T2L4 Transport across Membranes Flashcards
What is diffusion
The passive net movement of particles from an area of high concentration to an area of low concentration
What types of molecules transport across membranes by diffusion
Small uncharged
What is facillitated diffusion
Passive net movement of particles across the plasma membrane from an area of high concentration to an area of low concentration through channel or carrier proteins
Example of substances transported by facilitated diffusion
Sodium
What is osmosis
The passive net movement of water from an area of high water concentration to an area of low concentartion across a partially permeable membrane
Explain the relationship of solute conc and Hydrogen bonds in osmosis
The higher the solute conc is the more hydrogen bonds there are the less water moves across the membrane and vice versa
What is active transport
The net movement of particles from an area of low concentration to an area of high concentration across the plasma membrane using ATP that releases energy (ATP to ADP is what releases it) - through specific carrier proteins that require energy to change shape.
What is endocytosis
Bulk movement of particles into the cell. the cell membrane binds to a large molecule resulting in the formation of a vesicle. The vesicle containing the large molecules then enters into the cell.
What is exocytosis
Bulk movement of particles out of the cell. is, a vesicle containing molecules of substances fuses with the inside of the cell membrane and the molecules are secreted from the cell.
What happen swhen there is too little water in the mucus in the airways
Chloride ions are pumped in from basal membrane
Cl ions diffuse out across apical membrane through CFTR protein
Na diffuses from basal into apical through gaps between cells due to electrical gradient
Increased salt in mucus draws water into the mucus from the epithelial cells
What happens when there is too much water in the mucus
Sodium is pumped across the basal membrane
Sodium diffuses from the mucus into the cells
Cl goes from the mucus to the basal down the electrical gradient
Increased Cl and Na in the basal membrane draws water into the basal membrane from the cells
Lower water content in the cells means water is drawn out of the mucus into the cells
What happens to the mucus in people with CF who do not have a functioning CFTR protein
CFTR protein means chloride ions cannot diffuse into the mucus so the salt content in the epithelial stays high which means more water is drawn out of the mucus by osmosis
