Acid-Base Regulation - Jan 17 - Dr K

The weak organic acid, lactic acid, has a pKa of 3.86. During strenuous exercise, lactic acid can accumulate in muscle cells to produce fatigue. If the ratio of the conjugate base form lactate to the conjugate acid form of lactic acid in muscle cells is approximately 100 to 1, what would be the pH in the muscle cells? A. 1.86 B. 2.86 C. 3.86 D. 4.86 E. 5.86

5.86

Normal blood pH is tightly regulated in a small range of ___. The sources of protons in blood are both volatile (carbonic acid derived from CO2) and nonvolatile (SO4, PO4, lactic acid, and keto acids). The major buffer system that regulates H+ levels in the blood is bicarbonate (HCO3-, and hemoglobin to a lesser extent).

7.35 to 7.45

pH = to?

The negative logarithm to the base 10 of the hydrogen ion concentration

The ___ phosphate ion converts a strong base to a weak base

dihydrogen

COO- group accepts a hydrogen ion in the presence of ___

excess acid

NH3+ group releases a hydrogen ion in the presence of ___

excess base

The kidneys have 2 vital roles in maintaining acid-base balance, including?

*Reabsorb* bicarb from urine, and *excrete* H ions into urine

pKa can be mathematically expressed differently how?

-logKa

pH+pOH=

14

When the HCO3- is 24 mEq/L, and the PaCO2 is 40 mm Hg, the base to acid ratio is 20:1 and the pH is ___. H-H equation confirms the 20:1 ratio. When the HCO3- is 29 mEq/L, and the PaCO2 is 80 mm Hg, the base to acid ratio decreases to 12:1 and the pH is ___. In contrast, when the HCO3- is 20 mEq/L, and the PaCO2 is 20 mm Hg, the base to acid ratio increases to 33:1 and the pH is ___. H-H equation confirms the 33:1 ratio

7.4 (normal); 7.18 (acidic); 7.62 (alkalotic)

A patient attempted suicide by ingesting 50 aspirin tablets. This led to a fairly severe metabolic acidosis. A decrease of blood pH from 7.5 to 6.5 would be accompanied by which one of the following changes in ion concentration? A. A 10-fold increase in hydroxyl ion concentration B. A 10-fold increase in hydrogen ion concentration C. An increase in hydrogen ion concentration by a factor of 7.5/6.5 D. A shift in concentration of buffer anions, with no change in hydrogen ion concentration E. A decrease in hydrogen ion concentration by a factor of 6.5/7.5

A 10-fold increase in hydrogen ion concentration The pH is the negative log of the hydrogen ion concentration, [H+]. Thus, at a pH of 7.5, [H+] is 10−7.5, and at pH 6.5, it is 10−6.5. The [H+] has changed by a factor of 10−6.5/10−7.5, which is 101, or 10. Any decrease of 1 pH unit is a 10-fold increase of [H+], or a 10-fold decrease of [OH−]. A shift in the concentration of buffer anions has definitely occurred, but the change in pH reflects the increase in hydrogen ion concentration in excess of that absorbed by buffers. A drop of 1 pH unit in a metabolic acidosis is a very severe condition.

Buffer

A solution that resists changes in pH value on addition of small amounts of acid or base Buffers typically involve a weak acid or alkali together with one of its salts. e.g.: Mixture of carbonic acid and sodium bicarbonate

What is a base

A substance that accepts protons H+ eg: lactate is a conjugate base that accepts a proton to form lactic acid

Describe an acid

A substance that donates protons (H+) eg: lactic acid is an acid because it donates protons

Each NH3 binds to protons from the blood to produce ___, which is filtered into the urine.

NH4+

What are the 3 primary systems that regulate acid concentration in our body fluids to prevent acidosis or alkalosis?

Acid-base buffer systems in our fluids, the resp center, and the kidneys

In the given equation H+ + HCO3- ↔ H2CO3 ↔ CO2 + H2O Severe diarrhea is accompanied by a loss of HCO3-. If untreated, will the condition result in (acidosis or alkalosis)?

Acidosis. The removal of HCO3- will pull the equilibria in the direction of HCO3-, which will produce H+, thereby lowering the pH.

