The document summarizes key aspects of the vascular system including the arterial, arteriolar, capillary and venous components. It notes that large elastic arteries like the aorta have a windkessel effect where they stretch during systole to prevent a rise in blood pressure and recoil during diastole to push blood forward and lower blood pressure. Arterioles are resistance vessels where sympathetic vasoconstriction occurs. Capillaries have the maximum total cross-sectional area for exchange of gases, nutrients and waste. Veins contain over half the blood volume and have lower elasticity than arteries.

1. Vascular system

2. Arterial system

3. Large elastic A (windkessel
vessel)
• Aorta & its immediate
branches
• More elastic tissue
• Windkessel effect
• Stretched during
systole  prevent rise
in BP
• Recoil back during
diastole  Px fall in BP
& push blood forwards
Large muscular A
• More muscular tissue &
less elastic tissue
• Radial ulnar & popliteal
A
Arterioles
• Resistance vessels
• Major site of vascular
resistance

4. Windkessel effect d/t elasticity

5. Arterioles or resistance vessels
• Sympathetic
vasoconstriction
• H+
• Lactic acid
• CO2
• Adenosine
Vasodilation

7. Capillaries
• 5 % of total blood
• Maximum total cross sectional area
• Minimum cross sectional area for aorta

9. Maximum area & macimum
drop in velocity exchange
vessels

10. • Precapilary sphincter ulike
arterioles have very little
sympathetic innervation
• Muscle fibres are controlled
almost entirely by local
metabolites like CO2 , pH

11. • Order of capillary permeability in decreasing order are
• Kidney >GIT >heart> lung>skeletal muscle>skin> brain
• Capillaries in brain is least permeable allow passage of only small molecules

14. Critical closing pressure of capillaries
• Critical pressure below which capillaries close

16. arteriole
• Abundant smooth muscles
• Innervated by sympathetic
nervous system
• Resistance is maximum
@ level of resistance

18. Veins
• Thin walled
• Reservoir vessels
• Veins contain 54 % of blood volume
• Decreased elastance  less compliance
• Blood in veins  unstressed volume

21. Velocity is inversely proportional to SA

23. • Aorta  lower SA than capilalries
• Maxmm vvelocity in aorta
• Minimum velocity in capillaries

24. Poiseulle hagen formula
• R = 8ηL/πr4

25. Mean arterial pressure  organ perfusing
pressure

28. • Normal arm to tongue circulation time is 15 sec after injection of bile
salt in to an arm vein

30. Korotkoff sounds are d/t turbulence

33. LAW OF LAPLACE
• the smaller the radius of a blood vessel, the
lower the tension in the wall necessary to
balance the distending pressure.
• DISADVANTAGE
• When the radius of a cardiac chamber is increased, a
greater tension must be developed in the
myocardium to produce any given pressure;
consequently, a dilated heart must do more work
than a nondilated heart