MCM-SV-Water, Acids Bases, and Buffers

What are the five functions of Water?

Solvent, Transport, Homeostasis, Thermal regulation, participates in chemical rxns.

What are examples of Extracellular fluid (ECF)

Plasma, Interstitial fluid, Lymph, Eye humor, Gastrointestinal secretions

What are some of the causes of Dehydration?

Inadequate water intake (Comatose patients, loss of appetite, cerebral injuries, etc.), impaired re-absorption (such as in intestinal lumen or urine), or because of high [] of solutes excreted in urine.

Why does high concentration of solutes in urine = dehydration?

Because of osmosis pressure. The low concentration of solutes forces water to go out of the cells into the ECF and then carried through blood and excreted in the urine.

What are the two usual causes of Hypotonic Hydration? What is it usually due to?

Increased water retention or decreased water excretion. These pathologies are usually due to renal insufficiency.

A patient comes into the clinic with nausea, vomiting, edema and hyponatremia. What is the cause and how would you treat it?

Cause: Over hydration (Hypotonic Hydration) and you would give them more electrolytes in order to drive osmotic pressure away from the cells.

what are the symptoms of Over hydration?

nausea, vomiting, cerebral edema, convulsion, coma, death

Which cations/anions are majority present in the ECF/ICF

ECF: NA+, Cl-; ICF: K+, HPO42-

What is the major metabolic source of acid?

CO2

What is the reaction for the bicarbonate-carbolic acid buffer?

H2O +CO2 —> H2CO3 ——> HCO3 + H+ (with the help of carbonic anhydrase)

What are the three ways in which the body maintain adequate pH levels? How fast do they act?

Buffers (seconds), Respiratory center (minutes), Renal System (hours-days)

List out the major buffer systems and where they are found

Bicarbonate-carbonic acid: ECF

Hemoglobin: RBC

Phosphate: All cell types

Ammonium/phosphate ions: Kidnesy

Which metabolic pathway is a majority of CO2 produced?

TCA

When pH falls, how does respiration change and why?

when pH falls, more protons are produced which pushes the bicarbonate buffer system towards the reactants, ie CO2. In order to remove this CO2, respiration increases to expel more CO2

When pH rises, how does respiration change and why?

When pH rises, less H+ ions which pushes the carbonic buffer system towards the products (more H+, HCO3). This results in less CO2 and the body compensates by breathing less often, thus decreasing rate of CO2 expiration.

Explain the bicarbonate/Hemoglobin buffer system in the RBC

CO2 produced in TCA —> transported to IF —> Picked up by RBC from plasma —> Carbonic anhydrase converts it to H+ and HCO3 —> H+ is picked up by Hb to form HBh —> HCO3- gets transported out in exchange for an Cl- atom

If there is a mutation within the RBC that prevents Cl- transportors to function, which solute [] will be higher than normal?

HCO3- becasue the RBC needs to transport Cl- into the cell in order to transport HCO3- out.

How is the bicarbonate system linked to the delivery of oxygen to tissues?

In the lungs, the equilibrium is shifted due to low levels of CO2. This causes the bicarbonate reaction to shift towards the reactants. Thus, Hb loses its H+ in order to combine with HCO3 in order to compensate for low levels of CO2. This loss of protons from Hb allows for higher affinity to oxygen and thus increases oxygen delivery to tissues indirectly.

What are the mechanistic causes of Metabolic Acidosis and the compensation? What would the lab results for H+, pH, pCO2, and HCO3- be (changes in levels)?

For some reason, H+ is increased. This causes the bicarbonate reaction to shift towards the reactants. This would then decease the levels of HCO2 as it is reacting to the H+ and this would produces more CO2. To compensate, the body would breath more rapidly in an effort to expire this increased level of CO2. LAb results: Increased H+, Decreased pH, Decreased CO2, Decreased HCO3

What are some pathological reasons for Metabolic Acidosis?

Diabetic Ketoacidosis, Renal Disease, Lactic Acidosis (respiratory failure or cardiac arrest leads to tissue hypoxia), certain drug overdose/poisoning

What happens to respiration in the event of a cardiac arrest?

a cardiac arrest will induce tissue hypoxia due to the heart not being able to provide oxygen to the tissue. They will then induce lactic acidosis in order to get ATP without Oxygen. This decrease the pH of the body and respiration will increase because this decrease in pH will cause an increase in CO2 due to the equilibrium of the Bicarbonate buffer system.

What are the mechanistic causes of Respiratory Alkalosis? What would the lab results for H+, pH, pCO2, and HCO3- be (changes in levels)?

Cause: hyperventilation causes CO2 to expire rabidly. This raises pH as the lack of CO2 drives the bicarbonate reaction towards the reactants. As a result, H+ and HCO3 reacts with each other, resulting in lower levels of the two molecules. Lab result: pH raises, H+ decrease, CO2 decrease, HCO3 decrease.

What are some pathological causes of Respiratory Alkalosis?

Hysterical overbreathing, Mechanical over-ventilation in intense care patient, raised intracranial pressure or hypoxia

What are the mechanistic causes of Respiratory Acidosis? What would the lab results for H+, pH, pCO2, and HCO3- be (changes in levels)?

Lack of respiration increases concentration of CO2 in the body. This drives the bicarbonate reaction towards the products, resulting in increased H+ and HCO3 in the body. This would make the lab results show increased CO2, Increased H+, Increased HCO3 and decrease pH.

What are some pathological causes of respiratory Acidosis?

Choking, bronchopneumonia, exacerbation of asthma, Chronic obstructive airways disease

What are the mechanistic causes of Metabolic Alkalosis and the compensation? What would the lab results for H+, pH, pCO2, and HCO3- be (changes in levels)?

For some reason, Lots of H+ is being lost. This drives the bicarbonate buffer reaction towards the products, producing more H+ and HCO3. As a result however, the levels of CO2 falls. The body then compensate for this by decreaseing respiration rate. LAb result: H+ decreases, pH increases, CO2 increase, HCO3 increases.

What are some pathological causes of Metabolic Alkalosis?

Prolonged vomiting, Potassium deficiency (potassium ions move out of the cell in exchanged for protons)