MK - Diuretics II Flashcards
What is the primary hormone involved in blood volume and osmolarity control?
Antidiuretic hormone/Vasopressin
What is the requirement for kidney function in terms of circulation?
Kidney function REQUIRES good perfusion at SUFFICIENT blood pressure
What is the requirement for circulation?
Circulation REQUIRES control of Blood Volume and Ionic concentrations to produce appropriate blood pressures to ensure SUFFICIENT tissue perfusion
What is the Renin-Angiotensin-Aldosterone System (RAAS)?
A regulator of blood pressure and cardiovascular function
What occurs in the RAAS?
Renin from juxtaglomerular cells convert Angiotensinogen (from liver) into Angiotensin I, then ACE in lung can convert to active Angiotensin II
What does Angiotensin II and Aldosterone cause?
Angiotensin II causes vasoconstriction in blood vessels
Aldosterone causes reabsorbtion of NaCl and H2O
What do the juxtaglomerular cells secrete renin in response to? (3)
- Sympathetic stimulation (beta-1 adrenergic receptor)
- Decrease in renal perfusion pressure
- Decrease in NaCl at the macula densa
What are the effects of ACE inhibitors (ACEi) on volume regulation?
- Reduces ADH and Aldosterone release
- Decreases water and Na retention
What is the function of ACE and how do ACEi alter this?
Angiotensin I
Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu
Angiotensin II
Asp-Arg-Val-Tyr-Ile-His-Pro-Phe
ACE acts to cleave 2 amino acids from Angiotensin I to Angiotensin II
- Acts as a dipeptidase
ACE inhibitors prevent conversion of Angiotensin I → Angiotensin II
What are 4 effects of ACEi?
- Inhibit AngII
- Reduced degradation of Bradykinin produces dry cough as a side effect
- Hyperkalemia
- Hypertension
What physiological condition triggers the release of Atrial Natriuretic Peptide (ANP)?
Atrial stretch, particularly in congestive heart failure
How does Atrial Natriuretic Peptide (ANP) counteract the Renin-Angiotensin system?
Regulates salt-water balance and blood pressure by promoting renal sodium and water excretion and stimulating vasodilation
What are three receptor types for Atrial Natriuretic Peptide (ANP)?
A, B, and C receptors
What are the effects of the Atrial Natriuretic Peptide system? (3)
- Relaxes Vascular smooth muscle – resistance down
- Reduces Renin secretion (so less angiotensin II)
- Reduces Aldosterone secretion
What are the pharmacological interventions involving modifying salt/water balance beneficial for?
- Heart Failure – To correct volume overload
- Hypertension – To reduce blood volume and lower blood pressure
- Oedema such as Renal oedema – To lose salt and water
