Week 11 Flashcards
Exam 4
Intracellular fluid (ICF)
is all the fluid within cells
Extracellular fluid (ECF)
Extracellular fluid (ECF) is all the fluid outside the cells.
What is included in ECF
ECF includes the interstitial fluid, the intravascular fluid, and the various transcellular fluids
Sodium concentration is regulated by:
The sodium concentration is regulated by the renal effects of aldosterone
Water balance is regulated primarily by:
antidiuretic hormone (ADH)
What percent of ECF does sodium account for?
Sodium (Na+) accounts for 90% of the ECF cations (positively charged ions)
What are the major anions?
- Chloride
- Bicarbonate
What acts to regulate water balance?
- Sodium
- Chloride
- Bicarbonate
How do sodium, chloride and bicarbonate act to regulate water balance?
Sodium in concert with chloride and bicarbonate, the two major anions (negatively charged ions), acts to regulate water balance by contributing to extracellular osmotic forces.
The serum sodium concentration is normally:
135 to 145 mEq/L
How is the serum sodium concentration normally maintained?
By renal tubular reabsorption within the kidney in response to neural and hormonal influences.
What does aldosterone regulate?
Hormonal regulation of sodium (and potassium) balance is mediated by aldosterone,
Where is aldosterone secreted from?
Secreted from the adrenal cortex.
Aldosterone is a component of what system?
renin-angiotensin-aldosterone system
Aldosterone secretion is influenced by a number of factors, including:
Circulating blood volume, blood pressure, and plasma concentrations of sodium and potassium
Where is renin released from:
Secreted by the juxtaglomerular cells of the kidney,
When is renin released?
When the circulating blood volume or blood pressure is reduced, renin is released.
What is another reason renin may be released?
Renin also is released when sodium levels are depressed or potassium levels are increased.
Once released, renin stimulates the formation of what?
Angiotensin I
Angiotensin I
an inactive polypeptide, from angiotensinogen
Where is angiotensinogen secreted by?
Secreted by the liver
Where are Angiotensin-converting enzyme (ACE) found?
Angiotensin-converting enzyme (ACE), found primarily in pulmonary vessels and to a lesser extent in endothelial and renal epithelial cells.
What does the Angiotensin-converting enzyme (ACE) do?
Converts angiotensin I to angiotensin II , a potent vasoconstrictor.
What does vasoconstriction do to blood pressure and renal perfusion?
Vasoconstriction elevates blood pressure and restores renal perfusion.
What does Angiotensin II stimulate?
Angiotensin II also stimulates both the secretion of aldosterone from the adrenal cortex and antidiuretic hormone from the posterior pituitary.
What does aldosterone promote?
Aldosterone promotes sodium and water reabsorption, in addition to the excretion of potassium within the renal tubules.
What is the major anion and provides electroneutrality?
Chloride
Natriuretic peptides are produced by what?
Are hormones primarily produced by the myocardium.
Natriuretic peptides cause what?
Natriuretic peptides cause vasodilation and increase sodium and water excretion, decreasing blood pressure.
Water balance is regulated by what?
Water balance is regulated by the secretion of ADH, also known as vasopressin .
Where is ADH is produced by what? What is it secreted by?
ADH is produced in the posterior pituitary
Sodium imbalances occur with what?
Sodium imbalances occur with gains or losses of body water.
Water imbalances develop with what?
Water imbalances develop with gains or losses of salt.
Isotonic fluid loss causes what?
Isotonic fluid loss causes hypovolemia.
Isotonic fluid excess is causes what?
Isotonic fluid excess causes hypervolemia.
Hypertonic fluid alterations occur when?
Hypertonic fluid alterations develop when the osmolality of the ECF is elevated above normal
What are the most common causes of hypertonic fluid alterations?
The most common causes are:
- hypernatremia (increased concentration of ECF sodium) or a
- deficit of ECF water,
- or both.
Hypernatremia
Increased concentration of ECF sodium
Dehydration
water deficit
When does hypernatremia occur?
Hypernatremia occurs when serum sodium levels exceed 145 mEq/L.
When does hypernatremia occur?
Hypernatremia occurs when serum sodium levels exceed 145 mEq/L.
Increased levels of serum sodium cause what?
hypertonicity
Water is redistributed osmotically to the hypertonic extracellular space, causing intracellular dehydration.
Hypernatremia can occur in what three forms:
- Isovolemic
- Hypovolemic
- Hypervolemic
Isovolemic (euvolemic) hypernatremia:
- most common
It occurs when a deficit of free water is accompanied by normal or near-normal body sodium concentration.
Water deficiency w/o sodium loss
Most common causes of Isovolemic (euvolemic) hypernatremia are:
The most common causes include inadequate water intake, excessive sweating (sweat is hypotonic), fever, vomiting, diarrhea, burns, or respiratory tract infections.
Hypovolemic hypernatremia
occurs when a loss of sodium is accompanied by a relatively greater loss of body water.
Common causes of hypovolemic hypernatremia:
Common causes include use of loop diuretics (diuretics that inhibit sodium and chloride reabsorption in the kidney loop of Henle) or renal failure in which the kidneys fail to concentrate urine and excrete a large volume of urine.
Hypervolemic hypernatremia
It occurs when an increase in total body water is accompanied by a greater increase in total body sodium level, resulting in hypervolemia.