Lecture 22 Flashcards
Final exam content
How do the kidneys compensate for respiratory alkalosis?
They choose not to reabsorb bicarb and retain H+ (turn off proton secretion)
Why don’t we see a differentiation between acute and chronic metabolic alkalosis and acidosis?
The neural control system and lungs can fix metabolic acidosis and alkalosis in under 3 minutes
Where does the phrenic nerve originate from the spinal cord?
C3, C4, C5 keep the diaphragm alive!
What is albumin critical for? Is albumin more abundant or hemoglobin?
Albumin is critical for maintaining osmotic pressure in the plasma for the cardiovascular system
What is the main role of hemoglobin with regards to homeostasis?
Hemoglobin is in RBC’s (a component of the ICF- the hematocrit portion) and is responsible for blood buffering
What do buffers do?
They combine with excess H+ or release them
They can correct problems in either direction (alkalosis versus acidosis)
What are the three main buffers in the body in order of importance?
- Bicarb
- proteins
- Phosphate
pK of a buffer is the pH at which_____
the buffer has equal quantities of ionized components and unionized components
What isohydric principle?
We may have multiple pKs of multiple different buffers but they all interact with the same proton pool and their combined activity is greater than their individual activity
List a few things that can lead to respiratory acidosis…
- anesthetics, opiates, sedatives
- brain injury/ stroke
- hypercapnia/ hypoxia
- phrenic nerve injury
- polio, botulism, tetanus
- myasthenia gravis
- paralytics (curarelike drugs)
- kyphoscoliosis or obesity
- lung restriction (pulmonary fibrosis, sarcoidosis, pneumothorax, pleural effusion)
- pneumonia or pulmonary edema
- airway obstruction (COPD, collapsed vocal cords, tumors/ scar tissue in upper airway)
List a few things that can lead to respiratory alkalosis…
- seizures
- extreme anxiety
- hyperventilation
- inflammation (encephalitis or meningitis)
- salicylates
- progesterone
- acute asthma exacerbation
- Pulmonary embolism
- overventilation
- Hypoxia at high altitude
List a few things that can lead to metabolic acidosis…
- ingested toxins (methanol, ethanol, salicylates, ethylene glycol, ammonium chloride)
- excessive diarrhea
- pancreatic fistulas
- renal dysfunction
What is ethylene glycol?
a component of antifreeze
What is ammonium chloride?
a component of fertilizer
List a few things that can lead to metabolic alkalosis…
- loss of hydrogen ions (excessive vomiting, gastric fistulas, diuretics, overproduction of steroids (aldosterone/cortisol- increased secretion of K+ and H+)
- ingestion of excess bases (antacids)
- too much IV bicarb
What is the main cation measured in anion gaps?
Na+
What are the main anions measured in anion gaps?
Cl- and HCO3-
How do you measure an anion gap?
sodium - (chloride + bicarb)
What is the normal anion gap?
12 +/- 4 mEq/L
142 - (106 + 24) = 142 - 130 = 12
What maintains electroneutrality in the blood if the anion gap is about 12?
There are more cations, but there are unaccounted for proteins, sulfur and phosphate species that bridge the gap
If unmeasured cations increases, in a balanced system what happens?
Na+ decreases (the same side of the equation changes to maintain electroneutrality)
If we have a decrease in unmeasured anions, in a balanced system what happens?
Cl- and/or Bicarb increases to maintain electroneutrality
In a balanced system, if we have a reduction in bicarb what happens to chloride?
Cl- increases. (inverse relationship)
The opposite is true if we have an increase in bicarb. (Cl- goes down)
An increase in nonvolatile gasses________ the anion gap.
increases
