the uterus)

  Day 1: If the egg is not fertilised levels of progesterone drop restarting the cycle
• Oestrogen role in mentrual cycle

  1. Released by ovaries
  2. Causes lining of uterus to thicken and grow
  3. A high level stimulates an LH surge
• Progesterone role in menstrual cycle

  1. Released by corpus luteum after ovulation
  2. Maintains lining of uterus
  3. Inhibits release of FSH and LH
  4. When progesterone levels fall the uterus lining breaks down
  5. Low progesterone levels allow FSH to increase
• FSH role in menstrual cycle

  1. Released by pituitary gland
  2. Causes a follicle to mature in one of the ovaries
  3. Stimulates oestrogen production
• LH role in menstrual cycle

  1. Released by pituitary gland
  2. LH surge stimulates ovulation causng the follicle to rupture and an egg released
  3. Stimulates remains of follicle to develop into corpus luteum- which secretes progesterone
• Hormonal contraceptives

  • Oestrogen can be used to prevent release of FSH and therefore an egg and eventually stop egg development
  • Progesterone can be used to reduce fertility. Stimulates production of thick cervical mucus, which prevents any sperm from getting through the uterus and to an egg
  • Some contraceptives include both oestrogen and progesterone
  • The mini pill and injection contain progesterone only
• Hormonal methods of contraception

  When used correctly, hormonal methods are more effective at preventing pregnancy than barrier methods however can have bad side effects like headaches and mood changes. Also, it doesnt stop STIs
• Barrier methods of contraceptives

  Examples of barrier methods are condoms and diaphragms (flexible dome shaped devices that fit over the opening of the uterus and are inserted before sex.). They are less effective however dont have many side effects.
• What is ART?


  Assisstive Reproductive Technology is a fertility treatment that involves eggs being handled outside of the body. IVF is an example of this.
• What is IVF and how does it work?

  IVF is when you grow eggs from a womans body and then insert them in once grown. It works by collecting eggs from ovaries and fertilising them in a lab with sperm. These are then grown into embryos, which once grown into balls of cells, one or two are transferred to the womans uterus to improve chance of pregnancy. FSH and LH are given before egg collection to stimulate egg production.
• What is Clomifene therapy and how does it work?

  Clomifene therapy is a drug that helps women ovulate. They can take a drug if infertile due to no ovulation causing more FSH and LH to be released by the body which stimulate egg maturation and ovulation.
• Homeostasis is maintaining a constant internal environment

  Conditions in the body need to be kept steady so that it functions properly. To maintain a constant internal environment a body needs to respond to both internal and external changes whilst balancing inputs with outputs such as:

  • Blood glucose regulation
  • Regulating water content ( balance in water you gain and remove from your system)
  • Regulating body temperature
• How does Insulin work?

  If the blood sugar concentration is too high, insulin is secreted by the pancreas to make the liver turn glucose into glycogen when glucose moves from blood into the liver and muscle cells meaning glucose levels are reduced.
• How does Glucagon work?

  If your blood sugar concentration is too low, the pancreas secrete glucagon to make the liver turn glycogen into glucose which is then released into blood, making the blood glucose concentration to increase.
• What happens to glucose when it enters the body

  Eating foods containing carbohydrates puts glucose into the blood. Metabolism of cells and exercise removes glucose from the blood and then extra glucose is stored as glycogen in your liver and muscles.
• Type 1 Diabetes


  A condition where the pancreas produces little to no insulin meaning blood sugar levels are too high, which can even result in killing someone with it. This can be treated with injecting insulin into the subcutaneous tissue from where it will enter the bloodstream. This is often done after meals to immediately remove the glucose entering. As well as this, people can also think about limiting the amount of simple carbohydrates they eat and getting regular exercise.
• Type 2 diabetes


  A condition where the pancreas dont produce enough insulin or a body is resistant to insulin, meaning blood glucose levels increase. Obese people have an increased risk of developing Type 2 diabetes. Type 2 diabetes can be controlled by eating a healthy diet, getting regular exercise and losing weight.
• The correlation between BMI and Type 2 Diabetes

  Obese people have a more likely chance of developing Type 2 Diabetes. Obese people are classified as having a BMI of over 30 (equation is mass/height^2). Also, where the body stores excess fat is important as alot of fat being stored near the abdomen can increase risk of Type 2 Diabetes. Calculating a persons waist to hip ratio can give an indication of how fat is stored