Blood Pressure

Every time your heart beats, the left ventricle squeezes hard and pushes pure, oxygen-rich blood into the arteries. That blood does not slide along quietly. It presses outward on the inner walls of the arteries, in the same way water presses on the inside of a garden hose when the tap is opened fully. This push of blood on the walls of the blood vessels, and most of all on the walls of the arteries, is blood pressure.

How strong this push is depends on four things inside the body:

• the size of the blood vessel
• the flow of blood through it
• the amount of blood in the body
• the force created when the ventricle contracts

A narrow vessel, more blood, or a harder squeeze of the ventricle all raise the pressure. Blood pressure also depends on the person: their mental state, age, sex and physical state. That is why one person's reading changes during a day. It goes up when they are angry, frightened or running, and comes down when they sit and rest.

Blood pressure is measured in the unit mmHg, read aloud as millimetres of mercury. The number says how many millimetres high the pressure could push a column of mercury in a glass tube.

The heart does two jobs in turn. The ventricle contracts and pumps, then it relaxes and fills again. The pressure in the arteries is highest while the ventricle contracts and lower while it relaxes. So blood pressure is always given as two values, an upper reading and a lower reading.

The normal blood pressure of an adult is 120/80 mmHg, said as "120 over 80". Here 120 mmHg is the systolic pressure and 80 mmHg is the diastolic pressure. The slash only separates the two readings. It does not mean divide.

The device used to measure human blood pressure is the sphygmomanometer. A cloth cuff is wrapped around the upper arm and pumped up with air until it presses the artery shut for a moment. As the air is let out slowly, blood starts to push through again, and the health worker reads the upper and lower values on the scale.

Nowadays blood pressure is also measured by digital methods. A digital machine pumps its own cuff and shows both readings as numbers on a small screen, so it is common in homes and health posts. Because mood and activity change the pressure, a person should sit quietly for a few minutes before the reading is taken.

Suppose a man's reading is 150/95 mmHg. His systolic pressure of 150 mmHg is above 140, and his diastolic pressure of 95 mmHg is above 90. His reading exceeds 140/90 mmHg, so he has high blood pressure. A person with high blood pressure may show these symptoms:

• headache and shortness of breath
• bleeding from the nose
• sweating and fatigue
• a red face
• sleeplessness and anxiety

High blood pressure has many causes. Most of them are habits of daily life, and one is passed down in families:

• lack of regular physical exercise
• high blood pressure running in the family (heredity)
• smoking and drinking alcohol regularly
• excessive body weight
• a physically and mentally stressful life
• eating too much salty and fatty food

Think of how each one acts. Extra body weight means the heart must push blood through more tissue. Fatty food can leave deposits that narrow the arteries, and a narrow vessel raises the pressure. Stress makes the heart beat harder. Each cause adds to the push on the artery walls.

High blood pressure leads to many physical and mental problems, so it is best avoided by paying attention in time. These habits help:

• Pay attention to your daily meals and eat less salty and oily food.
• Avoid smoking and drinking alcohol.
• Eat a balanced diet.
• Take physical exercise every day.
• Do yoga, meditation and pranayama.
• Check your blood pressure often.
• Live a stress-free life.
• Take part in recreational activities.

When rice, bread or fruit is digested, it gives glucose, a sugar that enters the blood. Body cells use this glucose for energy, but they need the hormone insulin to take it in and use it. When insulin becomes low for any reason, the cells cannot take in enough glucose. It stays in the blood, and the blood sugar level rises.

• excessive thirst and hunger
• frequent dizziness and unconsciousness
• frequent urination
• blurred vision
• the person becomes thin and tired
• muscle spasms and numbness in the hands and legs
• wounds that heal slowly

These symptoms fit together. The extra glucose leaves the body in urine, which pulls water out with it, so the person urinates often and feels thirsty. The cells are short of glucose even though the blood is full of it, so the person feels hungry and tired and slowly becomes thin.

• not enough insulin being secreted
• obesity and an inactive lifestyle
• an imbalanced diet
• eating too much food rich in fat and carbohydrate
• heredity

• Eat plenty of green vegetables and fruits.
• Exercise regularly.
• Keep your weight right for your body.
• Keep an active lifestyle.
• Live a stress-free life.
• Go for a morning walk every day.
• Eat a balanced diet.

Some foods contain a substance called purine. The body also needs purine all the time, because it uses purine to build DNA and RNA. When purine is broken down, during digestion and during metabolism inside body cells, it forms uric acid. Eating too much purine-containing food produces more uric acid than usual.

Uric acid is made mainly in the intestine and the liver. The blood carries it to the kidneys, which pass it out of the body. On the way it does useful work: it helps remove other toxic substances, including plaque deposited on the walls of blood vessels, and so keeps blood circulation smooth. Trouble begins only when there is too much of it.

• pain in the joints
• deep pain in the muscles
• a greater chance of kidney stones
• redness, swelling and a burning feeling in the skin
• severe pain in the joints of the toes
• difficulty in walking and moving

So if an old man's toes and knees swell and ache after a feast of meat, lentils and fried snacks, uric acid is the first thing to suspect.

• The kidneys cannot work properly because of diabetes or another disease, so they cannot excrete uric acid.
• Eating too much purine-rich food.
• The habit of drinking too little water.

Notice that the first reason links two conditions of this topic. Diabetes can damage the kidneys, and weak kidneys let uric acid pile up in the blood.

• Exercise regularly.
• Drink enough water, a little at a time, many times a day.
• Avoid drinking alcohol and smoking.
• Consume baking soda.
• Eat cherries. They contain anthocyanin, an antioxidant that helps lower uric acid in the blood.
• Eat less fatty red meat, sea food, pulses and similar foods.
• Keep purine-rich food to a small amount.