Acid-Base Balance Flashcards
concentration of hydrogen ions is regulated sequentially by:
- Chemical buffer system
- Respiratory center
- Renal (kidney) mechanisms
Chemical buffer systems
- In the blood
- acts within seconds
- temporarily binds to H+
- Raise pH but do not remove H+ from the body
Respiratory center
- In the brainstem
- acts within 1-3 min
Renal (kidney) system
-require hours to day to effect pH changes
3 major chemical buffer systems:
- Bicarb
- phosphate
- protein
Protein buffer system
- Most abundant buffer in the ICF and blood plasma
- Hemoglobin in RBCs
- Albumin in blood plasma
Carbonic acid-bicarb buffer system
-The respiratory systems regulation of acid-base balance (physiological buffering system)
Phosphate buffer system
- Located mostly in ICF
- binds to H+
The lungs can eliminate carbonic acid by eliminating what
CO2
What organ can rid the body of metabolic acids and prevent metabolic acidosis
the kidneys
In response to acidosis the kidneys
- generate bicarb ions and add them to the blood
- An equal amount of hydrogen ions are added to the urine
Respiratory acidosis and alkalosis
- result from failure of the respirator system
- PCO2 is the single most important indicator of respiratory inadequacy
Respiratory alkalosis
- common result of hyperventilation (CO2 is to low)
- Clinical signs: headaches, restlessness, lethargy, coma, dysrhythmias, nausea, vomiting
Causes of metabolic acidosis
decreased bicarb and pH levels in blood
- excessive alcohol intake
- diarrhea
- kidney dysfunction
- accumulation of lactic acid
- shock
- ketosis in diabetic crisis
- starvation
Causes of metabolic alkalosis
increased bicarb and pH levels in blood
- vomiting of acid contents of the stomach
- Intake of excess base (antacids)
- constipation (excess bicarb is reabsorbed)
Respiratory compensation
-The respiratory system will attempt to correct metabolic acid-base imbalances
Renal compensation
-The kidneys will work to correct imbalances because of respiratory disease
Acidosis Manifestations
- alterations in cardiac contractions
- decreased vascular response to catecholamines (pt won’t respond to fight or flight situation)
- decreased response to certain medications
- can lead to loss of consciousness
Alkalosis Manifestations
- impaired near function
- impaired muscle function
- tingling sensations, nervousness, muscle twitches
PaCO2
-The amount of CO2 dissolved in arterial blood
35-45 Hg
HCO3
-calculated value of bicarb
(22-26 mEq/L)
-Bicarb tells us what the kidneys are doing
PO2
-amount of oxygen in the blood
-normal 80-100 RA
-prefer 90-100
-
Respiratory acidosis
-Clinical signs: headache, restlessness, confusion, dyspnea, respiratory distress, shallow respirations, tachycardia, dysrhythmias
Clinical signs of metabolic acidosis
-headache, lethargy, nausea, anorexia, vomiting and diarrhea, coma, death
Clinical signs of metabolic alkalosis
-dizziness, lethargy, coma, weakness, muscle twitching, cramps, tetany
Respiratory control center
-Medulla oblongata and pons
Magnesium (Mg+)
1.5-2.5 mEq/L
Phosphate (PO4-)
2.4-4.4 mg/dL
Calcium (Iodized)
4.6-5.3 mg/dL
Potassium (K+)
3.5-5.0 mEq/L
Calcium (Ca+)
8.6-10.2 mg/dL
Bicarb (HCO3)
22-26 mEq/L
Chloride (Cl-)
96-106 mEq/L
Sodium (Na+)
135-145 mEq/L
BUN
-To assist in assessing for renal function toward diagnosing disorders such as kidney failure and dehydration
Creatinine
-To assess kidney function found in acute and chronic renal failure, related to drug reaction and/or disease
Hematocrit
- Often used to check anemia
- Usually along with hemoglobin or in a CBC
- May be used to screen for, diagnose, or monitor a number of conditions and diseases that affect the proportion of the blood made of RBCs.
- Used to monitor response to tx of anemia or polycythemia, decisions about blood transfusions, evaluate dehydration
Total protein
- Frequently ordered as part of a Comprehensive Metabolic Panel (CMP)
- Usually used for routine health checkups
- Provides general info about nutritional status
- Can be ordered along with other tests to provide info when someone has symptoms that suggest liver, kidney, bone marrow disorders, or to investigate the cause of abnormal pooling of fluid in tissue (edema)
Albumin
-To screen for and help diagnose a liver disorder or kidney disease, sometimes to evaluate nutritional status, especially in hospitalized pts
Active transport
- A process in which molecules move against a concentration gradient
- External energy is required for this process
Diffusion
-the movement of molecules from an area of high concentration to an area of low concentration
Osmosis
-the movement of water “down” a concentration gradient, from a region of low solute concentration to one of high solute concentration, across a semipermeable membrane
Osmotic pressure
-the higher the concentration the greater the osmotic pressure
Osmolarity
-measures the concentration of molecules per volume of solution or total milliosmoles per liter of solution
Osmolality
-measures the number of millosmoles per kg of water, or the concentration of molecules per weight of water
Hydrostatic pressure
-the force within a fluid compartment
Oncotic pressure
-the osmotic pressure caused by plasma colloids in the solution
