B3 so far

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  • B3 so far
    • The Kidneys
      • Transplants
        • Kidney disease
        • Can be rejected, treated as foreign body antibodies attack
          • Close matching tissue type used
          • Antirejection drugs suppress immune system
        • Donor register / carry donor card
      • Dialysis
        • Kidney failure
        • Filters blood for them
        • Done regularly to keep substances at correct concentrations + to remove waste
        • Dialysis fluid - same conc of salts + glucose as in blood so none is lost
        • barrier = permeable so ions and waste substances can move acrss but not big molecules
      • Water content
        • Negative feedback
          • Adjusts water content of blood
          • Osmoregulation
          • ADH from pituitary gland
          • Brain detects water gain
            • Pituitary gland releases less ADH
              • Less ADH = kidneys reabsorb less water + pee more
                • Hydrated
                  • Brain detects water gain
                    • Pituitary gland releases less ADH
                      • Less ADH = kidneys reabsorb less water + pee more
                        • Hydrated
            • Brain detects water loss
              • PG releases more ADH
                • ADH = kidneys absorb more water, pee less
                  • Hydrated
                    • Brain detects water loss
                      • PG releases more ADH
                        • ADH = kidneys absorb more water, pee less
                          • Hydrated
          • Ultrafiltration #1
            • High pressure squeezes water, ions, urea and glucose out of the blood into the Bowman's capsule
              • Glomerulus + Bowman's capsule = filters - big molecules (proteins and blood cells) stay in blood, aren't squeezed out
          • Release of wastes #3
            • Urea + excess water go out of nephrone to bladder as urine. Released through the urethra
          • Reabsorption #2
            • All glucose reabsorbed against conentration gradient
              • Water reabsorbed by osmoregulation
          • 3 main roles
            • Revmoves urea from the blood
              • Produced in liver by breakdown of amino acids
              • End product = urine
                • Adjusts ion levels in the blood
                • Adjusts water content of blood
            • Adjusts ion levels in the blood
        • Menstrual Cycle
          • FSH
            • Follicle stimulating hormone
              • Causes follicle to mature
                • Stimulates oestrogen production
          • Oestrogen
            • Causes lining to thicken +grow
          • Progesterone
            • Maintains lining of uterus + prevents production of FSH and LH
              • When levels of it fall + theres low oestrogen levels the lining breaksdown
                • low progesterone level llows FSH to increase, restarting cycle
          • LH
            • Luteinising hormone, LH surge stimulates ovultation day 14
              • Follicle ruptures, egg is released
                • Stimulates remains of follicle to develop into a corpus luteum which secretes progesterone
          • Negative feedback
            • FSH causes ovary to release oestrogen
              • Oestrogen prevents release of FSH from PG
                • After FSH has caused follicle to mature negative feedback keeps levels low to prevent more follicles
          • Egg
            • Haploid nucleus, when fertilised, right number of chromosomes
            • Nutrients in cytoplasm to feed embryo
            • after fertilisation membrane changes structure to stop more sperm getting in - ensures correct amount of DNA
          • Sperm
            • transport male DNA to egg
              • Haploid nucleus, one copy of chromosomes
            • Tales to help them swim
            • mitochondria in middle bit to provide energy (from respiration)
            • acrosome where enzymes are stored, needed to digrest membrane of egg
          • 4 stages
            • day 1 - bleeding - uterus lining breaks down and is released (mensturation)
            • day 4 - 14, lining of uterus builds up again, spongy layer of blood vessels ready to recieve fertilised egg
            • day 14 - egg released from ovary (ovulation)
            • day 14-28, lining mantained until day 28, if no fertilised egg has landed on the uterus the lining starts to break dow again
          • Pregnancy
            • If fertilised egg implants in the uterus, levels of progesterone stay high maintaining the lining
              • Lining has blood vessels wich supply blood to placenta allowing it to develop.
