Lecture Chapter 3 Section 3 Flashcards
Permeability
Membrane characteristic that determines which substances can pass through
Plasma membrane
Phospholipid bilayer
Contains integral proteins
Barrier separating ECF and cytoskeleton
Selectively permeable
Plasma membrane allows some, but not all, substances to pass
Selective permeability is based on:
Characteristics of substance
Features of the membrane
Characteristics of substances
Size and shape
Electric charge
Lipid solubility
Features of membranes
Types of integral proteins present
Ex: receptors, channels, pumps
Diffusion
Passive, movement of a substance along its concentration gradient-higher to lower
Why diffusion?
Continuous random movements (due to kinetic energy) and collisions of particles
Equilibrated substance
Random movement, no net movement
Types of membrane transport
- Passive transport
2. Active transport
Passive transport
Does not require ATP
Diffusion and osmosis
Carrier-mediated➡️ion channel
Active transport
Requires ATP
Vesicular transport
Carrier-mediated➡️pump
How do ion channels get there name?
The ion they let through
Diffusion rates are directly related to:
Temperature
Size of concentration gradient
Diffusion rates are inversely related to:
Distance of diffusion
Molecular size of substance
Electrical forces
Attraction: can accelerate diffusion
Repulsion: can reduce diffusion
How would a decrease in the oxygen concentration in lungs affect the diffusion of oxygen into the blood?
It would slow down the rate
Movement across lipid portion
No protein needed
Oxygen, Carbon, and lipid-soluble