B1

All the different topics in B1.

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Blood pressure

Blood is pumped around the body..

1) By contractions of the heart- increase the blood pressure

2) Blood leaves the heart through arteries. These split into a thousand capillaries, which take the blood to every cell in the body. Blood then flows back to heart through veins

3) Blood pressure is highest when the heart contracts - systolic pressure. When the heart relaxes the blood pressure is low - diastolic pressure.

4) Blood pressure is measured in mm of mercury (mm Hg) - Shouldn't be higher than 135 (systolic pressure) or lower than 85 (diastolic pressure)

You can get high blood pressure by- Getting older, a diet with too much salt, being overweight, drinking too much alcohol, smoking, being under lots of stress for a long period of time and not doing enough exercise.

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Blood Pressure (2)

High or Low blood pressure can cause health problems

If the pressure of the blood is too HIGH it can cause, blood vessels to burst which could lead to strokes, brain damage and kidney damage.- could be corrected by lifestyle change. - consuming less salt and alcohol,doing more exercises and losing weight.

LOW blood pressure is less common but still can cause problems. Like poor circulation and tissues not being able to get all of the food and oxygen needed. If that happens you can get dizzy and faint.

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Respiration

Respiration is the process of releasing energy for glucose. - this energy is used to do things like build up large molecules, contract muscles and maintain a steady body temperature. There are TWO types of respiration aerobic and anaerobic.

Aerobic respiration is what happens when there's plenty of oxygen. Aerobic just means ''with oxygen'' and is the most effective way to release energy from glucose that's why you use it most of the time.

Glucose + oxygen --> Carbon Dioxide + water (+ energy)

C6H12O + 6O2 --> 6CO2 + 6H2O (+ energy)

 

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Respiration

Anaerobic respiration doesn't use oxygen at all. When you do really vigorous sport your body can't get you enough oxygen to your muscles. Your muscles have to start respiring anaerobically as well. Anaerobic just means ''without oxygen''. It releases much less energy than aerobic. In anaerobic respiration, the glucose is only partially broken down, and lactic acid is also produced.

Glucose --> Lactic Acid (+ energy)

Lactic acid builds up in your muscles which become painful and causes your muscles fatigued. But at least you can keep on using your muscles. After resorting to anaerobic respiration, when you have stopped exercising you'll have an oxygen debt. Basically you still don't have enough oxygen in your muscles because they haven't been getting enough for a while and you also need to get rid of the lactic acid that has been building up in your muscles, meaning you have to breathe heavily for a while to repay the 'debt'. Lactic acid has to be carried to liver to be broken down, so your heart rate has to stay high too. Anaerobic respiration doesn't release as much energy as aerobic respiration - although it's useful in emergencies. Unfit people have to resort to anaerobic respiration quicker.

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Eating Healthily

  • Carbohydrates - (e.g glucose) provide energy
  • Fats - provide energy, act as an energy and provide insulation (fatty acids and glycerol
  • Proteins - needed for growth and repair of tissue and provide energy in emergencies. (amino acids)
  • Vitamins - has various functions. (e.g vitamin C is needed to prevent scurvy)
  • Minerals - had various functions (e.g iron is needed to make haemoglobin for healthy blood)
  • Water - Need a constant supply to replace water lost through urinating, breathing and sweating.

A balanced diet is different for everyone. - e.g teenager and children need more protein to grow and old people need more calcium to protect against bone diseases. Females need more iron to make up for the amount lost in periods. Active people need more protein for muscle development, and more carbohydrate for energy.

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Different diets

People choose not to eat certain food for certain reason such as-

  • Religious reasons - Hindus don't eat cows because they believe they are sacred.
  • Personal reasons - vegetarians don't eat meat for many reasons - some think it's cruel for animals, some don't like the taste and others think it's healthier not to eat it. Vegans don't eat any products from animals e.g milk, eggs and cheese.
  • Medical reasons - Some people are intolerant to some foods e.g dairy products and wheat. Eating them can leave the person feeling bloated and ill. This is often because they can't make the enzyme needed to digest that food properly. Some people are allergic to foods (nut allergies are quite common) - they get severe reactions which can be fatal.
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Diet problems

Eating to much can lead to obesity - it is a common disorder, 20 % over recommended body weight. Too much sugary and fatty foods or too little exercise are the cause. It's not always people's fault for being obese they can have and under active thyroid gland - not common. Obesity can increase the risk of diabetes, arthritis, high blood pressure (stroke), coronary heart disease (CHD) and sometimes even some form of cancer.

