Kidney and Body Fluids 1

Nota:

• Mole: 6.022X10^23 Molarity vs Molality Molarity: Moles of substances per litre of the solution. Molality: Moles of substance per kg of solvent Osmolarity vs Osmolality Osmolarity: osmoles per litre of solution Osmolality: Osmoles per kg of solvent Some molecules liberate more than one particle in solution. NaCl vas Na2so4. Osmosis: Movement of water to a semi-permeable membrane from a compartment in which solute conc is lower to one which is higher. I.e low osmoses to higher osmoses. Osmotic pressure is pressure needed to stop water movement of osmosis.

1. Van't Hoff's Law

   Nota:

   • pi= nCRT osmotic pressure = number of dissociable particles/molecues X Total solute concentration X Gas Constant X Absolute Temperature.
2. Comparing Solutions
   1. Tonicity

      Nota:

      • Tonicity of a solution depends on the osmolarity concentration and whether the solute can permeate the cell. Permeant solutes, it is different. For example, with the same amount of solute i.e Nacl and urea. NaCl has a pump so it pumps out stuff, so there's like no change. Whereas, urea, it goes into the cell, so the water also gets into the cell to maintain tonicity.
   2. Colloid osmotic pressure

      Nota:

      • Also known as oncotic pressure, it si the pressure exerted by proteins and other cations.

Nota:

• Typical 70kg man consists of water, proteins and related substances, mineral Fats. Total body water varies with age (young more, old less) Obesitity and women, i.e more fat more water storage.

Nota:

• Indicator Dilution Technique: V = Q/c Q= amount injected - amount lost

Nota:

• More changes in intracellular content due to loads of proteins. Plasma electrolyte composition is controlled by kidney. Plasma vs Interstitial fluid composition is maintained by: Capillaries that thens to hold protein Gibbs-Donnan effect Extracellular vs intracellular: Cell membrane Selective ion pumps Gibbs-Donnan effects

Nota:

• Total body water is controlled by thirst, kidney and ADH.

1. Kidney

   Nota:

   • Regulates: water and electrolyte balance, acid-base balance Excretion: Metabolic waste products, foreign chemicals and other bioactive substances. Regulate: Arterial BP, RBC production, VIt D and gluconeogenesis.