Fluid, Electrolyte, And Acid-Base Imbalances

Question 1

What makes up the Extracellular Fluid (ECF) Compartment

Answer 1

• Interstiitial fluid (tissue fluid)
• Blood Plasma
• Lymph
• Specialized fluids: CSF, synovial fluid, aqueous humor, serous fluid

Question 2

Where does H2O in the body come from?

Answer 2

• Ingestion of fluids and food
• Product of cell respiration

Question 3

How is water lost in the body?

Answer 3

• Urine
• Perspiration/sweat
• Exhaled air (water vapor)
• Feces

Question 4

What is the thirst mechanism in the hypothalamus?

Answer 4

• Osmoreceptors sense fluid volumes and concentrations
• Promotes intake of fluid as needed

Question 5

How does ADH regulate water intake and output

Answer 5

• Promotes reabsorption of H2O from kidney tubules into blood -> LESS FLUID LOST via urine

Question 6

How does Aldosterone regulate water intake and output?

Answer 6

• Increases reabsorption of Na from kidney tubules -> H2O follows the Na via osmosis
• Conserves more fluid when there is a deficit

Question 7

How does ANP regulate water intake and output?

Answer 7

• Promotes loss of Na ions and H2O in urine (excrete more urine)

Question 8

What are electrolytes?

Answer 8

-Chemicals that dissolve in H2O, dissociating into ions
-> most are inorganic (minerals)
-> Cations: (+) ions
-> Anions: (-) ions
- Create osmotic pressure, regulates movement of H2O between compartments
-> areas of higher electrolyte concentration have higher osmotic pressure

Question 9

How does Aldosterone regulate electrolytes?

Answer 9

Increases reabsorption of Na and the excretion of K by the kidneys
-> Increases blood Na levels
-> Decreases blood K levels

Question 10

How does ANP regulate Electrolytes ?

Answer 10

Increases excretion of Na by the kidneys
decreases blood Na levels

Question 11

How does Parathyroid hormone regulate electrolytes?

Answer 11

• Increases reabsorption of Ca from bones and increases absorption in small intestines
• Decreases reabsorption of phosphate at convoluted tubules
• Increases blood calcium levels, decreases blood phosphate levels

Question 12

How does Calcitonin regulate electrolytes?

Answer 12

• Promotes removal of Ca and phosphate from blood to form bone matrix
• Decreases blood calcium and phosphate levels

Question 13

What is the most abundant cation and anion in the intracellular fluid?

Answer 13

• Most abundant cation: K
• Most abundant anion is HPO4
• Protein anions are also abundant

Question 14

What is the most abundant cation and anion in the plasma of the Extracellular fluid

Answer 14

Plasma
- Most abundant cation: Na
- Most abundant anion: Cl
- Protein anions are significant

Interstitial (tissue) fluid
- same as plasma except fewer protein anions

Question 15

What are Sodium’s (Na) functions

Answer 15

• Most abundant cation in ECF
• Regulates osmotic pressure in ECF
• Essential for electrical activity of neurons and muscle cells

Question 16

What are Potassium’s (K) functions

Answer 16

• Most abundant cation in ICF
• Regulates osmotic pressure in ICF
• Essential for electrical activity of neurons and muscle cells

Question 17

What are Calcium’s (Ca) functions

Answer 17

• Most is found in bones and teeth
• Maintains normal excitability of neurons and muscle cells
• Essential for blood clotting

Question 18

What are Magnesium’s (Mg) functions

Answer 18

• Most is found in bones
• More abundant in ICF than in ECF
• Essential for ATP production, as well as neural and muscle activity

Question 19

What are Chloride’s (Cl) functions

Answer 19

• Most abundant anion in ECF
• Diffuses easily in and out of cells; helps regulate osmotic pressure
• Part of HCl in gastric juice

Question 20

What is Bicarbonate’s (HCO3) functions

Answer 20

• Part of bicarbonate buffer system

Question 21

What is Phosphate’s (HPO4) functions

Answer 21

• Most is found in bones and teeth
• Primarily an ICF anion
• Part of DNA,RNA, ATP, phospholipids
• Part of phosphate buffer system

Question 22

What is Sulfate’s (SO4) functions

Answer 22

• Part of some amino acids and proteins

Question 23

How do fluids circulate throughout the body?

