Animal coordination, control and homeostasis Flashcards
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What is a hormone?
+Hormones are chemicals released directly in the blood. +They are carried in the blood to other parts of the body, but only affect particular cells in particular organs (target organs) +Produced (and secreted) by various glands, called endocrine glands. +These glands make up your endocrine system.
What is the Pituitary gland?
+Produces many hormones that regulate body conditions. Eg - FSH, LH +Sometimes called the “master gland” because these hormones act on other glands, directing them to release hormones that bring about change
What is The Thyroid Gland
+Produces thyroxine, which is involved in regulating things like the rate of metabolism, heart rate and temperature.
What are the ovaries?
+Produces oestrogen, which is involved in the menstrual cycle.
What are the testes?
+Produces testosterone, which controls puberty and sperm production in males.
What are the adrenal glands?
+Produce adrenaline which is used to prepare the body for a “fight or flight” response.
The Pancreas?
Produces insulin, which is used to regulate the blood glucose level.
What are the differences in neurons and hormones?
Neurons: +Very fast action +Act for a very short time +Act on a very precise area Hormones: +Slower action +Act for a long time +Act in a more general way
What is adrenaline?
+A hormone released by the adrenal glands +Prepares the body for “fight or flight” +Activates processes that increase the supply of oxygen and glucose to cells. +When your brain detects a stressful situation, it sends nervous impulses to the adrenal glands - which respond by secreting adrenaline - gets the body ready for action.
What are the processes of adrenaline?
+Adrenaline binds to specific receptors in the heart - causes heart muscle to contract more frequently & with more force - so heart rate and blood pressure increase. +Increases blood flow to the muscles, so cells receive more oxygen and glucose for increased respiration. +Binds also to receptors in the liver - causes the liver to break down its glycogen stores to release glucose. +Increases the blood glucose level, so there’s more glucose in the blood to be transported to the cells.
What is negative feedback?
+The process of regulating body conditions by triggering a response to a change. When the body detects that level of a substance has gone above or below the normal level, it triggers a response to bring the level back to normal again.
What is thyroxine?
+A hormone released by the thyroid gland which regulates metabolism (the speed at which chemical reactions in the body occur).
What is the process of the thyroxine negative feedback system?
+When the blood thyroxine level is lower than normal, the Hypothalamus (a structure in the brain) is stimulated to release thyrotropin releasing hormone (TRH). +TRH stimulates the pituitary gland to release thyroid stimulating hormone (TSH). +TSH stimulates the thyroid gland to release thyroxine, so the blood thyroxine level 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.
What are the symptoms of less/more thyroxine?
+An underactive thyroid gland can cause weight gain. +Less thyroxine is produced, so your metabolic rate drops. +This means that less of the glucose you take in gets broken down in respiration, so more is stored as fat.
What is the menstrual cycle?
A monthly sequence of events in which the female body releases and egg and prepares the uterus (womb) in case the egg is fertilised.
What are the four stages of the menstrual cycle?
+Stage 1 - When menstruation starts - the lining of the uterus breaks down and is released. +Stage 2 - the uterus lining is repaired (day 4-14) until it becomes a thick spongy layer full of blood vessels ready for a fertilised egg to implant there. +Stage 3 - An egg develops and is released from the ovary (ovulation) at day 14. +Stage 4 - The lining is then maintained for about 14 days, until day 28. If no fertilised egg has landed on the uterus wall by day 28, the lining starts to break down and the cycle starts over.
