Lecture 21 - acid base physiology Flashcards
How does a high acid level affect the body?
- high acid levels can alter shapes of proteins
- can cause hyperkalemia in ECF
- can cause hypercalemia in ECF
How do high acid levels in the body alter shapes of proteins?
- the free h+ ions disturb existing hydrogen bonds
How does high acid levels cause hyperkalemia?
- high acid levels cause acid to enter into cell and K+ to leave into the ECF
How does high acid levels cause hypercalcemia in the ECF?
- high H+ reduce the amount of Ca2+ bound to albumin causing increased Ca2+ levels in the ECF
How do high base levels affect the body?
- hypocalemia in ECF - low levels of K+
- can alter the shape of proteins
- can cayse hypocalcemia in the ECF
How are strong acids and strong bases dissociated?
they are completely dissociated in aqueous solution
How are weak acids and bases classified in terms of dissociation?
they are partially dissociated in aqeuous solution
What is a buffer solution?
a solution in which when an acid or base is added to it - the buffer solution minimises the change in PH
What acids contribute to our daily acid load?
- carbonic acid - acid produced by the hydrolysis of CO2 (ie CO2 binding to water)
- non carbonic acid
What is an acid-base disorder?
change of normal value of the extracellular PH that may result when renal or respiratory function is abnormal
What is acidemia?
a lower than normal arterial PH
What is a alkalemia?
- a higher than normal arterial PH
What is acidosis?
a process leading to acidemia (lower PH) - can be of respiratory or metabolic origin
What is alkalosis?
a process leading to alkalemia- again can be of metabolic or respiratory origin
What are the different chemical buffers in the body?
bicarbonate system
haemoglobin system
protein system
phosphate system
they can bind to acids if the PH is decreased
What is the overview of the role of the lungs in acid-base balance?
- metabolism of fats/carbs results in the formation of CO2 which is exhaled by the lungs
- lungs can increase of decrease ventilation rates depending on the concentration of CO2 in the blood
What is the overview of the role of the kidneys in acid base balance?
- the metabolism involving proteins or foods containing phosphates or sulfates produces non carbonic acids which are excreted by the kidney
- if the blood is too acidic- the kidney can excrete H+ and increase HCO3- reabsorption and production in the PCT
- if the blood is too basic, the kidney can excrete more HC03- and reabsorb H+
What are the 4 main acid-base disorders?
- respiratory acidosis
- respiratory alkalosis
- metabolic acidosis
- metabolic alkalosis
What is respiratory acidosis?
- HYPOVENTILATION - breathing too slow
- this is when the plasma concentration of CO2 (ie pCO2) is too high and the breathing rate / ventilation of the lungs is not sufficient enough to eliminate all the CO2 being produced in the body
What is respiratory alkalosis?
- HYPERVENTILATION - breathing too fast
- this occurs when the** plasma concentration of CO2 is too low**, (pCO2 is too low) and the ventilation of the lungs is too fast and more CO2 is being eliminated than the amount being made in the body
what is metabolic acidosis?
- fall in plasma HCO3-
what is metabolic alkalosis?
when the plasma HCO3- concentration is too high
what are compensation processes in terms of acid base orders? What 2 headings do they lie under?
- the mechanisms that are activated to bring plasma PH back to normal values
- repsiratory compensation (ie increae or decrease ventilation)
- renal compensation (ie increase/ decrease reaborption of H+ or HCO3-)
what is the normal range of pCO2 in the body?
36-44 mmHg
what is the normal plasma conc range of HCO3-?
normal range is 22-26mM
How can we see whether the acid base disorder is metabolic or respiratory when given values for pC02 and plasma PH?
- using ROME
- respiratory opposite metabolic equal
- ie if the alteration of the pCO2 changes in the opposite direction of the PH, then it is respiratory
- if the alteration of the pCO2 is equal to the direction of the PH, then it is metabolic