Our journey begins with a molecule of rich oxygen. As we enter the nose, the oxygen makes its way through the nose hairs and into the nasal cavity. The nasal cavity is lined with mucous so there are no unwanted bacteria traveling with us. After floating a rough trip through the hairs and mucous, we make our way to the sinuses. These sinuses are air pockets in the skull; we’ll only be here for a little while. The sinuses are lined with mucus and cilia to again stop any bacteria or unwanted air particles from traveling with us. We continue our way through the sinuses and into the pharynx which has even more cilia and mucus! Oh, wait. What’s that flap ahead of us? This “flap” is the epiglottis. The epiglottis shifts to direct food into the esophagus
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On our way up to the heart, we move through the venules and into the dorsal digital vein. We can finally breathe. Oh, wait, we can’t breathe carbon dioxide! As we continue up, we move through the dorsal venous arch, up the anterior tibial vein, climb the popliteal vein and femoral vein. Only a two veins to go! We continue through the external iliac vein and right into the inferior vena cava! We are now in the right side of the heart, literally, the right atrium. The SA node’s action potential fires again and through the tricuspid valve we go. We’re now in the right ventricle. This one is roomy like the left so we have to wait with the AV node until the ventricle fills up some more. Finally! The AV bundle fires and we pump through the pulmonary semilunar valve into the pulmonary trunk and out the pulmonary arteries. We are on our way back to the lungs now. It gets a little small again as we pump through the pulmonary arterioles and into the capillaries. Here we have our last gas exchange with the capillaries. Our carbon dioxide is now red blood cell free and on its way out of the body! In the alveoli, we have to push through the bronchiole tree again. First we float through the terminal bronchioles, then the tertiary bronchiole, through the secondary bronchi, and finally past the primary bronchi. We move through the
On our way up to the heart, we move through the venules and into the dorsal digital vein. We can finally breathe. Oh, wait, we can’t breathe carbon dioxide! As we continue up, we move through the dorsal venous arch, up the anterior tibial vein, climb the popliteal vein and femoral vein. Only a two veins to go! We continue through the external iliac vein and right into the inferior vena cava! We are now in the right side of the heart, literally, the right atrium. The SA node’s action potential fires again and through the tricuspid valve we go. We’re now in the right ventricle. This one is roomy like the left so we have to wait with the AV node until the ventricle fills up some more. Finally! The AV bundle fires and we pump through the pulmonary semilunar valve into the pulmonary trunk and out the pulmonary arteries. We are on our way back to the lungs now. It gets a little small again as we pump through the pulmonary arterioles and into the capillaries. Here we have our last gas exchange with the capillaries. Our carbon dioxide is now red blood cell free and on its way out of the body! In the alveoli, we have to push through the bronchiole tree again. First we float through the terminal bronchioles, then the tertiary bronchiole, through the secondary bronchi, and finally past the primary bronchi. We move through the