mechanism of dialysis

Question 1

step 1

Answer 1

Blood is drawn from the vein in the patient’s arm and is allowed to be pumped through the tubing in the dialysis machine

Question 2

step 2

Answer 2

The tubing is bathed in a specially controlled dialysis fluid. The walls of the tubing are partially permeable

Question 3

step 3

Answer 3

Small molecules, like urea and other metabolic waste products, diffuse out of the tubing into the dialysis fluid. Blood cells, platelets and large molecules remain in the tubing

Question 4

step 4

Answer 4

The filtered blood is then returned to a vein in the patient’s arm

Question 5

features

Answer 5

• dialysis fluid contains the same concentration of essential substances as blood (eg. glucose, amino acids, minerals) so that these substances do not diffuse out of the blood into the machine
• dialysis fluid does not contain metabolic waste products to maintain concentration gradient for the diffusion of waste products
• dialysis tubing is narrow, long and coiled to increase the surface area to volume ratio for faster rate of diffusion of substances
• direction of blood flow is opposite from flow of the dialysis fluid to maintain the concentration gradient for faster diffusion of substances