Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Kidney failure occurs when the kidneys cannot effectively filter waste products like (urea) from the blood or regulate the balance of and mineral ions.
Dialysis (haemodialysis) is a clinical process where blood is diverted into an external machine to be cleaned. It relies on the principle of diffusion across a partially permeable membrane.
The dialysis fluid (dialysate) contains a concentration of (glucose) and mineral salts equal to that of healthy blood to prevent their loss from the patient's body.
The dialysis fluid contains urea, creating a steep concentration gradient () so that diffuses out of the blood rapidly.
Kidney transplant involves surgically placing a healthy donor kidney into the patient. This requires a close 'tissue match' based on antigens to minimize the risk of rejection.
Post-transplant, patients must take immunosuppressant drugs for life to prevent their immune system from attacking the new organ.
Comparison: Dialysis is a temporary, time-consuming solution requiring strict diets, whereas a transplant offers a more 'normal' life but carries surgical risks and the danger of organ rejection.
📐Formulae
💡Examples
Problem 1:
Explain why the concentration of in the dialysis fluid is kept the same as the concentration in the patient's blood.
Solution:
To prevent the net movement of out of the blood via diffusion.
Explanation:
If the fluid had a lower concentration, essential needed for respiration would leave the blood. By keeping the concentrations equal, the concentration gradient () is zero, so no net diffusion occurs.
Problem 2:
Why must the dialysis fluid be constantly refreshed during the procedure?
Solution:
To maintain a steep concentration gradient for and other waste products.
Explanation:
As diffuses out of the blood into the fluid, the concentration in the fluid increases. If not refreshed, the fluid would eventually reach equilibrium with the blood (), and excretion of waste would stop.