Cardiovascular system

CARDIOVASCULAR SYSTEM

Cardiovascular system

  • The cardiovascular system consist of heart and blood vessels, the heart keeps the blood on motion and blood vessels circulate the blood to and from all parts of the body, the lymphatic vessel, an ancillary set of vessels, which circulate lymph and lymphocytes. The circulatory system is closed in fishes.
  • The heart of fishes is known as branchial heart, because its main function is to pump venous blood to ventral aorta and from ventral aorta into gills (branchial) and then to somatic vasculature. The heart of fishes consists of four chambers, a sinus venosus, an atrium, a ventricle and a conus or a bulbous arteriosus.
  • The heart performance basically depends on two factors: the heart rate and the stroke volume. The volume is termed stroke volume and the time of the heart beat is known as heart rate.

Sinus venosus

  • The sinus venosus is not an active part of the heart although pacemaker property starts in this chamber. It is actually a continuation of the venosus vessels and its main function is to receive blood and to pass it on to the atrium. Sinus venosus receives blood through two ducti Cuvieri; Hepatic veins pour the blood from liver. The ventral ductus Cuvieri receives blood from anterior and posterior cardinal veins. Normally the sinus venosus is purely a muscular in some fishes. The matrix of this chamber is made up of elastic and collegen fibres, the sinus venosus opens into atrium by a sinuatrial ostium, which is provided by two sinuatrial valves.

Atrium

  • The atrium is a large muscular contractile chamber. It is situated dorsal to the ventricle in almost all fishes. In fishes, the atrium is also called as auricle, but actually the appendages of the atria are called as auricles. Pulmonary blood drains directly into left side of the atrium, whereas the systemic venous blood is collected in the sinus venosus through ducti Cuvieri. The blood from the sinus venosus goes to the side of the atrium.

Atrioventricular funnel

  • The atrium communicates with the venticles through a tubular structure referred to as canalis auricularis or atrioventricular funnel.

Ventricle

  • The teleost ventricle is either tubular, pyramidal or sac like in appearance. It is relatively a large muscular chamber. It is undivided in elasmobranches and teleost, but it is partially divided into left and right chambers by muscular septum in Dipnoi. The muscular septum is posterior to the atrioventricular plug in all the three genera but extends anteriorly along the ventral surface in Lepidosiren.

Lung fish

Source : http://www.biosci.uga.edu/almanac/bio_104/notes/may_7.html .

 
Last modified: Sunday, 18 September 2011, 4:49 AM