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