Tissue Fluid Lecture Notes

Introduction

• Topic: Tissue fluid
• Presenter: Miss S
• Key Points:
  • What tissue fluid is
  • How tissue fluid is formed
  • How tissue fluid is reabsorbed

What is Tissue Fluid?

• Definition: Liquid surrounding body cells.
• Components:
  • Water
  • Glucose
  • Amino acids
  • Fatty acids
  • Dissolved ions and minerals
  • Oxygen
• Function: Provides cells with essential molecules for survival (e.g., respiration).

Formation of Tissue Fluid

• Capillaries:

  • One cell thick with tiny gaps between cells.
  • Allows water and small molecules to be forced out.

• Blood Flow Process:

  • Arteries → Arterioles → Capillaries
  • High pressure in capillaries leads to ultra-filtration.
  • Acts like a sieve: small molecules forced out, large molecules remain.

• Molecules Forced Out:

  • Water, dissolved minerals, salts, glucose
  • Small proteins, amino acids, fatty acids, oxygen

• Molecules Not Forced Out:

  • Red blood cells, platelets, large proteins

Reabsorption of Tissue Fluid

• Importance: Prevents liquid overflow and swelling.

• Process:

  • Occurs at the venule end of capillaries (near veins).
  • Large molecules in blood create a negative water potential.
  • Osmosis: Water in tissue fluid moves back into capillaries down the water potential gradient.

• Waste Removal:

  • CO2 and urea dissolve in water, reabsorbed into blood.

Lymphatic System

• Role: Absorbs remaining tissue fluid not reabsorbed by capillaries.
• Components:
  • Lymph vessels (similar to veins)
  • Lymph vessels reintroduce fluid into blood near the heart.
• Terminology: Absorbed fluid is called 'lymph.'

Summary

• Tissue fluid is essential for cell function and waste removal.
• Formation driven by high hydrostatic pressure.
• Reabsorption through osmosis and the lymphatic system ensures fluid balance.

Ensure you understand how the pressure gradients and the lymphatic system function to maintain homeostasis.