OCR B1

Healthy- being free of infections or diseases 

Fit- a measure of how well you can complete physical activities. Can be measure through strength, stamina (a good indication of cardiovascular efficiency), agility, flexibility and speed.

Blood pressure is at its highest when the heart contracts (systolic pressure)

Blood pressure is at its lowest when the heart relaxes (diastolic pressure)

systolic pressure should be about 135mmHg and diastolic pressure should be about 85mmHg

Factors that increase your blood pressure- smoking, being overweight, drinking too much alcohol and being under stress for a long period of time

High blood pressure- causes blood vessels to burst leading to strokes, brain damage and kidney damage. High blood pressure can be decreases by lifestyle changes and drugs.

Low blood pressure- causes poor circulation and lack of food/oxygen to tissues. This can cause dizziness and fainting.

Carbon monoxide- combines with haemoglobin which reduces the amount of oxygen they carry. To make up for this the heart rate increases which increases the blood pressure.

Nicotine- The heart contacts more frequently which increases the blood pressure.

Saturated fat- diets high in this is linked to high levels of cholestral, you need some to make cell membranes but too much can start to build up in the arteries which can cause plaques which narrows the arteries. This can restrict blood flow to the heart causing heart attacks.

Salt- Increases blood pressure, this can cause damage of arteries, this increases the build up of plaques which can lead to heart attacks.

If coronary arteries become narrowed blood flow to the heart becomes restricted. Thrombosis' also restrict blood flow. A narrowed artery and a thrombosis can lead to a heart attack.

Carbohydrates- provide energy. Made up of simple sugars and stored in the liver as glycogen

Fats- provide energy and insulation. Made up of fatty acids and glycerol and stored under the skin or around organs as adipose tissue.

Protiens- growth and repair of tissues and emergency energy. Made of amino acids and arent stored.

Vitamins and minerals- vitamin C prevents scurvy, iron is needed to make haemoglobin.

Water- prevents dehydration

Essentail amino acids- cant be made by diet so have to get them from your diet 

First class protiens- come from meat

Second class protiens- dont contain all essentail amino acids

Age- children need more protien for growth. Old people need more protien for their bones

Gender- Females need more iron to replace that lost in the menstrual cycle 

Physical activity- Active people need more protien for muscle development and carbohydrates for energy 

Kwashiokor- caused by eating too little protien

Overpopulation means more demand for protien rich food so not enough for everyone

Lack of money- Cant invest in agriculture and so cant provide enough protien rich food

EAR (estimated daily allowance of protien)= 0.6 x body mass (kg)

EAR varies- Teenagers need more protien for growth 

Pregnant women need extra protien for baby and to produce milk after birth 

Anorexia leads to self starvation. Bulimia leads to binge eating and self induced vomiting. These both lead to liver failure, kidney failure, heart attacks, muscle wastage and mineral deficiences. Both can be fatal.

BMI- decides if someone is overweight, normal or underweight. It isn't always reliable e.g. athletes have lots of muscles which makes them heavier but their not overweight.

BMI= body mass(kg)/ (height)2 (m)

Four types of micro-organisms- fungi (athletes foot), bacteria (cholera), viruses (flu), protozoa (dysentry)

Malaria- caused by a protozoan that is a parasite (an organism that lives off of another organism (the host) and often causes it harm. The mosquitos are vectors- they carry the disease without carrying it themselves. 

We can reduce the amount of mosquito's by- draining the water where they lay their eggs, introducing fish to eat them and using pesticides and mosuito nets.

White blood cells attack pathogens by- engulfing them.

producing antitoxins to counter the effect of the poisens the pathogens produce

produing antibodies- each pathogen has a unique molecule (antigens). When white blood cells come across a foriegn antigen they produce matching antibodies to lock onto and kill the pathogen. Some of the white blood cells stay (memory cells), so if the same antigen appears they ca kill it immediately.

Four types of micro-organisms- fungi (athletes foot), bacteria (cholera), viruses (flu), protozoa (dysentry)

Malaria- caused by a protozoan that is a parasite (an organism that lives off of another organism (the host) and often causes it harm. The mosquitos are vectors- they carry the disease without carrying it themselves. 

We can reduce the amount of mosquito's by- draining the water where they lay their eggs, introducing fish to eat them and using pesticides and mosuito nets.

White blood cells attack pathogens by- engulfing them.

producing antitoxins to counter the effect of the poisens the pathogens produce

produing antibodies- each pathogen has a unique molecule (antigens). When white blood cells come across a foriegn antigen they produce matching antibodies to lock onto and kill the pathogen. Some of the white blood cells stay (memory cells), so if the same antigen appears they ca kill it immediately.

Active immunity- the immune system makes its own antibodies when stimulated by a pathogen. It includes natrual and artificial immunity. It is permenant.