What is Ka?

An acid dissociation constant that's a quantitative measure of the strength of an acid in solution It's the equilibrium constant for a chemical reaction known as dissociation in the context of acid-base reactions.

Mutations in the formation of Pyruvate Dehydrogenase Complex increases the level of Pyruvate which eventually converted to lactate. Diffusion of lactate out of the cell into blood resulting in lactic acidosis or also called ___.

Autosomal recessive metabolic acidosis

What do kidneys control excretion of?

Bicarb

It's important we maintain a 20:1 ratio of ___:___

Bicarb : Carbonic Acid (HCO3- : H2CO3)

___ RESIST changes in pH when protons or hydroxides are added IF the ___ is in its ___ region

Buffer(s)(ing) (The buffering region for a buffer is *within one pH unit above or below the pKa* of the weak acid composing it)

What do lungs control excretion of?

CO2

Normal metabolism generates ___, ___ (e.g., lactic acid and ketone bodies), and ___ (e.g., sulfuric acid). The major source of acid is CO2, which reacts with water to produce ___.

CO2, metabolic acids, inorganic acids, carbonic acid

Summary of the three main ways that the kidney can regulate plasma bicarbonate, and hence plasma [H']. (A). ___ catalyzes the formation of H' and HCO3-, from water and CO2. HCO3- is transported into the blood and H' is transported into the urine where it is partially buffered by filtered HCO3-. (Note, the mechanisms for transporting H' out of the cell are manifold and depend on the specific region of this kidney under consideration.) (B). New HCO3- is also produced if the supply of filtered HCO3- is exhausted in the tubules by complete reabsorption. HCO3-, and H' are produced in the same was as in (A), it's just that the transported H+ is combined with filtered HPO42- and excreted. (C) Finally, tubular epithelial cells metabolize glutamine into NH4+ and HCO3-. This reaction is catalyzed by the enzyme ___, the levels of which are regulated according to acid-base balance. ___ is induced by chronic acidosis to assist in HCO3- production (mainly in the proximal tubule)

Carbonic anhydrase (CA); glutaminase

What's the 1st line of defense against pH shift?

Chemical buffer systems, including Bicarb, Phosphate, and Protein buffer systems

A patient with an enteropathy (intestinal disease) produced large amounts of ammonia (NH3) from bacterial overgrowth in the intestine. The NH3 was absorbed through the intestine into the portal vein and entered the circulation. Which of the following is a likely consequence of his NH3 absorption? A. Kussmaul respiration B. Conversion of NH3 to ammonium ion (NH4+) in the blood C. Increased expiration of CO2 D. A decreased concentration of bicarbonate in the blood

Conversion of NH3 to ammonium ion (NH4+) in the blood NH3 is a weak base that associates with a proton to produce the ammonium ion (NH3 + H+ → NH4+), which has a pKa of 9.5. Thus, at pH 7.4, most of the NH3 will be present as ammonium ion. The absorption of hydrogen ions will tend to increase, not decrease, the pH of the blood. With the decrease of hydrogen ions, carbonic acid will dissociate to produce more bicarbonate (H2CO3 → HCO3− + H+), and more CO2 will go toward carbonic acid. Kussmaul respiration, an increased expiration of CO2, occurs under an acidosis, the opposite condition.

The composite pKa of the bicarbonate system, 6.1, may appear to make it ill-suited for buffering blood at physiologic pH of 7.4. Nevertheless, the system is very effective at buffering against additions of noncarbonic acids. Changes in the bicarbonate/carbonic acid ratio in such cases can be regulated by: A. Recruitment of bicarbonate reserves from the peripheral tissues. B. Recruitment of bicarbonate reserves from the peripheral tissues. C. Conversion of carbonic acid to CO2 followed by removal by the lungs. D. Reaction of excess carbonic acid with the amino termini of blood proteins. E. Binding of carbonic acid by hydroxide ions from the fluid phase of blood.

