The process in which there is separation of small molecules from large molecules across semipermeable membran… - IGNOU PB Bsc Nsg.Entrance-2026

IGNOU PB Bsc Nsg.Entrance-2026

Applied Physiology

Easy

Appeared in: IGNOU PB Bsc Nsg.Entrance-2026

Explanation

Dialysis is defined as the separation of molecules in a solution by differences in their rates of diffusion through a semipermeable membrane.
The key feature of this process is the size-selective nature of the membrane, which allows small solutes (like waste products such as urea) to pass through while retaining large molecules (like proteins and blood cells).
This principle is fundamental to the function of artificial kidneys (hemodialysis) in treating renal failure, where waste products are filtered from the blood.

Option B: Diffusion describes the general movement of any particles from a region of higher concentration to a region of lower concentration. It does not specifically describe the process of separating molecules based on size, although it is the mechanism that drives solute movement during dialysis.
Option C: Gravitation is a fundamental physical force of attraction between two objects with mass. It is not involved in the selective transport of molecules across a biological or synthetic membrane.
Option D: Osmosis specifically describes the net movement of a solvent (typically water) across a semipermeable membrane, from an area of lower solute concentration to an area of higher solute concentration. The question asks about the separation of solutes, not the movement of the solvent.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Transport and separation processes across a semipermeable membrane as background academic context rather than a clinical decision trigger.
This concept is the foundation of renal replacement therapy, specifically hemodialysis and peritoneal dialysis, for patients with End-Stage Kidney Disease (ESKD).
Nurses play a critical role in managing dialysis treatment, which includes preparing the equipment, monitoring the patient's vital signs, managing the dialysis access site (fistula, graft, or catheter), and assessing for complications like hypotension, cramping, and fluid/electrolyte imbalances.
What if? - If a patient on hemodialysis develops sudden hypotension (low blood pressure), the nurse's immediate actions are crucial. The nurse should reduce or temporarily stop the ultrafiltration rate, administer a bolus of normal saline as prescribed, and place the patient in the Trendelenburg position (head down, feet up) to improve blood flow to the brain.

How to Approach the Question

First, carefully read the question and identify the key phrases: 'separation', 'small molecules from large molecules', and 'semipermeable membrane'.
Recognize that the question is asking for a specific process defined by these characteristics, which is essentially a size-based filtration.
Evaluate each option based on its scientific definition.
Eliminate 'Gravitation' as it is an unrelated physical force.
Differentiate between the remaining options. 'Osmosis' is the movement of the solvent (water), not the separation of solutes. 'Diffusion' is the movement of solutes down a concentration gradient, but it doesn't inherently describe separation by size.
'Dialysis' is the precise term for separating solutes of different sizes using a semipermeable membrane.

Concept Tested & Keywords

Concept Tested: Transport and separation processes across a semipermeable membrane
Stem keywords: separation, small molecules, large molecules, semipermeable membrane
Lead-in keywords: is
Negative lead-in flag: false

QsWMgHCOmzD_25I91VZRSC

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 24-26

E6 Medicine Harrison 22e Part 2 p. 302-304