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INDEX

1. Quick Facts 2. The Location, Size and Shape of the Heart 3. Functions and Circulation of the Human Heart 3.1. Functions of the Human Heart 3.2. Types of Circulation 4. Structure of the Human Heart 4.1. Pericardium 4.2. Structure of the Heart Wall 4.3. Chambers of the Heart 4.4. Blood Vessels 4.5. Valves 5. Intersting Facts about Human Heart 6. Human Heart in Leonardo's Drawings

INDEX

The heart is a four-chambered double pump that is the centre of the circulatory system.In humans it is situated between the two lungs and slightly to the left of centre, behind the breastbone; it rests on the diaphragm, the muscular partition between the chest and the abdominal cavity.

General facts

1. Quick Facts

The heart consists of several layers of a tough muscular wall, the myocardium. A thin layer of tissue, the pericardium, covers the outside, and another layer, the endocardium, lines the inside.

Location

The heart is located underneath sternum in a thoracic compartment called mediastinum, which occupies the space between the lungs.

Size

The human heart is approximately the size of a man’s fist (230-350 grams).The average size of the human heart: 14 cm long and 9 cm wide.

Shape

The heart is shaped like an inverted cone. About two thirds of the heart’s mass is located to the left of the body’s midline.The narrow end of the heart (called apex), is directed downward to the left andis located at the approximate level of the fifth or sixth rib, just above the arch of diaphragm.The broad end of the heart (called base)is directed upward and to the right and lies at the approximate level of the second rib.

2. The Location, Size, and Shape of the Heart

3.1. Functions of the Human Heart

Because of this task, the heart may be considered one of the most important organs of the body, such that even small dysfunctions or abnormalities may cause drastic changes or effects in the human organism. The heart is a muscle whose working mechanism is made possible by the many parts that operate together. The organ is divided into several chambers that take in and distribute oxygen-poor or oxygen-rich blood. These chambers are accompanied by veins and arteries that facilitate the same function. With all of its parts working together towards the same goal, the heart successfully pumps blood with ease.

The human heart is an organ that pumps blood throughout the body via the circulatory system, supplying oxygen and nutrients to the tissues and removing carbon dioxide and other wastes.

The pericardium is a tough double layered fibroserous sac which covers the heart.The space between the two layers of serous pericardium , the pericardial cavity, is filled with serous fluid which protects the heart from any kind of external jerk or shock.

4.1.Pericardium

The pericardium is a double-walled sac containing the heart and the roots of the great vessels. The pericardial sac has two layers, a serous layer and a fibrous layer. It encloses the pericardial cavity which contains pericardial fluid.

function:-Sets heart in mediastinum and limits its motion-Protects it from infections coming from other organs (such as lungs) -Prevents excessive dilation of the heart in cases of acute volume overload -Lubricates the heart Clinical significanceere

Epicardium

The epicardium covers the outer surface of the heart. It is also referred to as the visceral pericardium, which is the inner layer of the pericardium. The epicardium is a serous membrane that consists of an external layer of simple squamous and an inner layer of areolar tissue. The squamous cells secrete lubricating fluids into the pericardial cavity.

Myocardium

The myocardium is the thick middle layer of the heart wall. It consists of numerous layers of cardiac muscles fibers that wrap around the heart wall. Contraction of the myocardium pumps blood out of the heart into the aorta and pulmonary trunk arteries.

Endocardium

The endocardium is the innermost layer of tissue that lines the chambers of the heart.The endocardium underlies the much more voluminous myocardium, the muscular tissue responsible for the contraction of the heart.

4.2. The Structure of the Heart Wall

4.3 Chambers of the Heart

The heart has four chambers: two atria and two ventricles.

The atria open into the ventricles via the atrioventricular valves, present in the atrioventricular septum. This distinction is visible also on the surface of the heart as the coronary sulcus.There is an ear-shaped structure in the upper right atrium called the right atrial appendage, or auricle, and another in the upper left atrium, the left atrial appendage. The interatrial septum separates the atria and the interventricular septum separates the ventricles, visible on the surface of the heart.

The right atrium receives blood from the veins and pumps it to the right ventricle. The right ventricle receives blood from the right atrium and pumps it to the lungs, where it is loaded with oxygen. The left atrium receives oxygenated blood from the lungs and pumps it to the left ventricle. The left ventricle (the strongest chamber) pumps oxygen-rich blood to the rest of the body. The left ventricle’s vigorous contractions create our blood pressure.

4.4 Blood Vessels

The blood vessels are the components of the circulatory system that transports blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away from the tissues.Blood vessels are needed to sustain life, because all of the body's tissues rely on their functionality.There are five types of blood vessels: the arteries, which carry the blood away from the heart; the arterioles; the capillaries, where the exchange of water and chemicals between the blood and the tissues occurs; the venules; and the veins, which carry blood from the capillaries back toward the heart.The size of blood vessels is different for each of them. It ranges from a diameter of about 25 millimeters for the aorta to only 8 micrometers in the capillaries. This comes out to about a 3000-fold range.Blood vessels function to transport blood. In general, arteries and arterioles transport oxygenated blood from the lungs to the body and its organs, and veins and venules transport deoxygenated blood from the body to the lungs. In addition to carrying oxygen, blood also carries hormones, waste products and nutrients for cells of the body.Blood vessels play a huge role in virtually every medical condition. Cancer, for example, cannot progress unless the tumor causes angiogenesis to supply the malignant cells' metabolic demand. Atherosclerosis, the formation of lipid lumps in the blood vessel wall, is the most common cardiovascular disease, the main cause of death in the Western world.

A heart valve normally allows blood to flow in only one direction trough the heart.The four valves are commonly represented in a mammalian heart that determines the pathway of blood flow trough the heart. A heart valve opens or closes incumbent on differential blood pressure on each side.The four valves in the mammalian heart are:- The two atrioventricular (AV) valves,the mitral valve (bicuspid valve), and the tricuspid valve, which are between the upper chambers (atria) and the lower chambers (ventricles).- The two semilunar (SL) valves, the aortic valve and the pulmonary valve, which are in the arteries leaving the heart.The mitral valve and the aortic valve are in the left heart; the tricuspid valve and the pulmonary valve are in the right heart.The heart also has a coronary sinus valve , and a inferior vena cava valve, not discussed.

4.5. Valves

5. Intersting Facts about Human Heart

Every day, your heart beats about 100,000 times, sending 7,000 pints of blood surging through your body.An average adult heart beats 72 times in a minute.Your heart is located in your chest and is well protected by your rib cage.The heart is made up of four chambers, the left atrium, right atrium, left ventricle and right ventricle.Heart attacks cause scar tissue to form amongst normal heart tissue, this can lead to further heart problems or even heart failure.Every day, the heart creates enough energy to drive a truck 20 miles. In a lifetime, that is equivalent to driving to the moon and back.The fetal heart rate is approximately twice as fast as an adult’s, at about 150 beats per minute. By the time a fetus is 12 weeks old, its heart pumps an amazing 60 pints of blood a day.

6. Human Heart in Leonardo's drawings

laoreet

Ştefania Apostolescu

Julia Jurkiewicz

Roxana Ene

Raisa Cătuneanu

Task 1.2 Group 3

Weronika Zalewska

Iasmina Iancu

Viola Pierini

Miron Antonia

Maria Dragomir

Alexia Stan