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Biology1 revision

  1. 1. BIOLOGY
  2. 2. Nerves and hormones• Information being sent to the brain is by • The body contain lots of organs. nerves. • These organs work together to be able to• These are fast moving electrical communicate with one another. impulses.• The brain then send more impulses •Hormones also convey messages around the body. between organs. •Hormones are chemicals made by the glands.•Nerves carry information to and from the •A gland is an organ that makes andbrain and spinal cord. These make up the releases useful substances. This is calledcentral nervous system. secretion.•Nerves contain special cells called nerve •The gland secrete the hormones into thecells and carry information as electrical blood and carry throughout theimpulses. bloodstream around the body.
  3. 3. Nerves and behaviour: Hormones and target organs:• Whilst making a simple movement • In the nervous system, nerves carry huge amount of information are being information between one organ and another. passed along nerves. • Hormones also move around the• These are between the eye, brain body by blood vessels. and muscles. • Most hormones affect a few organs• Tiny adjustment are being made and these are called target organs. constantly. • The hormone adrenaline has more• All the information used then target organs than most hormones. produces a perfectly coordinated • Adrenaline affects the heart, piece of behaviour. breathing muscles, eyes and digestive system.
  4. 4. Receptors Vision- eyesReceptors are special cells that (light)detect stimuli.Stimulus is a change in the Smell-environment. nose (chemicals)Receptors send electrical impulsesalong nerves to your brain. Taste- tongueYour brain then sends impulses Hearing – ears (chemicals)speeding along other nerves to Touch- skin (sound anda muscle e.g. in the hand or leg. (temperature movement)All your muscles are effectors. and pressure) •eyes to seeAn effector is an organ that does •ears to hearsomething to respond to a •nose to smellstimulus. •tongue to tasteAs well as muscles being effectors, our •skin to touch andgland are also effectors. feel
  5. 5. Neurones•It carries information from the nervous system as electrical impulses.•These cell that carry this information are called nerve cells or neurones. •This is a sensory neurone. •It carries information from the receptor to the CNS. •This is a motor neurone. •It carries information from the CNS to the effector.
  6. 6. Transducers • Receptor are transducers • A transducer is a devise that converts one form of energy into another kind of energy, when one is chemical energy. • Receptors transfer energy from a stimulus to electrical energy in neurones. For example: •In the eyes are receptors called rod cell •When light energy hits this rod cell, it starts up an electrical impulse that travels in a neurone along an optic nerve to the brain. •The rod cell is a transducer because it transferred light energy into electrical energy.
  7. 7. In a reflex action: Reflex actions A receptor detects a stimulus. The receptor sends an electrical• The tap on the knee in the knee jerk impulse along a sensory test is a stimulus. neurone• Its detected by receptors in the thigh These impulses are sent to the muscle connected to your knees. CNS.• The receptor sends signals to your The CNS sends an electrical spinal cord. impulse along a motor neurone• The spinal cord sends nerve impulses to an effector. to your leg muscles.• The leg muscles respond by The effector responds to the contracting which pulls your lower leg stimulus. upwards.A reflex action is a fast, automatic A reflex action is a fast, automaticresponse to aastimulus. response to stimulus.
  8. 8. Reflex arc Synapses •The tiny gap between the end of one neurone•A reflex arc is pathway and the start of the next is a synapse.taken by nerve impulses asit passes from receptor. •Electrical impulses cannot jump across these gaps.•It then goes to the centralnervous system and then to •Instead when the impulse get to the end ofan effector. the neurone, it causes a chemical to be secreted. •This diffuses across the gap but at a slower rate than an electrical impulse travelling the same distance. •The chemical diffuses across the gap and arrives at the beginning of the next neurone. •This starts off an electrical impulse that whizzes along that neurone.
  9. 9. Water Controlling water and ions:• Cells in your body are always •The blood had many dissolved substances working. in it. •Some are ions such as sodium and• Chemical reaction take place chloride, both in salt. inside them. •To much salt and not enough water in the• These need to happen at the right blood can lead to high blood pressure. time and speed. •People who eat to much salt can increase• The conditions need to be perfect risks of a heart attack. and constant. •The kidney helps keep balance of water and ions. •They do this by varying the amount of waterThese conditions include: and water from the body in urine.•The water content•The ion (salt) content•The temperature•The concentration of sugar in blood Your body can lose water: •From the lungs when you breathe. •From your skin when you sweat. •From the kidneys when you urinate.
