Responding to Change
- Your nervous system carries impulses around your body.
- Hormones are carried around the body by blood and are released by glands.
- They have long lasting effects.
- Stimuli are picked up by receptors.
- Receptors are in the sense organs.
- Information passes along sensory neurones.
- Impulse reaches CNS (Central Nervous System) made up of the brain and the spinal cord.
- CNS co-ordinates information.
- Motor neurones send impulses to the effector organs.
- Effector organs are muscles or glands.
- Receptor - Sensory Neurone - Co-ordinator (CNS) - Motor Neurone - Effector
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- Reflexes are there to help you avoid dangers.
- They involve 3 neurones: sensory, motor and relay.
- Relay neurones connect sensory and motor and can be found in the CNS
- The reflex arc is the process of reflexes.
- Junctions between the nerves are called synapses.
- An electrical message travels along neurone and then reaches the synapse and is transferred to a chemical message and back again for the next neurone.
- Stimulus - Receptor - Co-ordinator - Effector - Response
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The Menstrual Cycle
- 28 days long - during this time the womb lining thickens and an egg matures.
- At about day 14 egg released from ovary and lining stays thick for a few days.
- If egg not fertilised a period takes place.
- All changes brought about by hormones.
- FSH secreted by pituitary gland, makes eggs mature and stimulates ovaries to produce oestrogen.
- Oestrogen is made and secreted by ovaries, stimulates womb lining to thicken and secretion of LH.
- LH secreted by pituitary gland stimulates release of a mature egg.
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The Artificial Control of Fertility
- Oral contraceptives (contraceptive pill) contain female hormones, mainly oestrogen.
- The pill inhibits FSH production so no eggs mature in the ovaries.
- If you use the pill you have to use it regularly to keep the hormone levels up.
- For couples who are infertile, it might be that the female dosen't produce FSH so artificial FSH drugs are available.
- Fertility drugs are also used when couples are going through IVF.
- During IVF eggs are removed from the ovaries and fertilised outside of the body then implanted in the womb.
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The Artificial Control of Fertility (cont)
- The woman is given fertility drugs to help produce as many ripe eggs as possible.
- Many advantages and disadvantages.
- The pill has helped decrease poverty ans control population growth.
- Fertility drugs can lead to multiple births which can be devastating for parents if one is lost and can cost the state a lot of money.
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- It is important to keep everything constant internally, this is called homeostasis.
- Water moves in and out of cells, how much depends on the ions in it.
- Water and minerals enter the body through food and drink.
- Water and salt leaves when you breathe out, in your sweat and in your urine.
- Kidneys change the amount of salt and water lost in your urine depending on body conditions.
- It is important that body temperature is kept at 37 because enzymes work best at this temperature.
- After a meal is digested glucose passes into your blood.
- Glucose levels are kept constant by insulin made in the pancreas.
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Diet and Exercise
- A healthy diet contains: carbohydrates, proteins, fats, vitamins, minerals, fibre and water.
- If diet is unbalanced then you will end up malnourished.
- If you don't have enough vitamins and minerals you will have a deficiency disease.
- Males need more energy than females - unless they are pregnant.
- The more you exercise the more food you need as fitter people have more muscle and muscle tissue burns more energy than fat.
- The climate around you affects energy levels, the warmer it is the less energy needed.
- The metabolic rate is the rate at which chemical reactions occur in the body.
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- Your BMI compares your mass to your height.
- The average BMI ranges between 20 and 30. A BMI below 18.5 or above 35 could indicate health problems.
- If you take in more energy then necessary the excess is stored as fat.
- Obesity can lead to arthritis, diabetes, high blood pressure and heart disease.
- You can lose weight by reducing the amount of energy taken in and by exercising.
- Starvation is when you become very thin and muscles wear away, your immune system becomes weak and for females periods could become irregular or stop altogether.
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- The type and amount of fat in you diet and affect cholesterol levels.
- Cholesterol is substance made in the liver and carried around in your blood.
- It is necessary to make the membranes in cells and hormones.
- High levels of cholesterol increase the risk of heart disease or diseased blood vessels as it builds up and eventually blocks them.
- The amount of cholesterol in the blood depends on the way your liver works and the amount of fat in your diet.
- Cholesterol is carried around the body by two types of liproproteins
- Low Density Liproproteins are 'bad' cholesterol, raise risk of heart problems.
- High Density Liproproteins are good.
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Fast Food (cont)
- There are 3 types of fat: saturated fats raise cholesterol, mono unsaturated fats reduce cholesterol and improve the balance between LDLs and HDLs and polyunsaturated fats do the same but better.
- Salt is vital in the diet but too much of it can lead to high blood pressure.
- High blood pressure can damage the heart and kidneys and increase the risk of a stroke.
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- Drug is a substance which alters the way the body works.
- They are everywhere: coffee, tea, cigarettes and alcohol.
- There are some illegal drugs: cocaine, ecstacy and heroin.
- Sometimes you become addicted to a drug, then when you stop taking it you exprerience withdrawal symptoms.