Eating too little can also cause problems -  too little protein can cause kwashiorkor - swollen stomach. Many parts of world intake too little protein. (recommended daily allowance = 0.75 x body mass (kg)) Some psychological disorders cause under nutrients (anorexia). All the time they want to be thinner even if they are just skin and bones. This can cause a host of illnesses e.g. liver failure, kidney failure, heart attacks, muscles wastage, low blood pressure and mineral deficiencies. FATAL.

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Body Mass Index

It is a guide to help decide whether someone is underweight, normal, overweight or obese. It's calculated from their height and weight: body weight (kg) divided by (height)2 (m)

Below 18.5 - underweight

18.5-24.9 - normal

25 -29.9 - overweight

30 - 40 - moderately obese

above 40 - severely obese

BMI isn't always reliable. Athletes have a lot of muscle, which weighs more than fat meaning they can come out with a high BMI even though they are not overweight. Alternate is to measure %body fat.

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Digestion

Is the breaking down of the nutrients in your food so they can be absorbed into the blood.

BIG molecules are broken down into SMALL molecules. First the big lumps are physically digested (in mouth and churning in stomach) so they can pass easily through digestive system. Then you use chemical digestion to break down molecules that are two big to pass through cell membranes - uses enzymes.

There are three main types of digestive enzymes. Carbohydrases- break down big carbohydrates (starch) into simple sugar. They are present in two places, then mouth and small intestine. 2) Proteases - convert proteins into amino acids. They are present in two places the stomach and the small intestine. 3) Lipases - convert Fats into fatty acids and glycerol. They are present in the small intestine.

Other chemicals are also present in your body which help the enzymes work- Stomach acid - lowers the pH in stomach. Bile is made in the liver and is stored int the gall bladder. Helps digestion in the small intestine in two ways. 1) Bile is alkaline. It neutralises the acid from the stomach. 2) It also emulsifies fat.(breaks fat into tiny droplets. This gives a bigger surface area for lipsase enzymes to work on.

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Digestion

1) The small mole ules can diffuse into the blood. Glucose and amino acids are small enoughto diffuse into the blood plasma.

The products of fat digestion can't get into the blood plasma so they diffuse out of the gut (intestines) and into fluid called lympth, in the lymphathic system. From here they are amplified into the blood.

2) The nutrients then travel to where they are needed, and then diffuse out again. e.g. glucose travels to muscles for respiration during excersise.

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Infectious Disease

Pathogens are micro-organisms that cause disease. There are four types-

  • Fungi - e.g atheletes foot
  • Bacteria - e.g cholera
  • Viruses - e.g flu
  • protozoa (single celled organisms) - e.g Malaria

The symptons of an infectious disease are caused by cell damageor by toxins produced by the pathogens. Malaria is caused by protozoan. It's carried by mosquitoe - protozoan is a parasite, the person it effects it the host and the mosquitoe it the vector (carry the disease without getting it themselves. They pick up the malarial parasite from an infected animal and then inserts the parasite into another animal's blood vessel when feeding from it.

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Immune system dealing with pathogens

Once micro-organisms have entered your body they reproduce rapidly, unless they are destroyed - job of immune system and white blood- cells (important). They are always travelling around your body looking for micro-organisms and then invading them by-

1) Consuming them - White blood cells can engulf foreign cells and digest them.

2) Producing antitoxins - Antitoxins counter the effect of any poisons (toxins) produced by the invading bacteria

3) Producing antibodies - Every pathogen have their own unique molecules on the surface of the cell - antigens. When the white blood cells come across foreign antigen they start to produce proteins called antibodies, which lock onto the invading cells. The antibodies produced are specific to that pathogen. Antibodies are then produced rapidly and go through the whole body killing the similar bacteria or viruses. If the person is effected by the same pathogen again, they will produce the same antibodies to kill them - naturally immune now.

