Compendium 5 Flashcards
Explain the cell membrane
Phospholipid bilayer - hydrophilic phosphate heads face intracellular and extracellular fluids, hydrophobic lipid tails face inside
Also contains cholesterol
“Fluid mosaic” - mosaic cause made of different parts, fluid due to phospholipids = not ridged structure but constantly moving and can shape based on environment and diet
Proteins found in membrane to aid in molecule movement that requires no extra energy, determine what can come in and out of cell and involved in communication of cell with its environment– INTEGRAL go all the way through, PERIPHERAL sit on very outside or inside
Can contain membrane channels for flow of substances
Can attach cells to other cells and surrounding matrix
What are channel proteins
Form tiny channels through membrane
Molecules of certain size, shape, and charge can pass through
Can be gated-ion channels which are open and closed by stimuli or non-gated ions channels which are always open and allow free flow of molecules
What are carrier proteins
Also called transporters
Integral proteins move ions from each side of membrane to the other, they have:
-specific binding sites
-can change shape (shut one side, open other side to be released)
-resume original shape after transport
-can be UNIPORTERS (transport only 1 molecule), SYMPORTERS (2 in same direction), ANTIPORTERS (2 in opposite directions)
Difference between solute, solvent and solution
Solute: dissolved substance in a solution
Solvent: liquid holding solute
Solution: mixture formed when solute dissolved in solvent
What is diffusion
Molecules move from area high conc. to area of low conc. down concentration gradient
Continues until molecules evenly distributed
Can be through cell membrane or facilitated
Explain diffusion through cell membrane
Certain specific non-lipid soluble molecules or ions diffuse through membrane channels
Other non-lipid soluble molecules for which membrane channels are not present, can’t enter the cell
Lipid soluble molecules diffuse directly through plasma membrane
Explain facilitated diffusion
Moves large, water soluble molecules of electrically charged molecules across the membrane
Amino acids and glucose in, manufactured proteins out
Passive
Carrier proteins bind with molecule on outside of plasma membrane, carrier will then change shape and release molecule on the other side
What is osmosis
Diffusion of water across selectively permeable membranes
Let’s water but not all solute pass through
Water diffuses through channels called aqua porins in membrane
What is the effect of a semi permeable membrane during osmosis
Solute added to one side of membrane, the molecules are too big to cross through channels of membrane
Solute will distribute evenly on side it is on
Water moves from side with low solute conc. to side with high solute conc. (area of high water concentration to area low water conc.)
Water moves down its conc. gradient
What is the effect of the concentration of the solution during osmosis
Solute on one side may be highly concentrated
Water will continue to move from area low solute conc. to high solute conc. (down its concentration gradient)
However, the higher the concentration of the solute, the more water that will move across as it tries to equalise the water amount on both sides
Therefore solute conc. affects - more concentrated a solution is, the more that solution will pull water towards it
What is osmolarity
The pull on water created by solutes
Measured in mOsmoles/L (smaller value = smaller pull)
Weak solution = low osmolarity
Concentrated = high osmolarity
Explain osmolarity and body cells
The osmolarity of the intracellular fluid of a normal cell under normal conditions is ~290mOsmol/L
Greater difference in osmolarity = greater movement of water from extracellular fluid to intracellular fluid
Can be isotonic, hypertonic and hypotonic solutions
Explain isotonic solution
The solution the body wants
When a cell is placed in a solution with the same osmolarity as inside the cell
Water moves between intracellular and extracellular fluids at equal rates, there is no concentration gradient and the cell is at equilibrium
Explain hypertonic solution
When cell is placed in solution that has a higher osmolarity than that of the inside of the cell
Higher osmolarity = greater solute concentration = stronger pull on water
Water is forced/pulled out of the cell- the cell shrinks/crenates as it loses water and will become dehydrated
Explain hypotonic solution
Cell place in solution with lower osmolarity than that of the inside of the cell
Lower osmolarity = lower solute concentration= the cell wants to pull/take in water
Causes cell to swell (lysis) and burst
“Cell is hypotonic on the outside compared to the inside”