                • Placenta removes urea and CO2 and supplies baby with oxygen, glucose + nutrients
        • Fertility
          • Hormones
            • FSH too low to get eggs to mature so eggs arent released so they cant get pregnant
              • FSH and LH can be injected to stimulate release of egg
                • PRO -  helps woman to get pregnant
                • CON - doesnt always work, may have to do it lots of times
                • CON -  can be expensive
                • CON - too many eggs can be produced causing twins/triplets
          • IVF
            • In vitro fertilisation
            • collecting eggs from woman and sperm from man and fusing them in lab
            • When embryos are balls of cells one or two are transferred into woman's uterus to improve chance of pregnancy
            • Before egg collection FSH and LH are given to stimulate egg production so more than one can be collected
            • PRO - can give infertile couple a child
            • CON - some woman have abdominal pain/vomiting/dehydration when given hormones
            • CON - there are reports of increased risks of cancer due to the hormone treatment
            • CON -  multiple births can occur increasing the risk of still birth / miscarriage
          • Surrogacy
            • Asking another woman to carry her baby
              • IVF can be used to produce embryo and sperm or donors can be used
                • Embryo then implanted into surrogate who gives birth to it
                  • PRO -  couple can have baby if a medical condition made it too risky before
                  • CON - Surrogate mum has right to keep child until it is adopted as it is legally hers
          • IVF with donated eggs
            • Use eggs from donor and use IVF to concieve
              • PRO - woman can have a baby
              • PRO - donated eggs helps prevent risk of genetic disorders
              • CON - emotionally difficult knowing child has a different mum
        • Chromosomes and disorders
          • Male/female
            • 22 pairs of chromosomes are matched, the 23rd are labelled XX or XY and determine your gender
            • Xy = male
            • XX = female
            • X and Y are drawn apart in the first stage of meiosis 50% chance of getting X 50% chance of getting Y. Similar in eggs but the original has two X's and so all eggs have 1 X chromosome
          • Genetic Diagram
            • genetic diagrams show the probability of getting a boy/girl
            • 50 % chance = boy 50% chance = girl
          • Colour blindness
            • Woman need two of the recessive allele to be colour blind, men only need one - rarer in women
            • If woman has 1 copy she is a carrier. she isnt colour blind herself but she can pass the allele onto her kids
            • 25 % chance of child from carrier being colour blind, 50% if they're a boy
          • Sex linked genetic characteristics
            • Y is smaller than X and so carries fewer genes. Most are only carried by X's.
            • men don't have  a back up X chromosome and so even recessive alleles will have their characteristics shown
            • disorders by faulty alleles are called sexlinked genetic disorders 9colourblindness and haemophilia are examples)
        • Bacteria
          • Pasteur
            • Until 19th century people thought diseases spontaneously appeared
              • Louis Pasteur said microbes in the air cause disease and decomposition
                • Pasteur  heated broth in two flasks one with a straight neck and another with a curved neck. the one with the curved neck remained good because the microbes couldn't get to the broth because they collected in the curved neck where as the broth in the straight neck went off because the microbes got into it. from this he concluded that microbes caused decay.
              • Pasteurisation 70 degrees then cooling it, kills off germs shouldn't make you ill - aseptic  technique (reduce contamination)
                • Pasteurisation is preferable to sterilising (heating to severe temperature to kill ALL bacteria) because it makes everything taste funny and destroys some of its vitamins
          • Resazurin dye
            • sensitive to oxygen. when there's lots of oxygen it's blue, as the oxygen decreases it goes to lilac then mauve then pink then colourless.
              • microorganisms respire and use up oxygen. the more microorganisms there are the greater the colour change
                • allowing us to see how temperature or pH affect bacteria growth
        • The immune system and immunisation
          • Jenner
            • Edward Jenner, first vaccine, small pox
              • smallpox killed lots of people + left scars
                • Jenner took pus/bits of scab from a milkmaid with cowpox (Sarah)
                  • He put them into two cuts on James's arm, he got a little unwell but soon recovered
                    • Jenner then exposed James to smallpox but the boy didn't catch smallpox. the cowpox antigens triggered the boys Blymphocytes to produce antibodies. smallpox has some of the same antigens as cowpox and so when he was infected with smallpox, his immune system responded quickly, preventing him from getting the disease.
          • Pros and cons
            • PRO - some diseases have been virtually wiped out e.g small pox
            • CON - It doesn't always work
            • PRO - epidemics can be prevented if large %'s of the population are immunised. people not immunised are still less likely to catch it because there are less people to spread it
            • CON - sometimes there are bad reactions like swelling / seizures or fever
          • How immunisation works
            • immunisation is getting injected with dead or  inactive microorganisms. they are antigenic so are harmless but make antibodies attack
            • antigens trigger memory lymphocytes to be made too which kill off the pathogen immediately should a live version infect you
          • Memory Lymphocytes
            • When a pathogen enters the body for the first time the response is slow because there aren't many B lymphocytes
              • eventually the body will produce enough antibodies to overcome the infection
                • after being exposed to the antigen memory lymphocytes are produced (special B lymphocytes)
                  • These remain in the body for a long time and remember specific pathogens. the person is now immune and their immune system can respond quickly to a 2nd infection. the pathogen will usually have been gotten rid of before you start to show symptoms on the 2nd infection.