  10. 10. Sweating •Sweating keeps us cool. •It is made by glands in the skin. •The gland take water and ions out of Insulin the blood to make sweat.• sugar content in the body is controlled •The sweat travels through a sweatby a hormone called insulin. duct and lies on the surface of the skin.•A meal with starch or sugar, a sugar •It is a mixture of water, ions and smallcalled glucose is absorbed into the amounts of urea.blood. •When you sweat you lose these.•The blood carries this all over the body. •The water in sweat evaporates.•Cells need glucose for energy. •As it changes from liquid water to•If a meals contains to much sugar or water vapour, it takes out from the skin.starch then the blood glucose level risesand the pancreas detects this.•It responds by excreting the hormoneinsulin.•This is carried to the liver in the blood.•The liver takes out glucose from theblood and stores it.•If your glucose levels fall then the liverstores this glucose back into the blood.
  11. 11. Reproductive hormonesMenstrual cycle • The menstrual cycle is controlled by• The cycle, is when an egg is hormones: released from a womans • FSH- secreted by the pituitary gland. ovaries every 28 days. • LH- secreted by the pituitary gland. • Oestrogen- secreted by the ovaries.• Before the egg is released, the lining of the womb thickens.• If the egg is fertilised the womb In the pituitary In the ovary is ready to conceive the tiny gland FSH causes embryo. FSH is secreted and egg to• If not the lining breaks down. mature• This passes through and is FSH cause called menstruation. Oestrogen the ovary to stops the secrete pituitary oestrogen secreting FSH oestrogen LH causes the cause the mature egg to pituitary to be released from the ovary
  12. 12. Hormones and menstrual cycle •Concentration of FSH, LH and Oestrogen change during the cycle. •As oestrogen levels rise they cause the thickness of the uterus lining. •As oestrogen levels fall, the lining breaks down. 1. On the first day of the 2. One week into the cycle, the cycle, menstruation begins. lining build up. An egg is ripening The thick lining of the uterus in the ovary. breaks down and is lost through the vagina. Two weeks into the cycle, an egg is released from the ovary. The lining is soft 4. Three weeks into the cycle, the egg and thick and ready to has almost reached the uterus. If it hasn’t receive if egg is fertilised. been fertilised, it will die.
  13. 13. Controlling fertility• When a women doesn’t produce IVF- In Vitro Fertilisation eggs, then she can be given fertility treatment. The women is given fertility drugs in The women is given fertility drugs in• The hormones used are called her ovaries to mature the eggs. her ovaries to mature the eggs. fertility drugs. These eggs are then removed and These eggs are then removed and• The hormone FSH, can used. This some are placed inside a Petri dish some are placed inside a Petri dish stimulates the women eggs to containing a special solution. containing a special solution. mature in the ovaries.• This egg is then released into the Then some of the mans sperm cells Then some of the mans sperm cells oviduct and conceive normally. are added to this mixture. are added to this mixture. These eggs can then fertilise, then These eggs can then fertilise, thenOral contraceptives when they form into tiny balls, the when they form into tiny balls, the•The contraceptive pill contains chosen embryos are then placed back chosen embryos are then placed backhormones such as oestrogen. into the women’s uterus. into the women’s uterus.•This hormone stops the production of Then ififthe process is successful a Then the process is successful aFSH, and then the eggs don’t mature in baby can develop. baby can develop.the ovaries.•So no egg in released into the ovariesand she cannot get pregnant.
