Fluid compartments and Solutes

Sodium ions are found in much higher concentrations extracellularly than intracellularly

Potassium ions are found in much higher concentrations intracellularly than extracellularly

By anions like negatively charged large molecules like DNA and proteins, phosphorylated proteins etcetera

The main extracellular anion is chloride and the main intracellular anion is phosphate (bound to organic compounds)

The difference in pH between blood plasma and cytoplasm is 0.3 (7.1 in cells, 7.4 in plasma) which is equivalent to approximately twice the protons in cells compared to extracellularly

Identical osmolarity seen between cells and extracellular fluid is not seen in the kidneys where the excreted fluid is much more concentrated than intracellular osmolarity

Osmol/L is the unit for osmolarity and it is defined as the number of moles of particles dissolved into a solution

Because in biological system permeability of membranes plays a role, osmolarity does not appropriately account for the outcomes of differences in osmolarity

The Na/K-pump actively pumps out sodium ions that flow down their concentration gradient to establish no net movement of sodium ions that therefore maintain a dynamic equilibrium in which there is higher intracellular concentration of impermeant solutes

Organs for donation are cooled to around 4 degrees Celcius

The University of Wisconsin solution prevents organ cells from hypothermic swelling and enhance the preservation for transplantations

The absence of sodium of chloride ions in the solution prevent an influx of sodium that can make membrane lose integrity, impermeant solutes like lactobionate and raffinol equalise osmolarity and starch acting as colloids to maintain high osmolarity in vascularity to prevent oedema

Allopurinol and gluathione serve as antioxidants to prevent against damage from reactive oxygen species that are released in hypothermic state

When Na/K-pump stops functioning, sodium ions start entering the cell and potassium starts the leaving the cell and water will follow the inward flow of sodium and this causes the membrane to lose its integrity and burst and this results in cell death

Fluid can leave the capillaries through small pores between endothelial cells

Lipid-soluble substances pass through the endothelial cells to leave the capillary

Exchangeable proteins are transported through endothelial cells in vesicles that are transported from the luminal side of endothelial cell to outside into the tissue

The osmotic pressure created in blood plasma by large insoluble plasma proteins that increase the blood plasma osmolarity such that only limited amounts of fluid leave capillary

By hydrostatic pressure that is caused by pumping of the heart, fluid and molecules are pushed out of capillary pores

Excess loss of fluid from a capillary into the interstitial space, due to loss of colloid osmotic pressure

In increased permeability plasma proteins that maintain the colloid osmotic pressure are lost, which means there is less resisting force of fluid leaving the capillary and the blood and this leads to excess fluid loss to the interstitial space

Lymphatic capillaries have a lower internal pressure than the interstitial fluid, which leads to a net movement of the fluid into the capillaries

The blood flows into interstitial fluid, which flows into lymphoid capillaries, which flows into lymphoid veins, which flows into lymphoid ducts which empties in the bloodstream in large veins

Lymphoid fluid can be returned to the blood circulation via lymphatic ducts emptying in large veins or via lymph nodes where lymphoid fluid can be returned through capillaries