Brief Summary: The Anatomy Of The Human Body

The heart is a muscular organ that pumps blood throughout the body. The human heart is con shaped and has the size of a closed fist. In accordance to that, a bigger person has a bigger fist and therefore a bigger heart. Moreover, it is the only involuntary striated muscle that is consisting of four chambers: two upper chambers “atria” and two lower one “ventricles”, where the right side of the heart is separated from the left side by an inter-ventricular septum, and they are connected by pulmonary arteries and pulmonary veins.

Although the human heart is the first organ that starts development, it takes several stages to be formed (figure1):

• First stage: Formation of the primitive heart tube: That is done after the fusion of endocardial

• The apex (inferior tip of the heart) sits on top of the diaphragm (the muscle that helps in breathing).

1.1 Anatomy of the Heart

1.1.1 Serous Pericardium

It is composed of two layers (figure 3):

• The outer layer called the Parietal layer and it stuck tightly to another layer called Fibrous Pericardium which is made of tough dense connective tissue that holds the heart in his place and prevents from over filling of blood.

• The inner layer called the visceral layer and it stuck directly to the heart itself, forming the pericardium (the outer layer of the heart).

The cells of the serous pericardium secrete a protein rich-fluid that fills the space between the parietal and visceral layers. The cell’s secretion help on lubricating the heart, preventing heart friction with its surrounding organs during contractions, holding the heart inside the chest and maintaining a hollow space for the heart to expand into when it is full of blood.

1.1.2 Structure of the heart wall

The heart wall is composed of 3 layers (figure 3):

• Epicardium: As mentioned before, the epicardium is at the same time the outermost layer of the heart wall and the inner wall of the pericardium (visceral layer). It protects and lubricates the

• Systole is when the cardiac muscle contracts to push out the blood from the chamber they are in it. During ventricular systole the blood pressure increases in arteries.

• Diastole is when the cardiac muscle is relaxed allowing allow the chamber to fill with blood. During ventricular diastole the blood pressure decreases in arteries.

This leads to conclude that the higher blood pressure is the systolic pressure (for example 120 mmHg), and the lower blood pressure is the diastolic pressure (for example 80 mmHg).

1.2.2 The Cardiac