  14. 14. Diet and Energy • Different people require different energy needs.A balanced diet • Exercise takes up lots of energy. • The amount of energy you need alsoCarbohydrates- for Energy depends on the type of job you do .Fats – for stored energy and •Another reason that affects the amount of food you eatmaking cell membranes is our metabolic rates.Proteins- for growth and •All our metabolic rates are and energy •Metabolic rate is the rate at which chemical reactions happen in the cells.Vitamins and Minerals- for •Men tend to have faster metabolic rates then women.keeping healthy and not •Young people have faster metabolic rates than olderdeveloping deficiency people.diseases •The greater the proportion of muscle to fat in you body the higher your metabolic rate is.Fibre- to help the •It can also be affected by genes.digestive system •In winter people tend to have higher metabolic rateswater than in summer due to the less amount of food we need. BMI – Body Mass Index = weight (kg) height (m)²
  15. 15. FAT • Babies have brown fat • 5% of babies weight in brown fat • Brown fat cells have a very high• We have fat in our bodies metabolic rate.• Most is white fat • It is used to generate heat • It the baby is cold, then the brown• It is found beneath the skin fat cells generate the heat fast. around the organs, e.g. Kidneys• It is an energy store• It helps to insulate our bodies and keep heat in• It can protect internal organs from bruising
  16. 16. Obesity• The more food you eat each day, can lead to excess store of fat in the body• You need fat but to much is bad. •People who are overweight are called obese. •Being obese can lead to a high risk of being ill. Problems include: •Arthritis •Diabetes •High blood pressure •Heart disease
  17. 17. Illnesses by obesity Diabetes Arthritis • An illness where a person cannot • This is ‘inflammation of the joints’ control their blood glucose level. • Anyone can get it but its common in • In Type 1 diabetes, the pancreas obese people doesnt make enough insulin. • Arthritis in the knee joint is common • In Type 2 the body cells don’t respond in UK and many need to get their to the insulin. joint replaced. • Type 2 is mostly suffered by obese • A major and expensive operation. people. • This is dangerous because you have to much glucose in the blood which can damage cells as it draws water out ofHigh blood pressure them.•Blood pressure is the pressure of the blood inthe arteries.•The pressure is highest just after the heartbeats. The pressure falls between heartbeats.•The average blood pressure is 130 over 85.•High blood pressure is when it is too high.•This is bad because it puts strain on the heartand their is an increases chance of bloodvessels damaging.
  18. 18. StarvationMalnutrition- diet is in adequate When a person doesn’t have enough••Insome countries, some people live In some countries, some people live to eat:by growing their own crops. by growing their own crops. • their resistance to diseases is lowered.Sometimes they can be affected by: Sometimes they can be affected by: • They can die from diseases such••Droughtsor floods, so crops can’t Droughts or floods, so crops can’t as, cholera, tuberculosis.grow properly. grow properly. • Women’s periods become••Awar, so people can’t visit their A war, so people can’t visit their irregular or stop.fields or look after their kids. fields or look after their kids.••Peopleare to poor to buy food. People are to poor to buy food.•Shortage of food affects little kids.•This is because they’re still growing.•They need protein for cells.•Without protein they cant grown and becomeweak and even die.•They may receive energy from some foods butno enough protein.
  19. 19. Cholesterol and Salt Fast food contains lots of fat and salt. Salt SaltCholesterol ••Weneed some salt but We need some salt but• Too much cholesterol in the blood can not too much not too much form blockage in blood vessels and ••Tomuch can increase To much can increase increased risk of heart disease. blood pressure blood pressure• Saturated fats are found in animal ••Processedfoods Processed foods products e.g. Eggs, meat and dairy products. contains lots of salt contains lots of salt• Some fats lower your cholesterol levels. ••Likecrisps and nuts Like crisps and nuts These are unsaturated fats, e.g. Plant oils ex sunflower oil.• Cholesterol can be used to make cell membranes e.g. Your liver makes cholesterol.• If you eat a diet with less saturated fats then your cell will have enough.• If you have too much then the liver makes less.• The amount of cholesterol you have depends on your genes and how much fat you eat.
  20. 20. Cholesterol and heart disease • Cholesterol can’t dissolve in water, therefore it can’t dissolve into watery blood plasma. • Instead it is carried around in tiny ball mixed up with proteins called lipoproteins. •The plaque reduces the space that blood can flow through. • High density lipoproteins (HDLs)- is a •It slows down the blood, so it clots. good cholesterol and keeps you •If clots break away, they get carried healthy. along in the blood and get stuck in • Low density lipoproteins (LDLs)- is a smaller blood vessels, blocking blood bad cholesterol and can lead to heart flow. disease.•Sometimes a clot block one of the arteriesthat oxygenate blood to the heart muscle. • High levels of LDLs in the blood can•The muscle cant work, and the heart can’t increase the risk of developing plaquesbeat properly. in the wall of the arteries and can lead•This can cause a heart attack. to heart problems • HDLs can protect us against heart disease. They help remove cholesterol from the walls of blood vessels.
  21. 21. Different fatsSaturated fats- raise blood cholesterol Mono un-saturated fats- they reduce levels overall blood cholesterol levelsFound in foods such as meat, butter and improve balance between and cheese. LDLs and HDLs in the blood Found in foods such as olive oil, olives, peanuts and many margarinesPolyunsaturated fats- these are betterat reducing blood cholesterol levelsand balances HDLs and LDLs morethat mono unsaturated.Found in foods such as corn oil,sunflower oil, oily fish and manymargarines.
