Blood Vessels Flashcards
Which vessels carry blood AWAY from the heart?
Arteries
Where do arteries carry blood?
Away from the heart to the capillaries in tissues.
Large arteries that leave the heart divide into medium-sized (______) arteries.
Distributing
Distributing arteries branch to form what?
Arterioles
What is the term for the CONTRACTION of blood vessel walls?
Vasoconstriction
What is the term for the RELAXATION of blood vessel walls?
Vasodilation
Vasoconstriction _________ blood pressure.
Vasoconstriction INCREASES blood pressure.
Vasodilation _________ blood pressure.
Vasodilation DECREASES blood pressure.
Where are arteries more elastic, and why?
Arteries closer to the heart are more elastic, giving resistance to the high blood pressures of the blood leaving the left ventricle.
Where are arteries more muscular?
Arteries further from the heart have more muscle to help them maintain BP.
Define ‘lumen’
(from Latin lumen, meaning “an opening”; plural lumina) LUMEN: the inside space of a tubular structure, such as an artery or intestine.
What is the innermost layer of an artery?
Endothelium - a thin layer of epithelial cells; in contact with blood.
Endo-: internal; within // -thelium: layer of (specified kind of) cellular tissue
What is the middle layer of an artery?
Tunica media - central layer of elastic tissue and smooth muscle that can stretch and contract.
What is the ‘tunica externa’?
The outer layer of the artery; a thick layer of elastic and connective tissue that allows for expansion of the artery.
What is the purpose of smooth muscle in artery walls?
The smooth muscle around arteries helps to regulate blood flow and pressure. By contracting or relaxing it alters the diameter of the artery and adjusts the volume of blood as required.
What is the effect of vasoconstriction on the diameter of an arteriole?
The diameter DECREASES.
What is the effect of vasodilation on blood pressure?
Blood pressure DECREASES.
Where do veins carry blood?
Back from the tissues to the heart.
Where do venules carry blood?
From capillary beds to larger veins.
Which type of blood vessel contains approx 59% of blood in the body?
Veins, and their branches.
When several capillaries unite, they form….
….small veins called VENULES.
Veins are made up of essentially the same 3 layers as arteries but have ____ elastic and muscle tissue and a ______ lumen.
…LESS elastic and muscle tissue and a LARGER lumen.
Venules closest to capillaries are missing which layer?
Tunica media
Blood flowing in the ___ has ____ a lot of pressure because it has passed through the narrow _______ vessels.
Blood flowing in the VEINS has LOST a lot of pressure because it has passed through the narrow CAPILLARY vessels.
What structure in veins is made necessary due to lower blood pressure?
One-way (Jesus) valves
What is another term for the endothelium?
Tunica intima