Anatomy and Physiology of Heart
2
Anatomy of heart In the human body, the heart is normally situated to the left of the middle of the thorax, underneath the breastbone. The heart is usually felt to be on the left side because the left heart (l eft ventricle) is stronger (it pumps to all body parts). The left lung is smaller than the right lung because the heart occupies more of the left hemithorax. Structure of heart The heart is a pear shaped, muscular organ in vertebrates, responsible for pumping blood through the blood vessels by repeated, rhythmic contractions The heart is composed of cardiac muscle, an involuntary muscle tissue which is found on ly within this organ. The heart is enclosed by a sac known as the pericardium and is surrounded by the lungs. The pericardium is a double membrane structure which encloses a cavity called pericardial cavity . In this cavity lymph like fluid called pericardial fluid is present. The mediastinum, a subdivision of the thoracic cavity, is the name of the heart cavity. The pericardium prevents the over extension of heart size due to blood pressure. It provides heart the moist environment. In normal adults, the mass of the heart is 250-350 g (9-12 oz), or abo ut three fourths the size of a clenched fist, but extremely diseased hearts can be up to 1000 g (2 lb) in mass due to h ypertrophy . It consists of four chambers, the two upper atria (singular: atrium ) and the two lower ventricles .On both sides, the lower ventricles are thicker and stronger than the upper atria. The muscle wall surrounding the left ventricle is thicker than the wall surrounding the right ventricle due to the higher force needed to pump the blood through the systemic circulation. The two auricles are completely separated from each other by inter-auricular septum. The two ventricles are separated by inter-ventricular septum. Since the left ventricle has the harder job of pumping blood to the entire body, its walls are thicker than those of right ventricle, which pumps blood to the lungs which are relatively at the shorter distance. The right atrium opens into the right ventricle by an opening called right auriculo-ventricular aperture. This aperture is guarded by a valve called tricuspid valve. The left atrium opens into left ventricle by the left auriculo ventricular aperture guarded by a valve called bicuspid valve (also called Mitral valve) . These valves are held in position by thread-like structures in the ventricles known as chordae tendeneae. The chordae tendeneae at one end are attached with valve at other to the wall of ventricles by special papillary muscles. The right ventricle opens int o the pulmonary artery by the pulmonary semi lunar valve. The left ventricle opens into the aorta by the aortic semi lunar valve. The valves maintain the flow of blood in one direction. Circulation of blood in heart The function of the right side of the heart (see right heart) is to collect deoxygenated blood, in the right atrium, from the body and pu mp it, via the right ventricle, into the lungs (pulmonary circulation) so that carbon dioxide can be dropped off and oxygen picked up (gas exchange). This happens through a passive process called diffusion. The left side (see left heart) collects oxygenated blood from the lungs into the left atrium. From the left atrium the blood moves to the left ventricle which pumps it out to the body.
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Transcript of Anatomy and Physiology of Heart
7/30/2019 Anatomy and Physiology of Heart
http://slidepdf.com/reader/full/anatomy-and-physiology-of-heart 1/2
Anatomy of heart
In the human body, the heart is normally situated to the left of the middle of the thorax, underneath the breastbone. The heart is usually felt to be on the left side because the left heart (left ventricle) is
stronger (it pumps to all body parts). The left lung is smaller than the right lung because the heart
occupies more of the left hemithorax.
Structure of heart
The heart is a pear shaped, muscular organ in vertebrates, responsible for pumping blood through the
blood vessels by repeated, rhythmic contractionsThe heart is composed of cardiac muscle, an involuntary muscle tissue which is found only within this
organ.
The heart is enclosed by a sac known as the pericardium and is surrounded by the lungs. The
pericardium is a double membrane structure which encloses a cavity called pericardial cavity. In thiscavity lymph like fluid called pericardial fluid is present. The mediastinum, a subdivision of the
thoracic cavity, is the name of the heart cavity. The pericardium prevents the over extension of heartsize due to blood pressure. It provides heart the moist environment.In normal adults, the mass of the heart is 250-350 g (9-12 oz), or about three fourths the size of a
clenched fist, but extremely diseased hearts can be up to 1000 g (2 lb) in mass due to hypertrophy.
It consists of four chambers, the two upper atria (singular: atrium ) and the two lower ventricles.On
both sides, the lower ventricles are thicker and stronger than the upper atria. The muscle wallsurrounding the left ventricle is thicker than the wall surrounding the right ventricle due to the higher
force needed to pump the blood through the systemic circulation.
The two auricles are completely separated from each other by inter-auricular septum.
The two ventricles are separated by inter-ventricular septum. Since the left ventricle has the harder job
of pumping blood to the entire body, its walls are thicker than those of right ventricle, which pumps blood to the lungs which are relatively at the shorter distance.
The right atrium opens into the right ventricle by an opening called right auriculo-ventricular aperture.
This aperture is guarded by a valve called tricuspid valve. The left atrium opens into left ventricle by
the left auriculo ventricular aperture guarded by a valve called bicuspid valve (also called Mitralvalve) . These valves are held in position by thread-like structures in the ventricles known as chordae
tendeneae. The chordae tendeneae at one end are attached with valve at other to the wall of ventricles
by special papillary muscles.
The right ventricle opens into the pulmonary artery by the pulmonary semi lunar valve. The leftventricle opens into the aorta by the aortic semi lunar valve. The valves maintain the flow of blood in
one direction.
Circulation of blood in heart
The function of the right side of the heart (see right heart) is to collect deoxygenated blood, in the right
atrium, from the body and pump it, via the right ventricle, into the lungs (pulmonary circulation) so that
carbon dioxide can be dropped off and oxygen picked up (gas exchange). This happens through a passive process called diffusion. The left side (see left heart) collects oxygenated blood from the lungs
into the left atrium. From the left atrium the blood moves to the left ventricle which pumps it out to the
body.
7/30/2019 Anatomy and Physiology of Heart
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uThe right auricle collects the deoxygenated through the vena cava from the body.
uThen this blood travels through the tricuspid valve to the right ventricle.
uDeoxygenated blood flows through the pulmonary semilunar valve to the pulmonary
artery.
u
Then it moves to the lungs. Here the iron atoms of erythrocytes (red blood cells)hemoglobin carry the oxygen from lungs by the process of diffusion. So the blood
becomes oxygenated.
uThe oxygenated blood travels through the pulmonary vein to the left aurical.
uThen it moves to the left ventricle through the bicuspid valve (Mitral).
uIt travels through the Aortic semilunar valve to the aorta.
1. Right Atrium2. Left Atrium
3. Superior Vena Cava
4. Aorta
5. Pulmonary Artery6. Pulmonary Vein
7. Bicupsid ('Mitral') Valve
8. Aortic Semilunar Valve
9. Left Ventricle10. Right Ventricle
11. Inferior Vena Cava12. Tricuspid Valve
13. Pulmonary Semilunar Valve