- These can be aches, sweating, shaking, headaches and cravings.
- Drugs can make you feel very good about yourself.
- Cannabis can be thought of as a safe or soft drug but it can cause psychological problems.
- Hard drugs like cocaine and heroine are extremely addictive and can lead to severe health problems
- Sometimes they can lead to diseases like hepatitis, STDs and HIV/AIDS.
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Legal and Illegal Drugs
- All recreational drugs affect the way your brain and nervous system work. People enjoy this change and it makes them addicted.
- Caffeine, nicotine and cocaine speed up the activity of the brain.
- Alcohol and cannabis slow down the brain.
- Heroin stops impulses travelling in your nervous system.
- The sport world has a major problem with illegal drug usage.
- Drugs can build up muscle mass, make the body produce more blood, make you more alert and speed up reactions.
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- In small amounts alcohol makes people feel relaxed and cheerful.
- It is poisonous but your liver can get rid of it before it does damage
- The alcohol goes into your boodstream and eventually slows down reactions.
- If you drink large amounts, your liver can't cope and you would suffer from alcohol poisoning.
- This can lead to unconsciousness, coma and even death.
- Alcoholics' livers and brains suffer long term damage.
- They could develop cirrhosis of the liver and liver cancer.
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Smoking an Health
- Nicotine is the addictive drug in tobacco smoke.
- Non smokers have tiny hairs called cilia which move mucus away from the lungs.
- Smoking anaethetises cilia, allowing dirt down the lungs and the mucus to build up and cause coughing.
- Tar builds up in the lungs and turns them grey, it leads to alveoli breaking down and emphysema.
- Tar is a carcinogen (cancer causing substance).
- Smoking raises blood pressure, causing heart attacks, strokes and thrombosis.
- Carbon Monoxide is in cigarette smoke; it reduces amount of oxygen carried in the blood.
- This is why expectant mothers may suffer a premature birth, a baby with a low birth rate or a stillbirth.
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- Microorganisms which cause disease are called pathogens.
- Bacteria are single celled organisms, some cause disease but most are harmless.
- Viruses are smaller than bacteria. They can only reproduce by taking over another cell.
- Bacteria and viruses reproduce rapidly in the body. (Bacteria divide into two)
- Bacteria produce toxins which affect the body, viruses rarely produce toxins.
- Common disease symptoms are a high temperature, headaches.
- Many women in Ignaz Semmelweiss' hospital died of childbed fever.
- Semmelweiss realised medical students were goin straight from the mortuary to the delivery room so he insisted people wash their hands and fewer mothers died.
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- There are 4 main ways that pathogens spread: droplet infection, direct contact, contaminated food and through a break in the skin.
- Skin covers body and prevents pathogens reaching tissues.
- When skin is cut platelets in the blood form a clot which dries into a scab, sealing the cut and stopping pathogens entering.
- Breathing organs produce mucus to trap pathogens.
- Stomach acid destroys pathogens which enter through the mouth.
- The white blood cells are put of the immune system.
- They ingest microorganisms.
- They produce antibodies which target particular pathogens through the antigens.
- Once you have produced an antibody once it is easier to make again
- Some white blood cells produce antitoxins which counteract toxins.
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Using Drugs to Treat Disease
- Often medicine has no effect on the pathogen, just the symptoms.
- Antiseptics an disinfectants are used outside of the body.
- Antibiotics kill disease inside the body.
- Antibiotics damage bacterial cells without damaging your cells.
- They do not work on viruses.
- It is very difficult to kill a virus without killing your own cells.
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- If you use antibiotics properly, the bacteria are almost killed.
- The ones that are left may mutate and become resistant.
- If you don't finish the course or use them too often then bacteria become resistant due to natural selection.
- Hospitals often contain bacteria which aren't affected by common antibiotics, this is why diseases like MRSA are spread.
- To stop MRSA all medical staff must wash their hands between patients, visitors must wash their hands on entering, infected patients must be kept in isolation, the hospital should be clean.
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Developing New Medicines
- A good medicine is effective, safe, stable and easy to consume and excrete.
- To develop a new drug researchers target a disease, then start computer testing, possible drugs are sythesised in the lab.
- To test, first in vitro screening occurs with cell cultures, then it's animal testing, human testing on humans without the disease, a small amount of humans with the disease then a large amount.
- Meanwhile animal testing continues to test for long term side affects
- Then the medicine has to be granted a license, before it is monitored for a time.
- We test drugs so thoroughly after thalidomide in the 50s, when animal tests on pregnant animals weren't carried out.
- Thalidomide successfully stopped morning sickness but had a tragic effect on developing fetuses.
- Many babies were born with limb abnormalities.
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- Antigens are proteins found on the outside of every cell.
- White blood cells produce antibodies to attach antigens.
- As white blood cells remember antibodies you can become immune to diseases.
- Vaccines are dead or weakened forms of diseases which help white blood cells form the right antibody.
- Society needs as many people as possible to be immunised for it to be effective.
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