          • Immune system
            • microorganisms reproduce rapidly until they are destroyed. the immune system destroys microorganisms using white blood cells
            • When B lymphocytes find invading microorganisms the produce antibodies
              • every pathogen has antigens on its surface and these are unique to the pathogen
                • when B lymphocytes come across a foreign antigen they produce proteins called antibodies which bind and kill the invading cells. these antibodies are specific to that pathogen
                  • antibodies are produced rapidly and kill all the similar viruses/bacteria
        • Monoclonal Antibodies
          • How they're made
            • antibodies are produced by B - lymphocytes. in order to cure many antigens you would need many B lymphocytes but they don't divide easily.
              • tumour cells divide lots and so are fused with B lymphocytes to make B lymphocytes that multiply quickly to produce more lymphocytes
                • a mouse is injected with the chosen antigen and B lymphocytes are taken from it. fast dividing tumour cells are then fused with the B lymphocytes to make a hybridoma. this divides to produce lots of monoclonal antibodies.
                  • monoclonal antibodies will only bind to antigens of certain molecules
          • Pregnancy tests
            • the bit of the stick you wee on has some antibodies to the hormone you produce when you're pregnant. it also has blue beads attached to these antibodies
              • the test strip turns blue if you're pregnant. this has more antibodies stuck onto it so they cant move
                • if you're pregnant the hormone binds to the antibodies on the blue beads. your urine then moves up the strip to the test strip, carrying the hormone and beads with it which bind to the new antibodies. the blue beads get stuck to the strip turning it blue, showing that you're pregnant.
                • if you're not pregnant your urine will still move up the stick but the blue beads will have nothing to stick them onto the test strip and so they move on past, meaning the test strip doesn't turn blue, showing you're not pregnant.
          • Diagnosing cancer
            • monoclonal antibodies are labelled with a radioactive element. this is then given to the patient through a drip and the blood carries it around the body.
            • when the anitbodies come into contact with cancer cells they bind to the tumour markers. when a photo is taken on a camera that detects radioactivity a bright spot appears showing where the cancer is, what size it is and if it's spreading.
          • Treating cancer
            • an anti cancer drug is attached to the monoclonal antibodies which are given to the patient through a rip. they target specific cancer cells because they only bind to tumour markers. this menas the drug kills cancer cells but no other cells.
            • other cancer treatments would affect other non-cancerous cells too and so the side effects of using antibody based drugs are lower than radiotherapy for example which involves high energy beams.
          • Blood clots
            • proteins in the blood join together to form clots to stop bleeding. monoclonal antibodies have been developed to bind to these proteins
              • radioactive elements can be attached to these antibodies. you can then inject the patient with these antibodies and take a picture using a radiation sensitive camera. the bright spot will indicate where the potentially dangerous blood clot is. it can then be removed before it causes the patient harm.
        • Plants
          • Asprin
            • treat pain and lowers fever
            • developed from a chemical found in leaves and the bark of willow trees
          • Taxol
            • anticancer drug
            • from bark of a pacific yew tree, discovered when scientists were screening plants for ne treatments
          • Quinine
            • treatment against malaria
            • from a cinchona tree
          • Pests
            • crops are lost to pests such as fruit flies  dandelions and fungi.
            • insects such as fruit flies eat most of the crop
            • weeds grow near plants for the nutrients in the soil. because the crop then cant get as much nutrients the crop yield will be lower because the plants wont grow as well.
              • if a plant is infected with a pathogen some of its energy and nutrients is taken. energy can also be lost to replacing parts of the plant that have been killed. this means less energy is used to make the crop and so the yield is lower.
            • pests increase the money required to produce food as pesticides are then needed as well as disease or insect resistant crops. this and low crop yields drive up prices for consumers.
        • Rhythms
          • Photoperiodic
            • day length gradually increases from midwinter to midsummer 21st june before decreasing again
              • photoperiodic response is a response to the amount of light in a 24hr cycle. some plants only germinate, grow or flower in a certin amount of light / dark. this makes sure they only grow at the time of year that best suits them.
                • Artic plants only germinate if the days are really long ensuring they grow in summer when its warm
                • some buds use increasing day length to tell them if its far enough away from winter to sprout without being killed by frost
                • some plants eg spinach only flower when the day is long to make sure they flower near to midsummer
                • others only flower when the days are below a certain length so they flower in early spring or autumn. this way the right insects are about to pollinate the right flowers.
          • Circadian Rhythms
            • biological processes that follow a 24hr cycle including chemical patterns, , physiological patterns nd patterns of behaviour
              • animals plants and microogranisms have circadian rhythms controlled internally. they can be influenced by environmental factors such as light intensity.
                • in animals sleep patterns and urine production are common examples. the body's master clock gets information about light intensity from our eyes. it uses this to produce the hormone melatonin which makes you sleepy. dark - melatonin levels increase, light - decreased levels of melatonin. regular sleep patterns is good for your health + makes you feel awake at the right times. Urine production is also controlled by the body's master clock which controls ADH production. at night ADH levels increase to reduce urine production so your sleep isn't disturbed.