Answer 23

• Movement depends on relative hydrostatic and osmotic pressures within compartments *

Filtration
-> High pressure to low pressure
-> Hydrostatic pressure is “push” force to move fluid OUT of an area

Osmosis
-> Low solute concentration to higher solute concentration
-> Osmotic pressure is “pull” force to draw fluid INTO an area

Question 24

What are the potential causes of excess fluid?

Answer 24

• Kidney disease
• Liver disease
• Hypoalbuminemia
  -> Decreased production in liver
  -> Kidney disorder causing excess protein excretion
  -> Malabsorption syndromes
  -> Low dietary intake of protein
• Electrolyte imbalance

Question 25

What are the sign/symtomes of excess fluid

Answer 25

*signs and symptoms may vary depending upon the cause of the fluid imbalance* - localized edema/swelling (feet, hands, ascites) - weight gain - lethargy; possible seizures - pale or red skin color - slow, bounding pulse - high BP - pulmonary congestion, cough - decreased hematocrit - increased urine output; low specific gravity

Question 26

What are potential causes of fluid deficit

Answer 26

- Dehydration -> vomiting and diarrhea -> excessive sweating (affects Na and H2O levels) -> Insufficient water/fluid intake -> diabetic ketoacidosis - loss of fluid, electrolytes, and glucose in urine -> severe hemorrhage -> 3rd spacing following trauma

Question 27

What are sign/symptoms of fluid deficit

Answer 27

*Signs and symptoms may vary depending upon the cause of the fluid imbalance - Sunken eyes - Fatigue, weakness, possible confusion - Pale skin, decreased skin turgor - Dry mucous membranes - Weight loss - Rapid, weak, thready pulse - Low BP and orthostatic hypotension - Increased hematocrit - Decreased urine output, high specific gravity

Question 28

What is Hyponatremia and what are the possible causes?

Answer 28

*Low sodium imbalance* Possible causes - Excessive sweating, diarrhea, or vomiting - Renal failure - Excessive water intake - Hormone imbalances

Question 29

What is Hypernatremia and what are the possible causes

Answer 29

*Excessive sodium levels* Possible causes - Excessive sodium ingestion w/o increased water intake - Loss of thirst mechanism - Hormone imbalance (insufficient ADH) - Severe watery diarrhea

Question 30

What is Hypokalemia and what are the possible causes

Answer 30

*Low Potassium levels* Possible causes - Excessive losses caused by diarrhea or vomiting - Diuresis associated with some medications - Endocrine dysfunction - Decreased dietary intake -> may occur with alcoholism, eating disorders - Kidney disease

Question 31

What is hyperkalemia and what are the possible causes

Answer 31

*Excessive Potassium levels* Possible causes - Renal failure - Endocrine dysfunction (aldosterone deficit) - “Potassium-sparing” diuretics - Extensive tissue damage (burns or crush injuries) -> leakage of intracellular potassium into ECF

Question 32

What is hypocalcemia and what are the possible causes

Answer 32

*low calcium levels* Possible causes - Hypoparathyroidism - Malabsorption syndromes ->decreased intestinal absorption of calcium or vitamin D - Renal failure

Question 33

What is hypercalcemia and what are the possible causes

Answer 33

*Excessive calcium levels* Possible causes - Hyperparathyroidism - Demineralization caused by immobility -> Decrease stress on bone leads to increased osteoclast activity - Increased calcium and vitamin D intake - Malignant bone tumors -> uncontrolled release of calcium ions from bones

Question 34

Normal pH range of blood and intracellular fluid

Answer 34

Normal pH range of blood: 7.35-7.45 Normal pH range of intracellular fluid: 6.8-7.0

Question 35

What are the 3 mechanisms to control pH

Answer 35

1. Buffer systems - Fastest mechanism 2. Respiratory system - Alter CO2 (carbonic acid) levels to change pH 3. Kidneys - Modify excretion rate of acids - Modify production and absorption of bicarbonate ions - Most significant control mechanism - Slowest mechanism

Question 36

What do Buffer Systems do?