Conversion of carbonic acid to CO2 followed by removal by the lungs. Ingestion of an acid or excess production by the body, such as in diabetic ketoacidosis, may induce metabolic acidosis, a condition in which both pH and HCO3− become depressed. In response to this condition, the carbonic acid-bicarbonate system is capable of disposing of the excess acid in the form of CO2. The equilibrium between bicarbonate and carbonic acid shifts toward formation of carbonic acid, which is converted to CO2 and H2O in the RBC catalyzed by carbonic anhydrase, an enzyme found mainly in the RBC. The excess CO2 is then expired by the lungs as a result of respiratory compensation for the acidosis (Figure 1-2). The main role of the kidneys in managing acidosis is through excretion of H+ rather than CO2.

___ is a condition marked by hyperglycemia and low blood pH that often afflicts individuals with uncontrolled diabetes. The lack of insulin prevents glucose from being taken up by cells to produce energy. Consequently, the body switches to degrading fatty acids for energy. The degradation (via B-oxidation) of fatty acids generates acidic compounds called ___. They include acetone, acetoacetic acid, and B-hydroxybutyric acid. The dissociation of the latter two ___ releases H+, which causes the pH of the blood to decrease. The symptoms of this disease above include dehydration, vomiting, confusion, and coma and may lead to death.

Diabetic ketoacidosis (DKA); ketone bodies (B-hydroxybutyric acid, acetoacetate)

A patient is in early diabetic ketoacidosis (DKA). Which one of the following would this patient be expected to exhibit upon examination? A. Low blood glucose B. Excess fluid in the tissues of the lower extremity C. Decreased urine output as an attempt to preserve water D. Increased respiratory rate E. Decreased respiratory rate

Increased respiratory rate Because of the high concentration of ketone bodies (acid) in the blood, the patient would have a lower blood pH and a metabolic acidosis. To help compensate for this acidosis, the respiratory rate would increase to "blow off CO2." The decrease of blood CO2 would increase the formation of carbonic acid from bicarbonate and a proton, thereby reducing the proton concentration and raising the blood pH. Decreasing respiration would do the opposite and actually increase the proton concentration to further decrease pH and worsen the acidosis. A patient with DKA has abnormally high blood glucose and ketone body levels, which greatly increase blood osmolality; this leads to water leaving the tissues and entering the blood to help balance the increased osmolality, which results in intracellular dehydration. The kidney normally would decrease urine output in dehydration, but the high osmolality of the glomerular filtrate increases the water content of the filtrate in order to dilute these ions. This movement of water increases urine output, leading to the patient becoming even more dehydrated.

A 39-year-old female with type 2 diabetes mellitus (T2DM) presents with a chief complaint of weakness and chest discomfort. Her blood pressure is 150/98 mm Hg and an EKG reveals tall, peaked T-waves. Blood results show hyperkalemia, and decreased aldosterone and plasma renin activity, suggestive of type IV RTA. In type IV RTA, there is a defect in aldosterone secretion, as well as ammonium (NH4+) excretion. What characteristics best describe the ammonia (NH3) present in the kidney? A. It is produced by epithelial cells in the distal nephron. B. It is classified as a titratable acid. C. Its synthesis is increased in respiratory acidosis. D. It is impermeable to the epithelial cells of the proximal tubule. E. It reduces the concentration of bicarbonate in the plasma.

Its synthesis is increased in respiratory acidosis The rate of ammonia production increases during acidosis. This is important because it increases the total amount of H+ ion that can be excreted in a given volume of urine.

A 9-month-old child is presented to the emergency room by his parents who report that he has been vomiting and has severe diarrhea. The infant exhibits signs of failure to thrive, weight loss, and hepatomegaly. Laboratory tests show metabolic acidosis with coagulation deficiency. These clinical and laboratory findings are most consistent with the accumulation of which of the following molecules? A. Lactate B. Fumarate C. Acetoacetate D. β-hydroxy butyrate

Lactate

The enzyme that produces lactic acid from pyruvate in presence of NADH: A. Acetoacetate decarboxylase B. Lactate dehydrogenase C. Hydroxybutyrate dehydrogenase D. Pyruvate dehydrogenase E. Succinate dehydrogenase

Lactate dehydrogenase

Addition of protons (from HCl, for example) to the HAc <=> H+ + Ac- system will drive the reaction to the left due to ___. This will increase the amount of HAc and decrease the amount of Ac-. The total amount of HAc and Ac- will remain the same in a system. Addition of NaOH (strong base) the same system will drive the reaction to the right, causing there to be less HAc and more Ac-

Le Chatelier's principle

___ stating that if a constraint (such as a change in pressure, temperature, or concentration of a reactant) is applied to a system in equilibrium, the equilibrium will shift so as to tend to counteract the effect of the constraint.