                • examples of circadian rhythms in plants are stomata opening and flower opening. stomata respond to light intensity, they open during the day. during the day photosynthesis occurs, stomata open to let CO2 and O2 in + out. at night photosynthesis stops so stomata close to reduce water loss. Flower opening - plants only need to be open when creatures that pollinate are active e.g. tobacco flowers only open at night because they are pollinated by moths.
              • chemical eg hormone production, patterns of behaviour eg sleeping & eating, physiological patterns eg body temp
        • Conditioning
          • Classical
            • when an animal learns passively to associate a neutral stimulus with an important one
              • Ivan Pavlov conditioned dogs, he noticed they salivated when shown food and so began to ring a bell everytime he gave them food. soon the dogs would salivate at the sound of a bell because they thought food was coming.
          • Operant
            • Where an animal learns actively to associate a reward or punishment with a specific behaviour.
              • Burrhus Skinner trained rats and mice using a Skinner Box. if they pressed a particular lever or button they got food as a reward. He found they used a system of trial and error.
          • Train animals
            • training often uses operant conditioning to get them to do what you want them to do, you give them a food treat or if they do something wrong you punish them by saying NO!
            • Guide dogs stop at a roadside and wait for a command. Sniffer dogs retrieve drugs and police horses only respond to commands from their rider
            • classical and operant condition can be used together when the reward cant be given at the exact time when the job is done eg a dolphin might usually be rewarded with a fish after it does a jump but at a show the trainer might get the dolphin to associate a whistle with fish so that when it jumps the trainer will blow the whistle which thedolphin will interpret as getting food later
        • Innate & learned behaviour
          • Innate
            • inherited - genes Animals can respond to a stimulus even though they've never done it before e.g suckling their mother. Innate behaviour = simple reflex / complex courtship ritual
              • reflex = sneezing blinking salivation, simple reflexes, they protect us from things and we dont have to think about them
                • comple reflex - earthworms show negative phototaxis (move away from light) and sea anemones wave their tentacles when stimulated by chemicals emitted by their prey
          • Learned
            • learned behaviour lets animals respond to their changing conditions and so can learn from previous experiences.
              • if you give an animal a stimulus that doesnt reward or punish it, it'll learn to ignore it. by ignoring non threatening and non rewarding stimuli animals can spend their time and energy more efficiently. this is an important learning process for young animals At first crows may be scared by big or bright scarecrows but later learn they dont do anything and so learn not to respond. This is called habituation.
          • A mixture
            • Imprinting is learned and innate, it learns to recognise it's parents but instinctively follows them
        • Social Behaviour
          • Sound
            • whales and dolphins communicate over large distances using low frequency, bird's calls are used to declare territory attract a mate or warn others.
          • Chemicals
            • Chemicals called pheromones can be released by an animal to show where it is or where it has been. animals also have sexual attractants. some male moths can detect a female's pheromone from several km away. animals also use scent around the boundaries of their territory.
          • Visual
            • honey bees do a waggle dance to tell others they've found food. most mammals communicate through posture and gestures eg chimps stare or raise their arm to intimidate others, avoiding actual fights.
            • behaviours can also be used t admit defeat, a dog rolling over on its back shows submission. courtship behaviours can be funny dances to gifts to elaborate nest building. facial expressions can also be used, chimps look like they're laughing when actually they're showing fear.
          • Why they need to communicate
            • to help the group keep together, to warn others, to communicate with parents, to coordinate attack, to show where food is. communication of mood can help to avoid unnecessary fighting.
        • Studies
          • Tinbergen
            • Studied innate behaviour in herring gulls. saw newly hatched chickspeck parents beak for food. wanted to see whether the red dot made them want to peck it. he showed newly hatched gulls cardboard gull heads with different coloured spots on and counted how many times each colour was pecked, red was pecked the most showing they are born wth te instinct to peck red spots this helps them to find food.
          • Lorenz
            • studied imprinting in geese 1935.  took one group of eggs to hatch in an incubator without their mother and another group to hatch with their mother. those who hatched with their mother saw her first but those who hatched in the incubator saw Lorenz first, these chicks followed Lorenz as the others followed their mum. the goose chicks had formed an attachment to the first thing they saw. this is imprinting and helps chicks recognise their mum. they also follow the first thing they see, helping them no to get lost.
          • Choice chambers
            • two or more chambers, different environments, animals choose which conditions they like the bmost eg closest to their natural habitat. different humidities / light intensities.
            • Woodlice and maggots will start off in the middle and then go towards the dark wet chamber.

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