B1 - Understanding Ourselves

1. Fitness and Blood Pressure
   1. Being Fit is NOT the same as being healthy
   2. "Healthy means being free of any infections or diseases, whereas being fit is a measure of how well you can perform physical tasks"
   3. Fitness profiles measure: Strength, Speed Agility and flexibility, together with stamina
   4. Blood Leaves the heart and flows through the arteries when carrying oxygen, these split into thousands of capillaries which takes blood into every cell in the body. the deoxygenated blood then flows back to the heart through veins. the pressure get lower as the blood flows through the system.
   5. Blood pressure is highest when the Heart contracts, this is called systolic pressure. when the heart relaxes the pressure is at its lowest, this is diastolic pressure.
   6. A healthy persons blood pressure shouldn't be over 135 over 85
   7. High blood pressure can be caused by:
      1. Smoking
      2. Excessive Alcohol Consumpstion
      3. Being Overweight
      4. Excessive stress for prolonged periods of time
2. High Blood Pressure and Heart Disease
   1. Smoking increases blood pressure
   2. Carbon Monoxide increases blood pressure, it combines with haemoglobin in the red blood Cells, which reduces the amount of oxygen they carry. So that the tissue gets enough oxygen the heart rate has to increase, which increases the blood pressure.
   3. Nicotine also increases heart rate.
   4. If your diet is high in Saturated fat or salt, you are more at risk of developing heart disease
   5. Cholesterol is a fatty substance, eating diet high in saturated fats is linked with high blood cholesterol levels.
   6. You need some Cholesterol for things like making cell Membranes. However, if you get too much Cholesterol it will start to build up in the artery walls, which narrow the Arteries. this forms plaques in the artery wall which further narrow the arteries. The plaque restricts the blood which can lead to a heart attack.
   7. Salt also causes high blood pressure
   8. The heart muscle s supplied with blood by the coronary arteries, if these become narrowed blood flow to the heat will become restricted and the heart muscles will receive less oxygen.
   9. A thrombosis (blood clot) also restricts. if a thrombosis occurs in an already narrow coronary artery, blood flow to the heart might be blocked completely. if this happens an area of the heart muscle will be cut of from its oxygen supply completely. This will lead to a heart attack.
3. Controlling Blood Sugar Levels
   1. Eating foods containing carbohydrates puts glucose into the blood from the Gut
   2. Normal respiration in cells removes glucose from the blood
   3. Vigorous exercise also removes glucose from the blood
   4. The level of glucose in the blood must be kept steady. Changes in blood glucose are monitored and controlled by the pancreas, using insulin...
      1. when blood glucose levels are too high, insulin can be released by the pancreas which will turn the Glucose into Glycogen. Glucose will then be removed by the liver.
      2. When the blood glucose levels are too low, insulin won't be added. More glucose will be added by the liver and the liver will turned the stored glycogen into glucose.
   5. Glycogen can be stored in the liver until the blood sugar level is low again
   6. Diabetes
      1. Type 1
         1. Type 1 diabetes I when the pancreas produces little or no insulin. the result is that a persons blood glucose levels can rise to a level that can kill them.
         2. People with type 1 diabetes can partly control the condition by having a carefully controlled diet, but they also need insulin therapy. This usually involves injecting insulin into the blood several times a day. this makes sure that glucose is removed from the body quickly once the food has been digested, this stops the level of glucose in the blood from getting to high.
      2. Type 2
         1. Type 2 diabetes is when a person becomes resistant to insulin (they don't respond properly to the hormone), this can cause blood sugar levels to rise to a dangerous level.
         2. Type 2 Diabetes is usually controlled by limiting the intake of foods rich in simple Carbohydrates like sugars.

1. Eating Healthily
   1. There are 6 essential nutrients needed for a balanced diet...
      1. Carbohydrates are made up of simple sugars like glucose. they are stored in the liver as glycogen or converted to fats.
      2. Fats are made up of fatty acids and glycerol. They can be stored under the skin and around organs as adipose tissue.
      3. Proteins are made up of amino acids. They don't get stored.
         1. Animal proteins are called 'first class proteins'. Plant 'Proteins are called 'Second class proteins'
2. Diet Problems
   1. Consuming too little protein can lead to Kwashiorkor, the most common symptom is a swollen stomach.
   2. Calculation for Estimated Average daily Requirement (EAR) of protien formula: EAR(g) = 0.6 x body mass(kg)
   3. EAR is only an estimate, it will also vary with teenagers and pregnant and breastfeeding women
   4. Body Mass Index or BMI can be measured with this formula: Body mass(kg) ÷ (height)²
   5. However, BMI can be inaccurate. because muscle weighs 4x as much as fat, a very muscly person would be classed as overweight or obese. A very tall and thin person is likely to be classed as Underweight.

