Patho: Acid-Base Balance Flashcards
What is the pH scale?
0-7 Acid (Acidic) 7-14 Base (Alkalotic)
How can a change in Hydrogen or base concentration alter pH and acidity?
-Normal ECF pH is controlled to be between 7.35-7.45
-An Acid is a molecule that can release H+
-A Base is a molecule that can accept/combine H+
Release of H into the ECF increases acidity
Most found in the body are weak acids and bases.
Ex: Carbonic Acid and Bicarbonate
Difference between Volatile and Non-Volatile.
1)Non-Volatile: Acids that are buffered by body proteins and bicarbonate and then are eliminated by the kidneys. Ex: Bicarnonate
2)Volatile: Acids that are excreted by the lungs.
Ex: Carbonic Acid (H2CO3) is volatile, and CO2 is excreted by the lungs.
What are the metabolic sourced of body acids?
Inorganic Acids:
-Produced by protein metabolism (leads to ketosis)
-Sulphuric, hydrochloric, and phosphoric acids.
-Lactic acid (No O2 metabolite)
Results in more Non-Volatle acids (metabolic disorder)
Vegetarians have decr. acid production and have net production of base b/c of their diet.
How is Carbon Dioxide transported in the bloodstream?
1) Dissolved in plasma (soluble in plasma) Ex:soda
2) Bound to Hemoglobin in the form of Carbaminohemoglobin
3) Bicarbonate in Plasma
How does Carbon Dioxide attach itself to Bicarbonate in Plasma?
-CO2 combinbes with H20 = HCO3 in RBC’s.
-H+ is released to try and increase O2 release (tissues) and CO2 loading. (RBC-> Lung)
-H+ is buffered by hemoglobin, so causes little pH change.
-Once formed, HCO3 (bicarbonate) exits RBC’s and travels in the plasma towards the lungs.
-Once is reaches the lungs, it’ll renter RBC’s and combine with H+ = Carbonic Acid( H2CO3) which will spilt into H2O and CO2, and CO2 will be released by the respiratory system.
(Note: CO2 + H2O = HCO3 in RBC’s. Travels to lungs, reneters RBC’s and combines with H = H2CO3 = H2O + CO2. then CO2 is released by lungs.)
Carbondioxide combined to Hemoglobin
Forms Carbaminohemoglobin:
-Causes changes in colour of blood.
-Dark red= deoxygenated.-Red= oxygenated.
It does not compete with O2It is influences by PCO2 (partial pressure) and amount of bound O2
What mechanisms regulate pH in the ECF?
1) An Intracelluler and Extracellular buffering system
2) Respiratory controls3)Renal Controls.
1) What is the Intracelluler and Extracellular Buffering system for pH regulation?
2) What are the Three General Buffering mechanisms to prevent large changes in pH?
1) -Consists of weak acids/bases that act as buffers and absorb small changes in pH.
- Buffers will bind with excess acids (H+) and prevent large changes in pH.(Will trade strong acid for weak acid, or a strong base for a weak base to prevent large changes in pH)
2) Three General Buffering mechanisms to prevent large changes in pH:
1) Proteins
2) Bicarbonate
3) Hydrogen
- Potassium Exchange.
Protein Buffer
- The Largest buffer system in the body.
- Can buffer acids or bases.
- Mostly located witin cells.
- Albumin and plasma proteins act as buffers in the bloodstream.
Bicarbonate Buffer
-Easy supply d/t the large presence of bicarbonate in the bloodstream (b/c of the CO2 transport) and breathing provides a nice outlet for excess CO2
Hydrogen-Potassium Exchange
-Body cells transport excess H+ into the cells for exchange for K+ and vice versa for acid base balance.
Ex: When K lvls are low, K is reabsorbed in to the kidneys and Hydrogen is secreted into the urine, resulting in metabolic alkalosis in order to bring the K lvls back up again.
Respiratory System for pH regulation.
- A rapid means of eliminating CO2-Cannot regulate pH alone as they cannot diectly get rid of H+
- Resp system is only getting rid of half the problem b/c it’s not getting rid of H+
Renal System for pH regulation
- Reabsorbs bicarbonate and excreting H+ by the kidneys.
- Aids in returning pH to near-normal levels.
- This is the best mechanism for pH regulation.
Differences between Metabolic and Respiratory Acid/Base Disorders
1) Metabolic:
- produces an alteration in bicarbonate concentration.
