5. Salt/Water and Acid/Base Balances

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?

Kussmaual breathing

Define the normal range of pH values in the urine.

4.4-6.5

What are the major effects of aldosterone?

1. Salt and water retention

2. K+/H+ secretion

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

1. Reabsorb chloride from the filtrate

2. Secrete bicarbonate

Define the normal value for buffer base.

48 mmol/L

How do pH parameters change in metabolic alkalemia?

1. Standard bicarbonate: Increase

2. BB(Buffer Base): Increase

3. BE(Base Excess): Increase

How do pH parameters change in metabolic acidemia?

1. Standard bicarbonate: Decrease

2. BB(Buffer Base): Decrease

3. BE(Base Excess): Decrease

Which pH parameter is changed primarily in metabolic alkalosis?

HCO³- increases

Define tonicity.

Effective osmotic pressure of the plasma and extracellular fluid

Define the normal osmotic concentration of the blood.

280-300mOsm/L

The accumulation of which substances can cause hypertonicity?

1.Na+

2.Glucose

The accumulation of which substances can cause hyperosmolarity without hypertonicity?

1. Urea

2. Methanol

3. Ethanol

What is the main trigger of ADH secretion?

High extracellular Na+ concentration

What is the primary site of ADH?

In the renal collecting ducts

Define exsiccosis.

Loss of salt and water

List some examples for natriuretic factors.

1. ANP(Atrial Natriuretic Peptide)

2. BNP(Brain Natriuretic Peptide)

3. Renal kinins

4. Renomedullary lipids

5. Prostaglandins

What are the effects of angiotensin 2?

1. Vasoconstriction

2. Stimulation of aldosterone secretion

3. Stimulation of thirst

What is the direct stimulus for activation of RAAS?

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

Define non-specific factors that activate ADH.

1. Severe hypovolemia

2. Surgery

3. Stress

4. Fear

5. Pain

Define the anion gap.

• Anion gap= Serum[Na+]- (Serum[Cl-] +Serum[HCO3-])

• 11mmol/L= 140mmol/L-(105mmol/L+24 mmol/L)

How can we calculate the plasma osmotic concentration?

Applying the formula: (2× Na+ +Carbamide+ Glucose)

Define the osmotic gap.

Difference between measured and calculated plasma osmolarity

Define the plasma level of potassium.

3.5-5.5 mmol/L

Define the normal plasma level of sodium.

135-145 mmol/L

How do brain cells protect themselves from slowly developing hypertonicity?

By producing osmotically active IC substances, idiogenic osmoles.

Define the 4 mechanisms of oedema formation.

1. Decreased oncotic pressure

2. Increased hydrostatic pressure

3. Increased capillary permeability

4. Disorder of the lymphatic system