Le Chatelier's principle

A 45-year-old female with renal failure, missed her dialysis and was feeling sick, what could be the reason? A. Respiratory acidosis B. Metabolic acidosis C. Metabolic alkalosis D. Respiratory alkalosis

Metabolic acidosis

What's the 2nd line of defense against pH shift?

Physiological buffer systems, including Respiratory and Renal mechanisms (The second line of defense, the respiratory system, acts within a few minutes to eliminate CO2 and, therefore, H2CO3 from the body)

Neutral and dicarboxylic AAs oxidation is an ex of a proton-___ rxn

Proton-consumptive

Gluconeogenesis is an ex of a proton-___ rxn

Proton-consumptive 2 lactate + 2 H+ → Glucose

Ureagenesis is an ex of a proton-___ rxn

Proton-productive CO2 + 2 NH+4 → urea + H2O + 2 H+

Ketogenesis or production of ketone bodies (in fasting state) is an ex of a proton-___ rxn

Proton-productive Fatty acids → ketone bodies + n H+

Anaerobic glycolysis in muscles and RBCs is an ex of a proton-___ rxn

Proton-productive Glucose → 2 CH3CHOHCOO- + 2 H+

Lipolysis is an ex of a proton-___ rxn

Proton-productive TAG → 3 FA + glycerol + 3 H+

A patient arrives in the trauma center suffering from unknown internal injuries as a result of a traffic accident. She is semiconscious with a blood pressure of 64/40 mm Hg and appears to be going into shock. Blood gases reveal a PCO2 of 39 mm Hg (normal = 40 mm Hg) and a bicarbonate of 15 mM (normal = 22-30 mM), with pH = 7.22. The best course of action to manage this patient's acidosis would be to start intravenous administration of a solution of: A. Sodium bicarbonate B. Normal saline C. 5% dextrose D. Sodium lactate E. Sodium hydroxide

Sodium bicarbonate

Which of the following two organs function as the most important physiological buffer systems? A. The thyroid gland and the heart B. The stomach and the liver C. The adrenal glands and the testes D. The lungs and the kidneys

The lungs and the kidneys

Ammonia is an affective important urinary buffer for which of the following reasons: A. The acid base reaction has lower pKa B. The walls of the renal tubules are impermeable to NH3 C. The walls of the renal tubules are impermeable to NH4+ D. Its production in the kidney decrease during chronic acidosis

The walls of the renal tubules are impermeable to NH4+

The blood contains many compounds that serve to buffer the pH of the fluid such as bicarbonate and phosphate ions. Which of the following most correctly defines the meaning of the term buffering? A. a solution containing a large concentration of a base such that the pH will not change significantly when an acid is added B. a solution containing a large concentration of an acid such that the pH will not change significantly when more acid is added C. a solution or substance which resists changes in pH when small quantities of an acid or base are added to it D. pH at which a molecule or solution is neutrally charged e. pH at which an equivalent distribution of acid and conjugate base exists in solution

a solution or substance which resists changes in pH when small quantities of an acid or base are added to it A buffer is a molecule that tends to either bind or release hydrogen ions in order to maintain a particular pH. More precisely, a buffer is defined as a mixture of a conjugate acid-base pair that can resist changes in pH when small amounts of strong acids or bases are added to it.

