AQA B5 - Homeostasis and Response (excluding controlling fertility , adrenaline and thyroxine)
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- Created on: 17-10-17 17:03
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- B5 - Homeostasis and Response
- Homeostasis
- This is the regulation system to maintain a stable internal environment in response to external and internal changes
- There are automatic control systems in the body
- These include nervous and hormonal communication systems
- There are systems to control body temp, blood glucose level and amount of water in the body
- These include nervous and hormonal communication systems
- Negative Feedback works to keep internal environment stable.
- Whenever something gets too high or too low, body uses negative feedback to combat this
- Increase - Receptor detects a stimulus
- The coordination centre (Central Nervous System) receives information and organises a response
- An effector is triggered which produces an response to restore optimum level so the level decreases.
- The coordination centre (Central Nervous System) receives information and organises a response
- receptor detects stimulus is too low
- Coordination centre receives information and triggers a response via an effector which restores the increase to optimum level.
- Increase - Receptor detects a stimulus
- Whenever something gets too high or too low, body uses negative feedback to combat this
- The Nervous System
- Central Nervous System is the brain and spinal cord, this is connected to body by sensory and motor neurons
- sensory neurons carry electrical impulses from receptors - CNS
- Motor Neurons carry electrical impulses from CNS to effectors
- Effectors are Muscles and Glands
- The difference between the nerve system and hormonal system is
- Nerves - fast acting , Hormones - slow acting
- Nerves - act for short time, Hormones - last for long time
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- The difference between the nerve system and hormonal system is
- Central Nervous System is the brain and spinal cord, this is connected to body by sensory and motor neurons
- Synapses and Reflexes
- Synapses are gaps between neurons (a gap between 2 neurons) where the nerve signal is transferred by chemicals across the gap via diffusion.
- Reflexes are rapid automatic responses to a stimulus to reduce chances of injury
- Reflex actions don't involve the conscious part of the brain
- Passage of information from receptor to effector is called the reflex arc.
- When a stimulus is detected by receptors, impulses are sent along the sensory neurone to relay neurone
- The signal moves along the relay neurone through synapses until the impulses reach the motor neurone
- The impulses travel along the motor neurone to the effector
- The signal moves along the relay neurone through synapses until the impulses reach the motor neurone
- The Endocrine System
- This is the hormonal system and releases hormones into blood
- The difference between the nerve system and hormonal system is
- Nerves - fast acting , Hormones - slow acting
- Nerves - act for short time, Hormones - last for long time
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- The difference between the nerve system and hormonal system is
- Pituitary Gland, Thyroid, Ovaries, testes, Adrenal Glands, Pancreas
- The pituitary gland is known as the master gland a the hormones secrete from it act on other glands to secrete hormones.
- This is the hormonal system and releases hormones into blood
- Controlling Blood Glucose
- If blood glucose level is too high
- Insulin secreted by pancreas
- Now there is too much glucose as well as insulin
- Glucose moves into liver and muscle cells
- Insulin causes liver to convert glucose into glycogen
- Glucose moves into liver and muscle cells
- Now there is too much glucose as well as insulin
- Insulin causes liver to convert glucose into glycogen
- Insulin secreted by pancreas
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- If glucose level is too low , glucagon is added
- Glucagon is secreted by pancreas
- Too little glucose as well as glucagon
- Glucose is released by liver into the blood
- Glucagon causes liver to turn glucagon into glucose
- Glucose is released by liver into the blood
- Too little glucose as well as glucagon
- Glucagon causes liver to turn glucagon into glucose
- Glucagon is secreted by pancreas
- Type 1 and Type 2 diabetes
- Ttpe 1
- Pancreas produces little or no insulin they may have to take injections of insulin throughout the day , this is to make sure glucose is removed from the blood once food is digested.
- Type 2 diabetes - this is where someone becomes resistant to their own insulin. insulin is still produced but cells don't respond to it, this can lead to a sharp increase in blood glucose level. Overweight and obesity is a huge factor in this.
- Ttpe 1
- If blood glucose level is too high
- Puberty and the Menstrual Cycle
- Stage 1 (day 1 -4) the lining breaks down
- stage 2 (day 4 -14) the lining builds up again ready to receive a fertilised egg
- Stage 3 (day 14-21) at around day14 an egg is released from the ovaries , this is called ovulation)
- Stage 4 ( day 21-28)if no egg has landed on the lining of the uterus by day28 , the ling breaks down and whole cycle repeats.
- Stage 3 (day 14-21) at around day14 an egg is released from the ovaries , this is called ovulation)
- stage 2 (day 4 -14) the lining builds up again ready to receive a fertilised egg
- FSH(follicle stimulating hormone) this is produced in pitutarty gland and causes an egg to ature in an ovary. Stimukates ovaries to produce oestrogen
- LH (luteinising Hormone) is responsible for the release of an egg. produced by pituitary gland
- Oestrogen - produced in ovaries, causes lining of the uterus to grow, Stimulates relase of LH and stops release of FSH
- Progesterone - produced in ovaries by remains of follicle after ovulation , maintains lining of wall during 2nd half of the cycle , if level of progesterone falls, lining breaks down. Stops release of LH and FSJ
- Oestrogen - produced in ovaries, causes lining of the uterus to grow, Stimulates relase of LH and stops release of FSH
- LH (luteinising Hormone) is responsible for the release of an egg. produced by pituitary gland
- Stage 1 (day 1 -4) the lining breaks down
- Homeostasis
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