B5 - Homeostasis
- Created by: sophie2014
- Created on: 08-03-20 13:55
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- B5
- The Nervous System
- the nervous system detects and reacts to stimuli
- stimulus - a chnge in the environment
- multicellular organisms need to communicate with each other to respond to its environment - developed hormonal and nervous communication systems
- means that humans can react to their surroundings and coordinate their behaviour
- central nervous system (CNS) - consist of the brain and spinal cord only connected to the body by sensory and motor neurons
- CNS coordinates the responce
- stimulus
- receptor
- sensory neurone
- CNS
- motor neurone
- effector
- response
- effector
- motor neurone
- CNS
- sensory neurone
- receptor
- stimulus
- CNS coordinates the responce
- sensory neurones - carry infomation as electrical impulses from the receptors to the CNS
- motor neurons - carry electrical impulses from the CNS to effectors
- Effectors - your muscles and glands, respond to nervous impulses
- the nervous system detects and reacts to stimuli
- Homeostasis
- maintaining a stable internal environment
- it's all about the regulation of conditions inside your body and cells to maintain a stable internal environment
- conditions within the body need to be kept stable in order to function properly, including the right conditions for enzyme action
- negative feedback counteracts change - keep internal environment stable
- when the level of something (e.g water or glucose) gets too high or too low negative feedback combats this
- receptor detects a stimulus - level is too high
- coordination centre receives and processes the information, organises a response
- effector produces a response, counteracts change and restores optimum level - decreases.
- coordination centre receives and processes the information, organises a response
- receptor detects stimulus - level is too low
- coordination centre receives and processes the information, organises a response
- effector produces a response, counteracts change and restores optimum level - level increases
- coordination centre receives and processes the information, organises a response
- receptor detects a stimulus - level is too high
- when the level of something (e.g water or glucose) gets too high or too low negative feedback combats this
- you have lots of automatic control systems in your body that regulate your internal environment
- there are control systems that maintain your blood glucose level, body temperature and water content
- hormonal & nervous communication systems
- all automatic control systems are made up of 3 main components, work together to maintain a steady condition - cells: receptors, coordination centres (brain, spinal cord & pancreas) & and effectors
- there are control systems that maintain your blood glucose level, body temperature and water content
- automatic - a process that happens without thinking about it
- maintaining a stable internal environment
- Synapses & reflexes
- synapse - gap between two neurons
- a nerve signal is transferred by chemicals which diffuse across the gap
- these chemicals set off a new electrical signal in the next neurone
- a nerve signal is transferred by chemicals which diffuse across the gap
- neurons transmit information very quickly to and from the brain
- reflexes help prevent injury. they're rapid and automatic responses to certain stimuli, don't involve the conscious part of the brain - reduce the chance of being injured
- e.g a bright light gets shone into an eye, pupil dilates, reduces amount of light in eye & stops it getting damaged
- passage of information in a reflex is called a reflex arc
- neurons go through the spinal cord or an uncontious part of the brain
- stimulus
- receptor
- sensory neurone
- synapse between trigger chemicals to be released. chemicals cause impulses to be sent to the relay neurone. repetes for relay + motor
- relay neurone
- motor neurone
- effector
- response
- effector
- motor neurone
- relay neurone
- synapse between trigger chemicals to be released. chemicals cause impulses to be sent to the relay neurone. repetes for relay + motor
- sensory neurone
- receptor
- stimulus
- neurons go through the spinal cord or an uncontious part of the brain
- synapse - gap between two neurons
- The Endocrine System
- hormones - chemical molecules relesed directly into the blood
- travel to their target organ and control things within the organs and cells that need constant adjustment
- produced and secreted by various glands and tend to be long lasting
- Pituitary Gland, Thyroid, Ovaries, Testes, Adrenal Gland, Pancreas
- pituity gland is known as the master gland as the hormones secrete from it and act on other glands to screte hormones
- Pituitary Gland, Thyroid, Ovaries, Testes, Adrenal Gland, Pancreas
- hormones and nerves are very different and have differences. nerves are fast, act for a short time and act on a precise area. hormones are slower action, act for a long time and act in a more general way.
- hormones - chemical molecules relesed directly into the blood
- Controlling Blood Glucose
- glucose level is too low glucagon is added. glucagon is secreted by the pancreas
- too little glucose as well as glucagon
- glucagon goes into the liver where the liver turns glucagon into glucose
- blood glucose increased
- glucagon goes into the liver where the liver turns glucagon into glucose
- too little glucose as well as glucagon
- glucose level is too high, insulin is secreted by the pancres
- theres too much insulin and glucose
- insulin goes into the liver which then causes the liver to convert glucose into glucagon
- blood glucose reduced
- insulin goes into the liver which then causes the liver to convert glucose into glucagon
- theres too much insulin and glucose
- type 1 & 2 diabetes
- type 1 - pancreas produces little or no insulin. have to take insulin shots throughout the day, make sure glucose is removed from the blood once food is digested. regular exercise helps remove excess glucose from the blood
- type 2 - someone becomes resistant to their own insulin, still produced but cells don't respond to it. leads to a sharp increase in blood glucose levels and being overweight can increase chances of getting type 2 diabetes. controlled through diet + exercise
- glucose level is too low glucagon is added. glucagon is secreted by the pancreas
- Puberty and The Menstrual cycle
- stage 1 - uterus lining breaks down (Day 1-4)
- day 2 - uterus lining builds back up again ready to recieve a fertalised egg. (Day 4 - 14)
- stage 3 - from day 14 an egg is released from ovaries, ovulation (Day 14-21)
- stage 4 - no egg has landed on the uterus lining by day 28, lining breaks and the cycle repeates (Day 21-28)
- stage 3 - from day 14 an egg is released from ovaries, ovulation (Day 14-21)
- day 2 - uterus lining builds back up again ready to recieve a fertalised egg. (Day 4 - 14)
- menstrual cycle happens usually every 28 days
- at puberty body produces sex hormoones; oestrogen and testosterone
- FSH (follicle stimulating hormone) produced by pitutary gland causes eggs to mature in an ovary and stimulates ovaries to produce oestrogen
- LH (luteinising hormone) is responcible for the release of an egg. produced by pituitary gland
- Oestrogen - produced in ovaries, causes lining of uterus to grow, stimulates release of LH and stops release of FSH
- Progesterone - produced in ovaries by remains of follicle after ovulation, maintains lining of wall during 2nd part of the cycle, level falls lining breaks down & stops release of FHS & LH
- Oestrogen - produced in ovaries, causes lining of uterus to grow, stimulates release of LH and stops release of FSH
- LH (luteinising hormone) is responcible for the release of an egg. produced by pituitary gland
- stage 1 - uterus lining breaks down (Day 1-4)
- Adrenaline & Thyroxine
- adrenaline is released by adrenal glands, above the kidney. it prepares you for flight or fight as it responds to stressful situations as your brain detects fear or stress which then send nervous impulses to the adrenal glands which then secrete adrenaline
- thyroxine regulates metabolism and is a hormone released by the thyroid gland, in the neck. also stimulates protein synthasisfor growth and development
- hormone release can be affected by negative feedback
- The Nervous System
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