CARDIOVASCULAR SYSYTEM
- Consists of heart and blood vessels
- Heart is enclosed in the pericardium and is situated in the thoracic cavity in the middle
mediastinum between the lungs.
Pericardium -
Pericardium covers the heart.It has 2 layers-
- outer fibrous pericardium and
- inner serous pericardium which has 2 layers.
- inner visceral layer which is in contact with the surface of heart and
- outer parietal layer that lines the inner surface of fibrous pericardium.
The narrow space between the 2 layers of serous pericardium has minimum amount of
pericardial fluid in it which facilitates slight movements of heart.
HEART-
Hollow muscular organ which is roughly conical in shape.
Has 4 chambers- right atrium, left atrium, right ventricle and left ventricle.
The wall of each chamber consist of 3 layers.
1. Outer layer of Epicardium formed from the visceral layer of serous pericardium.
2. Middle layer of Myocardium made of cardiac muscle
3. Inner layer of Endocardium which is the epithelium lining the interior of heart.
External surface features of heart- Has a
- Base
- Apex and
- 3 surfaces - Sternocostal , Diaphragmatic and Left surface
- 4 borders - right ,left ,superior and inferior borders
, - The base of heart is located posteriorly and is formed mainly by the Left atrium
- Apex of the heart is formed by the left ventricle .It is located posterior to the 5th left
intercostal space in adults about 10 cms from midline.It is the point of maximum pulsation.
- Sternocostal surface/anterior surface- mainly formed by the right ventricle.
- Diaphragmatic surface/ inferior surface- formed by both the ventricles, mainly by left.
Related to the central tendon of diaphragm.
- Left surface- formed by the left ventricle.
Right border of heart is formed by the right atrium, left border by the left ventricle and
lower border is mainly by right ventricle. On the surface of heart, a groove separates atria
and ventricles called atrio ventricular sulcus or coronary sulcus.A small appendage is seen
on the upper part of right and left atrium called the right and left auricles.
COURSE OF BLOOD THROUGH THE HEART-
SYSTEMIC CIRCULATION -
Oxygenated blood from the heart is pumped by the left ventricle into the aorta from which it
is distributed to different parts of the body through arteries. Arteries branch to form
arterioles and capillaries .Capillaries exchange blood with tissue and drain the received
blood to venues which join to form veins.Finally through the superior and inferior venacava
deoxygenated blood is returned to the right atrium of heart. This circulation is called
systemic circulation.
PULMONARY CIRCULATION-
From right atrium the deoxygenated blood, flows to the right ventricle through right
atrioventricular orifice (guarded by Tricuspid valve ). From there blood is pumped to
pulmonary trunk and its branches. Blood is then oxygenated in the lungs and returned to left
atrium through 4 large pulmonary veins. Through left atrio ventricular orifice guarded by
bicuspid valve , blood reaches left ventricle from where it is pumped to different parts of the
body.
- Consists of heart and blood vessels
- Heart is enclosed in the pericardium and is situated in the thoracic cavity in the middle
mediastinum between the lungs.
Pericardium -
Pericardium covers the heart.It has 2 layers-
- outer fibrous pericardium and
- inner serous pericardium which has 2 layers.
- inner visceral layer which is in contact with the surface of heart and
- outer parietal layer that lines the inner surface of fibrous pericardium.
The narrow space between the 2 layers of serous pericardium has minimum amount of
pericardial fluid in it which facilitates slight movements of heart.
HEART-
Hollow muscular organ which is roughly conical in shape.
Has 4 chambers- right atrium, left atrium, right ventricle and left ventricle.
The wall of each chamber consist of 3 layers.
1. Outer layer of Epicardium formed from the visceral layer of serous pericardium.
2. Middle layer of Myocardium made of cardiac muscle
3. Inner layer of Endocardium which is the epithelium lining the interior of heart.
External surface features of heart- Has a
- Base
- Apex and
- 3 surfaces - Sternocostal , Diaphragmatic and Left surface
- 4 borders - right ,left ,superior and inferior borders
, - The base of heart is located posteriorly and is formed mainly by the Left atrium
- Apex of the heart is formed by the left ventricle .It is located posterior to the 5th left
intercostal space in adults about 10 cms from midline.It is the point of maximum pulsation.
- Sternocostal surface/anterior surface- mainly formed by the right ventricle.
- Diaphragmatic surface/ inferior surface- formed by both the ventricles, mainly by left.
Related to the central tendon of diaphragm.
- Left surface- formed by the left ventricle.
Right border of heart is formed by the right atrium, left border by the left ventricle and
lower border is mainly by right ventricle. On the surface of heart, a groove separates atria
and ventricles called atrio ventricular sulcus or coronary sulcus.A small appendage is seen
on the upper part of right and left atrium called the right and left auricles.
COURSE OF BLOOD THROUGH THE HEART-
SYSTEMIC CIRCULATION -
Oxygenated blood from the heart is pumped by the left ventricle into the aorta from which it
is distributed to different parts of the body through arteries. Arteries branch to form
arterioles and capillaries .Capillaries exchange blood with tissue and drain the received
blood to venues which join to form veins.Finally through the superior and inferior venacava
deoxygenated blood is returned to the right atrium of heart. This circulation is called
systemic circulation.
PULMONARY CIRCULATION-
From right atrium the deoxygenated blood, flows to the right ventricle through right
atrioventricular orifice (guarded by Tricuspid valve ). From there blood is pumped to
pulmonary trunk and its branches. Blood is then oxygenated in the lungs and returned to left
atrium through 4 large pulmonary veins. Through left atrio ventricular orifice guarded by
bicuspid valve , blood reaches left ventricle from where it is pumped to different parts of the
body.
