General Aspects of the Cardiovascular System Flashcards
Where is the site of higher resistance? Why?
- arterioles
- high drop of pressure 🔼P
- they can constrict (⬆️ P1) or vasodilation (⬇️ P1)
How is the exchange at the capillaries optimized?
large cross-sectional area ▶️ ⬇️ velocity of blood
What factor reducing the Reynold’s number can promote turbulent blood flow? (Paradoxically: ⬇️ Reynold number ▶️ laminar flow)
Atherosclerosis
What could be the effect of some pathological process as sepsis, anaphylaxis, neurogenic shock on MAP? Why?
- ⬇️⬇️ MAP
- uncontrolled vasodilation in periphery (“all faucets opened”)
What mechanism can mimic vasodilatory effects with some drugs?
- block NE’s (alpha blockers), prevent NE release, liberate NO, activate B2, block Ca entry to smooth muscle, open K channel in smooth muscle (minoxidil)
What type of drugs can mimic vasoconstriction mediate by NE?
- alpha-1 agonists, NE releasers, NE reuptake inhibitors
Where is the compliance of the whole body for practical proposes?
Venous system
Which are that variables that represent the upstream and downstream pressure of the venous return?
- right atrial pressure (RAP): downstream pressure
- mean systemic filling pressure (Psf): upstream pressure
What variables can increase venous return? What is the stimuli?
- ⬆️ Psf: ⬆️ blood volume, ⬇️ venous compliance (sans (+) ▶️ muscle pump, venoconstrictor (“squeeze the veins”)
How do you decrease the venous return?
- ⬇️ Psf: ⬇️ blood volume, ⬆️ compliance (sans inhibition, venodilator, alpha block [care more arterial dilation than venous, “trick”])
Why a severed or puncture vein above heart has the potential to introduce air into the system?
Veins above the heart maintain a pressure significant below atmospheric (negative)
*venous pressure at heart level is close to zero ▶️ venous pressure quickly becomes subatmospheric
