SUPP

• The body is made up of 45 to 70% water with the average being 60%
• There are 2 major components of body water: ICF and ECF
• ICF makes up 2/3 of total body fluid. It is located within cells and facilitates their chemical rxns
• ECF makes up 1/3 of body fluid. It is divided into intravascular fluid which is in between blood and lymph vessels and then interstitial fluid which is between vessels and cells
• Third spacing or third spaced fluids are ECF collected in various parts of the body because of a pathological condition. They're not functional and accumulate in these places: pleural, pericardial, peritoneal, joint and intestines
• Fluid equilibrium is controlled in the hypothalamus in 2 areas: the thirst center and the neurohypophysis or posterior pituitary
• Thirst center works with the help of osmoreceptors that measure tonicity; if blood is thicker, the person begins to feel thirsty
• The 2nd method of regulating fluid equilibrium is through the neurohypophysis through the hormone ADH. It reabsorbs water back into the body and lowers the hypertonicity of the blood. The fxn of the hormone Aldosterone also helps as it retains Na+ which water follows passively
• Average adult takes in about 2.5 L of water per day
• Water enters the body thru: liquids (1.5 L), foods (.75 L) and cellular respiration (.25 L)
• water exits body thru the kidney or urine(1.5 L), lungs or water vapor (0.3 L), skin or sweat/evaporation (.55 L) and intestines or feces (.15 L)
• Normally fluid intake should be equal to fluid output
• Thirst is the greatest regulator fluid intake
• Body fluid proteins help maintain proper location of fluids of the ECF
• Negative nitrogen balance occurs when fluid intake is less than output
• Proteins maintain the colloid osmotic/oncotic pressure of the plasma
• Proteins are absorbed in the small intestine and metabolized in the liver. The waste products of this process is called ammonia and its excreted by the kidneys as urea and creatinine in urine
• Solutes are classified as electrolytes, nonelectrolytes, crystalloids and colloids. Electrolytes are like ions and they have charges. Nonelectrolytes don't have an electrical charge and are things like proteins and lipids. Crystalloids are particles who diameter is < 1 nm. Colloids are particles who's diameter is 1-100 nm like proteins
• The solvent or water in the body is moved by 2 types of pressure: osmotic pressure(albumin) and hydrostatic pressure (bloodpressure)
• Osmotic pressure consists of these 2 types: Crystalloid and colloid/oncotic. In crystalloid the pressure is produced by small particles (e.g ions)that can pass thru a membrane. In colloid the pressure is produced by large particles that can't pass through a membrane and makes a pulling pressure
• Hydrostatic pressure refers to the pressure from a column of water against the walls of its container; referred to as pushing pressure sometimes
• Solutes are transferred by diffusion or active transport
• There are 4 factors affecting diffusion: distance(far=slow), temperature (cold=slow), size(big=slow) and charge(opposite charges attract)
• Na+ is primarily located in the ECF and it regulates the crystalloid osmotic pressure of the ECF. It participates in various chemical rxns within the cell and stimulates nerve/muscle tissue. It also assists in maintaining balance between acids and bases and combines with Cl- and HCO3
• K+ is the major cation of the ICF
• Na+ is the major cation of the ECF
• Cl- is the major anion of the ECF and it aids in maintaining osmotic pressure of the blood in conjunction with Na+. It also helps regulate acid and base imbalances
• K+ fxns in nerve/muscle activity and acid and base imbalance.
• During acidosis, H+ exchanges into the ICF for K+. This causes hyperkalemia in acidosis
• The kidneys can excrete H+/K+ in exchange for Na+
• 99% of Ca+ is found in bones while the rest is found in cells and blood serum(of that, 50% if bound to albumin and other plasma proteins with the rest is ionized and physiologically active).
• As serum protein decreases, less Ca+ is bound which means more is ionized
• Ca+ fxns to provide strength to bones, has a sedative effect on nerve cells and activates enzymes that participate in essential chemical rxns such as blood coagulation
• PO4- is the major anion of the ICF
• Fxns of PO4: provides strength to bones/teeth which also contain about 75% of it. It also involved in chemical rxns of the body, aiding normal action of nerves/muscles and helps in maintaining acid and base balance
• When blood pH is below 7.35, it is in a state of alkalosis
• There are 3 ways the acid/base balance is maintained in the body: chemical buffers(in blood and adjust pH within minutes), lungs(resps can change to change level of CO2 and takes minutes to hours) and kidneys(very effective but can take hours to days)
• The lungs are an important regulator of pH because they remove one of the sources of acidity which is CO2( combines with h20 to make carbonic acid which produces H+)
• The kidneys function in acid and base balance by tubular secretion or reabsorption of H+ ions