Homeostasis Flashcards
What does homeostasis mean? Whats important about it?
Means Maintaining a stable environment
- its importang to keep all conditions inside a living organism stable or constant
Which two system work together? What do they do?
The nervous system and endocrine system work together to control your interval conditions
What is a system that helps maintsin homeostasis known as? What is it made up of?
An automatic control system
Made of up of receptors, coordination centre and effectors
How does the negative feedback system work when levels are high?
1) . Receptor detects a stimulus - level is too high
2) . The coordination centre recieves and processes the info, then organises a response
3) . Effector produces a response which counteracts the change and restores the optimum level - the level decreases
How does the negative feedback system work when levels are low?
1) . Receptor detects a stimulus - level is too los
2) . The coordination centre recieves and processes the info, then organises a response
3) . Effector produces a response which counteracts the change and restores the optimum level - the level increases
What is vasodilation?
1) . If you’re too hot, you appear pink/flushed as the blood flowing to the surface has increased
2) . To achieve this, the blood vessels that supply the capillaries of the skin dilate allowing more blood to reach the skin, sweat is produced from sweat glands
3) . Heat from the blood radiates from the skin, cooling you down.
What is vasoconstriction?
1) . If you’re too cold, your skin may appear pale/blue as there is a decrease in blood flowing to the skin
2) to achieve, the blood vessels that supply he capillaries of the skin contract allowing less blood to reach the skin, sweating stops & skeletal musclss contract (shiver).
3) . Less heat is radiated from the skin, conserving warmth
What is the endocrine system?
A series of glands which secrete chemicals called hormones directly into the bloodstream
What is the Pituitary gland?
Found in the brain, referred as the master gland as it secretes several hormones into the blood in response to body conditions
What are the kidneys?
Responsible for filtering the blood, they remove waste materials from the blood to produce urine otherwise known as filtration
What is deamination?
As proteins cant be stored in the body, any excess amino acids are converted into fats/carbohydrates which can be stored -> deamination
Whag happens during deamination?
Ammonia is produced as a waste product, as ammonia is so toxic it’s converted to urea in the lover, its then transported to the kidneys where its filtered out and excreted from the body in urine.
What are ions?
They are taken into the body in food, and then absorbed into the blood
What happens if the ion content is unbalanced? How are some ions lost?
- It could affect osmosis which changes the volume of water in and out of the cells
- some ions are lost in sweat, this can’t be regulated so the right balance of ions in the body must be maintained by the kidneys
What do kidneys do to ions?
Remove excess ions from the blood & the rest is removed from the body in urine
How is water taken into and out if the play?
- Taken into the body via drinking and eating, also produced by respiration.
- lost from the skin by sweat& from the lungs when breathing out
How do glucose levels increase?
After eating/drinking foods that are rich in sugar or carbohydrates, food is digested in the stomach/ small intestine and the sugars are abrobed into the bloodstream as they move through the small intestine
What levels remove glucose from the blood? What are the levels of glucose monitored by?
- Normal metabolism of cells remove glucose from the blood
- the level is monitored by the pancreas using the hormones insulin and glycogen in a a negative feedback cycle
What happens when blood glucose levels are too high?
1) . An increase in blood glucose is detected by the pancreas
2) . The pancreatic cells secrete insulin hormone
3) . Insulin removes glucose from blood, converting it into glycogen
4) . Glycogen is stored safely in the muscles and the liver as an energy store
5) . The gluose levels return to normal
6) . The pancreas stops secreting insulin (negative feedback)
What is insulin?
Causes sugar to move out of the blood and into the cells which lowers blood sugar levels
What does glucagon do?
Causes sugars to be released from the liver when glycogen is broken down, this increases blood sugar levels
What happens when blood glucose levels are low?
1) . A decrease jn bloody gluscose is detected by the pancreas
2) . The pancreatic cells respond by secreting glucagon hormone
3) . Glucagon travels in the bloodstream to the liver/muscles
4) . Glucagon causes the glycogen to be broken down into glucose again
5) . Glucose levels return to the normal
6) . The pancreas stops secereting glucagon (negative feedback)
What happens if the system in maintaing blood glucose level fails?
The ability to control blood glucose levels does not happen and diabetes occurs
What is type 1 diabetes?
A disorder in which the pancreas fails to produce sufficient insulin, which can lead to high blood sugar levels which can be fatal
What is type 2 diabetes?
When the body cells no longer respond to insulin produced by the pancreas
How can type 1 diabetes be controlled?
Insulin injections need to be used to ensure glucose is removed from the blood once food has been digested stopling the levels getting too high
- limiting the intake if foods rich in simple carbohydrates & regular exercise
How can type 2 diabetes be controlled? What is the risk of type 2?
Eating a carbohydrate- controlled diet and regular exercise
- obesity is a risk factor
What does the pituitary, thyroid, and adrenal glands do?
