Flashcards
Acid Base Balance and pH
Cards in this deck (76)
- 1What is pH?a measure of Hydrogen ion concentration in solution
- 2In pure water, what is the ratio of Hydrogen ions to Hydroxide ions?1:1
- 3What is involved in protein denaturation?adding or removing hydrogen ions from proteins, causing conformational change and denaturing the protein
- 4What effect can a low pH have on the central nervous system?a low pH has a depressive effect on the CNS
- 5What is the usual range of pH for extracellular fluid?7.36-7.44
- 6What is the usual range of pH for intracellular fluid?7.10-7.20
- 7Is the pH of body fluids always closely associated with the pH of plasma?no, can largely deviate from each other like in gastric juice and pancreatic juice
- 8What kind of scale is the pH scale and what does this mean about small pH changes?logarithmic scale, so a small increase in pH can equal a large change in ionic concentrations
- 9What is the first line of defense against H+ concentration changes and how quickly does it react?body's buffer systems, reacting almost immediately
- 10What is the second line of defence against H+ concentration changes and how quickly does it react?the lungs, reacting rapidly but not as immediately as buffer systems
- 11What is the third line of defence against H+ concentration changes and how quickly does it react?the kidneys, reaction time can take up to several hours
- 12What are the lungs unable to do regarding H+ changes that the buffers and kidneys can do?remove excess acids or bases
- 13What does the Law of Mass action state?the rate of a reaction is proportional to the product of the concentrations of the reactants
- 14What is a weak acid or alkali?one that only partially dissociates in solution
- 15What is formed when an alkali accepts a proton?a conjugate acid
- 16In what blood vessels is H+ concentration highest?in venous blood
- 17H+ concentration rises as blood flows through which vessels?peripheral capillaries
- 18What is the relationship between pH and H+?negative logarithm: pH = -log10[H+]
- 19What are volatile acids?an acid that can be easily removed when an animal breathes
- 20How are volatile acids derived?from CO2, as H+ can be made from H2CO3 (potential acid)
- 21What are non-volatile acids?acids that cannot be eliminated by the lungs
- 22In an animals, where do non-volatile acids derive from?produced during metabolism (lactic acid) and are then rapidly metabolised to H20 and CO2
- 23Problems with which system can affect CO2 levels in the body?respiratory system
- 24The influence of dietary feed on acid-base balance depends on what ratio?the ratio between the content of dietary bases and the components that metabolise into non-volatile acids
- 25In carnivores, is there a net acid or net base production?net acid (net acid producers)
- 26When organic anions are metabolised, what is produced?HCO3-
- 27What happens to excess HC03- that is produced from anion metabolism?excess bicarbonate is excreted in the kidneys
- 28Why do some herbivores/omnivores have alkaline urine?the dietary bases are higher than the production of non-volatile acids and so they produce more excess HCO3-, which is excreted in the urine
- 29Why do carnivores have the highest acid production?there is a higher concentration of dietary proteins and as these are oxidised, they produce non-volatile acids
- 30What does a a buffer do?a buffer minimises the change in pH when an acid or base is added
- 31What is a base?a proton acceptor
- 32What is an acid?a proton donor
- 33What are amphoteric buffers?a buffer with both basic and acidic characteristics and can accept or donate protons
- 34What equation can be used to predict changes in pH?Henderson-Hasselbalch equation :
pH= pK + log[base]
[acid] - 35Buffers work best when there is what kind of difference between pH and pK?small difference, pH and pK should ideally be close together
- 36When pH=pK, how does H+ changes affect pH?any H+ changes will have a minimal effect on pH
- 37Out of all the body buffering systems, which one maintains around half the body's buffering capacity?intracellular buffers inc. proteins and inorganic/organic phosphates
- 38Which buffering systems are involved in long term acidosis?Carbonate in bone and Ion exchange in bone
- 39What is meant by a closed buffer system?a system where the sum of the two components of the buffer pair is constant
- 40What is meant by an open buffer system?a system where the concentrations of both components of the buffer pair are subject to regulation
- 41Why is the bicarbonate buffer system so important in the body?two elements of the system can be regulated, as changes work across a 3 part equilibrium at both ends of the equations, making it flexible for acidosis and alkalosis
- 42How do kidneys control the H+ concentration in ECF?can produce acidic or alkaline urine to compensate for H+ balance changes, by varying H+ secretion and bicarbonate reabsorption)
- 43How do the lungs control Carbon Dioxide levels in the body?can vary respiratory rate to increase or decrease the pCO2
