CV HTN Flashcards
What fraction of time is spent in diastole?
2/3
What fraction of time is spent in systole?
1/3
What is the major determinant of SBP?
CO
What largely determines DBP?
Total peripheral resistance (TPR)
Define CO
Fxn of SV, HR, & venous capacitance
Define PCT (What is it responsible for?)
- Major site for NaCl & NaHCO3 reabsorption
- Responsible for 60-70% of total reabsorption of Na
What permits rapid reabsorption of CO2?
Conversion of HCO3 to CO2 via carbonic acid
What is the most common loop diuretic?
Furosemide (Lasix)
- Others: Bumetanide, Torsemide
What are the most common thiazides?
- Chlorthalidone
- Hydrocholorothiazide (HCTZ)
What are the most common potassium sparing?
- Amiloride
- Triamterene
What is the most common aldosterone antagonist?
Spironolactone
What does diuresis result in?
Decreased plasma & SV
Diuretics MOA
Blocks reabsorption of Na & Cl
- H2O follows due to the osmotic pressure within the nephron created by the ions
Define TAL (What is it responsible for?)
- Pumps Na, K, & Cl out of lumen into kidney
- Major site of Ca & Mg reabsorption
- Responsible for 20-30% of Na reabsorption
Loop diuretics MOA
- Blocks Na+K+Cl- symporter at TAL
* More potent diuresis, smaller decrease in PVR, & less vasodilation
Loop diuretics: Efficacy
- Diuresis exceeds BP lowering
- Preferred in HF or severe edema
- Less likely to cause hyperglycemia, hyperlipidemia
What are some characteristics of Furosemide?
- Short duration of action
- Poor anti-hypertensive
- Use in pts w/ kidney disease or fluid retention
What is Torsemide?
Effective BP med at low dosage
What 2 meds are used in tx of hypercalcemia?
- Furosemide
- Torsemide
Describe the DCT (What is it responsible for?_
- Pumps Na & Cl out of lumen via Na/Cl carrier (NCC)
- Target of thiazide diuretics
- Responsible for 5-8% Na reabsorption
- Ca also reabsorbed via PTH
Thiazide diuretics MOA
- Blocks reabsorption of Na & Cl in DCT, H2O follows
- Initial diuresis - decreased plasma & SV
- Provides chronic anti-hypertensive action via decrease in PVR & SM relaxation
What does ADH do?
Facilitates H2O reabsorption from collecting tubule by activation of V2 receptors
What do V2 receptors do?
Stimulate adenyl cyclase via Gs
What does increased cAMP cause?
Insertion of additional aquaporin (AQP2) channels into mem