hormonal co-ordination

• A hormone is a chemical substance, produced by a gland and carried in the bloodstream, which alters the activity of specific target organs
• An example of this is the release of the hormone adrenaline, which is released by the adrenal gland.
• One of its target organs is the heart, where it increases the heart rate.
• Once a hormone has been used, it is destroyed by the liver.
• Hormones can control the body, and the effects are much slower than the nervous system, but they last for longer.
• The pituitary gland in the brain is known as a 'master gland'. It secretes several hormones into the blood in response to the body's condition, such as blood water levels. These hormones can also act on other glands to stimulate the release of different types of hormones and bring about effects.
• The body produces a range of different chemical hormones that travel in the bloodstream and affect a number of different organs or cells in the body
• Important hormones released into the bloodstream include ADH (anti-diuretic hormone), adrenaline and insulin.
• thyroid gland produces :thyroxine
• the pancreas produces insulin
• the adrenal glands produce adrenaline
• ovaries produce oestrogen
• testes produce testosterone
• Insulin- in Pancreas- effects Liver- role controlling blood glucose levels effects- Increases conversion of glucose into glycogen for storage
• Adrenaline- source- Adrenal glands- organ- Several targets including the respiratory and circulatory systems-role-Preparation for 'fight or flight'-effects-Increases breathing rate, heart rate, flow of blood to muscles, conversion of glycogen to glucose
• Testosterone - Testes - Effects Prostate gland, Seminal vesicles, Penis, Scrotum, Sperm production - Role is to control development of male secondary sexual characteristics and spermatogenesis.
• Oestrogen -source- Ovaries-organ- Targets include reproductive system, mammary gland, bone tissue, liver, brain-role-Female sex hormone-effects-Stimulates growth of uterus lining during menstrual cycle, stimulates development of female secondary sexual characteristics (breasts), increases calcium absorption from diet by bones, inhibits production of FSH and LH
• ADH- source- Pituitary gland - organs- Kidneys- role- Controlling the water content of the blood - effects- Increases reabsorption of water by the collecting ducts
• In animals, conditions such as water concentration, temperature, and glucose concentration must be kept as constant as possible. Control systems that keep such conditions constant are examples of homeostasis
• A negative feedback control system responds when conditions change from the ideal or set point and returns conditions to this set point. There is a continuous cycle of events in negative feedback.
• In general this works by:

  • if the level of something rises, control systems reduce it again
  • if the level of something falls, control systems raise it again
• An example of negative feedback is the control of body temperature. Body temperature is controlled by the hypothalamus in your brain, and if your body gets too hot, your body begins to sweat to try and reduce it. Conversely if the body gets too cold, it begins to shiver to try and raise the temperature.
• Thyroxine is produced from the thyroid gland, which stimulates the basal metabolic rate. It controls the speed at which oxygen and food products react to release energy for the body to use.
• hyroxine plays an important role in growth and development.
• Thyroxine levels are controlled by negative feedback.
• The hypothalamus and pituitary gland have important roles in detecting and controlling thyroxine levels.
• 1. Lowthyroxine levels in the bloodstream stimulate the hypothalamus to release TRH and this causes the pituitary to release TSH so the thyroid releases more thyroxine. So blood levels return to normal.
• 1. Normal thyroxine levels in the bloodstream inhibit TRH release from the hypothalamus and this inhibits the release of TSH from the pituitary, so normal blood levels are maintained.
• Adrenaline is produced by the adrenal glands in times of fear or stress. It targets vital organs, increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for 'flight or fight'. 
• Adrenaline is not controlled by negative feedback.
• When adrenaline is released into the bloodstream it creates multiple effects:

  • increases breathing rate, heart rate, and conversion of glycogen to glucose so more energy is released in the muscles
  • it diverts blood away from areas, such as the digestive system, towards the muscles
• The effects of adrenaline allow the body to prepare for action in situations where a quick response may be essential.
• Glucose is needed by cells for respiration
•  It is important that the concentration of glucose in the blood is maintained at a constant level and controlled carefully. Insulin is a hormone - produced by the pancreas - that regulates glucose concentrations in the blood.
• If the blood glucose concentration is too high, the pancreas produces the hormone insulin that causes glucose to move from the blood into the cells
•  In liver and muscle cells excess glucose is converted to glycogen for storage, and will be used at a later date.
• Diabetes is a condition where the blood glucose levels remain too high
• The extra insulin causes the liver to convert glucose into glycogen, which reduces the blood glucose level.
• Type 1 diabetes is a disorder in which the pancreas fails to produce enough insulin. 
• type one diabetes can be detected at an early age