Acid base balance Flashcards
(22 cards)
Homeostasis (3)
-the act of maintaining some variable within a predetermined range suitable for the environment
-Things like temperature, ion balance and acid base status are all examples of homeostasis
-Deviating can be lethal
pH (3)
-pH is the acidity or alkalinity of a solution
-determined by the concentration of protons
-its a log scale, so 1 pH unit is 10x acidity or alkalinity ex going from 7 to 8 means one solution is 10x more alkaline than the other.
Why does pH homeostasis matter?
Enzymes are pH sensitive, so every enzyme reaction rate, like O2 binding to respiratory pigments is dependent on a specific pH
Protein pH sensitivity
-slight deviations in pH can disrupt protein function
-Proteins function is dictated by equilibriums where:
Protein-NH3 <–> Protein NH2 + H+
-if pH increases (less H+) the equation shifts to the right to produce more protons
-if pH decreases (more H+) the reaction shifts to the left to remove protons
Because of this, when pH is more acidic, the proteins will have a net negative charge and vice versa
Acid base homeostasis and fluid
The right pH for homeostasis depends on the type of fluid. For blood its around 7, and for stomach acid its between 1.5-3. These must be tightly regulated, for blood there is only a 0.05 margin and if your stomach acid becomes greater than 3 it limits digestion by fucking up pepsin
Why does pH change?
Metabolism constantly alter acid-base status by producing CO2. The CO2 then becomes hydrated in fluids and acidifies them
Types of acid base regulation (3)
-Acid-base buffering systems (Very fast)
-Respiratory acid base regulation (kind of fast)
-Renal acid-base regulation (slow)
Buffering systems (3)
-buffers are formed of a weak acid/base in a pH sensitive equilibrium
-they mitigate pH changes by accepting or releasing protons
-For example, bicarbonate buffer is called the “life buffer” as it helps maintain the correct ratio of carbonate to carbon dioxide in the blood
Protonation states
The specific number of protons attached to a molecule
Protein buffering (2)
-Proteins can change their protonation states to buffer
-Protein is largely the determining factor of intracellular pH
Respiratory acid-base regulation (3)
-CO2 is an easily evaporated acid, allowing it to be manipulated by breathing
-Therefore breathing can rapidly change the CO2 in your blood:
Fast breathing = more CO2 = equilibrium shifts left = more Alkaline
Slow breathing = less CO2 = equilibrium shifts right = more Acidic
Renal Acid base regulation (5)
-Kidneys are slow but strong acid-base regulators, with their functions including:
-Excreting urinary acids (like NH4) (ammonium)
-Removal of non-volatile acids
-recycling HCO3 (bicarbonate) back into the blood
-Performing ammoniagenesis
Volatile definition
can evaporate easily
Ammoniagenesis (3)
1). Glutamine breaks down into 2 ammonium and 2 bicarbonates
2). ammonium is excreted as urinary acid
3.) bicarbonate is transported back into the blood
Proximal tube
-Part of the kidney
1). Carbonic Anhydrase breaks down water and carbon dioxide to ensure that there is plenty of protons and bicarbonate available
2). NHE3 and proton pumps transport protons into the lumen using sodium pumped into the lumen by the sodium potassium pump as a counter ion
3). biCarbonate is moved into the blood by bicarbonate / chlorine exchangers
Urea production
Ammonium that isnt excreted from ammoniagenesis is converted to urea by the liver, resulting in net-acid producion
NHE3
Sodium hydrogen exchanger
Respiratory acidosis and alkalosis (3)
-Respiratory acid-base problems happen when pH levels go up or down because of changes in CO₂ levels.
-Acidosis occurs if you do not exhale enough CO2 (buildup of Co2 = more acid)
-Alkalosis occurs if you exhale too much CO2, like when hyperventilating (Not enough Acid = more alkaline)
Metabolic acid-base disturbances (5)
-If pH changes while CO2 is stable, it likely means that bicarbonate levels change and is a result of metabolism
-Ketoacidosis: Ketones form from breakdown of fatty acids and removal of amino acids, lowering pH
-Lactic acidosis: Anaerobic metabolism makes lactic acid, lowering pH
-Renal tubular acidosis: Kidneys get stuck acidifying urine
-Diarrhea: Loss of large amounts of bicarbonate = lower pH
Aquatic species (4)
-most of the acid-base regulations of the mammalian lungs and kidneys are combined in the gills of aquatic species
-Kidneys or smaller glands may be present but aren’t always involved
-because there is much less oxygen in water than air, aquatic animals usually hyperventilate to sustain oxygen demands
-CO2 is still exhaled but these species cannot rely on adjusting breathing rates to regulate acid-base balances
Aquatic Respiratory regulation (3)
-Gills maintain acid-base homeostasis through ion exchange
-This is often paired to Na+/Cl- transport using H+/HCO3 as the counterions
-Gills alkalize blood/hemolymph to counteract the increased CO2 (Acid) levels, and can collect or excrete bicarbonate (base) based on what is needed
Aquatic consequences of Acid-base disturbances due to climate change (3)
-Higher energy costs to survive as regulation of acids-bases costs energy. This leads to reduced energy for growth and reproduction
-Acidic waters causing shells to dissolve, causing increased energy for shell maintenance or loss of protection if the shell is dissolved completely
-Behavior shifts due to inhibiting olfaction processes, resulting in compromised predator/prey interactions
