CAM201 Lecture Notes - Lecture 3: Pinocytosis, Subclavian Vein, Paracellular Transport
Learning Objectives
• Review the structure of a capillary and a capillary bed
• Describe how substances traverse the capillary wall
• Define the Starling forces and explain how they relate to oedema
• Describe the structure and function of the lymph system
• Describe how blood flow through capillaries is varied according to the metabolic needs of
cells/tissues
The Capillary
• Smallest and most numerous blood vessel
• The average diameter is ~5-10um (RBC is ~7um)
• Collective length of ~100km and surface area of ~1000m2 (about 3 tennis courts)
Function
• Point of deliver of tissue nutrients (O2, glucose)
• Point of removal for tissue waste (CO2, lactate)
Properties
• Smooth, non-pulsatile blood pressure
• Slow blood flow velocity
• Thin and a little leaky for exchange
find more resources at oneclass.com
find more resources at oneclass.com
Thin and Leaky
• Passage of substances through the capillary wall can occur:
1. Across the cell membrane - lipid soluble molecules and gasses
• Oxygen, carbon dioxide, cholesterol etc.
• Diffusion
2. Between cells (paracellular)
• Water, small molecules such as urea
• Filtration
3. Pinocytosis - movement of specific molecules/substances across the cell membrane in
vesicles
• Blood brain barrier
Structure
find more resources at oneclass.com
find more resources at oneclass.com
Tissue-Specific Permeability
• The pore width is normally intermediate (large molecules diffuse through poorly, water
molecules more easily)
find more resources at oneclass.com
find more resources at oneclass.com
