hormones

• one of the systems that helps maintain a constant internal environment in response to changes in condition is the endocrine system
• thyroid- produces thyroxine which is used in the regulation of metabolism, heart rate and temperature.
• pituitary gland- produces many hormones that regulates body conditions. this is the "master gland" as hormones released affects other glands. hormones released include: ADH,FSH,LH
• pancreas- produces insulin used to control blood glucose concentrations
• adrenal glands are located on top of the kidneys and produce adrenaline which is used to prepare the body for "fight" or "flight"
• testes- produce testosterone which control puberty and sperm production in males
• ovaries- produce oestrogen which are involved in the menstrual cycle
• when your brain detects stressful situations it sends nervous impulses to the adrenal glands which responds by secreting adrenaline into the blood
• adrenaline works in the heart by binding to receptors into the heart and muscles contract more frequently with more force. so, heart rate and blood pressure increases. this increases rate of blood flow to the muscles . and cells receive more oxygen and glucose for more respiration.
• adrenaline works in the liver by binding to receptors in the liver. this makes the liver break down glycogen stores to release glucose. this increases blood glucose levels so more glucose can be transported to the cells for respiration.
• thyroxine- when levels are low the hypothalamus is stimulated and releases TRH, TRH stimulated the pituitary gland to release TSH. this stimulates the thyroid to release thyroxine so levels return to normal
• when thyroxine levels are high TRH is released from the hypothalamus is inhibited so the production of TSH is reduced and less thyroxine is released into the blood.