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Preventing and treating infectious Disease

Immunisation involves injecting dead or inactive micro-organisms into the body. These carry antigens and even though they are harmless your body makes antibodies to attack them. Now if the same type of micro-organism appear in your body they will be killed immediately.

  • Active immunity is where the imune system makes it's own antibodies after being stimulated by a pathogen. It includes becoming naturally immune and artifically immune (immunistation) - permanent
  • Passive immunity is where you use antibodies made by another organism e.g antibodies are passed to from mother to baby through breast milk.-temporary.
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Health Conditions

Healthy Disorders can be caused in various ways-

  • Vitamin deficiency, e.g can get scurvy if you don't get enough vitamin C
  • Mineral deficiency, e.g a lack of iron in the diet can lead to anaemia. Needed to make a protein haemoglobin (carries oxygen in red blood cells)
  • Genetic inheritance of disorders, e.g red-green colour blindness (hard to distinguish between red and green) and hemophilia (blood clotting disorder)

Cancer is caused by cells growing out of control - Forms a tumour (mass of cells) either Benign (where the tumour grows until there is no more room. Cells stay where they are. Not normally dangerous) Or Malignant (where tumour grows and can spread through body. Dangerous - fatal.

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Drugs

Depressants - Alcohol and temazepam. These decrease the activity of the brain. Stimulates parts of the brain which decrease the activity in other parts. Slows down responses in nervous system, causing slow reactions and poor judgement of speed and distance.

Stimulants - nicotine, ecstasy, caffeine. Opposite of depressants. They increase the activity of the brain. More alert and awake.Treat depression.

Painkillers - aspirin is a mild painkiller. Works by reducing the number of painful stimuli at the nerve ending near an injury.

Performance enhancer - anabolic steroids. Sometimes taken by athletes. They help build muscles and allow them to train harder. Banned.

Hallucinogens - cannabis and LSD. They distort whats seen and heard by altering the pathways nerve impulses normal travel along.

Class A - heroin, LSD, ecstasy and cocaine.- lengthy prison sentence because it's the most dangerous. Class B amphetamines (speed) Class C - cannabis, anobolic steriods - warning.

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Smoking

Burning cigarettes produce. - Carbon monoxide. - This stops haemoglobin carrying as much oxygen. Deprive foetus of oxygen leading to small baby at birth. Nicotine - Stimulant drug - makes smoking addictive. Tar - Covers the cilia (the little hairs in the respiratory tract) preventing them from moving mucus and bacteria out of your lungs. Contains carcinogens. Particulates - accumulate in the lung tissue causing irritation.

Causes all sorts of illnesses of the heart and blood vessels leading to heart attacks and strokes. Causes lung,throat, mouth and oesophagus cancer. It cause severe loss of lung function, leading to diseases like emphysema and bronchitis.

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The Eye

  • The cornea refracts light into the eye
  • The iris controls how much light enters the pupil
  • The lens focuses the light onto the retina
  • The retina is the light sensitive part and it's covered in receptors called rods and cones, which detect light.
  • Rods are more sensitive in dim light but can't sense colour.
  • Cones are sensitive to colours but are not so good in dim light
  • The optic nerve carries impulses from the receptors the brain

The eyes focuses light by changing the shape of the lens. Distant objects - The ciliary muscles relax, which allow the suspensory ligaments to pull tight. This makes the lens go thin. Near objects - The ciliary muscles contract which slackens the suspensory ligaments. The lens becomes fat.

Long sighted people wear convex lens and short sighted people wear concave glasses.Binocular vision - two eyes which work together. Monocular vision- two eyes that work separate (wider range)

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Neurones

Neurons transmit information as electrical impulses around the body. 1) The electrical impulse is passed along the axon of the cell. 2) Neurones have branched endings so they can connect with lots of neurons. 3) They have a sheath along the the axon which acts like an electrical insulator, which stops the impulse getting lost - speeds up the electrical impulse. 4) They're long, which also speeds up the impulse (connecting to another impulse slows the impulse down so one long neurone is much quicker than lots of short ones joined together) 5) Connection between two neurones is called a synapses.

