top of page

Physical Properties of Blood Vessels



Properties of Blood Vessels that Vary at Different Levels of Branching are:

  • Number of vessels

  • Radius & Wall thickness

  • Aggregate cross-section area of all the parallel vessels at a particular level

  • Volume

  • Pressure

  • Flow

  • Velocity of the blood

  • Circulation time

  • Structure of the wall

  • Elastic property

Number of Vessels

  • Aorta: 1

  • Small arteries: 8000

  • Arterioles: 20 million

  • Capillaries: 40 billion

  • Towards veins: the numbers decrease as vessels merge

  • Vena cava: 2

Radius / Wall Thickness

  • The radius decreases as we go from aorta to capillaries. And increase from capillaries to vena cava.

  • Aorta: 12 mm / 2 mm

  • Medium-size artery: 2 mm / 1 mm

  • Arteriole: 15 Îźm / 20 Îźm

  • Capillary: 3 Îźm / 1 Îźm

  • Venule: 10 Îźm / 2 Îźm

  • Vein: 2.5 mm / 0.5 mm

  • Vena cava: 15 mm / 1.5 mm

Cross Section Area

Of Individual vessel

The radius decreases as we go from aorta to capillaries. And increase from capillaries to vena cava

↓

Crosss section area of individual blood vessel decreases as we go from aorta to capillaries. And increase from capillaries to vena cava.


Aggregate Cross-Section Area All the Parallel Vessels at a Particular Level
  • Aggregate cross-section area = number of vessels at that level × cross-section area of unit vessel

In general, with branching, combined cross-section area of daughter vessels exceeds cross-section area of the parent vessel

↓

As arteries branch into subsequent levels

↓

Aggregate cross-section area increases i.e.

Aorta: 4 square cm

Small arteries: 60 square cm

Arterioles: 140 square cm

Capillaries: 2800 square cm

↓

Postcapillari venules: Have maximum aggregate cross-section area in spite of their fewer number than capillaries. This is because their significantly wider diameter than capillaries overcompensates for their slightly fewer numbers.

Volume

  • Systemic arteries: 700 ml

  • Systemic capillaries: 300 ml

  • Systemic veins: 3200 ml

  • Pulmonary circulation: 450 ml

  • Heart: 350 ml

  • Total: 5000 ml

Other parameters are more like physiological parameters and are explained in other videos.

 

Next >>

Comments


bottom of page