Blood Vessels Flashcards
The function of blood vessels
- Deliver blood to the organs and tissues of the body
- Exchange nutrients, waste products and gases
- Transport substances such as hormones and enzymes
- Regulate blood pressure
- Direct blood flow to tissues
Where do arteries and arterioles carry blood?
Away from the heart
Where do veins and venules carry blood?
Back to the heart
What are the 3 layer of blood vessels?
Tunica Adventitia
Tunica Media
Tunica Media
Tunica Adventitia
Outer layer
Fibrous Tissue to protect and support the vessel
Tunica Media
middle layer
Containing variable amounts of smooth muscle and elastic tissue
Tunica Intima
inner layer
AKA inner endothelium
1 cell thick
smooth lining layer
present in capillary walls
Arteries
carry blood away from the heart
Arterial walls are thicker that venous walls to withstand high pressure of arterial blood.
classifications of arteries
Elastic
Muscular
Arteriole
Elastic Arteries
Tunica media contains much more elastic tissue and little smooth muscle allowing the wall to stretch and absorb the pressure generated by the heart contraction
Arterioles
Tunica Media consists mostly of smooth muscle allowing the diameter to be precisely controlled which regulates pressure within them.
Capillaries
- Smallest vessels
- Join Arterioles to venules
- Walls consist of a single layer of endothelial cells on a basement membrane
- form dense networks of tiny vessels that link the smallest arterioles and the smallest venules.
Capillary basement membrane
Incredibly thin so allows small molecules to pass through the capillary wall but not large molecules.
Veins
- Thinner walls than arteries although same 3 layers of tissue
- collapse when cut
- contain valves
- can stretch therefore hold a larger proportion of blood
- Blood is at a much lower pressure.
Blood Pressure
Measure of the force exerted on the vessel wall by the blood.
measured using a sphygmomanometer or an arterial line
