Biology 1

Healthy means being free of any infections or diseases. 

Being Fit is a measure of how well you can perform a physical task

Fitness profile measures strength, speed, agility and flexibility together with stamina.

The blood pressure is at its highest when the heart contracts- this is systolic pressure. 

When the heart relaxes, the pressure is at its lowest-this is diastolic pressure.

High blood pressure can be descreased by lifestyle changes, e.g. eating balanced diet and regular excerise.

Low blood pressure is much less common but it can cause poor circulation and tissues wont get the food and oxygen they need.  

Chemicals in cigarette:

1) Carbon Monoxide- This combines haemoglobin in red blood cells, which reduces the amount of oxygen they carry.

2) Nicotine- This increases heart rate. The heart contracts more often, increasing blood pressure. 

Staturated fats can build up cholesterol:

• Cholestrol is a fatty substance   Eating diet high in saturated fats has been linked to cholestrol in the blood.
• You need some cholestrol for things like making cell membranes. It can build up in your arteries. 
• This forms plagues in the artery wall, which narrow the arteries. They restrict blood flow which leads to heart attack. 

Narrow arteries increase the risk of a heart attack. 

1) the heart muscles is supplied with blood by the cornary arteries.

2) If these become narrowed blood flow tot he heart is restricted abd the heart muscles recieve less oxygen.

3) A thombrosis also restricts blood flow

4) If a thombrosis occurs in an already narrow coronary artery, bloof flow to the heart might be blocked completly. If this happens, an area of heart muscles will be cut off from its oxygen supply. 

5) This causes a heart attack. 

Carbohydrates are made up of simple sugars like glucose. They stored in the liver as glycogen or converted to fats.

Fats made up of fatty acids and glycerol. They can be stored under the skin and around organs. 

Proteins are made up of amino acids. They don't get stored

Choose to have different diet:

• Religious reasons-cows are sacred 
• Personal reasons- vegetarians don't eat meat 
• Medical reasons - some people are intolerant or allergc to certain foods

Too little protein causes Kwashiorkor. 

Overpopulation and not enough money to invest in agriculture are reasons for low protein in developing countries. 

Infectious diseases are caused by Pathogens. The four types are:

Fungi - Athlete's feet

Bacteria- Cholera

Virsus- Flu

Protozoa - Dysentry (infection in the intestines) 

Active Immunity is where the immune system makes its own antibodies after being stimulated by a pathogen. It includes becomign naturally and artificially immune. This is permanent.  

Passive Immunity is where you use antibodies made by another organism, This is temporary. 

Drugs developed to treat disease need to be tested. 

Computer models are often used first of all-these stimulate huamn responses to a drug. 

The drugs then are developed further by testing on human tissues. 

The last step is to develop and test the drug using animals. 

Smoking causes all sorts of illness: 

Heart Disease 

Lung, throat, mouth and oesophangal cancer

Smokes cough and severe loss of lung function

Low birth weight babies

Parts of an eye:

Cornea, iris, lens, retina, rods, cones and optic nerve.

To look at distant objects:

• The ciliary muscles relax which allows the suspensory ligaments to pull tight. 
• This pulls the lens into a less rounded 

To look at close objects:

• The cilliary muscles contracts, which slackens the suspensory ligaments. 
• The lens becomes more rounded shape, so light is refracted more. 

Binocular vision which includes two eyes to work together. 

The central nervous system coordinates information. In the CNS it contains a Stimulas, receptor, sensory neuron, CNS, motor neuron, effector and response. 

Reflex actions stop you from injuring yourself. They act as a protecting role for example snatching your hand back when you touch something hot. 

Neurones transmit information around the body as electrical impulses. 

Homeostasis is maintaining a constant internal environment. You need to balance feedbacks:

• Levels of Carbon dioxide
• Water Content
• Body Temperature. 

Negative Feedback is changes in the environment which triggers response that counteracts the changes. 

When your hot: hairs lie flat, lots of sweat is produced and blood vessels close to the surface of the skin widen (vasodilation). 

When your cold: hairs stand on the trap, very little sweat is produced and blood vessels near the surface constrict (vasoconstriction) 

Insulin controls blood sugar levels. Insulin is a hormone. Hormones travel in the blood, so it can take a while for them to get to where they're needed in the body. 

Blood glucose level too high-insulin is added.

Blood glucose level to low- insulin is not added. 

Type 1 diabetes is where the pancreas produces little or no insulin. The result is that a person's blood glucose level can rise. 

Type 2 diabetes is where a person  becomes resistant to insulin . This can cause blood sugar levels to rise. 

Auxins are plant growth hormones. 

Shoots are positivly phototropic (grows towards light)

Shoots are negatively geotropic (grows away from gravity)

Roots are positivly geotropi (grows towards gravity)

Roots are negatively phototropic (grows away from light)

Commericial use of plant hormones:

• As selectve weedkiller
• Growing from cuttings with rooting powder
• Controlling the ripening of fruit
• Controlling Dormancy

There are 3 sources of genetic variation:

• Gamete Formation
• Fertilisation
• Mutations 

Health, intelligence and sporting ability is determined by both genes and enviornment. 

If you're homozygous for a trait you have two alleles the same for particular gene. 

If you're heterozygous for a trait you have two different alleles for that particular gene. 

All men have X and Y chromosomes and Y causes male characteristics. 

All women have an X and X chromosome  and the ** combination causes femal characteristics.