  • The nerve signal is transferred by transmitter chemicals which diffuse across gap
  • These chemicals then set off a new electrical impulse in the next neurone
  • Stimulant drugs increase the amount of transmitter chemical at some synapses, which decrease the frequency of impulses set of along neurone 2. Decreases brain activity.
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Reflexes

The central nervous system consists of the brain and spinal cord.  Information gets sent from stimulus to receptor to sensory neurone to CNS to motor neurone to effector to response.

Reflex action stop you injuring yourself -

1) The nervous system uses electrical impulses to allow very quick responses. Reflex actions are automatic so it is even quicker.

2) The conscious brain isn't involved in a reflex arc. The sensory neurone joins to relay neurone in the spinal cord (part of the CNS) which links directly to the right motor neurone, so no time is wasted thinking about the response.

3) Reflex actions often have a protective role e.g snatching back your hand when you touch a hot plate happens almost before you realise you have done it.

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Homeostasis

Homeostasis is maintaining a constant internal environment - so cells can function properly. Like level of CO2 - respiration constantly produces CO2, which you need to get rid of. Water content-  you need to keep a balance between the water you gain (in drink, food and respiration) and the water you urinate, sweat and breathe out. Body temperature - You need to get rid of excess body heat when you're hot but retain heat when  you are cold.

When you're too hot - Hairs lie flat, lots of sweat is produced - when it evaporates it transfers heat to the environment, cooling you down and blood vessels are close to the surface of the skin. This allows more blood to flow near the surface, so it can radiate more heat into the surrounding - vasodilation.

When you're too cold - Hairs stand on end to trap an insulation layer of air that helps keep you warm, very little sweat is produced, Blood vessels near the surface constrict so that less heat can be transferred from the blood to the surroundings and you shiver so the movement generated heat in the muscles.

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Controlling blood sugar

Insulin controls blood sugar levels. Eating foods rich in carbohydrate puts a lot of glucose into the blood from the gut. Normal respiration in the cells removes glucose from the blood. Vigorous exercise also removes a lot of glucose from the blood. Levels of glucose in the blood must be kept steady. Changes in blood glucose are monitored and controlled by the pancreas using insulin.

Glucose is added and removed by liver according to the amount you have in your blood.

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Genes and chromosomes

Chromosomes are divided into different regions called genes. - 46 chromosomes arranged in 23 pairs for humans. They are also long lengths of DNA coiled up and a gene is a short section of this DNA.

Genes - each separate gene is a chemical instruction showing how to make a particular protein which control most processes in the body (enzymes) They help build cell membranes. Cells make proteins by stringing amino acids together in a particular order. - which the genes tell them.

The DNA double helix is made up of two ''strands'' that are joined together by things called bases. There are four different bases in DNA - A, T, C , G. The order of the bases in gene controls the order of amino acids in a protein. They all contain different sequences. 

Only use 20 different aminno acids. Genes control what proteins are made in a cell and this determines what type of cell it is. e.g white blood cell, skin cell. etc. 

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Genetic Variation

Two sources of genetic variation. Gamete Formation - making sperm cells and egg cells. Gametes are formed in the ovaries or testes from reproductive cells. Reproductive cells (like all human body cells) have 23 pairs of chromosomes. In each pair there's one that was originally inherited from mum, and one that was inherited from dad. When when reproductive cells split into two some of your dad's chromosomes are grouped with you mums. This shuffling of chromosomes leads a variation to the next generation. But we don't know which two will join together in fertilisation.

Mutations - changes the genetic coded. Occasionally a gene mutates - usually changes the sequence in the DNA bases.This could either stop the production of a protein or it might mean a different protein is produced instead. This can lead to new characteristics increasing variation. This can happen spontaneously or increased by exposing yourself to nuclear radiation and chemicals called mutagens. Mutations are usually harmful. - develop abnormally or die or cause cancer. Occasionally beneficial - natural selection.

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Genetic Diagrams

Dominant alleles are always shown with a capital letter (C).

Recessive alleles alleles with a small letter (c).

 If you're homozygous for a trait you have two alleles the same for that particular gene e.g CC or cc.

But if you're heterozygous for a trait you have two different alleles for that particulat gene e.g Cc.

 

 

Draw diagram to explain. (text book)

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