CVS 2 Flashcards
What are systolic, diastolic, and pulse pressures?
Systolic = peak pressure during heart contraction, Diastolic = pressure during relaxation, Pulse Pressure = Systolic - Diastolic
What causes Korotkoff sounds during blood pressure measurement?
Turbulent flow through a partially compressed artery
What affects arterial pressure waves as they move through the vasculature?
Stroke volume, velocity of ejection, artery elasticity, and total peripheral resistance (TPR)
Where is blood flow velocity the slowest and why?
In capillaries, due to their large total cross-sectional area
What mechanisms assist venous return to the heart?
Gravity, skeletal muscle pump, respiratory pump, venomotor tone, systemic filling pressure
What is the formula for Mean Arterial Pressure (MAP)?
MAP = Cardiac Output (CO) × Total Peripheral Resistance (TPR)
What is the arterial baroreflex?
A short-term control mechanism that adjusts heart rate and vessel tone in response to pressure changes
What happens to baroreceptor firing when pressure increases?
Firing rate increases
What physiological changes occur upon standing?
↓ EDV, ↓ SV, ↓ CO, ↓ MAP → baroreflex activates to restore MAP
What is the cardiovascular response to the Valsalva manoeuvre?
↑ Thoracic pressure → ↓ venous return → ↓ MAP → baroreflex ↑ CO/TPR → recovery
What are Starling’s forces?
Balance of hydrostatic and oncotic pressures that control fluid movement across capillaries
What is oedema and its common causes?
Excess interstitial fluid; causes include raised CVP, lymphatic obstruction, hypoproteinaemia, inflammation
How does capillary structure relate to function?
Structure (clefts, pores) determines permeability and type of exchange (continuous, fenestrated, discontinuous)
What is Poiseuille’s Law and its relevance?
Resistance ∝ 1/r⁴ – small changes in radius greatly affect flow and TPR
Define active hyperaemia.
↑ Metabolism → metabolite accumulation → local vasodilation → ↑ blood flow to meet demand
What is pressure autoregulation?
↓ MAP → ↓ flow → metabolite buildup → vasodilation → flow restored
What does adrenaline do to different vascular beds?
α₁ receptors → vasoconstriction (↑ TPR), β₂ receptors → vasodilation (e.g., skeletal muscle)
What’s unique about pulmonary circulation in hypoxia?
↓ O₂ causes vasoconstriction to redirect blood to well-ventilated lung areas
What mechanisms control arteriolar tone?
Local: active hyperaemia, autoregulation, reactive hyperaemia; Central: sympathetic nerves, hormones (e.g., adrenaline)
How does coronary circulation cope during systole?
β₂-mediated vasodilation and strong active hyperaemia compensate for systolic interruption
