Physiology - Osmosis

Isosmotic Solutions

Solutions have same osmolality as plasma

Osmotic Pressure Proportions

-The Osmotic Pressure is directly proportional to the concentration of the solute. -The Osmotic Pressure is directly proportional to the absolute temperature.

Molarity

1 molar solution (1.0M) = 1 mole of solute dissolved in 1L of solution.

Methods of Transport Across Membranes

1. Diffusion 2. Osmosis 3. Facilitated Diffusion 4. Active Transport

Regulation of Blood Osmolality

Blood osmolality is maintained in narrow range around 300mOsm. If dehydration occurs, osmoreceptors in hypothalamus stimulate: ADH release. Which causes kidney to conserve H2O and thirst

Hypotonic Solutions

Has lower osmotic pressure. Has more water. Ex) If red blood cells are in this solution they will blood up like a balloon and potentially burst because all the water will be going into the cell. The water goes into the cell by osmosis

Hyperosmotic

Higher osmotic pressure

Tonicity

Is the effect of a solution on osmotic movement of H2O It is commonly used when describing the response of cells immersed in an external solution

Osmotic Pressure

Is the force that would have to be exerted to stop osmosis. It indicates how strongly H2O wants to diffuse. Is proportional to solute concentration. The greater the amount of solute dissolved in a solution, the greater the osmotic pressure. Osmotic Pressure draws liquid from a solution of low Osmotic Pressure towards the higher osmotic pressure

Osmotic concentration or Osmolarity

Is the measure of solute concentration (Osm) of solute per litre (L) of solution (osmol/L or Osm/L). Whereas molarity measures the number of moles of molecules per unit volume of solution, osmolarity measures the number of solute particles per unit volume of solution

Increasing Density

It increases the pressure. Ex) 1. The air's density and pressure are greatest at the earth's surface so there is more molecules there 2. Because of gravity, the density and pressure decrease with increasing height. So the molecules are becoming less packed in the air 3. The density and pressure approach zero in outer space. So the molecules are way spread apart and not packed in at all in space

Osmolality

It is equal to the sum of the individual osmolalities of the solutes

What is a Solute

It is what is dissolved. Ex) Ions molecules, glucose, proteins, DNA, etc.

What is a Solvent

It is what what you dissolve molecules in. In physiology this is water.

Hyposmotic

Lower osmotic pressure

How many Osmolarities is equal to NaCl (salt)

Since there are two molecules in salt (Na and Cl) they both will disassociate in water. So you get 1 OsM from Na and 1 OsM from Cl. So 1 OsM + 1 OsM = 2 OsM for NaCl

How many Osmolarities is equal to Glucose

Since there is only one glucose molecule in glucose and it will disassociate in water. You get 1 OsM from the 1 glucose molecule

Hypertonic Solutions

Solutions have higher osmotic pressure and are osmotically active. Has less water. Ex) If red blood cells are in this solution they will shriver up because all of the water will be going out of the cell

Isotonic Solutions

Solutions have same osmotic pressure. Ex) If red blood cells are in this solution they will be perfect because the same amount of water going into the cell is going out of the cell so it remains constant

What is Osmosis

The diffusion of water across a selectively permeable membrane. It is a special case of passive diffusion

Hydrostatic Pressure

The pressure in a gas/liquid is due to the net force of the molecules colliding with the walls. Pressure is proportional to the density of liquid. Increase the density you increase the pressure. When you're pumping blood in your system you would be under hydrostatic pressure.

How do Water Molecules move across a Membrane

They move from a low area of osmotic pressure to a high area of osmotic pressure. But over time, the water moves across the semi-permeable membrane and dilutes the particles so that the solute concentration on either side are equal.