Page 101 - Biology_Form_3

Biology for Secondary Schools

excessive water loss. Some chronic
Exercise 4.4
diseases gradually cause the kidneys to
1. How does the lung function as an stop functioning. Examples of such diseases
excretory organ? include high blood pressure and high blood
2. What would happen if the liver fails sugar. Obstruction of renal artery may also
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to remove bile pigments? lead to kidney failure because it blocks the
3. Why is sweating more important flow of blood to the kidneys. Toxicity from
for temperature regulation than heavy metals can also cause kidney failure.
excretion? Heavy metals such as Cadmium (Cd),

4. How does the liver contribute to Mercury (Hg), Lead (Pb), Chromium (Cr),
maintaining blood composition? Arsenic (As) and Platinum (Pt) are major
5. A person has difficulty breathing. environmental and occupational hazards
How might this affect excretion? that play a significant role in development
of renal failure.
Common complications and
disorders of the excretory system Chronic kidney disease (CKD) has also been
Task 4.4 linked to lifestyle factors such as poor diet,
smoking, and obesity. In addition to that,
Search for information from library and genetic predisposition may also play a role.
online sources about the complications The effects of renal failure include oedema.
and disorders of the human excretory Oedema is swelling of the legs, ankles, feet,
system. Write a short summary of the face or hands due to excess fluids and high
information you searched. levels of urea in the blood. Symptoms of

oedema include vomiting, nausea, weight
Excretory disorders involve infections or loss, blood in urine, difficulty in urinating
conditions affecting any of the excretory and loss of appetite. Kidney failure also
organs. There are several complications causes a rise in Potassium levels leading
and disorders associated with the excretory to failure of the body to produce enough
system. These include: erythroprotein for adequate red blood cell
production. As a result, a person suffers
(a) Kidney or renal failure from anaemia.
This is the failure of the kidney to function
adequately due to partial or total destruction Treatments include gene therapy trials and
of nephrones. It can be caused by several stem cell research for kidney regeneration.
factors including the damage of the kidney CKD cannot be fully cured especially at
due to accident or complications during late stages. The treatment usually depends
surgery. It may also be caused by low blood on the severity of the damage where the
volume due to excessive bleeding, poor focus is on managing the symptoms, and
intake of fluids and medication. Medicines preventing more complications. This can
such as diuretics or water pills may cause be achieved by monitoring and controlling

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