In Type 1 diabetes, the increased production of ketone bodies is primarily a result of which of the following? A. an increase in the rate of the citric acid cycle B. increased hepatic glucose release from glycogen driving acetyl-CoA production C. a substantially increased rate of fatty acid oxidation by hepatocytes D. decreased cyclic AMP levels in adipocytes which causes accelerated fatty acid release E. elevated acetyl-CoA levels in skeletal muscle driving ketone body synthesis

a substantially increased rate of fatty acid oxidation by hepatocytes The most frequent consequence of poorly controlled T1D is ketoacidosis, referred to as diabetic ketoacidosis, DKA. The hyperketonemia in DKA is the result of insulin deficiency and unregulated glucagon secretion from α-cells of the pancreas. Circulating glucagon stimulates the adipose tissue to release fatty acids which are taken up and oxidized, primarily by the liver. Under these conditions, the level of fatty acid oxidation is in excess of the livers' ability to fully oxidize the excess acetyl-CoA and, thus the compound is diverted into ketones synthesis. The ketones are released into the circulation and because they are acidic, lower the pH of the blood resulting in metabolic acidosis.

A blood pH < 7.35 is termed as ___, and that >7.45 is termed as ___. Primary acid-base imbalances occur when a single physiological mechanism is not functioning properly or is overwhelmed. These can occur due to either respiratory or metabolic imbalances. ___ imbalances are those in which the primary disturbance is in the concentration of CO2. ___ imbalances are those in which the primary disturbance is in the concentration of bicarbonate.

acidosis; alkalosis; Respiratory; Metabolic

When ___ (acidosis or alkalosis) occurs, the body will divert more glutamine from the liver to the kidney. This allows for the conservation of bicarbonate ion since the incorporation of ammonia into urea requires bicarbonate. When glutamine enters the kidney, glutaminase releases 1 mole of ammonia generating ___ and then glutamate dehydrogenase releases another mole of ammonia generating a-ketoglutarate. The ammonia will ionize to ammonium ion (NH4+) with dihydrogen phosphate which is excreted. The net effect is a reduction in the concentration of hydrogen ion [H'], and thus an increase in the ___ of the blood

acidosis; glutamate; pH

To maintain the pH of body fluids in a range compatible with life, the body has ___ such as bicarbonate, phosphate, and hemoglobin. Ultimately, respiratory mechanisms remove carbonic acid through the expiration of ___, and the kidneys excrete acid as ___ and other ions.

buffers, CO2, ammonium ion (NH4+)

During the course of normal cellular metabolism, the body generates large quantities of acid. Despite this, normal blood pH is maintained at a slightly alkaline pH of 7.4. Removal of which of the following is most responsible for the maintenance of the alkalinity of extracellular fluids? A. ammonia B. carbon dioxide C. ketones such as acetoacetate D. lactic acid E. phosphoric acid

carbon dioxide The vast majority of metabolic acid excretion is in the form of the volatile acid, CO2, which is removed via the lungs. Much smaller quantities of nonvolatile acids must be excreted in the urine. Within erythrocytes, metabolically produced CO2 is combined with H2O forming carbonic acid, which then ionizes to form a bicarbonate ion and a proton. The protons bind to hemoglobin displacing O2, which not only provides the necessary oxygen for metabolism but also results in increased CO2 removal. During periods of increased acidity, referred to as metabolic acidosis, chemoreceptors sense a deranged acid-base balance and compensate by increasing respiration rate, hyperventilation, to increase the rate of CO2 removal.

Which of the following is the primary source of the H+ that leads to displacement of O2 from hemoglobin in the tissues? A. 2,3-BPG B. bicarbonate ion C. carbonic acid D. phosphoric acid E. water

carbonic acid When the CO2 from metabolism is released to the circulation, it enters the erythrocyte and is converted to carbonic acid via the actions of carbonic anhydrase. The carbonic acid then dissociates to H+ and HCO3−. The resulting increase in H+ inside the erythrocyte in the capillaries of the tissues reduces oxygen-binding affinity and the hemoglobin thus releases the bound oxygen to the tissues.

The primary source of urinary ammonia (NH3 or NH4+) is which of the following? A. catabolism of glutamine within renal cells B. catabolism of polyamines within renal cells C. filtered ammonia D. filtered glutamine E. synthesis of alanine within renal cells

catabolism of glutamine within renal cells Glutamine is the major amino acid of the circulation and its role is to ferry ammonia to and from various tissues. In the kidneys, glutamine is hydrolyzed by glutaminase (yielding glutamate), releasing the ammonia into the urine. There, the ammonia ionizes to ammonium ion, NH4+, which reduces the circulating concentration of hydrogen ion resulting in an increase in the pH. Additionally, the glutamate can be converted to α-ketoglutarate yielding another mole of ammonia, which is ionized by hydrogen ions further increasing the pH.