1. Infectious Diseases are caused by Pathogens
   1. Pathogens are microorganisms that cause disease. There are four types...
      1. Fungi
      2. Bacteria
      3. Viruses
      4. Protozoa (single celled organisms)
         1. Malaria

            Anexos:

            • Malaria
2. The immune system deals with pathogens
   1. Once pathogens have entered the body they will rapidly reproduce rapidly unless destroyed.
   2. White blood cells have three lines of attack
      1. Consuming them
      2. Producing Antitoxins, this will counter the effect of any toxin brought in by the pathogen.
      3. Producing Antibodies
         1. 1. Every pathogen has unique molecules on the surface of its cells, these molecules are called antigens.
         2. 2. When your white blood cells come across a foreign antigen, they'll start producing proteins called antibodies which lock on to kill the invading cells. The antibodies are specific to that pathogen so the won't lock onto another one.
         3. 3. Antibodies are then produced rapidly and flow all around the body to kill all similar bacteria or viruses.
         4. 4. Some white blood cells stay around in the blood after the pathogen has been fought off, these are called memory cells. if the person is infected with the same pathogen again these cells will remember it and immediately make antibodies to kill it, the person is then naturally immune to that pathogen.
3. Preventing and Treating Infectious Disase
   1. Immunisation stops you getting infections
      1. 1. When you're infected with a new pathogen, it takes time for the white blood cells to produce antibodies, in this time you can get very ill or even die.
      2. 2. To avoid this you must be immunised against some diseases.
      3. 3. Immunisation involves injecting dead or inactive pathogens into the body. These carry antigens, so even though they're harmless they still trigger an immune response, your white blood cells produce antibodies to attack them.
      4. 4. Some of these white blood cells will remain in the blood as memory cells, so if live pathogens of the same type aver appear, the antibodies necessary will be produced immediately.
      5. There are two types of immunity:
         1. Active immunity is where the immune system makes its own antibodies after being stimulated by a pathogen. it includes becoming naturally immune and artificially immune. Active immunity is usually permanent.
         2. Passive immunity is where you use antibodies made by another organism, e.g. antibodies passed onto a baby from a mothers breast milk. Active immunity is usually temporary.
   2. Benefits associated with immunisation:
      1. Immunisation stops you from getting ill
      2. If most people are immunised the disease won't be able to spread as easily.
   3. Risks associated with immunisation:
      1. There are short term side effects. e.g. Swelling and redness at injection site.
      2. You can't have some vaccines if your already ill, especially if your immune system is weakened.
      3. Some people think that immunisation can cause other disorders.
4. Cancer is caused by body cells dividing out of control
   1. A Benign Tumour is where the tumour grows until there's no more room. the cancerous cells stay where they are. This type isn't normally dangerous.
   2. Malignant Tumours grow and can spread onto other sites in the body, these are very dangerous and can be fatal.