  22. 22. Statins• If a person’s liver seems to have their cholesterol making is permanently at high, then it is difficult fro them to keep cholesterol levels down.• They then have to take drugs called statins.• These affect the enzymes that control cholesterol synthesis in the liver and inhibits cholesterol production.
  23. 23. Drugs Dangers of drugs  Alcohol• A drug is something that changes  Cannabis the chemical processes in the  Cocaine and heroin body.  Tobacco• Recreational drugs are taken for pleasurable reasons. • Alcohol and tobacco are legal drugs. • Cannabis, cocaine and heroine are illegal. • People can become addicted to a drug. • They feel dependent on it. • Drug addiction can have long term affects. • They can affect the brain and liver. • The liver is damaged as its job is destroying harmful chemicals within the body. • Legal drugs can be misused and become a danger.
  24. 24. Trialling drugs1. Is it safe? • This process can take years and may not be successfulThe drug is tested in a lab to see if it is toxic. • Even if a drug gets through the stages, it is 5 years before it is2. Is it safe for humans? sold in chemistsThe drug is given the volunteers. They • When people use it, it may not be are given different doses to the miracle cure determine the maximum dose. Any side effects are recorded. E.g.3. Does it work? • Thalidomide.The drug is tested on the ill people who • This was originally developed as a the drug was made for. If it makes sleeping pill. them feel better it is sold • It was never tested on pregnant commercially. women. • It is now being used to treat leprosy. • But no pregnant women is allowed it.
  25. 25. Illegal drugs Cocaine and heroineCannabis • They come from opium poppies which are grown in Afghanistan and Columbia.• Drug made from dried leave. • They make people feel happy and• It can be smoked like tobacco and causes relaxed. bronchitis and lung cancer. • Heroine and cocaine are dangerous and• It makes you feel relaxed and happy. known as hard drugs.• People who suffer from multiple sclerosis • Cocaine is addictive and you can get say it makes them feel better. addicted after taking it once.• It is likely to cause the illness schizophrenia.
  26. 26. Alcohol• Is commonly used drug.• It can be misused. • The liver gets damaged because Alcohol affects the nervous system. It its job is to break down alcohol. causes: Reactions to slow down • Its changes it to harmless Loss of self control substances. Unconsciousness, coma and even • Too much can kill the livers cells. death, when a lot is drunk •People drink to relax and enjoy• Alcohol damages the brain and liver• Brain cells are affected quickly themselves. •If to much is drunk they get aggressive• The cells shrink and violent• People can get permanent brain damageAlcohol dependency•People can become dependent on alcohol•They can’t manage without out•They spend so much they cant support their families or themselves.•They can lose jobs and families
  27. 27. Alcohol is swallowed The cortex(the wrinkled surface layer of the and then absorbed into Blood carries brain) which is responsible for conscious the body alcohol the thought and actions through the brain stomach The cerebellum which controls movement and posture Blood The medulla stomach carries the which controls alcohol to the liver breathing and heart rateDepressants•Alcohol is a depressant.•These are drugs that slow down brain activity•A part of the brain called the cortex allows a person to think clearly and makedecisions.•Alcohol affects this ability•It also affects the cerebellum, which helps with coordination.•If to much is drunk, it can kill and cause a person to fall into a come or die due tothe inhibit of breathing.
  28. 28. Lung diseases Tobacco • A smoker get lung infections. • In the bronchitis, the smokers Cigarette poisons bronchi inflames. • Tobacco contains many different • Lots of mucus is produced. substances including nicotine, tar • This can cause excessive and carbon monoxide. coughing.Nicotine- affects the brain. It is addictive. • The air sacs lose stretchiness. • It is difficult to get oxygen into theTar – is a poison that causes cancer. Its a blood.carcinogen.Cigarette smoke often causes lung cancer, but • This is called emphysema.can risk development of other cancers. • Someone with this condition may have to breathe oxygen from aCarbon monoxide- takes the place of cylinder.oxygen in red blood cells, so the blood carriesless oxygen. This can harm body cells.In pregnant women this can be dangerous asthe baby will get less oxygen, it may not growproperly and have a low birth weight. A personwho smokes is likely to have heart disease.
