Pharmacology of Diuretics Flashcards
What is the sole purpose of diuretics?
To increase urine volume.
Drugs which increase the excretion of salts (mainly NaCl) and water by the kidneys.
They decrease blood volume and cardiac output. Many diuretics also dilate arteries.
Fill in:
The kidneys filter large quantities of —- (4% of the plasma CO), reabsorb those substances that the body must —-, and excrete substances that must be eliminated.
plasma
conserve
What does the kidney receive the most of?
Blood flow of any organ.
20% of cardiac output
What are the two things that the kidney controls?
What is in the blood and blood volume.
How does the kidney work to increase urine volume?
They increase salt and hence water secretion.
They reduce Na+ and Cl- reabsorption in the nephron, decreasing reabsorption of water.
How many sodium is usually reabsorbed and what does this mean?
99+% of Na+ and water filtered by the kidneys is normally reabsorbed.
This means a small decrease in % reabsorption will greatly increase urine volume.
What are 3 conditions which loop diuretics can treat?
- Heart failure (increased venous pressure due to reduced cardiac function)
- Renal disease (protein lost via kidneys, plasma protein falls)
- Hepatic disease (lover produces less albumin, plasma protein falls)
All of them are due to fluid being retained by oedoma.
What type of diuretics treats hypertension?
Thiazide-type diuretics
How many litres of blood leaves the vascular system in micro-circulation?
4L (goes into the lymphatic system and back into tissues)
What happens to protein concentration in renal disease and what does this cause?
decrease in protein concentration
the gradient causing water to move back into the capillary will decrease causing oedema to occur
What two absorption processes are proportionate to each other?
Sodium and water reabsorption.
Explain the affects of diuretics on sodium reabsorption
It slightly blocks sodium reabsorption and hence water reabsorption also.
This is what causes blood volume to decrease. Protein in the blood stays the same but the volume it is in decreases so this causes more fluid to be excreted due to diuretics.
What proteins regulate sodium and water reabsorption?
Sodium - angiotensin 2 and aldosterone
Water - ADH
How much sodium and water is reabsorbed in the proximal tubule?
2/3
What molecules are reabsorbed/secreted at the PT?
Reabsorbed = glucose, amino acids, bicarbonate
Secreted = protons and weak acids&bases
Explain how the secretion of weak acids and bases occurs at the PT
Pumps do this along the nephron. Between the capillaries and the PT, pumps move the weak a&b into the nephron. Weak acids are filtered and secreted by these pumps also.