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Explore the composition and roles of the plasma membrane, including lipids, proteins, and transportation mechanisms. Learn about diffusion, active transport, endocytosis, and exocytosis. Understand the distribution of water and solutes in the body compartments and the dynamics of transcapillary fluid movement.
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Components of Plasma Membrane Lipids Proteins ~50% ~50% 1) Peripheral (Associated) 1) Phospholipids (75%) 2) Cholesterol 2) Integral (Membrane Spanning) (20%) 3) Glycolipds 3) Glycoproteins (5%)
Protein Transporters 2) Carriers 1) Channels a) open b) gated* * triggered to open
Cell Transport Mechanisms Passive Active 1) Primary (Direct) 1) Diffusion 2) Facilitated Diffusion 2) Secondary (Indirect) 3) Vesicular 3) Filtration
Secondary Active (Indirect): e.g., Na+/Glucose transporter Symport
Distribution of Water and Solutes in the Body Compartments Inside cells • About 60-70% of body weight is water • 67% is intracellular • 33% is extracellular • 8% plasma • 25% interstitial
Transcapillary Fluid Dynamics ↑HP (plasma in capillary) ↓HP venous end arterial end ↑↑ COP ↑↑ COP Filtration Reabsorption ↓↓ COP ↓HP (interstitium) (ICF) = fluid movement Cells HP = Hydrostatic Pressure (force of a fluid on walls of its container) COP = Colloid Osmotic Pressure (force generated by proteins in solution)