Hormones 1 - Revision
- Created by: Ammarah123
- Created on: 20-01-18 18:15
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- Animal Coordination, Control and Homeostasis
- Hormones
- Chemical messengers released in the bloodstream
- They only affect target organs
- Endocrine glands
- Pituitary gland
- Produces many hormones that regulate body conditions
- Thyroid gland
- Produces thyroxine- Regulates the rate of metabolism, heart rate and temperature
- Adrenal glands
- Produces adrenaline- Needed to prepare the body for a 'fight or flight' response
- Testes
- Produces testosterone- Controls puberty and sperm production in males
- Pancreas
- Produces insulin- Used to regukate the blood glucose level
- Ovaries
- Produces oestrogen- Involved in the menstrual cycle
- Pituitary gland
- Hormone and Neurons
- Neurones- Very fast action + Act for a very short time + Acts on a precise area
- Hormones- Slower action + Acts for a long time + Acts in a general way
- Produced by the endocrine glands which make up your endocrine system
- Adrenaline and Thyroxine
- Adrenaline prepare you for 'fight or flight'
- 1 Released by the adrenal glands (just above the kidneys)
- Negative Feedback
- Ensures that, in any control system, changes are reversed and returned back to the set level
- eg. negative feedback keeps our body temperature at a constant 37°C. If we get too hot, blood vessels in our skin vasodilate (become larger) and we lose heat and cool down
- If we get too cold blood vessels in our skin vasoconstrict (become smaller), we lose less heat and our body warms up
- eg. negative feedback keeps our body temperature at a constant 37°C. If we get too hot, blood vessels in our skin vasodilate (become larger) and we lose heat and cool down
- Ensures that, in any control system, changes are reversed and returned back to the set level
- Thyroxine regulates metabolism
- 1 Released by the thyroid gland
- 2 It plays an important part in regulating metabolic rate- the speed at which chemical reactions in the body occur
- 3 A negative feedback system keeps the amount of thyroxine in the blood at the right level
- * When the blood thyroxine level is lower than normal, the hypothalamus (a structure in the brain) is stimulated to release TRH
- * TRH stimulates the pittuitary gland to release TSH
- * TSH stimulates the thyroid gland to release thyroxine so the blood thyroxine levels rises back towards normal
- * When the blood thyroxine level becomes higher than normal, the release of TRH from the hypothalamus is inhibited, which reduces the production of TSH so the blood thyroxine level falls
- * TSH stimulates the thyroid gland to release thyroxine so the blood thyroxine levels rises back towards normal
- * TRH stimulates the pittuitary gland to release TSH
- * When the blood thyroxine level is lower than normal, the hypothalamus (a structure in the brain) is stimulated to release TRH
- Adrenaline prepare you for 'fight or flight'
- Hormones
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