Page 127 - Biology Form Two

Biology for Secondary Schools

Symptoms of sickle-cell anaemia: cuts, extreme body weakness, anaemia,
Sickle-cell anaemia is characterised as well as throat and mouth infections
by fatigue or excessive tiredness, that may be recurrent.
shortness of breath during physical Prevention of leukaemia: The risk of
exercise, headeaches, dark-coloured getting leukaemia can be minimised by
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urine, abdominal pain, abnormal maintaining a proper lifestyle, including
heartbeat, and general body weakness. physical exercising, avoiding smoking
Prevention of sickle-cell anaemia: and maintaining healthy eating habits.

It is difficult to prevent sickle-cell High blood pressure (Hypertension)
anaemia since it is inherited, although The blood pressure of a normal human
premarital screening of sickle-cell being is 120/80 mmHg. Very high
anaemia may help to reduce the blood pressure (over 140/90 mmHg)
disorder. However, patients can be strains the blood vessels and causes
helped by making sure that they avoid hypertension and sometimes heart
excessive physical exercise and eat failure. An increase in blood pressure
a well-balanced diet which is rich may be caused by high fat levels due
in minerals and vitamins. Currently, to over-consumption of fatty foods, a
the introduction of gene therapy for lack of exercise, obesity, high emotional

sickle cell disease to correct the faulty stress, alcoholism, smoking, high salt
haemoglobin gene is enabling the body intake and arteriosclerosis.
to produce healthy red blood cells. Symptoms of hypertension: The signs
and symptoms of hypertension include
Leukaemia feeling dizzy, ringing sound in the
Leukaemia is a type of blood cancer. It ears, severe headache, and high blood

is caused by over production of white pressure over 140/90 mmHg recorded
blood cells and suppressed production in 3-4 consecutive days.
of red blood cells. The excess white
blood cells infiltrate body organs, Prevention of hypertension: Hypertension
for example, the liver and the spleen. can be prevented by engaging in regular
This causes reduced efficiency in physical exercise, avoiding alcoholism,
the functioning of these organs and and smoking. It can also be prevented
abnormal enlargement. by eating a balanced diet, limiting salt
intake, maintaining a healthy weight
Symptoms of leukaemia: Leukemia and reducing stress as much as possible.
is characterised by abnormally high
numbers of white blood cells and Coronary thrombosis
abnormal bleeding. For example, nose Coronary thrombosis occurs when
bleeding, bleeding even from minor blood clots occur in the blood vessels

Student’s Book - Form Two 121

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BIOLOGY FORM 2 NEW.indd 121