1. Medicinal drugs need to be Tested
   1. 1. Computer models are often used first off all, these stimulate a human response to a drug, so you don't need to test on live animals at this stage. they can identify promising drugs to be tested in the next stage. However it's not as accurate as testing the drug on a living organism.
   2. 2. The drugs are then developed further by testing on human tissues. However, you can't use human tissue to test that affect whole/multiple body systems. E.g. Testing a drug for blood pressure must b done on a whole animal with an intact circulatory system.
   3. 3. The last step is to develop and test the drug using animals. British law states that any new drug must be tested on two different animals, however there are some ethical issues on animal testing, on the other hand others believe that it is the safest way to make drugs safe.
   4. After the drug has been tested on animals, its tested on humans in clinical trials.
      1. There are two groups of patients. on is given the new drug, the other is given a placebo. This is done so scientists can see the actual difference the drug makes compared to the placebo effect.
      2. Scientists sometimes test new drugs against the best existing treatment rather than a placebo, this tells them how well the new drug compares to what is already is available.
      3. Clinical trials are blind, the patient doesn't know whether they're getting the drug or the placebo. Often trials are double blind, so the patient nor the scientists know until the results have been gathered.
2. Drugs can be beneficial or harmful
   1. Drugs are substances that alter the way the body works. Some drugs are medically useful, but many drugs are dangerous if misused.
   2. This is why you can buy some drugs over the counter, but others are restricted so you can only get them on prescription.
   3. People can get addicted to both legal and illegal drugs, so if they don't get regular intake then they get withdrawal symptoms.
   4. Tolerance develops with some drugs, this means the body gets used to having it so they need a higher dose to give the same effect. This can happen with both legal and illegal drugs.
   5. If someone's addicted to a drug but want to get off it, rehabilitation can help.
3. Types of drugs
   1. Depressants: E.g. Alcohol, solvents. These decrease the activity of the brain which slows down the response of the nervous system, causing slow reactions and poor judgement of speed and distance (hence a ban on drink driving).
   2. Stimulants: E.g. Nicotine, caffeine, ecstasy. These increase the activity of the brain, which makes you feel more alert and awake. Stimulants are often used to treat depressants.
   3. Painkillers: E.g. Aspirin, paracetamol. Mild painkillers like aspirin work by reducing the number of painful stimuli and the nerve endings near an injury.
   4. Performance enhancers: E.g. Anabolic steroids. These are sometimes taken by athletes, they help build muscle and allow the athletes to train harder.
   5. Hallucinogens: E.g. LSD. They distort what's seen and heard by altering the pathways that the brain sends messages along.

1. Parts of the eye
   1. The retina is the light sensitive part, its covered in receptors called rods and cones, which detect.
      1. Rods are more sensitive in dim light but can't sense colour.
      2. Cones are sensitive to different colours but are not so good in dim light.
   2. The optic nerve carries impulses from the receptors to the brain.
   3. The iris controls how much light enters the pupil
   4. The cornea refracts light into the eye
   5. The lens also refracts light, focusing it onto the retina
2. Focusing on near and distant objects
   1. To look at distant objects...
      1. 1. The ciliary muscle relaxes, which allows the suspensory ligaments to pull tight.
      2. 2. This pulls the lens into a less rounded shape so it refracts less.
   2. To look at close objects...
      1. 1. The ciliary muscles contract, which allows the suspensory ligaments to pull tight.
      2. 2. The lens becomes a more rounded shape, so light refracts more.
3. Some people are long- or short-sighted
   1. Long sighted people are unable to focus on near objects:
      1. 1. This occurs when the lens is the wrong shape and doesn't bend the light enough or the eyeball is too short.
      2. 2. The images of near objects are brought into focus behind the retina.
      3. 3. you can use glasses or contact lenses with a convex lens to correct it.
   2. Short sighted people are unable to focus on distant objects:
      1. 1. This occurs when the lens is the wrong shape and bends the light too much, or the eyeball is too long.
      2. 2. The images of distant objects are brought into focus in front of the retina.
      3. 3. You can use glasses or contact lenses with a concave lens to correct it. An alternative would be to have corneal eye surgery.
4. Binocular vision lets you judge better
   1. 1. Some animals, including humans have two eyes which work together, this is binocular vision.
   2. 2. When you look at an object, your brain compares the images seen by each eye.
   3. 3. The more similarities between the images, the further away the object.
   4. 4. This allows us to judge distances well, but gives us a narrow field of vision.

