Pathophysiology 606 (Salt / Water / Acid / Base Balance)

Please, define the normal blood pH!

7.35 — 7.42

What is the normal plasma level of bicarbonate?

24 mmol/l

What is the normal plasma level of carbonic acid?

1.2 mmol/l

How do we call the respiratory compensation of metabolic acidosis?

Kussmaul breathing.

Please, define the normal range of pH values in the urine!

~ 4.4 — 6.5

What are the major effects of aldosterone?

• Na+ and water retention,

• K+ and H+ secretion.

What kind of ion exchange are the intercalated cells responsible for?

They reabsorb Cl- from the filtrate and secrete bicarbonate.

Please, define the normal value of buffer base (BB)!

48 mmol/l

How do pH parameters change in metabolic alkalemia (standard bicarbonate, BB, base excess /BE/)?

They increase.

How do pH parameters change in metabolic acidemia (standard bicarbonate, BB, BE)?

They decrease.

Which pH parameter is changed primarily in metabolic alkalosis?

HCO3- increases.

Please, define tonicity!

it is the effective osmotic pressure of the plasma (and that of the extracellular fluid).

Please, define the normal osmotic concentration of the blood!

280 — 300 mOsm/L

The accumulation of which substances can cause hypertonicity (2)?.

• Na+,

• glucose

The accumulation of which substances can cause hyperosmolarity without hypertonicity (3)?

• Urea,

• methanol,

• ethanol.

What is the main trigger of ADH-secretion?

High extracellular Na+ concentration.

Where is primary site of action of ADH?

In the renal collecting ducts.

Please, define exsiccosis!

Loss of salt and water.

Please, list some examples for natriuretic factors (min. 3)!

• Atrial natriuretic peptid-ANP,

• BNP (brain natriuretic peptide)

• renal kinins,

• renomedullary lipids,

• prostaglandins.

What are the effects of angiotensin II (3)?

• Vasoconstriction,

• stimulation of aldosterone secretion,

• stimulation of thirst.

What is the direct stimulus for the activation of RAAS?

Decreased stretch (decreased tension in the vascular wall) of the renal afferent arteriole (decreased intraluminal pressure and/or perfusion).

Please, define non-specific factors that activate ADH (min 3)!

• Severe hypovolemia,

• surgery,

• stress,

• fear,

• pain.

Please, define the anion gap!

Anion gap = serum[Na+] - (serum[Cl-] + serum[HCO3-]) = 140 mmol/l - (105 mmol/l + 24 mmol/l) = 11 mmol/l

How can we calculate the plasma osmotic concentration?

2 x Na+ + (carbamid) + glucose

Please, define the osmotic gap!

The difference between the measured and the calculated plasma osmolarity.

Please, define the normal plasma level of potassium!

3.5 — 5.5 mmol/l

Please, define the normal plasma level of sodium!

135 — 145 mmol/l

How do brain cells protect themselves from slowly developing hypertonicity?

They produce osmotically active IC substances, idiogenic osmoles.

Please, define the 4 mechanisms of edema formation!

1) decreased oncotic pressure,

2) elevated hydrostatic pressure,

3) enhanced capillary permeability,

4) disorder of lymphatic system