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Homeostasis and the Kidney

Ultrafiltration and selective reabsorption

  • 3 things to know
  • Component 3

Overview

Three layers a substance crosses during ultrafiltration, three substances present in the glomerular filtrate and two components of blood that are not filtered.

What you need to know

Answer each one before you reveal it.

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Key term

What is ultrafiltration?

Key term

Name the three layers a substance crosses during ultrafiltration.

Key term

What are podocytes?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is ultrafiltration?

    Model answer

    The filtering of the blood in the glomerulus under high pressure, so that small molecules pass into the renal capsule.

  2. 2

    Name the three layers a substance crosses during ultrafiltration.

    Model answer

    The capillary endothelium, the basement membrane and the podocyte layer of the capsule.

  3. 3

    What are podocytes?

    Model answer

    The cells lining the renal capsule, whose finger-like projections leave gaps for the filtrate to pass through.

  4. 4

    Name three substances present in the glomerular filtrate.

    Model answer

    Water, glucose and urea, together with mineral ions and amino acids.

  5. 5

    Name two components of blood that are not filtered, and say why.

    Model answer

    Plasma proteins and red blood cells, because both are too large to pass through the basement membrane.

  6. 6

    What is selective reabsorption?

    Model answer

    The return of useful substances from the filtrate to the blood as the filtrate passes along the tubule.

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