W2 PP1 Flashcards
Bronstead lowry
Principle that a is is proton donor and base is proton acceptor.
Proton is H+
In water, the base will accept the H+
What determines the strength of the acid?
The concentration of protons and the ability to dissociate
HCL strong acid 100% dissociation
Weaker acids
Not complete dissociation
In the body acid usually comes to be formed
As the end product of the breakdown of carbohydrate proteins and fat metabolism
Ex. Conversion of glucose to lactate. Lactate is an acid
Volatile acid
Can be removed in gaseous form
Nonvolatile= removed by the kidneys
HCL
Produced by parietal cells. Breaks down every type of organic group
Anaerobic there can be a buildup of organic acids
Body goes to acidosis
What does pyruvate become in aerobic conditions
Acytl- Co enzyme A?
Becomes lactate in anaerobic-> acidosis
68 yo male from NH with 2 day Hx of fever cough and lethargy
101.2 , 118, 80/50, 93%
Lethargic, pale, LS-> scattered tales, rhonchi
CXR: multilobar pnemonia
LACTATE 4.4 (normal <2)
Sepsis! The tissue’s need for oxygen cannot be met, secondary for the increased metabolic demands due to the fever. He’s also hypoxic due to the pnemonia. The supply of oxygen is spread too thin
What are some bases found in the body
Proteins can be broken to ammonia which is quickly converted into urea by the liver
Ammonia can become glutamine-> alphaketoglutarate-> bicarbonate
pH
A logarithmic scale
1/10=10^-1
No units
Why does pH need such tight regulation
Ion trapping: keep and hold onto ions and decreases ability to be lost by diffusion. Glucose needs to be bound to Glucose-6-Phosphate.
Protein folding
A change in pH will denature a protein so it doesn’t work
Buffer
Absorb/resist large changes in pH
pH varies throughout the body
pH: 7.35 in arteries
pH: 7 in muscles
Release or bind to H+
A good buffer is a molecule that has the ability to either accept or donate protons at a given pH
Carbonic acid
Formed by carbon dioxide and water
Weak acid
Carbonic anhydrase enzyme catalyst and buffer!
Respiratory system is important for buffering.
If a patient has COPD and goes into respiratory stress, CO2 builds up and carbonic acid builds up and an acidic environment develops. Harder for acids and bases to convert. > respiratory rate to get rid of CO2 to < acid
Proteins can also serve as buffers such as the amino acid
Histidine has the closes pKa to plasma pH and us the most important AA buffer
Hb contains many histidine residues and is an important buffering system in blood. Carboxy group will be let go in a basic or acidic environment
pKa is a measure of
The strength of an acid in a solution. Predicts how effect a buffer will be in certain conditions
Kidneys maintain pH
In the distal tubules
In acidosis, your distal tubules excrete H+ and reabsorb bicarbonate
Requires carbon dioxide and water with the enzyme carbonic anhydrase. 10^6 rxns per sec. Reaction rate is really fast. Reverse is very slow.
CO2+water using carbonic anhydrase creates carbonic acid
Hydrogen ions+ ammonium (NH4) + phosphate (H2PO3) are excreted into the urine while bicarbonate is absorbed. This is acidotic (I believe)
D
Bone plays a role bc
Bone can exchange H+ for other ions to maintain acid base balance
Metabolic acidosis
Occurs when acid production is outpacing the buffering system. More acid produced than the buffering system can accommodate.
DKA- Diabetic KetoAcidosis, glucose cannot get into the cell secondary to a lack of insulin availability so the body switches from the metabolism of carbohydrates to the metabolism to proteins and fats. Result is a production of ketones and acids, thereby the pH starts to drop.
Assess metabolic acidosis:
Anion Gap:
[Na+]+[K+] - [Cl-]+[HCO3-]
Evaluating for the presence of unaccounted for anions. In the case of DKA, these anions are inorganic acids. An increase in the gap means there’s an increase concentration of anionic inorganic acids.
The normal anion gap 16<
Greater than 16 we consider this an anion gap acidosis, strongly suggests a metabolic acidosis.
Causes for metabolic acidosis
Most common is diabetic ketoacidosis
Severe lactic acidosis such as the first example
Toxic ingestions like methanol or ethylene glycol, aspirin overdoses, metformine (toxicalcohols).
Treatment for metabolic acidosis
Reverse underlying condition. IV fluids, IV bicarbonate
Toxic ingestion use antidotes for specific toxin
65 yo M w/ Hx of DM, CAD, HTN, & Hyperlipidemia
Saw PCP 6 days ago4 fever,cough
Had a normal CXR, Dix with bronchitis &Tx with albuterol,prednisone & an anti-tussive
Now 2 day Hx for > lethargy, fatigue,polydipsia, polyuria, & abdominal pain
VS: tachynpneic at 32 bpm, FSBS: 680mg/dL
I think he hasn’t been taking his insulin bc of the bronchitis/illness so now glucose can’t get into his cells and now his body is breaking down fats and proteins as energy which is building up the acid in his body.
Metabolic Alkalosis
-Increase loss of organic acids
-Excessive vomiting
Loss of Cl- shifts pH in distal tubules so Kidneys retain HCO3, thereby raising the pH
Causes of Metabolic Alkalosis
Vomiting
Overuse of diarretics
Overuse of antiacids (have bicarbs)
Signs and symptoms
Weakness
Muscle cramps
Confusion
Muscle tetany
A 76 yo 50 pack a year smoker with a Hx of COPD present to the ED with a 3 day Hx of worsening SOB. VS: 97.6, 110, 36, 85%
Lung sounds diminishing with only a few scant wheezes.
Respiratory Acidosis secondary to a COPD exacerbation
COPD IS
A disease of alveolar dysfunction and mucus plugging
Hypoventilation-O2 does not probably move across the alveoli—>hypoxic
Also might start to maintain carbon dioxide
If CO2 rate outpaces alveolar ventilation, you get HYPERCAPNIA
CO2 is converted to carbonic acid. Accumulation of carbonic acid, you get respiratory acidosis
Causes of respiratory acidosis
Hypoventilation secondary to a lack of oxygen. COPD, asthma, opioid overdose, pnemonia.
Signs and symptoms of Respiratory Acidosis
Neurological dysfunction: confusion or agitation.
Bc if the hypoxia, can be tachycardic or tachpnic
Cyanosis (blue discoloration of the lips or nails)
Treatment of Respiratory Acidosis
Reverse the causes
O2 supplements
Albuteral bets agonist (dilate those bronchi)
A 27 yo M w a Hx of anxiety disorder presents to the urgent care center with chest pain.
Is pale but warm and dry, his fingers are clenched into a fist (carpopedal spasm) but has an otherwise normal exam
VS: 98.8, 118, 40, 100%
Respiratory Alkalosis
Cause is hyperventilation. > respiratory rate, blows off lots of CO2 called-> Hypocapnia
Shifts phosphate out of the cell making it available to make it bond to other organic acids, increase in pH
Thyrotoxicosis, hyperthyroidism, sepsis, early on aspirin overdose.
pH 1x10^-5
pH= -Log[1x10^-5]
=5