Which of the following enzymes plays a key role in the formation of ammonium ions in the proximal renal tubule? A. carbonic anhydrase B. glucokinase C. glutaminase D. Na+/K+-ATPase E. PKA

glutaminase Major reactions that involve the regulation of plasma pH as well as the level of circulating ammonia involve the hepatic and renal enzymes glutamate dehydrogenase (GDH), glutamine synthase (GS), and glutaminase. Under acidotic conditions the liver diverts ammonia to glutamine via the GS reaction. The glutamine then enters the circulation. In the kidneys, glutamine is hydrolyzed by glutaminase (yielding glutamate) releasing the ammonia to the urine. There the ammonia ionizes to ammonium ion, NH4+, which reduces the circulating concentration of hydrogen ion resulting in an increase in the pH.

Which of the following enzymes plays a key role in the formation of ammonium ions in the proximal renal tubule? A. glucokinase B. Na+/K+-ATPase C. CPS D. glutaminase E. carbonic anhydrase

glutaminase Major reactions that involve the regulation of plasma pH as well as the level of circulating ammonia involve the hepatic and renal enzymes glutamate dehydrogenase (GDH), glutamine synthase (GS), and glutaminase. Under acidotic conditions the liver diverts ammonia to glutamine via the GS reaction. The glutamine then enters the circulation. In the kidneys, glutamine is hydrolyzed by glutaminase (yielding glutamate) releasing the ammonia to the urine. There the ammonia ionizes to ammonium ion, NH4+, which reduces the circulating concentration of hydrogen ion resulting in an increase in the pH.

The most abundant end product of nitrogen metabolism in humans is which of the following? A. allantoin B. ammonium ion C. glutamine D. urea E. uric acid

glutamine Glutamate plays the central role in mammalian nitrogen flow, serving as both a nitrogen donor and nitrogen acceptor. Glutamine is the nitrogen repository found in the circulatory system. Its role there is to carry ammonia to and from various tissues but principally from peripheral tissues to the kidney. In the kidneys, glutamine is hydrolyzed by glutaminase (yielding glutamate) releasing the ammonia to the urine. Additionally, the glutamate can be converted to α-ketoglutarate yielding another mole of ammonia which is excreted.

The most abundant end product of nitrogen metabolism in humans is which of the following? A. ammonium ion B. urea C. glutamine D. uric acid E. allantoin

glutamine Glutamate plays the central role in mammalian nitrogen flow, serving as both a nitrogen donor and nitrogen acceptor. Glutamine is the nitrogen repository found in the circulatory system. Its role there is to carry ammonia to and from various tissues but principally from peripheral tissues to the kidney. In the kidneys, glutamine is hydrolyzed by glutaminase (yielding glutamate) releasing the ammonia to the urine. Additionally, the glutamate can be converted to α-ketoglutarate yielding another mole of ammonia which is excreted.

Pyruvate dehydrogenase complex (PDHc) deficiency is an autosomal recessive disorder and leads to anion gap metabolic acidosis. Which of the following accumulates to cause metabolic acidosis? A. acetoacetate B. fumarate C. β-hydroxybutyrate D. hydrochloric acid E. lactate

lactate Inhibition of 3 PDHc results in impaired oxidation of pyruvate. As the level of pyruvate increases in the cytosol, it is reduced to lactate which can diffuse out of the cell into the blood resulting in lactic acidosis.

