1. IVF and Homeostasis

2. Fertility drugs Some women have problems becoming pregnant because they aren't producing enough FSH for their eggs to mature. Fertility drugs contain follicle-stimulating hormone (FSH) and luteinising hormone (LH), which stimulate eggs to mature in the ovaries. These fertility treatments do increase a woman's chance of becoming pregnant but the treatment is not always successful, although, because the treatment boosts the production of mature eggs, multiple conceptions sometimes occur and the woman can have twins or triplets. This increases the risk of problems in pregnancy and childbirth and the birth of premature or underweight babies.

3. In-vitro fertilisation IVF treatment If a couple are having problems conceiving a child because the quantity or quality of the man’s sperm is poor then an IVF treatment can be used. This is where the egg is fertilised outside the woman’s body in a lab before being implanted back into her uterus. FSH can also be used to encourage the production of several mature eggs all at once, so it is used as part of IVF to increase the number of eggs available for fertilisation. Many people worry about the ethical implications of the use of IVF treatments. They fear that people may start to want 'designer babies' with certain qualities, so might only want particular fertilised eggs.

4. Homeostasis Homeostasis Homeostasis is the control of the conditions inside the body. Some of these conditions include water levels, body temperature and the concentration of glucose in the blood. Body temperature is monitored and controlled by the thermoregulatory centre part of the brain. The pancreas monitors and controls blood glucose concentration. The lungs remove carbon dioxide from the body. The kidneys remove urea from the blood.

5. Controlling blood glucose blood glucose concentration The blood glucose concentration is controlled to provide cells with a constant supply of energy. The pancreas monitors and controls the concentration of glucose in the blood. It does this by producing the hormone insulin, which causes glucose to shift from the blood into cells. Insulin lowers the blood glucose concentration in the body if it has become too high. If the pancreas does not produce enough insulin or the body's glucose levels are not controlled a person can get diabetes.

6. Waste products If waste products are not removed from the body they may interfere with chemical reactions or damage cells. Waste products that must be removed include carbon dioxide and urea. Carbon dioxide is removed from the body by the lungs when we breathe out and the kidneys remove urea from the blood to make urine, which is temporarily stored in the bladder.

7. Temperature regulation The body's temperature is controlled because human enzymes work best at 37ºC. A part of the brain, the thermoregulatory centre, monitors and controls body temperature. It receives information as nerve impulses from temperature receptors in: The brain: sensitive to temperature of the blood flowing there The skin: sensitive to skin temperature

8. Temperature regulation There are several ways in which the body controls temperature: Too hotToo cold Sweating: sweat glands produce more sweat, which evaporates and therefore removes heat energy from the body Shivering: muscles contract rapidly, which requires energy from respiration, and some of this is released as heat Blood vessel dilation: they become wider, allowing more blood to flow through the skin and more heat to be lost Blood vessel constriction: they become narrower, allowing less blood to flow through the skin and heat to be conserved