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Chapter: 11th 12th standard bio zoology Human Body higher secondary school

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Blood Pressure : Intensive of hypertension

Blood pressure is the force exerted by the flow of blood against the walls of the main arteries while flowing through them. Blood pressure rises or falls as the heart responds to the varying demands made by the body during different activities such as exercise, stress and sleep.

Blood Pressure

Blood pressure is the force exerted by the flow of blood against the walls of the main arteries while flowing through them. Blood pressure rises or falls as the heart responds to the varying demands made by the body during different activities such as exercise, stress and sleep.

 

Two types of pressure are measured. Systolic (the highest) is the pressure created, by the ventricular muscle and the elastic recoil of the aorta (main vessel leaving the heart) as the blood flows through it. Diastolic pressure (the lowest) is recorded during relaxation of the ventricles between beats. It reflects the resistance of all the small arteries in the body and the load against which the heart must work. The pressure wave transmitted along the arteries with each heart beat is felt as the pulse.

 

Blood pressure is measured using a sphygmomanometer. A healthy adult has a blood pressure reading of about 120/80 mm Hg (120 mm.Hg - systolic and 80 mm Hg - diastolic). This often rises normally with age to about 130/90 at 60. Abnormally high blood pressure is known as hyper ten-sion. Hyper tension is defined as the 'Systolic pressure equal to or greater than 160 mm Hg and (or) the diastolic pressure equal to or greater than 95 mm Hg'. Abnormally low pressure is termed hypotension.

 

Intensive of hypertension

 

Hyper tension puts a strain on the heart and blood vessels. Apart from increasing the risk of having a stroke or developing heart failure or coronary artery disease, high blood pressure may cause kidney damage and retinopathy (damage to the retina at the back of the eye).

 

Causes

 

Hypertension is linked with obesity and in some people to a high intake of salt, alcohol, smoking appears to aggravate the effects of hypertension.

 

Preventive measures :- Alcohol consumption and smoking should be avoided. Obese persons should make an attempt to reduce weight through restriction of food intake and try regular exercise. The dietary intake of animal fat (milk, cream, cheese fatty meat and eggs) should be reduced. A restricted intake of salt is recommended.

 

Heart transplantation involves replacement of a person's damaged or diseased heart by a healthy human heart taken from a donor in whom brain death has been certified. Heart transplantation in animals was first achieved in 1959. The first human heart transplant was performed by Professor Christian Bernard in South Africa in 1967.

 

Limiting factors for Heart transplant surgery

 

1.Problem of timing : A heart transplant is possible only when a suitable donor heart is available at right time.

 

2.Problem of fall-back system : If the heart is rejected (attacked by the body's immune system) the only hope for the patient is another transplant.

 

3.Problem in the certification of brain death.

 

The success of heart transplant lies in allowing doctors to certify brain death while the heart was beating. Heart is generatly removed for transplantation from a person certified for brain death by doctors.

 

Pulse rate

 

The rhythmic expansion and contraction of an artery as blood is forced through it (pumped by the heart) is known as pulse.

 

The pulse can be described in terms of its rate (number of expansion per minute) its rhythm, strength and whether the blood vessel feels hard or soft.

 

The pulse rate is determined by counting the beats in a set period (minimum 15 to 20 seconds) and multiplying to give the beats per minute. The pulse rate usually corresponds to the heart rate which varies according to the persons state of relaxation or physical activity.

 

Abnormal rhythm may be a sign of heart disorder. If the pulse feels weak, it may be a sign of heart failure, shock or an obstruction to the blood circulation. Weak or absent pulse in one or both legs is a sign of peripheral vascular disease.

 

Cardio - Pulmonary Resuscitation

 

Cardio - pulmonary resuscitation is the administration of the life - saving measures of external cardiac compression massage and mouth to mouth resuscitation (Artificial respiration) to someone collapsing with Cardiac arrest (Cessation of heart beat)

 

It is vital to restore the circulation of oxygen carrying blood to the brain as quickly as possible because permanent brain damage is likely to occur if the brain is starved of oxygen for more than three to four minutes

 

The blood :-

 

The blood is a fluid connective tissue. It consists of liquid plasma and cells. The plasma makes up 55% of the total volume and 45% of cells or formed elements. The total blood volume in human female is about 4-5 litres and 5-6 litres in males.

 

Plasma :- The blood plasma is a slightly alkaline fluid. It is straw coloured.

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