Nitrogenous wastes spearated in haemodialyser by

Options

A. Actively
B. Diffusion
C. Facilitated transport
D. Both (1) and (3)

Answer

### Step-by-Step Solution:

1. **Understanding Hemodialysis**: Hemodialysis is a medical procedure used to remove waste products, such as nitrogenous wastes, from the blood when the kidneys are not functioning properly. This is particularly important in conditions like uremia, where urea accumulates in the blood.

2. **The Role of the Dialysis Unit**: In hemodialysis, blood is drawn from the patient and pumped into a dialysis unit, often referred to as an artificial kidney. This unit contains a special fluid that mimics the composition of blood plasma but lacks nitrogenous wastes.

3. **Use of Anticoagulants**: Before the blood enters the dialysis unit, an anticoagulant (like heparin) is added to prevent clotting during the process.

4. **Porous Membrane Function**: The dialysis unit has a porous membrane (often made of cellophane) that allows certain molecules to pass through. The separation of nitrogenous wastes occurs through this membrane.

5. **Mechanism of Separation**: The nitrogenous wastes in the blood diffuse across the membrane into the dialysis fluid. This process occurs due to the concentration gradient; since the dialysis fluid has a lower concentration of nitrogenous wastes (like urea), the wastes move from the area of higher concentration (blood) to the area of lower concentration (dialysis fluid).

6. **Diffusion Process**: The separation of nitrogenous wastes is primarily through simple diffusion, where molecules move freely according to their concentration gradient without the need for energy (ATP) or special transport proteins.

7. **Return of Cleared Blood**: After the nitrogenous wastes are removed, the cleaned blood is returned to the patient's body, often after adding an anticoagulant to prevent clotting again.

### Final Answer:
Nitrogenous wastes are separated in a hemodialyzer primarily by **simple diffusion**.

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