What happens to blood in the small circle of circulation in dogs? - briefly
In dogs, the small circle of circulation, also known as the pulmonary circuit, is responsible for transporting deoxygenated blood from the heart to the lungs and back again. Here, blood receives oxygen and releases carbon dioxide, preparing it for the larger systemic circulation where it will deliver oxygen to the body's tissues.
What happens to blood in the small circle of circulation in dogs? - in detail
The small circulation, also known as the pulmonary circuit, involves the movement of blood between the heart and lungs in dogs. This process is crucial for maintaining oxygen homeostasis and removing carbon dioxide from the body. Here’s a detailed breakdown of what happens to blood in this circuit:
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Deoxygenated Blood Entry: After delivering oxygen-depleted blood to various parts of the body, the inferior vena cava carries deoxygenated blood back to the right atrium of the heart. Simultaneously, the superior vena cava and coronary sinus contribute additional deoxygenated blood.
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Right Atrial Contraction: When the right atrium contracts, it pushes the deoxygenated blood through the tricuspid valve into the right ventricle. This contraction ensures that all the blood from the vena cavae and coronary sinus is efficiently moved forward.
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Right Ventricular Contraction: The right ventricle then contracts, forcing the deoxygenated blood through the pulmonic valve into the pulmonary artery. This high-pressure environment is necessary to push the blood against the resistance of the pulmonary circulation and into the lung capillaries.
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Pulmonary Arteries and Capillaries: The pulmonary arteries branch out, delivering deoxygenated blood to the tiny capillaries surrounding the alveoli in the lungs. Here, the blood comes into close proximity with the alveolar air, facilitating gas exchange.
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Gas Exchange: In the lung capillaries, carbon dioxide diffuses out of the blood and into the alveoli, while oxygen diffuses from the alveoli into the bloodstream. This process is driven by the concentration gradients between the blood and the air in the lungs.
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Oxygenated Blood Exit: Once the blood has been replenished with oxygen, it exits the capillaries via the pulmonary veins. These veins carry the newly oxygenated blood back to the heart, specifically to the left atrium.
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Left Atrial Contraction: The left atrium contracts, pushing the oxygen-rich blood through the mitral valve into the left ventricle. This step prepares the blood for distribution throughout the body.
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Left Ventricular Contraction: The left ventricle then contracts, propelling the oxygenated blood through the aortic valve and into the aorta. From here, it is distributed to all parts of the dog's body via arteries, arterioles, capillaries, venules, and veins, completing the large circulation.
This continuous cycle ensures that dogs receive an adequate supply of oxygenated blood, vital for sustaining their metabolic processes and overall health.