Cardiovascular System

Cardiovascular System (CVS)
Overview
• Components of CVS
• Func5ons of CVS
• Heart
o Loca5on
o Layers
o Chambers
o Valves
o Blood supply
• Blood vessels
o Arteries
o Veins
o Capillaries
§ Layers of blood vessels
• Types of circula5on (first two are the two types of circula5on, the third one is a part of
systemic circula5on)
o Pulmonary circula5on
o Systemic circula5on
o Portal circula5on
• Major arteries and veins

o Blood supply of the organs
Components of CVS
§ The heart
§ The blood vessels
§ Blood
Func5ons of CVS
§ Provide adequate blood circula5on throughout the body
§ Regula5on of Blood pressure, body temperature (to some extent)
§ Transporta5on of gases such as oxygen and carbon dioxide, nutrients, hormones, etc.
The heart
Anatomy of the heart: the heart is located in the thorax in a space bound anteriorly by the
sternum and the costal car5lages, posteriorly by the thoracic vertebrae, and laterally by the
two lungs. The space is called the medias5num.
The heart has three layers: the epicardium-outer layer, the myocardium-middle muscular
layer and the endocardium-inner layer. The heart is enclosed in a tough fibrous 5ssue known
as the pericardium. There is a fluid called pericardial fluid between the pericardium and the
epicardium to prevent fric5on as the heart beats.
The heart is made up of four chambers. Two upper chambers known as atria separated by
the interatrial septum and two lower chambers known as ventricles separated by the
interventricular septum. The right atrium receives deoxygenated blood by the way of two
caval veins-superior and inferior vena cava. The leQ atrium receives oxygenated blood from
the lungs by the ways of pulmonary veins. The right atrium pumps the blood to the right
ventricle through a valve called tricuspid valve, and the leQ atrium pumps blood to the leQ
ventricle though mitral valve. When the two ventricles contract, these valves close to
prevent the back flow of the blood to the atria. The right ventricle pumps the deoxygenated
blood to the lungs The leQ ventricle pumps the oxygenated blood to the body 5ssues. The
other two valves in the heart are semilunar valves known as pulmonary and aor5c valves.
The circula5on of the deoxygenated blood between the right side of the heart and the lungs
is called pulmonary circula6on whilst the circula5on of the oxygenated blood between the
leQ side of the heart and the body 5ssues is called the systemic circula6on.
Anatomy of the heart

Blood supply of the heart
The right and leQ coronary arteries are the first branches of the ascending aorta which
supplies the heart. They branch into several small arteries and capillaries. The heart is
drained by coronary veins such as small and great cardiac veins, right coronary vein, etc
which drain into the coronary sinus and returns the blood to the right atrium.
Fig: coronary vessels
Blood vessels
Arteries carry blood from the heart to the body 5ssues. Veins carries the blood from the
body 5ssues to the heart. Small arteries are called arterioles. Arterioles carry blood to the
capillaries where the exchange of gases, nutrients, etc. take place. venules carry blood from
capillaries to the veins and then to the heart. Arteries and veins have three layers (tunics).
Arteries have thick walls owing to thicker tunica media (than veins) containing smooth
muscle cells to withstand the pressure from the heart. The outer and inner layers are called
tunica externa and tunica in5ma respec5vely. The inner layer is lined by a simple squamous
epithelial cells called the endothelium (which also lines the endocardium of the heart).
Capillaries have only one layer of endothelium with its basement membrane. Arteries are
not collapsible while veins are. Veins have valves within them to prevent the back flow of
the blood. Arteries have no valves.
Three layers of blood vessels

Layers in the arteries and veins.
Portal circula5on
It is a subdivision of systemic circula5on in which blood from the abdominal diges5ve organs
and spleen circulates through the liver before returning to the heart. Blood from the
capillaries of the stomach, small intes5ne, colon, pancreas, and spleen flows into two large
veins, the superior mesenteric vein and the splenic vein, which unite to form the portal vein
The portal vein takes blood into the liver, where it branches extensively and emp5es blood
into the sinusoids, the capillaries of the liver. From the sinusoids, blood flows into hepa5c
veins, to the inferior vena cava and back to the right atrium.
Major systemic arteries
Major arteries of the human body

Major arteries with the regions they supply
Major veins
Major veins
Major veins and their drainage
Circle of Willis
Circle of Willis. This anastomosis is formed by the following arteries: internal caro5d, anterior
communica5ng, posterior communica5ng, and basilar. The cerebral arteries extend from the
circle of Willis into the brain.
Circle of Willis
Pulse sites
Reference:
1. Valerie C. Scanlon, Tina Sanders: Chapter 12: The Heart, Essen:als of Anatomy and Physiology (5th Edi:on).
2. Valerie C. Scanlon, Tina Sanders: Chapter 13: The Vascular System, Essen:als of Anatomy and Physiology
(5th Edi:on).

Cardiovascular System

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Cardiovascular System

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Cardiovascular System (CVS)

• Major arteries and veins

Anatomy of the heart

Fig: coronary vessels

Three layers of blood vessels

Major arteries of the human body

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