Cardiovascular System

The major organ involved in this system is the heart, which is responsible for pumping and distributing blood to all parts of the body through veins, arteries, arterioles and capillaries. This system provides the routes of transportation to bring nutrients, enzymes, hormones, etc. to each part of the body, and helps to dispose of waste products of cells.

Source: http://maturitabiologia.sengym-moodle.sk/vtaky/index.html

The heart lies in contact with the liver dorsally and laterally and is four-chambered, meaning it has two atria and two ventricles, like the mammalian heart. Between each atrium and each ventricle exist a pair of valves called the atrioventricular valves. They are structurally different than the valves found in mammalian hearts. The right atrioventricular valve has a single spiral flap of myocardium, or tissue, attached to the wall of the right ventricle. The left atrioventricular valve is tricuspid. Between the ventricles and the pulmonary artery and the aorta lie the semilunar valves. The whole heart is covered in a pericardial sac. The caudal vena cava and two cranial venae cavae, which carry blood lacking oxygen from the body, lead to the right atrium. The pulmonary vein carries oxygenated blood to the left atrium. The aortic arch that carries oxygenated blood to the body turns to the right in birds, as opposed to left in mammals.

The heart cut open. Veins leading to the heart and arteries leading
away from the heart are not shown because they were cut in order to free the heart.

The coronary arteries of the heart
Source: http://www.nsh.nsw.gov.au/services/nscec/education/booklets/003683876.shtml

The cardiac cycle, or the period of one complete cycle of cardiac contraction and relaxation, is split into two phases: diastole and systole. Diastole refers to the relaxation of a chamber of the heart, while systole refers to the contraction of a chamber of the heart. These phases occur thanks to stimulation of the heart by specialized conductive cells like the sinoatrial node which propagates action potentials within the heart and is considered the pacemaker because other specialized cells react to the stimuli sent from this region. The areas that react are the atrioventricular node and the bundle of His which also conduct action potentials to control the pumping of the heart. In addition, the atrioventricular valves are connected to the Purkinje fibers which carry the impulse from the atrioventricular node to the ventricles, signaling when the valves may open and when the ventricles can contract.

Blood flow through the heart
Source: http://www.nsh.nsw.gov.au/services/nscec/education/booklets/003683876.shtml

Source: http://www.lookfordiagnosis.com/mesh_info.php?term=Brachiocephalic+Trunk&lang=1 

The heart rate of a chicken is usually somewhere between 200 and 350 beats per minute. If the chicken has a high resting metabolic rate and or high normal body temperature this demands more from the heart and as a result, the chicken has a higher level of resting cardiac performance.

The blood consists of plasma and suspended elements such as erythrocytes, leucocytes, thrombocytes, monocytes, lymphocytes, basophils and eusinophils. It carries waste, hormones, enzymes, and antibodies, around the body among other things.

During the dissection, the heart was freed from the body to allow for a better examination of it. This is why there are no pictures showing veins or arteries leading to or away from the heart. Please refer to the diagrams  below to see where the brachiocephalic, carotid and subclavian arteries and the aortic arch, abdominal aorta and the hepatic portal vein are found.

Source: http://people.eku.edu/ritchisong/birdcirculatory.html

Source: http://people.eku.edu/ritchisong/birdcirculatory.html