Pituitary gland - releases hormones to control many conditions
Thyroid gland - produces thyroxine which controls metabolism, heart rate & temperature
Adrenal gland - releases adrenaline used in ‘fight or flight’ response
What does the pancreas, ovaries and testes do?
Pancreas- produce insulin & glucagon which control blood sugar levels
Ovaries - produce oestrogen as part of the menstrual cycle
Testes - prosuce testosterone which is responsible for sperm production & puberty
What do healthy kidneys do?
- filter out the blood
- reabsorb all of the sugar into the blood
- reabsorb ions and sugar as needed
- release urea and any excess ions and water as urine
What happens kf waste like CO2 and water aren’t removed?
They increase in concentration in the body & may interfere with chemical reactions or damage cells
What controls water content?
They hypothalamus controls it, it causes the pituitary gland to secrete anti-duretic hormone into the blood which targets the kidneys
What happens when there is too much water content?
1) . The hypothalamus detects hugh volumes of water in the blood
2) . ADH is released by the pituitary gland (less)
3) . ADH is transported to the kidneys, where it decreases water reabsorption into the bloody by the kidneys
4) . Fluid is stored in the bladder & produces more dilute urine - more often.
- > controlled by negative feedback
What happens when there is too little water content?
1) . The hypothalamus detects a decrease in water levels
2) . Hormone ADH is released from the pituitary gland
3) . ADH is then transported to the kidneys, where it increases reabsorption into the blood by the kidneys
4) . Less urine is produced, and is more concentrated
What is dialysis?
It is done regularly to keep the concentrations of dissolved substances in the blood at normal levels and to remove waste substances
What is ‘dirty’ blood?
Its high in the urea, its taken from the blood vessel in the arm where its mixed with blood thinners to prevent clotting and pumped into the machine
What happens inside the dialysis machine?
- Blood and dialysis fluid flow in opposite directions, they’re separated by a partially permeable membrane which allows substances to be exchanged where theres a concentration gradient
What are the glucose and ions level like in dialysis fluid? What isnt in dialysis fluid?
- Contains a similar concentration to a normal level in the blood
- ions contain a similar concentration to that found in normal blood plasma
- NO urea
How do substances move in dialysis fluid?
Move from the blood to the dialysis fluid depending on the concentration gradient between them
What does it mean for urea in dialysis fluid?
Having no urea means there’s a large concentration gradient meaning that urea moves across the partially permeable membrane, from the blood to the dialysis fluid by diffusion
What does it mean for glucose concentration in the dialysis fluid?
As the concentration is equal to a normal blood sugar level, this prevents the net movement of glucose across the membrane as no concentration gradient exists
What does it mean for ion concentration in the dialysis fluid?
As its similar to the ideal blood plasma concentration, movement of ions across the membrane only occurs where there is an imbalance
What three effects does kidney dialysis have on the blood that leaves the machine and returns to the patients arm?
- greatly reduced levels of urea as its cleaned blood
- no overall change in blood glucose levels
- the correct water & ion balancd maintained or restored (excess ions removed only)
What are the advantages of kidney dialysis?
- available to all kidney paitents
- no need for immune suppressant drugs
Whatbare the disadvantages for kidney dialysis?
- paitenrs have to limit their salt & protein intake between dialysis session
- expensive for NHS
- impacts on patients lifetsyle as sessions are regular
What are the advantages of a kidney transplant?
- paitentss can lead a more normal lifestyle without having to watch what they eat/drink
- cheaper for NHS overall
What are the disadvantages of a kidney transplant?
- any operation carried risk
- must take immune suppressant drugs which increase risk of infection
- shortage if organ donors
- kidney only lasts 8-9 years in average
During puberty, what do sexual hormones do?
Cause secondary sexy and characteristics to develop eg facial hair, breasts
What is the main female reproductive hormone?
Oestrogen
What is the main male reproductive hormone?
Stimulates sperm production and is produced by the testes
What does the Follicle Stimulating Hormone (FSH) do? 1
- secreted by the pancreas and causes the maturation of an egg in the ovaries
- stimulates the release of oestrogen by the ovaries
What does oestrogen do? 2
- causes the lining of the stomach to build up after menstration
- inhibits futher release of FSH and allows only one egg to mature
- stimulates the pituitary gland to release LH
What does the Leteinising hormone (LH) do? 3
- released by the pituitary gland and stimulates the release of the egg from the ovary at day 14
- also inhibits oestrogen
What does progesterone do? 4
- a hormone released by the ovaries after ovulation
- maintians lining of uterus during second half of the cycle, when level falls -> lining breaks down
- inhibits the release of LH and FSH
What is progesterone released by? What happens when there is a increae?
- released by the ovaries and travels in the bloodstream in the uterus
- increase in levels during menstrual cycle maintains the lining of the uterus (ready to receive an egg)
What happens when a fertilised egg attched and doesnt attach?