- Results from addition of non-volatile acids/bases to the ECF
- Procudes metabolic acidosis or metabolic alkalosis
- Incr. HCO3 and Incr. pH = Metabolic alkalosis
- Decr. HCO3 and Decr. pH+ Metabolic acidosis
2) Respiratory:
- Result from changes in respiratory rate increasing or decreasing and CO2
- Incr. PCO2 and Decr. pH = Respiratory Acidosis (d/t decr. RR)
- Decr. PCO2 and Incr. pH = Respiratory Alkalosis (d/t Incr. RR)
Compare and Contrast Primary causes and Compensatory Mechanisms
Primary Cause:
Main reason for acidosis or alkalosis
Compensatory mechanisms:
Homeostatic mechanisms trying to prevent large changes in pH without treating the underlying cause.(Temporary measures)
-A compensatory state usually develops from homeostatic responses to the primary event.
A compensation means another system is trying to permit survival.
Resp cannot compensate for resp.
Resp can compensate for metabolic.
Ex: hyperventilation (resp) when there are too many ketones in the blood(metabolic)
What is Metabolic Acidosis
Low pH (0-7 pH) caused by a decrease in bicarbonate. (Acidic)
What is the Metabolic Acidosis compensation?
It compensates by increasing the respiratory rate in order to decrease PCO2 and H2CO3 (carbonic acid) levels.
What are the causes of Metabolic Acidosis?
1) Increase in production of Non-Volatile metabolic acids.
2) Lactic Acid build up:
- incr. production or decreased clearance.
- produce by anaerobic metabolism in skeletal muscle (No O2)
- cleared by the liver and kidney. (so if there’s problems with those organs…)
- usually d/t inadequate O2 availability, such as in shock of cardiac arrest.
- Has also been reported in some cancers. 3)Ketoacids:
- produced by the liver from fatty acids and are used as fuel by many body cells.
- Overproduction occurs if there is insufficient CHO intake or inaccessible CHO.
- Common w/ uncontrolled DM, with fasting or starvation.
- Byproduct of protein breakdown to create glucose.
4) Decreased excretion of acid by kidney:
- Kidneys function to retain bicarbonate and excrete H+, in this case it doesn’t work and the acid isn’t removed.
- With kidney failure, wastes and metabolic acids are retained.
5) Excessive loss of bicarbonate ion:
- Caused by loss of body fluids (Diarrhea) or impaired reabsorption by the kidney.
6) Increase in chloride anion:
- Causes a proportional decline in bicarbonate ion.
- Can be caused by abnormal reabsorption in the kidney or use of chloride
- containing meds (Diuretics)
S/s of Metabolic Acidosis
True S/s:
- weakness
- fatigue
- malasie
- dull headache
- possible digestive problems.
Compensatory:
-Incr. RR (to reduce PCO2) to decr. blood pH
This is shown by rapid deep breaths “Kussmaul Breathing”.
As pH drops, it can cause dangerous cardiac complications (cardiac contractility can decr. and CO can decr.
Arrhytmias and ventricular fibrillation can occur.
Tx of Metabolic Acidosis
- Focused on correcting the underlying condition
- Restoring fluids and electrolytes that have been lost.
- Improving O2 b/c of lactic acidosis
- Supplemental sodium bicarbonate b/c the loss of bicarbonate incr. acidosis.
What is Metabolic Alkalosis?
High pH ( 7-14 pH) due to excess bicarbonate ions.
What are the causes of Metabolic Alkalosis?
1) Excess alkali intake:
- Alkali intake from bicarbonate containing antacids/meds.
2) Bicarbonate retention:
- Can be triggered by hypokalemia.
- Repeated vomiting results in alkalosis b/c it “drains” the body of Cl- and replaces it with bicarbonate ion. (dehydration)
3) Maintenance of Metabolic Alkalosis:
- Decr. in ECF fluid volume increases fluid rentention from the kidneys (to hold onto fluid), leading to an increased bicarbonate b/c it’s not being excreted.
S/s of Metabolic Alkalosis
True S/s:
- Can be asymptomatic or s/s of hypovolemia.
- Severe: mental confusion, hyperactive reflexes, tetany, carpopedal spam.
Compensatory:
- Hypoventilation
- hypoxia
- respiratory acidosis.
