In this class we’ll develop an anatomic-physiological description of the cardiovascular system. We will be interested in describing the cardiac cycle and the heart’s mechanical activity. Besides we will also introduce the concept of arterial pressure and related pathologies.
Heart Generalities
The heart possesses four compartments: 2 auricles (left and right) and 2 ventricles. At the center exists a structure of great importance, the septum which divides the heart in two compartments, the right or venous and the left or arterial heart.
The right auricle receives venous blood from the Superior Cave Vein and the Inferior Vein Cave.
The left auricle receives 4 vessels from the lung veins, and these carry blood of the arterial type with a large oxygen saturation level.
The left ventricle expels blood towards the aorta while the right ventricle will do the same towards the lung artery.
The lung artery transports venous blood , or with a low oxygen saturation level, which means that is more correct to describe them as discarded elements than as Carbon Dioxide. This is a remark necessary so we may reach a conceptual look. When we talk about venous blood we prefer to describe it as blood with low oxygen saturation since Carbon Dioxide in reality exists in every structure just as the discarded elements are.
If we are to analyze this with a “large circulation” and “small circulation” criterion, the Superior and Inferior Cave Veins and the Aorta belong to the “large” one whereas the lung artery and the lung veins belong to the “small” or lung circulation.
Mainly, or using general concepts the Superior Vein Cave drains blood from the body’s superior half whereas the Inferior one will do the same with the inferior half.
The Aorta will be a great exit out of the heart towards the rest of the body, a great way of blood distribution towards the whole system.
Its diameter, thus, is very considerable and deals with very high pressures. In that sense it is important to remark a first difference between large and small circulation: the pressure difference. The left heart will expel blood through the aorta with a pressure which allows it to reach the toes while through the lung artery it will have to get out to reach the alveolus, to the lung. Pressure differences, in consequence, will be great between the lung artery and the aorta.
I will now offer to you some data about pressure differences. These are quite useful and some of them are very necessary to our knowledge. They are measured in mmHg which is a pressure unity.
Right Auricle 4.5
Left Auricle 8.0
Right Ventricle 4.5 a 10
Left Ventricle 9.5 a 125
Lung Artery 10 a 25
Aorta 80 a 120
It is undoubted that the left heart requires a higher pressure and this is because it needs to propel blood into a larger surface thus requiring handling higher pressures.
Blood Circulation in the Heart. The lung vein will receive oxygenated blood from the heart. The lung veins end in the left auricle. They pass to the left auricle through a valve, the mitral valve which corresponds to the right side tricuspid valve. Both are auricle-ventricle valves. The tricuspid separates right auricle from right ventricle and the mitral valve the left ones. We then find the Lung Artery (to the right) and the Aorta (to the left). Between both ventricles and these two great vessels we can find sigmoid valves named according to those vessels (lung valve and aortic valve). If we follow the path: blood arrives from the periphery.
If it arrives from the inferior part of the body (inferior members, for example) it arrives through the Inferior Cave Vein, and if it comes from the superior parts (let us say head, superior members, thorax) it makes it through the Superior one. It enters through the right auricle, passes through the tricuspid valve and it enters the right ventricle. It passes through the sigmoid valves that at this level are denominated lung valves. It rises through the lung artery trunk and later on it divides itself into right and left lung artery which will end in the lung. These arteries will go to the lung, will oxygen themselves at the lung level and will return as lung veins. The lung veins will drain in the Left Auricle. They are 4 of them. Their names are right superior, left superior, right inferior and left inferior since they are disposed square-wise that way. The important thing is that now arterial blood enters the Left Auricle from the lung vein. This arterial blood goes through the mitral valve (auricle-ventricle) and will finally enter the Left Ventricle.
From the Left Ventricle passes through the aortic valves towards the Aorta describing a large curve named as aortic key. The aortic key will finally form the aorta and this formation will repeat in the whole body. The first aortic ramifications: those organs which receive blood from these ramifications will be organs receiving more oxygenated blood since this has just left the heart. They are the brain and the heart itself. This means that Anatomy is organized in such a way that takes care of those organs which might be sensible to any possible oxygen diminution thus giving them blood which recently left the heart and which possesses major oxygen saturation. The brain, therefore, also forms part of the coronary vascular process. Being aware of this system, which are the names of the valves and what type of vessel comes out of each side of the heart we are now ready to continue with other topics.
The right auricle receives venous blood from the Superior Cave Vein and the Inferior Vein Cave.
If it arrives from the inferior part of the body (inferior members, for example) it arrives through the Inferior Cave Vein, and if it comes from the superior parts (let us say head, superior members, thorax) it makes it through the Superior one. It enters through the right auricle, passes through the tricuspid valve and it enters the right ventricle. It passes through the sigmoid valves that at this level are denominated lung valves. It rises through the lung artery trunk and later on it divides itself into right and left lung artery which will end in the lung. These arteries will go to the lung, will oxygen themselves at the lung level and will return as lung veins. The lung veins will drain in the Left Auricle. They are 4 of them. Their names are right superior, left superior, right inferior and left inferior since they are disposed square-wise that way. The important thing is that now arterial blood enters the Left Auricle from the lung vein. This arterial blood goes through the mitral valve (auricle-ventricle) and will finally enter the Left Ventricle. 