DOES attach - levels decline and the lining breaks down and period comes
DOESNT attach - levels remain high and the lining stays in place and pregnancy occurs
What happens if a fertilised egg attaches?
Levels remain high, the lining stays in place and pregnancy occurs
What can oestrogen and progesterone be used for?
Oestrogen - used to prevent the release of an egg
Progesterone- reduces fertility by stimulating the production of thick mucus which prevents any sperm getting through and reaching an egg
What is the pill?
An oral contraceptive containg oestrogen and progesterone
What happens when you take the pill everyday?
Levels of oestrogen will become high, which inhibits the release of FSH which means after a while the maturation/ release of an egg stops
What will progesterone in the pill do?
Progesterone levels that are high will keep the lining intacts as well as the mucus which will stop any futher sperm from reaching an egg
How effective and what side effects can the combined oral contraceptive pill (oestrogen + progesterone) make? Whats the alternative?
- Its over 99% effective at preventing pregnancy
- can cause SE such as headaches, nausea as well as weight gain.
- theres a progesterone only pill which has fewer side effects than the pill and is just as effective
What doesnt the pill do?
Protect women from STI’s
What does the contraceptive implant do?
Its inserted ynder the skin of the arm, it continuously releases program which stops the ovaries from releasing an egg and can last upto three years before it should be replaced
What does the contraceptive patch do?
Contains oestrogen and progesterone and is stuck to the skin, it must be replaced once a week
What does the contraceptive injection do?
A needle is used to inject progesterone, it needs to be repeated every 2-3months
What does the intrauterine device (IUD) do?
A t-shaped device that is inserted into the uterus and prevents a fertilised egg implanting in the uterus wall
What do condoms do?
Male - they’re worn over the penis during intercourse
Female - they’re worn inside the vagina
Both protect from STD’s
What does a diaphragm do?
Plastic cup thats placed over the cervix to form a barrier; has to be used with spermicides
What are spermicides?
Chemical used to kills sperm, not the most effective form of contraception as its only 70-80% effective
Whats the natural method?
By tracking the menstrual cycle women can now calculate their most fertile days (ovulation) qne avoid intercourse at this time which reduces risk of pregnancy
What is abstinence?
Not to have intercourse
What is sterilisation?
Invloves cutting or tying the fallopian tubes in women or the sperm duct in a male, its a permanent procedure
What is the fertility drug?
Hormones FSH and LH are given to stimulate ovulation
What are the pros & cons of the fertility drug?
Pros
- helps a lot of women to get pregnant when previously they couldnt
Cons
- doesnt always work, some may have to do it many times which can be expensive
- too many eggs could be stimulated, which can result in multiple pregnancies
How does IVF work
1) . Involves giving mother a FSH and LH to stimulate the maturation of several eggs
2) . The eggs are collected from the mother and fertilised by sperm from the father in the laboratory
3) . The fertilised eggs develop into embryos
4) . At the stage when they’re tiny balls of cells, one or two embryos are inserted into the mothers uterus (womb)
What are the pros and cons of IVF?
Pros
- treatment can give an infertile couple a child
Cons
- can lead to multiple birthd which is risky both to mother and child
- success rate of ivf is low
- its very emotionally and physically stressful
What are the ethical isssues with IVF?
- process of ivf often results in unused embryos that are eventually destroyed which some think is unethical as each embryo is a potential human life
- genetic testing of embryos before implantation also raises ethical issues as some think it could lead to selection of preferred characteristics eg gender, eye colour
What is ICSI?
Used if the males sperm count is low, it injects sperm directly into the egg to increase the change of fertilisation
What is adrenaline? Why is released?
A hormone released by the adrenal glands
- its released in response to times of fear or stress, its gets the body ready for fight or flight by increasing the supply of oxygen & glucose to cells in muscles and brain eg it increases heart rate
What is thyroxine?
A hormone made in the thyroid gland
What to roles does thyroxine have?
1) . Regulating basal metabolic rate the speed at which chemical reactions in th body occur while the body is at rest
2) . Stimulating protein synthesis for growth and development
What is thyroxine released in response to?
Released in response to thyroid stimulating hormone (TSH) which is released from the pituitary gland
How does thyroxine work in the negative feedback system?
It keeps the amount of thyroxine in the blood at the right level, if the level of thyroxine is higher than normal, the secretion of TSH is inhibited. This reduces the amount of thyroxine releasedc so the level falls back towards normal
what do the cerebellum, cerebral cortex and medulla do?
- cerebellum is responsible for muscle coordination
- cerebral cortex is the wrinkly bit that’s responsible for consciousness, intelligence, memory and language
- medulla controls unconscious activities eg breathing and heartbeat
how do scientists study the brain?
- studying patients with brain damage
- electrically stimulating the brain
- MRI scans, that produce detailed images of brains
what are the consequences for messing with the brain?
- electrical stimulation can reduce muscle tremors caused by nervous system disorders eg parkinsons
- the brain is very complex and delicate, it carries risks