1. Homeostasis is Maintaining a Constant Internal Environment
2. Conditions in your body need to be kept steady so that cells can function properly. This involves balancing bodily inputs with outputs, fore example..
   1. Levels of CO2: Respiration constantly produces CO2, which you need to expel.
   2. Water content: You need a balance between the water you gain and the water you excrete out.
   3. Body temperature: You need to get rid of excess body heat when your hot, but also retain heat when the environment is cold.
3. Body temperature is controlled by the Brain
   1. Enzymes in the human body have an optimum temperature of 37°C
   2. There is thermoregulatory centre in the brain which acts as your own personal thermostat.
   3. It contains receptors that are sensitive to the blood temperature in the brain. It also receives impulses from the skin that provide information about the skin temperature. The brain can respond to this information and bring about changes in the body's temperature using the nervous and hormonal systems to initiate temperature control mechanisms. For example...
      1. When you're cold...
         1. Hairs stand on end to trap an insulating layer of air which helps keep you warm.
         2. Very little sweat is produced
         3. Blood vessels near the surface constrict, so that less heat can be transferred from the blood to the surroundings. This is called vasoconstriction.
         4. Your body temperature can drop to dangerous levels I your exposed to very low temperatures for a prolonged period of time, this is called hypothermia and you could die.
      2. When you're hot...
         1. Hairs lie flat
         2. Lots of sweat is produced, when sweat evaporates it uses heat from your skin to the environment, which cools you down.
         3. Blood vessels close to the surface of the skin widen, this allows more blood to flow near the surface, so it can radiate heat into the surroundings. This is called vasodilation.
         4. If your exposed to high temperatures for a prolonged period of time you can get dehydrated and could get heat stroke, which can kill you.
            1. Some has heat stroke when sweating stops as your so dehydrated and there's a big rise in body temperature. Your enzymes can't work properly and important reactions get disrupted, if you don't cool down you could collapse and die.

1. Auxins are plant growth hormones
   1. 1. Auxins are plant hormones which control growth at the tips of shoots and roots. They move through the plant in solution.
   2. 2. Auxin is produced in the tip and diffuses backwards to stimulate the cell elongation process which occurs in the cells just behind the tips.
   3. 3. Auxin promote growth in the shoot, but actually inhibits growth in the root.
   4. 4. Auxins are involved in the growth response of plants to light (phototropism) and gravity (geotropism).
2. Auxins change direction of Root and Shoot growth
   1. Shoot Growth
      1. Positively Phototropic
         1. 1. When a shoot tip is exposed to light, it accumulates more auxin on the side that's in the shade than the side that's in the light.
         2. 2. This makes the cells grow faster on one side than on the shaded side, so the shoot bends toward the light.
      2. Negatively geotropic
         1. 1. When a shoot is growing sideways, gravity produces an unequal distribution of auxin to the tip, with more auxin on the lower side.
         2. 2. This causes the lower side to grow faster, bending the shoot upwards
   2. Root Growth
      1. Positively Geotropic
         1. 1. A root growing sideways will also have more auxin on its lower side.
         2. 2. But in a root the extra auxin inhibits growth, this means the cells on top elongate faster, and the roots bend downwards.
      2. Negatively Phototropic
         1. 1. If a root starts being exposed to some light, more auxin accumulates on the more shaded side.
         2. 2. The auxin inhibits cell elongation on the shaded side, so the root bends downwards, back into the ground.
3. Commercial use of plant hormones
   1. 1. As selective weedkillers
      1. 1. Most weeds growing in fields of crops or in the lawn are broad leaved, in contrast to grasses and cereals which have very narrow leaves.
      2. 2. selective weedkillers have been developed from plant growth hormones which only affect broad leaved plants.
      3. 3. They completely disrupt their normal growth patterns, which soon kills them, whilst leaving the grass and crops untouched.
   2. 3. Growing from cuttings with rooting powder
      1. 1. A cutting is part of a plant that has cut off, like the end of a branch with a few leaves on it.
      2. 2. Normally, if you stick cuttings in the soil they won't grow, but if you add rooting powder, which contains a plant growth hormone, they will produce roots rapidly and start growing as a new plant.
      3. 3. This enables growers to produce lots of clones of a good plant very quickly.
   3. 2. Controlling ripening of fruit
      1. 1. Plant hormones can be used to delay the ripening of fruits, whilst they're still on the plant or in transportation.
      2. 2. This allows the fruit to be picked whilst it's still unripe.
      3. 3. Ripening hormone is then added and the fruit will ripen on the way to the supermarket and be perfect just as it reaches the shelves.
   4. 4. Controlling dormancy
      1. 1. Lots of seeds won't germinate until they've been through certain conditions, this is called dormancy.
      2. 2. A hormone gibberellin break this dormancy and allow the seeds to germinate.
      3. 3. Commercial growers can treat seeds with gibberellin to make them germinate at times of year where they wouldn't normally. It also helps to make sure all the seeds in a batch germinate at the same time.

Anexos:

• B1 - Genes