In anaerobic glycolysis, muscles generate ___, which dissociates into ___+___. The Protons are removed while reacting with bicarb to form ___, which breaks down to water and CO2 by ___.

lactic acid→lactate + H+; carbonic acid; carbonic anhydrase

Acidosis caused by a primary decrease in HCO3− concentration is termed ___, whereas alkalosis caused by a primary increase in HCO3− concentration is called ___. Acidosis caused by an increase in PCO2 is called ___, whereas alkalosis caused by a decrease in PCO2 is termed ___.

metabolic acidosis, metabolic alkalosis, respiratory acidosis, respiratory alkalosis

Vomiting typically induces a ___ due to a loss of hydrogen ions from the stomach, leading to an increase in pH. A. respiratory alkalosis B. respiratory acidosis C. metabolic alkalosis D. Metabolic acidosis

metabolic alkalosis Vomiting typically induces a metabolic alkalosis due to a loss of hydrogen ions from the stomach, leading to an increase in pH. This leaves an increased bicarbonate concentration (generally >24 mEq/L) in the bloodstream; therefore this patient does indeed have a metabolic alkalosis.

The ___ phosphate ion converts a strong acid to a weak base

monohydrogen

Henderson-Hasselbalch equation

pH = pKa + log [A-]/[HA]

Find the pH if pKa is 4.7 and log (conjugate base/acid) is 0.48?

pH = pKa + log [CB]/[A] = 4.7 + log 3 = 4.7 + 0.48 = 5.18

Find pKa if pH is 4.4 and log (conjugate base/acid) is 0.3?

pH = pKa + log [CB]/[A] = pKa = pH - log [CB]/[A] = pKa = 4.4 - 0.3 = 4.1

One of the major roles of the kidneys is to regulate the pH of blood. The kidneys can do so because of their ability to remove protons (H+) from the blood in the form of ammonium ion (NH4+) and to reabsorb bicarbonate (HCO3-). Therefore, low blood pH triggers an increase in both the removal of excessive ___ (as ammonium dihydrogen phosphate salts) and the reabsorption of bicarbonate. When the pH of blood is too high, fewer ___ are removed and less bicarbonate is reabsorbed.

protons

Lactic acidosis is a type of metabolic acidosis and is caused by a buildup of d-lactate (>5 mM) in blood and tissues. The patients present with rapid breathing, vomiting, and abdominal pain. Because lactate is the end product of glycolysis under anaerobic conditions, its accumulation usually signifies hypoxia. Deficiencies of ___ and pyruvate carboxylase are examples of genetic causes underlying lactic acidosis. This is also called autosomal recessive metabolic acidosis.

pyruvate dehydrogenase (PDH)

The Henderson-Hasselbalch equation: A. allows the graphic determination of the molecular weight of a weak acid from its pH alone. B. does not explain the behavior of di- or tri-basic weak acids. C. employs the same value for pKa for all weak acids. D. is equally useful with solutions of acetic acid and of hydrochloric acid. E. relates the pH of a solution to the pKa and the concentrations of acid and conjugate base.

relates the pH of a solution to the pKa and the concentrations of acid and conjugate base.

The amino groups from glutamine and glutamate are used to produce NH3 in a process called ___.

renal ammoniagenesis

Bicarbonate buffer converts a ___ acid to a ___ acid

strong to weak

Carbonic acid buffer converts a ___ base to a ___ base

strong to weak

The lower the pKa for an acid is, the ___ the acid will be

stronger

Most acids and bases in extracellular fluid that are involved in normal acid-base regulation are ___ acids and bases

weak

The larger the pKa for an acid is, the ___ the acid will be

weaker

The carbon skeleton of ___ will be used for glucose synthesis via gluconeogenesis.

α-Ketoglutarate

Which of the following ketoacids provides the carbon skeleton for an amino acid capable of carrying 2 atoms of nitrogen per molecule from other tissues to the liver and kidney via the blood? A. acetoacetate B. α-ketoglutarate C. α-ketoisocaproic acid D. oxaloacetate E. pyruvate

α-ketoglutarate α-Ketoglutarate is capable of accepting 2 moles of ammonia, first via the action of glutamate dehydrogenase yielding glutamate and then via glutamine synthetase yielding glutamaine. Glutamate plays the central role in mammalian nitrogen flow, serving as both a nitrogen donor and nitrogen acceptor. Glutamine is the nitrogen repository found in the circulatory system. Its role there is to carry ammonia to and from various tissues but principally from peripheral tissues to the kidney.