Plasma Membrane and Cell Transport Flashcards
What are the body fluid compartments and their distributions?
Body is 60-70% water
65% of that is intracellular
35% is extracellular
20% of extracellular is intravascular
80% is interstitial (in tissue)
What is the structure of the plasma membrane?
A meshwork of collagen and elastin fibers linked together and adhered to a gel-like ground substance and integrins
What factors are important for molecules to pass the plasma membrane?
Phospholipid Bilayer
Selective Permeability
Carrier-Mediated Transport
Passive Transport (Down gradient, no energy required)
Active Transport (Against gradient, requires energy)
What are the different types of passive transport?
Simple Diffusion - Small, non-polar, lipid-soluble particles
Facilitated Diffusion - Charged ions, large molecules (esp. Na, K, and glucose)
Carrier-Mediated - Protein carriers (specific, competitive, saturated)
Filtration - Water and solutes pass membrane from high pressure to low-pressure (non-selective, the only things left behind are too big)
What are the different types of active transport?
Solute Pumping - Proteins use ATP to transport solutes against gradient
Primary AT - Sodium-Potassium pump. K in, Na out
Secondary AT - Symporters
Bulk Transport (Two types)
Endocytosis - Things going inside a cell
Phagocytosis (solid), Pinocytosis (fluid)
Exocytosis - Things go outside a cell
Transcellular/Paracellular - Transport across epithelial membranes (systens eith a lot of absorbtion: digestive, urinary)
What are symports and antiports?
Both are cotransporters
Symports move substrates in the same direction
Antiports carry substrates in opposite directions
What factors are important for diffusion across the plasma membrane?
Magnitude of concentration gradient
Permeability of plasma membrane
Surface area of the membrane
Molecular weight of the substance
Distance over which diffusion takes place
Temperature
What is osmosis and how does it happen when there are penetrating molecules vs non-penetrating molecules?
Diffusion of water
Goes from area of higher concentration to lower concentration
Non-permeable solutes have same concentrations in different volumes because water is free to move when they are not
What is osmolarity?
Number of particles per L of water
What is tonicity?
The ability of a solution to change the shape of a cell by altering its internal volume
What is the difference between an isotonic, hypotonic, and hypertonic solution?
Isotonic - Water outside and inside cell is equal
Hyper - Lots if solute, More water goes OUTside, cell shrinks (crenation)
Hypo - More water goes INside cell, it grows until it lyses
What is direct cell signaling?
Cell-to-cell recognition - interaction of cell-surface (immune cells recognize PAMP)
Gap junctions - Cells connected by connection tunnels. Allows ions and water soluble chemicals to pass between cells
What is indirect cell signaling?
Autocrine signals - Cell releases a signal and affects itself
Paracrine Cells - Cell releases a signal and it affects neighboring cells
Endocrine signaling - Long-distance via hormones
What is the cell signaling mechanism for lipid soluble molecules?
Ligand binds to an intracellular receptor in the nucleus and crosses pm easily
Triggers transcription of a specific gene and synthesizes pf protein inside
What is the cell signaling mechanism for water soluble molecules (second messenger systems)?
When a chemical cannot cross the plasma membrane it finds a receptor and binds on the membrane and then –activates or inhibits– according to its purpose. Sometimes it activates a chain molecules until it achieves its purpose
