Cardiovascular System—
Anatomy of the Great Vessels
Lecture 3
Now we’re going to look at the anatomy of the system after the
blood leaves the heart. As soon as it’s ejected beyond that aortic and
pulmonary valve, it’s going to enter a network which is comprised of …
about 50,000 or 60,000 miles of vessels, an extraordinary amount, and
most of those are microscopic.
T
his lecture examines the anatomy of the three vessel networks that
carry blood from the heart to the body and back again, from the
heart to the lungs and back again, and through the portal hepatic
circulation of the liver. We begin by identifying and describing the structure
of the various vessels that form these networks. Next, we examine separately
the major circulatory routes for the blood: arterial and venous systemic
circulation, pulmonary circulation, and hepatic portal circulation.
Each vessel belongs to either the right or left side of the vascular system.
The left, or arterial, side pumps against the high resistance of the systemic
arteries. It distributes oxygenated blood and nutrients to the body. The right,
or venous, side is a lower-pressure system that carries deoxygenated blood
back to the heart from the lungs.
Pulmonary circulation
Pulmonary arteries carry deoxygenated blood from the heart to the lungs.
Pulmonary veins carry oxygenated blood from the lungs to the heart.
Overview and de nitions
The systemic and pulmonary circulations are both closed-loop systems with
the heart as the pump at the center. Systemic circulation carries blood from
the heart to arteries, then to capillaries, then to veins, then back to the heart.
Pulmonary circulation carries blood from the heart to lung arteries, then to
capillaries, then to veins, then back to the heart.
15
, Blood vessels are named for either the speci c part of the body they supply
or an area surrounding that speci c part. Vessels can change names as they
run through different parts of the body. The brachiocephalic (“arms and
head”) trunk is the division of the aorta immediately after the aorta leaves
the heart. The brachiocephalic trunk splits into the carotid artery, which
supplies the head, and the subclavian (“under the collarbone”) artery. The
subclavian artery becomes the axillary (“armpit”) artery, then the brachial
(“arm”) artery as it moves outward along the arm. It splits into the radial
and ulnar arteries, which run along the radius and ulna bones.
On the arterial side, vessels decrease in size in the following sequence:
large arteries, medium arteries, small arteries, arterioles, and nally, arterial
capillaries (microscopic). Venous vessels increase in size as blood returns
from venous capillaries to venules, then to small veins, then to medium veins,
Lecture 3: Cardiovascular System—Anatomy of the Great Vessels
and nally, to large veins. Veins and arteries generally share the same name;
for example, a brachial artery will have a brachial vein next to it. Exceptions
include the jugular vein and the vena cava.
Exchange of oxygen, carbon dioxide, nutrients, and waste materials occurs
at the capillary level. The capillaries are the only functioning exchange part
of the vascular system. The other vessels are merely channels or conduits for
the passage of blood.
The smooth muscle of the arteries regulates blood pressure, distribution,
and volume. Capillaries comprise most of the 50,000 miles of vessels. The
vasa vasorum (“vessels of the vessels”) feed the walls of the blood vessels
themselves.
Arteries
The word artery is derived erroneously from words meaning “to carry air.”
Artery walls are composed of elastic tissue and smooth muscle, which is
involuntary, out of conscious control. The lumen is the hollow center through
which blood ows. The walls of arteries are thicker than those of veins.
Conducting arteries are large-sized and contain more elastic tissue than
muscle tissue. The largest elastic arteries are the aorta, the carotid, and
pulmonary arteries. Elastic recoil maintains pressure between pumping
16
Anatomy of the Great Vessels
Lecture 3
Now we’re going to look at the anatomy of the system after the
blood leaves the heart. As soon as it’s ejected beyond that aortic and
pulmonary valve, it’s going to enter a network which is comprised of …
about 50,000 or 60,000 miles of vessels, an extraordinary amount, and
most of those are microscopic.
T
his lecture examines the anatomy of the three vessel networks that
carry blood from the heart to the body and back again, from the
heart to the lungs and back again, and through the portal hepatic
circulation of the liver. We begin by identifying and describing the structure
of the various vessels that form these networks. Next, we examine separately
the major circulatory routes for the blood: arterial and venous systemic
circulation, pulmonary circulation, and hepatic portal circulation.
Each vessel belongs to either the right or left side of the vascular system.
The left, or arterial, side pumps against the high resistance of the systemic
arteries. It distributes oxygenated blood and nutrients to the body. The right,
or venous, side is a lower-pressure system that carries deoxygenated blood
back to the heart from the lungs.
Pulmonary circulation
Pulmonary arteries carry deoxygenated blood from the heart to the lungs.
Pulmonary veins carry oxygenated blood from the lungs to the heart.
Overview and de nitions
The systemic and pulmonary circulations are both closed-loop systems with
the heart as the pump at the center. Systemic circulation carries blood from
the heart to arteries, then to capillaries, then to veins, then back to the heart.
Pulmonary circulation carries blood from the heart to lung arteries, then to
capillaries, then to veins, then back to the heart.
15
, Blood vessels are named for either the speci c part of the body they supply
or an area surrounding that speci c part. Vessels can change names as they
run through different parts of the body. The brachiocephalic (“arms and
head”) trunk is the division of the aorta immediately after the aorta leaves
the heart. The brachiocephalic trunk splits into the carotid artery, which
supplies the head, and the subclavian (“under the collarbone”) artery. The
subclavian artery becomes the axillary (“armpit”) artery, then the brachial
(“arm”) artery as it moves outward along the arm. It splits into the radial
and ulnar arteries, which run along the radius and ulna bones.
On the arterial side, vessels decrease in size in the following sequence:
large arteries, medium arteries, small arteries, arterioles, and nally, arterial
capillaries (microscopic). Venous vessels increase in size as blood returns
from venous capillaries to venules, then to small veins, then to medium veins,
Lecture 3: Cardiovascular System—Anatomy of the Great Vessels
and nally, to large veins. Veins and arteries generally share the same name;
for example, a brachial artery will have a brachial vein next to it. Exceptions
include the jugular vein and the vena cava.
Exchange of oxygen, carbon dioxide, nutrients, and waste materials occurs
at the capillary level. The capillaries are the only functioning exchange part
of the vascular system. The other vessels are merely channels or conduits for
the passage of blood.
The smooth muscle of the arteries regulates blood pressure, distribution,
and volume. Capillaries comprise most of the 50,000 miles of vessels. The
vasa vasorum (“vessels of the vessels”) feed the walls of the blood vessels
themselves.
Arteries
The word artery is derived erroneously from words meaning “to carry air.”
Artery walls are composed of elastic tissue and smooth muscle, which is
involuntary, out of conscious control. The lumen is the hollow center through
which blood ows. The walls of arteries are thicker than those of veins.
Conducting arteries are large-sized and contain more elastic tissue than
muscle tissue. The largest elastic arteries are the aorta, the carotid, and
pulmonary arteries. Elastic recoil maintains pressure between pumping
16