  29. 29. PathogensMicroorganisms Microorganisms and disease• These are living things that we • Some bacteria and viruses can cannot see. cause disease.• They include bacteria and viruses • A microorganism that causes disease is called a pathogen.• Humans are visible organisms, which are made up of tiny cells. • If bacteria can get into the body, it reproduces rapidly.• Each bacterium is made up of one cell. • They produce toxins that make you feel ill.• Their cells are smaller than ours. • They are carried in the blood.• You can’t see bacteria clearly. • A virus can get into a cell and• Viruses are even smaller. reproduce there.• There are some viruses that can • When to much is produced they get into bacteria, so bacteria can can burst out of the cell and also get ill. destroy it.
  30. 30. Body defencesWhite blood cells Epidemic and pandemics• These are our defence forces. • Sometimes people get a flu.• They attack and destroy • When lots of people have an pathogens in the body. infectious disease at the same• They are part of our immune time, this is an epidemic. system. • When an epidemic spreads• Some white blood cells surround worldwide, its known as a bacteria and take them into its pandemic. cytoplasm.• They kill them and make antibodies, that destroy bacteria.• Or antitoxins, that neutralise the poisons that the bacteria makes.
  31. 31. Antibodies Phagocytosis • Other white blood cells, called lymphocytes, that attack pathogens in a different way. • They produce chemicals called antibodies. • This is an anti body molecule. •This shows how a white blood cell, called • The end bits fit onto molecules of the phagocytes. pathogen. •They surround and ingest bacteria. This • Each shape fits one kind of pathogen. activity is called phagocytosis. • So we have millions of lymphocytes. • The antibodies group around and stick to•This is what happens when you have an infected the pathogen.wound. • They can kill it directly or stick to it in•Some of the cells around the wound produce clumps, so phagocytes can gather andchemicals that tells the phagocytes they’re destroy them more easily.needed. • Some of the chemical that the•Extra blood flows to the infected site, bringing lymphocytes make can stick to themore phagocytes with it. dangerous toxins made and given off by bacteria, can destroy them•The would becomes inflamed and red. • These chemicals are called antitoxins.•But under the skin, they are dong their best to killthe pathogens.
  32. 32. Drugs against diseasePainkillers Sources of antibiotics• A drug used to get rid of pain. • Penicillin is made from a fungus.• You can buy these, e.g. Aspirin, • The drug companies are always on paracetamol and ibuprofen. the look out for new antibiotics.• They reduce symptoms of whatever • Nowadays, most antibiotics are is wrong with you. made chemically. • This is better then extracting themAntibiotics from fungi or other organisms•These are drugs that kill bacteria inside your because you know hat yourebody. getting.•They don’t kill viruses. • If you take it from fungus, you don’t•Antibiotics include penicillin and know the strength of it.streptomycin. • Making it chemically means you know its pure•We different ones as they dont all workequally well against all kind of bacteria.Antiviral•Viruses are more difficult to kill.•If they go inside a cell they are impossible to kill itwithout killing the cell.• Antivirals are used to kill viruses.
  33. 33. Resistance to antibiotics MRSA Resistance to antibiotics •Methicillin Resistant • This is a population of bacteria in Staphylococcus aureus. a person’s body. One of them is different. •Staphylococcus aureus is a common bacterium. •It doesn’t normally harm someone except a weak, very • The person takes antibiotics to young or very old person. kill the bacteria. It works but of •MRSA infection is in them is resistant to the antibiotic. hospitals. •It can’t be killed with usual • The bacterium has now divided antibiotics. and made copies of itself. There •It is difficult to kill once is now a population of bacteria someone is infected. that the antibiotic cannot kill.
  34. 34. VaccinationImmunisation • They can even make antibodies.• Means making immune • These stick to bits of the surface of• You can be immunised against the virus or bacteria and attack it. mumps, measles and rubella, polio They are called antigens. and diphtheria • The white blood cells make different• You have a small amount of dead or antibodies for each antigen. inactive viruses or bacteria jabbed • If you get infected by the real, live into you blood. pathogen, your white blood cells are• Your white blood cells don’t know ready to make the right sort of they’re harmless and attack them antibodies. like pathogens. • They will then destroy the pathogen before it makes you ill.The MMR jab•This is given to children to protect them against Measles,Mumps and Rubella.•These disease are caused by viruses.•In 1988 it was told MMR jab caused autism.•However scientist had no evidence that it was.