What term describes a decrease in the concentration of plasma proteins? What pathophysiological state will it result?
1.) Hypoproteinemia
2.) Edema
What are two common causes of hypoproteinemia?
1.) Poor diet
2.) Liver failure
What are some less common causes of edema?
1.) Lymph blockage
2.) Increased capillary permeability (by certain types of infection)
True or False?
The kidneys cannot function in any capacity in the absence of nervous and hormonal control.
False.
Aside from ADH in the latter portions of the nephron, the kidney's proximal tubule processes work on their own.
How does the sympathetic nervous system affect renal function?
SNS activity increases CO and MAP, and therefore GFR. The resulting autoregulation of GFR will lead to an increased PPT, decreasing proximal reabsorption and thereby increase urinary excretion.
True or False?
In regards to blood vessels, the SNS works primarily by vasodilation.
False.
The SNS works primarily by vasoconstriction.
Why is aldosterone categorized as a mineralocorticoid?
It deals loosely with minerals (Na+ / K+).
True or False?
Aldosterone is a steroid hormone.
True.
What are two stimuli for aldosterone?
1.) [K+]ECF
2.) Angiotensin II
Explain how aldosterone secretion is can indirectly be part of a sympathetic response.
1.) Epin. & norepin. released by SNS stimulate renin release
2.) Renin ultimately leads to angiotensin II circulation through body
3.) Angio. II stimulates aldosterone secretion.
In what two ways does aldosterone increase the efficiency of Na+ reabsorption in the late distal tubule and collecting ducts?
1.) Causes an increase in apical ENaC
2.) Increases activity of Na+ / K+ ATPase
What is the short term fix for low MAP?
Vasoconstriction by SNS.
What is the intermediate term fix for low MAP?
SNS activity stimulates renin release, leading to AngiotensinII circulation and thus increased vasoconstriction and ADH release (retains water).
Water is retained to correct low MAP in the intermediate term. How is correct osmolarity maintained in the long run as blood volume increases to normal ranges?
Angiotensin II stimulates aldosterone release, which results in more efficient Na+ reabsorption. The increase in [Na+]plasma keeps ECF osmolarity normal as fluid volume increases.
True or False?
Though correcting low BP requires nervous and hormonal help, high BP can correct itself by virtue of pressure diuresis.
True.
True or False?
Angiotensin converting enzyme is found only within the endothelial cells of the glomerular capillaries.
False.
ACE is in all endothelium, thereby allowing angiotensin I (from angiotensinogen and renin) to be converted to angio. II so it can work throughout the entire body.
As Na+ is removed from the LDT and collecting ducts by aldosterone, can Cl- follow as it can in the proximal tubule?
No.
How is electroneutrality maintained as aldosterone causes more efficient Na+ reabsorption?
Aldosterone also places ROMK's (a K+ channel) on the apical surface of LDT and collecting duct epithelial cells, allowing secretion of K+ in direct proportion with Na+.
Why can't excess secretion of aldosterone cause salt and water retention, and thus hypertension?
The resulting increase in MAP would lead to pressure diuresis, and MAP would be corrected.
True or False?
Aldosterone is actively secreted at all times to maintain ECF osmolarity.
False.
Under normal circumstances, aldosterone does not contribute to regulation of ECF sodium concentration.
What hormone is released to correct increased blood volume?
Atrial natiuretic peptide.
What location in the body monitors blood volume?
The atria of the heart.
Upon secretion of ANP, vasopressin secretion will be ___1___, GFR will be ___2___, renin secretion will be ___3___, aldosterone secretion will be ___4____, and salt / water excretion will be ___5___.
1.) Decreased
2.) Increased
3.) Decreased
4.) Decreased
5.) Increased
When both blood volume and ECF osmolarity are a problem, which is corrected first?
Osmolarity is always corrected first as long as the kidneys are functioning properly.
Example: If osmolarity is too high, the kidneys will retain water first and then secrete both fluid and NaCl.
Daily intake of K+ without excretion as a (small / large) effect on ECF K+ concentration.
Large.
Daily intake of K+ without excretion as a (small / large) effect on ICF K+ concentration.
Small.
Where along the nephron is the largest amount of potassium reabsorbed? By what mechanism?
The proximal tubule, by passive reabsorption.
Explain why secretion of K+ in the distal tubule and collecting ducts is a necessary process.
The kidneys over-reabsorb K+ in the early nephron. If no K+ is secreted in the later nephron, hyperkalemia will result.
Where is K+ actively transported out of the nephron?
The thick ascending loop of henle.
What allows the kidneys to secrete the K+ necessary to avoid hyperkalemia?
Aldosterone - this is the primary reason for the existence of the hormone in our bodies.
