Untitled Quiz

The circulatory system is categorized into open and closed transport systems.
Open Transport System: Blood is located in the coelomic spaces, bathing the organs. This system is suitable for sedentary animals, like nematodes. Circulation is driven by muscular contractions. In arthropods (like insects), there's a tubular heart with valves for unidirectional blood movement. Gaseous exchange isn't a primary function of the open circulatory system in insects, because of their efficient tracheal system.
Closed Transport System: Blood is confined to branching vessels, driven by a heart. This is the type of circulatory system in vertebrates (mammals, birds, fish).

Single Circulatory System: Found in fish, a tubular heart pumps blood to gill capillaries for gas exchange, then to larger vessels distributing oxygenated blood to the body. Venous system returns the blood to the heart.
Incomplete Double Circulatory System: Found in amphibians, the heart is partially partitioned with intercommunication between the ventricles. There's pulmonary and skin circulation. Blood from the right ventricle goes to the lungs or skin, then to the left atrium, left ventricle, body organs, and back to the right atrium.
Complete Double Circulatory System: Found in mammals and birds, this system has two separate circuits: pulmonary and systemic circulation. Blood from the right ventricle goes to the lungs for oxygenation, then to the left atrium, and then through the body.

Angiology: Study of blood vessels
Vascular plexus: Network of blood vessels
Anastomosis: Interconnection of blood vessels.
Retia Vasculosa: Wide mesh/network of blood vessels
Rete mirabile: Intercalated network of vessels in an artery.
Collateral vessels: Vessels that follow a course similar to a major vessel; common in limbs.
Collateral Circulation: Branches of a main artery anastomose (connect) to provide alternate blood supply.
Vena comitans: Veins that accompany arteries.
Venous sinuses: Thin-walled veins enclosed in membranes and often found in grooves.
Emissarium: Vein connecting venous sinuses to veins outside the skull.
Corpus Cavernosum: Erectile tissue with intercommunicating spaces.

The heart is the central pump in the circulatory system. It is composed of a right and left pump.
Right pump: receives deoxygenated blood and pumps it to the lungs.
Left pump: receives oxygenated blood and pumps it to the body.
Mammalian heart pumps 60% of blood volume each minute.

Heart is located in the middle mediastinum.
The mediastinum is a partition in the thorax, positioned between the lungs and extending from the thoracic inlet to the diaphragm.
The pleural membranes attach to the thoracic vertebrae dorsally and the sternum ventrally.

The heart is related to the lungs, trachea, esophagus, and large blood vessels dorsally and laterally.
In ruminants, the heart is closely related to the reticulum, which can be a clinical concern.

Heart is mostly invested by the pericardium, which is invested by the mediastinal pleura.
Heart is asymmetrically positioned in the thoracic cavity, with 60% located to the left of the midline.
Inclination of the long axis of the heart varies among species.

Heart position more to the left side means increased audibility on the left side, but also musculature reduces the area available for examination in large animals.
Heart is positioned in the thoracic cavity with the right ventricle bordering the cranial, and the left ventricle bordering the caudal regions.

Pericardium is a double-layered serous membrane sac enclosing the heart which contains serous fluid.
Visceral layer adheres very tightly to the epicardium.
Parietal and visceral layers reflected at base of heart and in large blood vessels.

The base of the heart is formed by thin-walled atria, separated by the coronary groove, containing coronary blood vessels.
Right and left atria unite to form a U-shape, with blind auricles (projections) on each side.
Ventricles are separated by the interventricular grooves, extending from the coronary groove towards the heart's apex.

Right atrium is located primarily on the right side.
Auricle extends to the cranial part of the pulmonary trunk.
The principal systemic veins discharge into the atrium (caudal and cranial vena cava).
There is a intervenous tubercle, and fossa ovalis.

The right ventricle is located on the right side and ends cranial to the left ventricle.
It's nearly completely divided by a supraventricular crest, with an outflow part and a conus arteriosus, and a right atrioventricular orifice.
Contains 3 cusps, the tricuspid valve, attached to a fibrous ring. The walls of the inflow part of the ventricle are corrugated by trabeculae carnae preventing blood turbulence. Septomarginalis runs from interventricular septum to ventricular wall (part of conduction system)

The inflow to the left atrium is primarily through pulmonary veins (5-8).
The interatrial septum might have a scar (foramen ovale).
Left atrium forms the caudal part of the heart's base; portion receiving the veins has a smooth wall, while the auricle has the m.pectinati.

The apex forms the apex of the heart
Receives blood from the left atrium; has a thicker wall compared to the right ventricle.
The interventricular septum is also thick and forms the external wall.
Atrioventricular orifice has a bicuspid valve (two cusps).
Inflow runs from the atrioventricular orifice to the apex of the heart.

Heart receives 15% of blood via coronary arteries. Branches off from the aortic sinuses.
Left coronary artery is larger; divides into paraconal (left interventricular) branches running through the paraconal grove to the apex of the heart. These branches supply the heart muscle.

Species differences in heart anatomy are described for various domestic animals

pulmonary trunk leaves right ventricle and curves; attached to the aorta by ligamentum arteriosum.
Artery divides into left and right pulmonary arteries to the lungs.