OCR Gateway GCSE biology - B1 Revision Slides

B1 :)

Fitness and blood pressure

Healthy means being free of infections/diseases Fitness is a measure of how well you can perform physical tasks Fitness can be measured in different ways: Strength Speed Agility Flexibility Stamina Cardiovascular efficiency (the ability of the heart to supply the muscles with oxygen). This is tested by measuring oxygen uptake during exercise and blood pressure The most effective way of measuring someone's fitness depends on the activity being carried out, e.g. you measure a runner's athlete by speed, not strength, like you would for a weight lifter Blood is pumped around the body under pressure This is done through contractions of the heart, which increase pressure of the blood The blood leaves the heart and flows through arteries Arteries split into thousands of tiny capillaries Capillaries take blood to every cell in the body The blood then flows back to the heart through veins The pressure gets lower as the blood flows through the system Systolic pressure in a healthy person is about 135 Diastolic pressure in a healthy person is about 85 Blood pressure is measured in millimetres of mercury (mmHg) Blood pressure can be increased by: Smoking Being overweight Drinking too much alcohol Being under lots of stress for a long time High blood pressure can cause: Blood vessels to burst. This can lead to strokes, brain and kidney damage High blood pressure can be decreased through lifestyle changes, e.g. eating a balanced diet & regular exercise In extreme cases drugs can be used to treat the problem Low blood pressure causes poor circulation. Tissues don't receive all the oxygen & glucose they need. If the brain doesn't receive enough glucose & oxygen, you can get dizzy & end up fainting