Very  nice layout and excellent subject material, nothing at all else we want : D.

<h2>Single and Double Circulation Systems</h2>
<p>The <a data-lesson="circulatory-system" data-subject="biology" data-tutorial="human-biology" href="https://app.ulearngo.com/biology/human-biology/circulatory-system">circulatory system</a> is a broad term that encompasses the <strong>cardiovascular</strong> and <strong>lymphatic</strong> systems. The <a data-lesson="lymphatic-system" data-subject="biology" data-tutorial="human-biology" href="https://app.ulearngo.com/biology/human-biology/lymphatic-system">lymphatic system</a> will be discussed later in this tutorial. The cardiovascular system consists of the heart (cardio) and the vessels required for transport of blood (vascular). The vascular system consists of arteries, veins and capillaries. Vertebrates (animals with backbones like fish, birds, reptiles, etc.), including most mammals, have closed cardiovascular systems. The two main circulation pathways in <a data-lesson="introducing-invertebrates" data-subject="biology" data-tutorial="invertebrates" href="https://app.ulearngo.com/biology/invertebrates/introducing-invertebrates">invertebrates</a> are the <strong>single</strong> and <strong>double</strong> circulation pathways.</p>
<h3><strong>Single Circulatory Pathways</strong></h3>
<p>Single circulatory pathways as shown in the diagram below consist of a double chambered heart with an atrium and ventricle (the heart structure will be described in detail later in this tutorial). Fish possess single circulation pathways. The heart pumps deoxygenated blood to the <a data-lesson="skin-and-gills" data-subject="biology" data-tutorial="respiratory-system" href="https://app.ulearngo.com/biology/respiratory-system/skin-and-gills">gills</a> where it gets oxygenated. Oxygenated blood is then supplied to the entire fish body, with deoxygenated blood returned to the heart.</p>
<div class="wp-caption alignnone" style="width: 571px"><img alt="" height="709" src="https://data.ulearngo.com/assets/1aa79984-0dbb-40f3-b710-b763d5b534df" width="571"/><p class="wp-caption-text">Single circulation system as found in a typical fish species. The red represents oxygen-rich or oxygenated blood, the blue represents oxygen-deficient or deoxygenated blood.</p></div>
<h3><strong>Double Circulatory Systems</strong></h3>
<p>Double circulation pathways are found in birds and mammals. Animals with this type of circulatory system have a four-chambered heart.</p>
<p>The right atrium receives deoxygenated from the body and the right ventricle sends it to the <a data-lesson="types-of-breathing" data-subject="biology" data-tutorial="respiratory-system" href="https://app.ulearngo.com/biology/respiratory-system/types-of-breathing">lungs</a> to be oxygenated. The left atrium receives oxygenated blood from the lungs and the left ventricle sends it to the rest of the body. Most mammals, including humans, have this type of circulatory system. These circulatory systems are called 'double' circulatory systems because they are made up of two circuits, referred to as the <strong>pulmonary</strong> and <strong>systemic</strong> circulatory systems.</p>
<div class="wp-caption alignnone" id="attachment_389649" style="width: 800px"><img alt="" class="size-full wp-image-389649" height="811" src="https://data.ulearngo.com/assets/5e9a7d2a-ffb1-47c6-9e1b-20211b17c9fa" width="800"/><p class="wp-caption-text">Summary of Double Circulation. Credit: <a href="https://byjus.com/biology/double-circulation/">Byju's</a></p></div>
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<h3>Fact:</h3>
<p>Humans, birds, and mammals have a four-chambered heart. Fish have a two-chambered heart, one atrium and one ventricle. Amphibians have a three-chambered heart with two atria and one ventricle. The advantage of a four chambered heart is that there is no mixture of the oxygenated and deoxygenated blood.</p>
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Single and Double Circulation Systems

Biology studies life and living organisms. Biology can be divided into different sections that cover the morphology, physiology, anatomy, behavior, and so on of living organisms.

Biology

Discover the support systems found in various animals, explore the structure and functions of different skeletons, learn about musculoskeletal tissues, joints and tendons, and discover the human circulatory system including the heart, blood vessels and associated diseases.


Single and Double Circulation Systems

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