Chapter 21 Flashcards
Arteries
Carry blood away from the heart
Has a thick muscular to elastic tunica media
High compliance
Two types elastic and muscular
What are the five main types of blood vessels?
Arteries, arteriole, capillaries, venules, and veins
Veins
Blood vessels that convey blood from the tissues back to the heart
Tunica interna
Forms the inner lining of a blood vessel and is in direct contact with the blood that flows through the lumen
Has an inner layer of endothelium and a basement membrane deep to the endothelium
Outer most layer between the tunica Interna and tunica media is the internal elastic lamina
Internal elastic lamina of the tunica interna
Thin sheet of elastic fibres with window like openings that facilitate diffusion of materials to the tunica media
Tunica media
Regulates the diameter of the lumen with vasoconstriction and vasodilation as well as vascular spasm to limit damage
Tunica externa
Outer covering of a blood vessel
consists of elastic and collagen fibres and contains nerves and blood vessels that supply tissue of the vessel wall called vasa vasorum
also helps anchor the tunica externa to surrounding tissues
Vasa vasorum
Small vessels that supply blood to the tissues of the vessels in the tunica externa
Elastic arteries
Largest arteries in the body
well defined internal and external elastic laminae
thick tunica media dominated by elastic fibres called elastic lamellae
the two major trunks that exit the heart are the aorta and the pulmonary trunk
Functions of the elastic arteries?
Propel blood onward while the ventricles are relaxing
walls stretch easily accommodating the surge of blood
elastic fibres momentarily store mechanical energy functioning as a pressure Reservoir
then they recoil and convert the stored energy in the vessel into kinetic energy of the blood
What is another name for elastic arteries and why?
Conducting arteries, because they conduct blood from the heart to medium sized more muscular arteries
Muscular arteries
Medium-sized arteries their tunica media contains more smooth muscle and fewer elastic fibres making the walls relatively thick
Tunica externa is often thicker than the tunica media
Functions of the muscular arteries?
Vasodilation and vasoconstriction
called distributing arteries because they distribute blood to each of the various organs
has the ability to maintain vascular tone
Stiffness in the vessel walls is important in maintaining vessel pressure and efficient blood flow
Anastomosis
Do union of branches of two or more arteries supplying the same body region
Collateral circulation
The alternative route of blood flow to a body part through and anastomosis
End arteries
Arteries that do not anastomose
Arterioles
Abundant microscopic vessels that regulate the flow of blood into the Capillery networks of the body tissues
have a thin tunica interna with a thin fenestrated internal elastic lamina that disappears at the terminal end
the terminal end of the arterial is called the metarteriole and tapers toward the Capillary junction
this junction the distal most muscle cell forms the precapillary sphincter which monitors the blood flow into the Capillary
Arterioles functions?
Play a key role in regulating blood flow from arteries into capillaries by regulating resistance
What is another thing arterioles are called?
Resistance vessels
Capillaries?
Smallest blood vessel, includes the microcirculation where blood from a metarteriole goes through Capillery’s into a post Capillary venule
What is the primary function of the capillaries?
Exchange of substances
What is something else the capillaries are called?
Exchange vessels
Vasomotion
Where blood flows intermittently through capillaries due to the alternating contraction and relaxation of the smooth muscle of metarterioles and the pre-capillary sphincters
Thoroughfare channels
Provides a direct route for blood from an arteriole to a venule bypassing capillaries