The Types of hearts Can be classified in bicameral, tricameral and with four chambers.
When we refer to the anatomy of the various species of the animal kingdom, the heart has become a clear example of evolution. In short, vertebrates have circulatory systems that have differentiated each other over time. Although there is still great biodiversity within ecosystems, the types of hearts are essentially three.
Within a general classification, fish exhibit a 2 chamber or bicameral heart, amphibians, reptiles (except crocodiles) and molluscs are distinguished by having 3 chambers, and mammals and birds are the most complex, with a system of 4 Cameras. We can also catalog them by their embryonic formation, where they emphasize the tubular, partition and accessory.
Classification of the types of hearts
Bicameral heart
The circulation of blood in the fish presents a simple circuit and at the same time closed. This means that it has a single direction, in which blood flows from the heart to the gills and then to the rest of the organs.
Because of their less complex anatomy, these animals have a precise circulatory system that makes use of 2 cameras. The one with the greatest muscle mass is called the ventricle. The lower musculature has been called the atrium.
The atrium receives the blood flow that has little oxygen reserves from the tissues and redirects it to the ventricle. From there it will pass to the gills so that it can be oxygenated and distributed throughout the organism of the animal.
Characteristic organs
In most of these species can be differentiated four essential elements for their operation; namely:
- Venous sinus . Through the ducts of Cuvier, he is responsible for collecting the blood to send it to the atrium.
- Atrium . This muscular pocket receives the venous blood (low in oxygen) and routes it towards the ventricle.
- Ventricle . By contraction, its thick walls send blood to the heart bulb.
- Heart bulb . It distributes the oxygenated blood to the ventral aortas, the branchial arteries, the dorsal aorta and the rest of the system.
Tricameral heart
At first, when they are in full development, tadpoles have a closed circulation like fish. Once they lose the gills and develop lungs, the system becomes double, which implies a greater circulation and a smaller circulation.
Because of these characteristics, amphibians have a heart that has 3 chambers that divide into one ventricle and two atria. This allows the circulations mentioned, where the most extensive represents the organism and the shortest and incomplete to the pulmonary system.
This double system generates two types of blood: arterial (oxygenated) and venous. The separation of this mixture is carried out by the sigmoid valve, which redirects the flow with oxygen to the main organs and the other to the pulmonary arteries.
The amphibian heart is composed of a venous sinus inside the right atrium, 2 atria separated by a septum covered by an endocardium and a rather muscular ventricle. It also has an arterial bulb with arterial and pulmonary branches.
Reptiles
Like amphibians, this class of animals has a configuration that exhibits 3 chambers with 2 atria and a ventricle with an incomplete dividing wall. The circulation is double, with a pulmonary circuit and a vascular circuit almost completely separated.
The pulmonary circulation is independent and comes directly from the heart. The systemic circulation uses a pair of arteries that leave the left ventricle. In this case they are the left aorta and the right aorta.
Heart with 4 cameras
In evolutionary terms, the birds do not have the left aorta, while the mammals did. The primary difference is that the double blood circulation is completely separated thanks to the interventricular septum that forms 4 cavities.
These chambers are represented by the right and left atria and by the right and left ventricles. On the right side circulates the venous blood flow, while on the opposite side arterial blood flows.
Short circulation begins in the right ventricle through the pulmonary artery that carries blood to the lungs. Once hematosis (gas exchange) occurs, the flow returns to the left atrium.
The longest general circulation originates in the left ventricle through the aorta, from where it travels throughout the organism. It then returns to the left ventricle via the superior and inferior vena cava.
Essential Processes
The hearts fulfill functions that are proper to their design and nature, without which we could not survive. The most important ones are:
- Automatism . This large muscle works by itself, generating a pulse that regulates the heart rate and depends on the sinus node.
- Conductivity . The conductive and contraction tissues allow a rapid diffusion of the electrical impulse to the whole system. This function varies to help the ventricles and atria function properly.
- Contractability . Due to its evolutionary development, this organ has an inherent capacity to contract and spread spontaneously. This mechanism enables the blood cycle and the corresponding oxygenation of the whole body.
- Excitability . All living beings constantly receive a great amount of stimuli that can alter our organic functions. The heart is one of those few organs that reacts in this way.
Other elements
This type of heart, which is also present in humans, contains three layers essential for its functioning:
- The endocardium . Composed of an endothelium, a basement membrane and connective tissue, it is reinforced with elastic fibers that favor the friction and the patter of the blood in the cardiac cavity.
- The myocardium . This central zone is formed by cardiac muscle tissue, whose changing fibers help the movement of contraction during the blood circulation.
- The pericardium . It represents an outer layer that can also change texture in the different areas of the heart. The fibrous pericardium protects it, secures it to other structures and prevents it from flooding with blood.
References
- Animal Biology (2017). Evolution of the cardiovascular system. Web: biology-animal.wikispaces.com
- Gil Cano, Ma. D. Ayala Florenciano and O. López Albors (no date). Heart of the fish. Veterinary anatomy, Faculty of Veterinary Medicine, University of Murcia. Web: um.es.
- Online teacher (2015). Cardiac morphology and physiology. Web: profesorenlinea.cl.
- Biocuriosities (2016). How many types of heart are there? Web: biocuriosidades.blogdiario.com.
- Elvira Estrada Flores and María del Carmen Uribe A (2002). Histology of vertebrates. Autonomous University of Mexico. Web: books.google.com.