bio - animal coordination + homeostasis (7)

• The human body has two communication systems: the nervous system and the endocrine system.
• The endocrine system sends hormones (chemical messengers) around the body.
• When hormones reach a target tissue, they produce a response.
• The endocrine system is made up of glands which secrete hormones directly into the bloodstream.
• Urea is produced from the breakdown of excess amino acids in the liver.
• Tissue typing allows us to check if an organ is compatible with the recipient before transplantation, which can lead to long waits for an organ but can prevent organ rejection.
• The pituitary gland secretes hormones into the blood to either influence the body or act on other glands to stimulate them to produce different hormones.
• The pancreas secretes insulin which controls blood glucose levels.
• The thyroid gland secretes thyroxine which controls metabolic rate, heart rate and temperature.
• The adrenal gland secretes adrenaline which is involved in the 'fight or flight' response.
• The ovary secretes oestrogen which is involved in the menstrual cycle and the development of female secondary sexual characteristics.
• The testes secretes testosterone which is involved in the production of sperm and the development of male secondary sexual characteristics.
• The blood transports the hormone to a target organ or tissue where it has an effect.
• Compared to the nervous system, the hormonal system is much slower but it acts for longer.
• Adrenaline is a hormone that is produced by the adrenal glands to prepare the body for a flight or flight response.
• A flight-or-flight response is the body’s response to a dangerous situation: historically this would have been being confronted by a dangerous animal, for example.
• Aspects of the fight or flight response include increased heart rate, increased blood pressure, increased flow to muscles, and increased blood sugar levels.
• Thyroxine regulates metabolic rate, which is important in growth and development.
• The levels of thyroxine are controlled by negative feedback.
• The menstrual cycle prepares for a potential pregnancy and begins with the lining of the uterus breaking down, leading to a woman having her period.
• The layer then builds up again, until ovulation occurs, at which point an egg is released from the ovary and moves to the uterus via the fallopian tube.
• If a fertilised egg has not been embedded in the lining after 28 days and the cycle continues, it is controlled by four hormones: Follicle stimulating hormone (FSH), oestrogen, luteinising hormone (LH), and progesterone.
• Hormonal methods of contraception include the contraceptive pill, the contraceptive patch, and the contraceptive implant.
• Vasoconstriction means blood does not flow so close to the surface, resulting in less heat lost.
• If the glucose levels are too high, the pancreas produces the hormone insulin.
• Type 2 diabetes: the body cells no longer respond to insulin, this condition is acquired and blood glucose levels can rise to a fatal amount.
• Sweating stops, skeletal muscles contract rapidly (shivering) to generate heat from respiration, hairs stand on end to create an insulating layer, trapping warm air.
• The urinary system is the bodily system that removes impurities and waste products from our blood.
• The main organ of the urinary system is the kidney.
• Blood containing impurities travels in the renal artery to the kidneys.
• Vasodilation means more blood flows closer to the surface of the skin, resulting in increased energy transfer from the body.
• Any excess is sent to the ureter for excretion, and eventually the bladder.
• Glucose to move from the blood into muscle cells for respiration, and excess glucose to be converted into glycogen which is stored in the liver.
• Type 1 diabetes: the pancreas cannot produce enough insulin, this condition is congenital and blood glucose level can rise to a fatal amount.
• The kidneys regulate the levels of salt, ions and urea in the blood.
• Diabetes is a disease where the body cannot control blood sugar levels properly.
• Obesity is a risk factor for Type 2 diabetes.
• The kidney is supplied by the renal artery and a renal vein takes blood away.
• The purified blood returns to the circulation by way of the renal vein.
• The ureter carries from kidneys to the bladder to be excreted out the body.