Passive immunity- antibodies made by another organism e.g. mother to baby through breast milk. Its only temporary.

Vaccination- injecting dead/ inactive pathogens into the body. White blood cells produce antibodies to attack them, the memory cells are also produced.

Immunisation benefits- stops you getting ill, disease wont be spread as easy

Immunisation risks- short term side effects, cant have vaccines if already ill, some people think they may cause disorders e.g. links between MMR vaccine and autism

Antibiotics- kill bacteria without killing body cells. They dont kill viruses. Antivirals stop viruses from reproducing. Misuse of antibiotics is increasing the rate of resistant strains so doctors have to be more careful.

Benign tumor- it grows until there is no more room. This type isnt dangerous.

Malignant tumor- it can grow and spread to other parts of the body. Dangerous and fatal.

Reducing risk of cancr- not smokig, eating less processed meat and more fibre.

Drug development process-

• Computer models are used first to stimulate human responses (not as accurate as a live human)
• Then tested on human tissues (not good for drugs that affect the whole body'
• Tested on animals- drugs must be tesed on two live mammals however some people think its cruel but its the safest way to ensure it doesnt harm humans
• Test on humans (clinical trial)- one group of people are given the real drug, one group is given a placebo to see if the drug actually works. Sometime scientists compare the drugs against the best selling drugs. Clinical tests are blind or double blind (neither the patient or doctor knows who has the real drug and who has the placebo)

• Drugs- A subastance that alters the the body works
• Addiction- They have a physical need for the drug and will experience withdrawal symptoms without it
• Tolerance- The body is used to it and so needs more to have the same effect

• Depressants (e.g. alcohol)- Descreases the activity of the brain slowing the response of the nervous system resulting in slow reactions and poor jusgement of speed and distance.
• Stimulants (e.g. caffiene)- Increase the activity of the brain making you alert and awake
• Painkillers (e.g. aspirin)- reduce the number of painful stimuli at the nerve endings near an injury
• Performance enhancers (e.g. anabolic steroids)- help to build up muscle allowing athletes to train harder
• Hallucinogens (e.g. LSD)- distort what is seen/ heard by altering the pathways the brain sends a message along.

In the UK there are three main categories for illegal drugs-

• Class A- heroin
• Class B- cannabis
• Class C- tranquillisers

Alcohol- makes people less inhibited. Alcohol is poisonous. It is broken down by enzymes in the liver producing toxic products which kill the liver cells and cause cirrhosis meaning the liver can't clean the blood. It also causes dehydration.

Being drunk leads to impaired judgement, poor balance, poor coordination, slurred speech, blurred vision and sleepiness.

Smoking illnesses:

• Heart disease- co reduce oxygen in the blood, if the heart doesn't recieve oxygen a heart attack will occur.
• Lung/throat/mouth cancer- tar(containing carcinogens) collects in the lungs. It cause mutations which can go out of control
• Emphysema- the cilia is damaged which encourages mucus production, it sticks to the passages, the lungs lose their elasticity causing emphysema.
• Low birth weight babies- the foetus can be deprived of oxygen causing lightweight baby.

Parts of the eye:

• Cornea- retracts light into the eye
• Iris- controls how much light enters the pupil
• Lens- retracts light and focsuses on retina
• Retina- detects light using rods(dim) and cones(colour)
• Optic nerve- carries impulses from receptors to the brain

Looking at distant objects:

• ciliary muscle relaxes allowing the suspensory ligaments to pull tight
• Pulls the lens into a less rounded shape so light is refracted less

Looking at close objects is the opposite to distant objects.

long sighted(can't focus on near objects): occurs when the eyeball is too short so the image is brought into focus behind the retina. Glasses with convex lenses needed

Short sighted(can't see distant objects): when the eyeball is too long so the image is focused I front of the retina. Glasses with concave lenses are needed.

Binocular vision- two eyes that work together. When you look at an image your brain compares the image from each eye, the more similarities the further away the object. This allows us to judge distances but gives us a narrow field of vision.

The CNS consists of the brain and the spinal cord. The NS is made of three types of nuerone- sensory, relay and motor. Process of the NS= stimulus, receptor, sensory neurone, CNS, motor neurone, effector, response.

Reflex actions are quicker than the CNS as they are automatic. In this case the sensory neurone links to a relay neurone in the spinal cord which is directly linked to the correct motor neurone, this is usually used in a protective role e.g. removing hand from something hot.

Neurones have branched endings and so can conect to other neurones. They have a sheath which acts as an insulator and speeds the electrical impulse up, they are long which also speeds it up. the connection between two neurones is the synapse. 

• The electrical impulse triggers the release of transmitter chemicals across the synapse
• The chemicals bind to the receptor molecules to set off a new impulse.

Homeostasis balances the inputs and outputs e.g. carbon dioxide intake, body temperature and water intake. 

