CAS BI 105 Lecture Notes - Lecture 9: Osmoregulation, Osmotic Concentration, Glucose Transporter
30 Apr 2018
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9/28: Osmotic Pressure
Solute v. Solvent
•Solute = dissolved
•Solutes SUCK - solute will suck solvent in their direction
•Question: If we move the solute, does the area gaining the solute gain volume? No.
•Solvent = dissolver
•Likelihood of osmosis occurring (osmotic pressure)
•Osmolarity
•Osmolarity - the number of particles (solute molecules) in a solution
•Molarity - the number of molecules in a solution
•Why are these two different?
•1 molecule = 1 particle if the atoms of the molecule do not dissociate in water (ex: glucose molecule)
•1 molecule does not equal 1 particle if the atoms dissociate in water to become MORE individual pieces
(ex: NaCl)
Endocytosis vs. Exocytosis
•-endo = in
•-exo = out
•-cyto = cell
Endings
•-hypo (less)
•-hyper (more)
•-iso (same)
•More particles in one solution than another = hyper osmotic
•Less particles in one solution than another = hypo osmotic
Osmolarity in the Body
•The ICF and ECF are in a state of osmotic equilibrium
•Water moves through water channels (aquaporins) in every cell
•Water will follow the higher ion concentration (the area of lower water concentration)
•Mnemonic - solutes suck
•ex: blood pressure, electrolyte drinks, osmotic balance of cells
Tonicity
•The number of particles in any solution surrounding a cell
•Describes changes in cell volume if a cell is placed in a solution
•More water molecules on the outside
•Tonicity - the ability of the surrounding solution to cause a cell to gain or lose water
•Hypotonic (less particles on the outside, more water will move in) - will burst
•Hypertonic (more particles on the outside, less water will move it) - will shrivel
•Isotonic (same amount of particles on the outside) - will be normal
Getting across the plasma Membrane
•Modes of transport:
•Active Transport - energy from the cell is used
•Energy from cell is used
•Primary
•ATP is used
•Goes AGAINST
•Secondary
•Goes AGAINST the concentration gradient
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