Osmolality10 is the number of particles (mmol) contained in one liter of water, so measured in mmol/L. i.e. it is the concentration by number
Osmolality vs Osmolarity11 Osmola Lity- It is the number of osmoles or moles per kg of solvent Osmola Rity-It is the number of osmoles per liter of solution- Osmole = the amount of a substance that dissociates in solutionto form one mole of osmotically active particles.- For example, a solution of 1 mol/L NaCl corresponds to anosmolarity of 2 osmol/L
Osmolality vs Specific Gravity12 Specific gravity is the mass of one milliliter of solution in grams. This gives an indication of both the number and weight of the particles in the urine. Most of the time, this provides an accurate estimate of urine concentration; however, if the urine contains particularly heavy particles such as glucose or x-ray dye, the specific gravity will overestimate urine concentration
Osmolality, Calculation13 normally ranges between 285 and 295 mmol/L
OBJECTIVES20 Use of Units in Physiology Plasma Osmolality Changes Plasma Osmolality Correction Counter-Current Multiplier & Exchange Mechanism
Osmolality Monitoring - General Concept21 A change in plasma osmolality of only 1% is detectable by the hypothalamus.
How plasma osmolality changes? General Concept22
How body adjust plasma osmolality changes? - General Concept23
How body adjust plasma osmolality changes? - General Concept24
How body adjust plasma hyposmolality (1)? – Suppress Thirst25
How body adjust plasma hyposmolality (2)? – Suppress of ADH26
How body adjust plasma hyperosmolality (1)? – Stimulate Thirst27 Usually the plasma osmolality must increase 5% to stimulate thirst. Thirst (causing the ingestion of water) is the most effective defense against increases in osmolality. This defense is so effective that, with ready access to water, alert people cannot develop significant increases in osmolality
How body adjust plasma hyperosmolality (2)? – Release of ADH28
How body adjust plasma hyperosmolality (2)? – Release of ADH29 3 Steps
Step 1: ADH – Stimuli30 The release of ADH in the setting of volume depletion and the inappropriate release of ADH are two important factors which can initiate the development of hyponatremia.
TO MEMORISE35 ADH ADds Hydration to the body by causing the formation of a concentrated urine.
OBJECTIVES36 Use of Units in Physiology Plasma Osmolality Changes Plasma Osmolality Correction Counter-Current Multiplier & Exchange Mechanism
Loop of Henle (Countercurrent Multiplier) &Vasa Recta (Countercurrent Exchange Mechanism)37 Interaction between the flow of filtrate through the loop of Henle (countercurrent multiplier) and the flow of blood through the vasa recta blood vessels (countercurrent exchanger)