1.1.acids, bases and buffers

Question 1

properties of water and its functions.

Answer 1

water is the solvent for life. functions:

1. solvent- compoungs in body
2. transport-molecules in the body
3. enviornment-created a homeostatic enviornment inside and outside of the cell
4. temperature regulation through prespiration
5. chemical reactions, used as reactant and product

Question 2

Describe a dist. of water between different fluid compartments of the body

Answer 2

water occupies two major compartements:

1. ICF-60%
2. ECF
   
   1. plasma
   2. interstitial fluid
   3. other: lymph, eye humor, gastrointestinal secretions

Question 3

Explain the causes an consequences of disorders of water balance

Answer 3

1. negative water balance-when water intake is less than output
   
   1. sweating, diarrhea, burns, impaired kidney, inadequate water intake,
   2. signs: cottonmouth, dry skin, mental confusion, fever
2. overhydration
   
   1. water intoxication via hyponatremia. exacerbated via perfuse sweating(exercise)
   2. due to
      
      1. over consumption 2< gal/day
      2. renal failure
3. edema- excess fluid accumulation
   
   1. due to
      
      1. increased blood pressure
      2. CGF
      3. decreased blood osmotic pressure
      4. impaired circulation

special cases:

• inadequate water intrake
  
  • comatose patients-cannot swallo
  • loss of appetite
  • cerebral injuries
• gastrointestinal water loss-impaired reabsorbtion(small intestine)
  
  • ~8-10 L/day of H2O reabsorbtion
• high concentration of solutes excreted in urine
  
  • osmotic diuresis-diabetic patients have excess ketone bodies and glucose in urine

Question 4

Explain the major sources of Hydrogen ions in our body

Answer 4

1. CO2
   
   1. TCA
2. Phosphoric acid
   
   1. catabolism of phosphorous containing compounds, releases P-acid into ECF
3. Lactic acid
   
   1. anaerobic glycolysis
4. ketone bodies
   
   1. fatty acid oxidation

Question 5

Give quick general Description as to how pH is maintained by four systems. What is the reaction rate of Buffers, respiratory center and the renal system on the pH of the body?

Answer 5

The acids are controlled by buffere systems until they can be properly expired.

1. bicarbonate-carbonic acid-ECF
2. Hemoglobin buffer system-RBC
3. phosphate buffer system-in all cell types
4. ammonium and phosphate ions- kidneys

Buffer-act within seconds

1. bicarbonate, phosphate and hemoglobin

respiratory center-acts in minutes

1. removing carbonic acid through expiration of CO2

renal system- requires hours to days to affectpH

1. ketone bodie, ammonium,

Question 6

Describe with detail the bicarbonate buffer system

Answer 6

There are two pathways 1. In the tissues 2.in the lungs

1. CO2 produced in TCA->interstitial bluid->blood plasma->RBC
   
   1. RBC’s carbonic anhydrase converts CO2 and H2O into H2CO3.
   2. H2CO3 is exchanged for a Cl-, into the plasma
2. RBC->CA catalyzes H2CO3 ->CO2+H2O and more H+ +HCO3- ->H2CO3
   
   1. Hb loses some of its H+ that allows it to bind to oxygen more readily

Question 7

Describe in detail the intracellular buffer system and mechanism

Answer 7

Phosphate anions, G6P, and Proteins(ones that accept H+) are the major buffers of ICF

1. they accept the free protons from bicarbonate generation
2. Dihydrogen phosphate ion has max buffering cap at normal pH

metabolism produces the following acids, which have a pKa of ~5

1. ketone bodies (acetoacetate &beta hydroxybuttyric acids) generated from FA oxidatin in the liver
2. Lactic acid is produced in anaerobic glycolysis.

Question 8

What does the cell do with anion metabolites generated in the cell.

Answer 8

they are transported outside of the cell together with H+

1. intracellular conditions become too acidic, H+ is exchanged for Na+
2. intracellular conditions become too alkaline, bicarbonate is transported out in exchange for Cl- ions

Question 9

How is the urinary system involved in acid/base buffering?

Answer 9

nonvolatile metabolics acids are excreted in the urine.

1. these are fixed acids that are not excreted by the lungs
   
   1. phosphate, NH3+, Uric acid, discarboxylic and tricarboxylic acids
2. excrection of H2PO4- helps reduce acidity
   
   1. HOW?
3. these metabolites buffer the urine between 5.5-7
   
   1. pH 5.0 is a minimum urinary pH

Ammonium is the major contributor to acidity of urine, but not blood.

1. -NH3 + H+ <->NH4+
2. must be kept in low [blood] due to toxic effects on neuronal tissues

Question 10

General description of HCl, stomach acid and how this acid is handled with in the body.

Answer 10

parietal cells produce strong acid to denature proteins and kill infectious agents

Stomach acid is neutralized by bicarbonate secreted by pancreatic cells and intestinal lining.

Question 11

Describe metabolic acidosis. two conditions with regard to anion gap.

Answer 11

Occurs when an there is an addition of acid to the blood or a loss of bicaronate from the blood. this shifts towards the formation of CO2 and H2O

CO2 +H2O <-H2CO3 <- HCO3- + H+

lungs-remove excess CO2

Kidney-retain HCO3-, H+ is excreted as ammounium and other acids in order to raise pH

high

liver-in “high anion gap metabolic acidosis” H+ is added from ohter resources: ketone bodies

1. high anion gap metabolic acidosis occurs when acids are added to from additional source
   
   1. anerobic glycolysis
      
      1. lactic acid
   2. ketoacidosis
      
      1. beta-hydroxybutiric acid
      2. acetoacetate

normal

Question 12

Describe metabolic alkalosis

Answer 12

Question 13

descreibe respiratory alkalosis

Answer 13

This shifts the equation to left side products formation

1. H2O + Co2 <-H2CO3 <- H+ +HCO3-

responses:

1. kidneys secrete HCO3- and retain H+

causes

1. excessive CO2 is removed by the lungs, hyperventilation
2. hypoxia sepsis
3. lung disease pregnancy

Question 14

describe respiratory acidosis

Answer 14

CO2 is not being properly excreted by the lungs. The equation shifts to the right and H+ is retained.

CO2 +H20 ->H2CO3 -> HCO3- + H+

causes:

1. thoracic injury, flail chest
2. CNS-comatose, drug overdose
3. airway obstruction
4. pulmonary edema
5. obesity-hypoventalation
6. neurmuscular weakness-myasthenia, Guillian Barre
7. interstitial fibrosis

Question 15

With arrows of increase/decrease describe the 4 possible states with regard to blood gasses.

(PCO2, [H+], [HCO3-] and pH)

Answer 15