Answer 36

- Prevent drastic changes in pH - Weak acid and base pairs react with strong acids or bases to prevent large shifts in pH - Fastest response, but lowest capacity -> react w/in fraction of second -> limited number of molecules in body fluids - Major systems -> Bicarbonate buffer system -> Phosphate buffer system -> Protein buffer system

Question 37

What is the Bicarbonate Buffer System

Answer 37

*Important in blood and tissue fluid* Components - Carbonic acid (H2CO3) and sodium bicarbonate (NaHCO3) - H2CO3 reacts with strong bases, producing weaker base that doesn’t affect pH as much - NaHCO3 reacts with strong acids, producing weaker acid that doesn’t affect pH as much Normally, more sodium bicarbonate is needed than H2CO3 - Ration of NaHCO3 to H2CO3 ~ 20:1

Question 38

What is the Phosphate Buffer System?

Answer 38

Components - Sodium dihydrogen phosphate (NaH2PO4) and sodium monohydrogen phosphate (Na2HPO4) *Important in regulation of blood pH by kidneys* - Cells of kidney tubules can remove excess H+ ions by forming NaH2PO4 which is excreted in urine - Retained Na ions returned to blood in peritubular capillaries, along with bicarbonate ions -> Bicarbonate ions are synthesized by renal cells from CO2 and H2O

Question 39

What is the Protein Buffer System?

Answer 39

*Most important intracellular buffer system* Ex: Hemoglobin buffers the H+ formed during CO2 transport - Amino acids have carboxyl group (COOH) and an amine (or amino) group (NH2) -> COOH group can act as acid (can “donate” hydrogen) -> NH2 group can act as a base (can “pick up” excess hydrogen)

Question 40

What is the Role of the Kidneys in Acid-Base Balance

Answer 40

*Greatest role in maintaining pH of blood and tissue fluid* -Kidney response when body fluids are too acidic -> Secrete more H+ ions into renal filtrate -> Return more bicarbonate to blood -> Increase blood pH back to normal - Kidney response when body fluids are too alkaline: -> Return H+ ions to blood -> Excrete more bicarbonate in urine -> Decreased blood pH back to normal

Question 41

How does Respiration affect Acid Base Balance

Answer 41

- Regulates amount of CO2 in body fluids - Chemoreceptors in medulla detect pH and CO2 levels -> RR and depth increase when pH lowers - More carbonic acid exhaled and pH increases -> RR decreases and breaths become shallower when pH is high - Body retains more carbonic acid to decrease pH

Question 42

What is acidosis (respiratory or metabolic)

Answer 42

- Excess H+ ions - Decreases in serum pH

Question 43

What is Alkalosis (respiratory or metabolic)?

Answer 43

- Deficit of H+ ions - Increase in serum pH

Question 44

What is Metabolic acidosis and what are the potential causes and compensation mechanisms

Answer 44

*decreased serum HCO3 ions* Potential causes - Kidney disease - Diarrhea or vomiting - Diabetic ketoacidosis Compensation Mechanisms - Increased respiratory rate - Deeper respirations

Question 45

What is Metabolic alkalosis and what are the potential causes and compensation mechanisms?

Answer 45

*Increased serum HCO3 ions* Potential Causes - Over ingestion of bicarbonate meds - Gastric suctioning Compensation Mechanisms - Decreased respiratory rate - Shallow respirations

Question 46

What is Respiratory acidosis and what are the potential causes and compensation mechanisms

Answer 46

*Increased CO2* Potential Causes - Decreased respiratory efficiency: lung infections, COPD, etc - Paralysis of respiratory muscles - Decreased RR from drug overdose Compensation Mechanisms - Kidneys excrete more H+ and reabsorb more Na and HCO3 ions into blood

Question 47

What is respiratory alkalosis and what are the potential causes and compensation mechanisms

Answer 47

*Decreased CO2* Potential Causes - Hyperventilation - Increased respiratory rate at high altitudes Compensation Mechanisms - Kidneys retain more H+ ions and excrete more Na and HCO3 ions into urine