Negative feedback- changes in the environment trigger a response that counteracts the changes

Enzymes have an optimium temperature, in the human body it is 3‎7 degrees. Theres a thermoregulatory system in the brain that contains receptors that are sensetive to blood temperature in the brain, it also has information about skin temperature. It responds to this and controls the temperature-

If your too hot:

• Hairs lie flat
• Lots of sweat is produced (when it evaporates it uses heat from your skin)
• vasodilation (vessels widen so their close to the skin so more heat radiates)

If your too cold:

• Hairs stand on end to trap an insulating layer of air to keep you warm
• Very little sweat is produced
• Vasoconstriction (vessels near the skin constrict which means heat is transferred)
• You shiver (the movement generates heat in the muscles)

Eating food containing carbohydrates puts glucose in the gut. Normal respiration and exercise remove the glucose. The levels of glucose are controlled by the pancreas-

Blood glucose level is too high- insulin is added:

• Insulin is released from the pancreas
• The glucose is removed by liver 
• Blood glucose is released

Blood glucose level is too low- insulin is not added:

• Insulin is not released
• Glucose added by the liver
• Blood glucose is increased

Type 1 diabetes- Can partly control the condition but need to inject insulin as well, this will make the liver remove the glucose. The amount of insulin depends on the diet/ exercise of the person.

Type 2 diabetes- When a person becomes resistant to insulin. Usually controlled by avoiding foods rich in simple carbohydrates.

Auxin promotes growth in the shoots and inhibits growth in the roots.

Shoots are positively phototropic- when a shoot is produced to light more auxin is produced on the side in the shade. The shaded side elongates so the plant bends towards to light.

Shoots are negatively geotropic- when a shoot grows sideways gravity produces more auxin on the lower sidee this cause the lower side to grow quicker and the shoot bends upwards.

Roots are positively geotropic- a root growing sideways will have more auxin on its lower side the cells ontop elongate faster and so the root bends downwards.

Roots are negatively phototropic- if a root is exposed to light auxin accumulates on the shaded side, cell elongation is inhibited on the shaded side so the root bends downwards.

Selective weedkillers- most weeds have broad leaves and crops have thin leaves. selective weedkillers have been developed from plant hormones to only target broad leaved plants which means the crops stay untouched.

Rooting powder- if you add rooting powder, which contains plant growth hormone, to a planted cutting they will produce roots and start growing. this enables the production of lots of clones.

Controlling the ripening of fruits- plant hormones can be used to delay the ripening of fruits, this allows th fruit to be picked when they are unripe, ripening hormone is added so it is ripe when it reaches the supermarket

Controlling dormacy- a hormone called gibberellin breaks plant dormacy and allows seeds to germinate. this means plants can grow at all times of the year, even when their not meant to.

• Most cells in your body have a nucleus which contain all your genetic information
• Animal hormones come in pairs. Human chromosomes have 23‎ pairs
• Chromosomes carry genes, different genes control development of different characteristics 
• A gene is a short length of the chromosome which is quite a long length of DNA 
• The DNA is coiled up to form the arms of the chromosomes 
• Alleles- different versions of the same gene giving different characteristics

Gamete (sperm and egg) formation-

• made in ovaries or testes
• gametes have 23‎ chromosomes. When they join they form 46 chromosomes.
• In each gamete sme of your dads chromosomes are mixed with some of your mums which causes variation

Fertilisation-

• when sperm and egg form to make a new cell with 46 chromosomes
• Fertilisation is random- you dont know which two gametes will join together

Mutations-

• Occaisionally a gene may mutate (change) creating new characteristics, increasing variation

Your environment also affects you-

• Health- Life style can affect the likeliness to get certain diseases e.g. smoking/ junk food
• Intelligence- Upbringing and school affects this 
• Sporting ability- training determines how good you will be at sports

If there are two different alleles the version that appears is the dominant allele will be expressed. The other allele is recessive which is only expresses if there are no dominant alleles. 

Homozygous- you have two alleles the same for that particular gene 

Heterozygous- you have two diffrent alleles for that particular gene

Genotype- your genetic makeup

Phenotype- the characteristics that these alleles produce

The 23‎rd pair are labelled XY and decide whether you are male or female. All men have an X and a Y chromosome: X, the Y chromosome causes male characteristics. All women have to X chromosomes: **. 

There is a 50:50 chance of having a boy or a girl however this is only a probability.

Cystic fibrosis has a recessive allele.

Knowing there are inhereted illnesses in your family raises problems:

• Should all the family member be tested? Some people prefer not to know but it could affect children.
• Is it right for someone with a genetic disease to have children?
• If a foetus is tested for the illness in the womb and is positive is it right to terminate the pregnancy? Some people believe that bortion is wrong under any circumstances.