- 44What does the amount of HCO3- absorbed depend on?the composition of the diet, with herbivores reabsorbing around 99%
- 45Why do carnivores continuously produce HCO3-?H+ is produced for metabolism and so bicarbonate is needed to buffer the acidic metabolism process
- 46What percentage of bicarbonate is reabsorbed in the proximal tubule?85%
- 47What percentage of bicarbonate is reabsorbed in the LoH?10%
- 48As HCO3- can't cross the apical membrane in the tubules, how is is reabsorbed into the capillary lumen?CO2 freely diffuses from the tubular lumen into the tubular cell, where it reacts to make bicarbonate which can then diffuse across the interstitium into the capillary
- 49What is the ionic movement within bicarbonate secreting cells?bicarbonate ions are secreted into the tubular lumen whilst Cl- is transported into the cell
H+ moves into the capillary from the tubular cell - 50What ionic movement takes place in H+ secreting cells?H+ is secreted into the tubular lumen in exchange for K+ ions
bicarbonate and Cl- are transported into the capillary lumen - 51What are the two types of urinary buffers?inorganic phosphate and ammonia/ammonium
- 52Which is the most important urinary buffer?ammonia/ammonium buffer as it can cope with large acid increases
- 53Why is the phosphate buffer only useful with small changes in H+?the concentration of phosphate in renal tubules is always low and so only limited H+ can be excreted in urine as bound to phosphate
- 54How does the inorganic phosphate buffer exist in solution?equilibrium between a weak base and a weak acid : Na2HPO4 (alkaline) and NaH2PO4 (acid)
- 55How does NH3 produce NH4+?crosses the membrane to 'mop up' H+ to convert into NH4+
- 56How does the ammonia/ammonium system also influence Na+ levels in the body?contributes to Na+ levels in the body by allowing Na+/NH4+ exchange
- 57What is acidosis?acidosis occurs when the arterial pH falls below 7.35
- 58What is alkalosis?alkalosis occurs when the pH of arterial blood rises above 7.45
- 59In acid-base disturbances, what is involved in Compensation?rapid, short term pH regulation using buffers and the respiratory system
- 60In acid-base disturbances, what is involved in Correction?longer term effect to return bicarbonate and carbon dioxide levels to normal
- 61How can respiratory acidosis/alkalosis occur?when the lungs remove CO2 at a lower or higher rate
- 62With respiratory acid-base disturbances, in what way do H+ and HCO3- concentrations change?both H+ and bicarbonate concentrations are changed in the same direction - in acidosis, both ion concentrations increase
- 63What system is involved in compensation of respiratory acid-base disturbances?The kidneys are used to regulate ECF pH back to normal levels in compensation
- 64In respiratory acidosis, what happens to kidney function?as the pCO2 increases and pH decreases, there's an increased stimulation of urinary H+ excretion and increased bicarbonate production
- 65How are metabolic acid-base disturbances defined?metabolic acid-base disturbances arise when the H+ comes from another source other than CO2, like lactic acid
- 66In metabolic acid-base disturbances, H+ and bicarbonate changes occur in which direction?H+ and bicarbonate change in opposite directions
- 67In metabolic acid-base disturbances, what system is involved in compensation and what type of compensation is it?the lungs compensate by altering pCO2, however this is only partial or incomplete compensation
- 68In metabolic acid-base disturbances, what system is needed for complete correction?kidneys
- 69What is the primary determinant of intracellular pH?arterial pH
- 70Do respiratory or metabolic changes have a greater effect on H+ secretion?changes in arterial pH due to respiratory changes more readily affect H+ secretion
- 71Why do respiratory changes have a more rapid effect on pH changes than metabolic changes?CO2 crosses cell membranes more easily than H+ and bicarbonate ions and so can more quickly change the pH levels
- 72In acid-base balance, what are the two main functions of H+ excretion?- facilitates bicarbonate reabsorption
- facilitates bicarbonate formation - 73Following arterial H changes, what is the most important determinant of H+ renal excretion?changes in K+ plasma concentration
- 74Why does K+ plasma concentration have a large effect on H+ excretion rates?K+ influences how H+ is transported across cell membranes, as they are often involved in carrier proteins or exchange mechanisms
- 75Hyperkalemia will cause what type of acid-base disturbance?metabolic acidosis - more K+ efflux will lead to a greater rate of H+ influx, so more H+ will be excreted into the urine
- 76Hypokalemia causes what type of acid-base disturbance?metabolic alkalosis
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- Animal Disease 1 Veterinary Medicine Flashcards on Acid Base Balance and pH, created by Louise Mason on 21/03/2017.
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- Louise Mason
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