Circulatory System

Cardiac Anatomy and Physiology

- The Pericardium is a fluid filled cavity which envelops the heart and eliminates friction between surrounding structures and the heart as it contracts. The pericardium has a visceral (deep) and a parietal (superficial) aspect.
- The Atria are the reservoirs where blood is received upon its return to the heart. They are located cranially and there is one atrium on either side of the heart. The right atrium receives blood from the body through the cranial and caudal branches of the Vena Cava, and the left atrium receives blood from the lungs
- Caudal to the atria are the Ventricles, which contract to pump blood away from the heart. The right ventricle pumps blood to the lungs through the pulmonary artery and the left ventricle pumps blood to the body through the Aorta. As blood flows through the aorta, it is distributed to arteries leading to the rest of the body by the Aortic Arch.

The Tricuspid Valve prevents the flow of blood backwards from the right ventricle to the right atrium.
The Bicuspid Valve, or mitral valve, is responsible for preventing backflow on the left side of the heart.
The Papillary Muscles and Chordae Tendineae attach the cuspid valves to the ventricular wall to prevent the leaves from folding into the atria.
The Pulmonary and Aortic Valves are semilunar valves which prevent backflow through the major arteries leaving the heart.
The Ventricular Septum is a muscular structure which separates the ventricles. The caudal tip of the heart is called the Apex.
The Coronary Arteries supply the cardiac tissue with oxygen.

Celiac Artery: Supplies blood to the stomach, spleen, liver, gallbladder, and pancreas.
Mesenteric Artery: Supplies blood to the midgut and the duodenum.
Hepatic Artery: Supplies blood to the liver, duodenum, and pancreas.
Pulmonary Trunk: Delivers blood to the pulmonary capillaries of the left ad right lung.
Brachiocephalic Trunk: Supplies blood to the parts of the upper body. EX: Arm, head, neck, and chest.

During circulation deoxygenated blood flows into the right atrium from the cranial and caudal vena cava.
From the Right atrium, the unoxygenated blood flows into the right ventricle and through the pulmonary artery.
The pulmonary artery leads to unoxygenated blood towards the lungs.
In the lungs, there is an increase in oxygen and a decrease in carbon dioxide.
Now, oxygenated blood flows through the pulmonary vein from the lungs.
The pulmonary vein leads the oxygenated blood to the left Atrium.
From the left atrium, the blood goes into the left ventricle then through the aorta.
The aorta then leads the oxygenated blood to the rest of the body.

Umbilical vein
- returns oxygen and nutrient-rich blood to fetus (liver) from placenta
2 Umbilical arteries
- abdominal aorta to placenta
- Carries oxygen poor blood away from fetus to placenta
Ductus arteriosus
- bypasses pulmonary arteries
Foramen ovale
- foramen between left and right atria
Ductus venosus
- bypasses hepatic sinusoids

Hepatic Portal Vein: Brings oxygen rich blood from the body to the liver.

Hepatic Vein: Brings oxygen-poor blood from the lungs to the body.

Hepatic Portal Vein: Brings nutrient-rich blood to the liver from the Gastrointestinal Tract.

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