CARDIOVASCULAR SYSTEM
(HESI/ TEAS/ATI)
Also known as the circulatory system.
Cardiopulmonary system.- Refers to cardiovascular system along with trachea, bronchi
and lungs.
Cardiovascular system is made up of;-
Heart
Blood vessels
Blood
HEART
About size of a fist
Hollow and cone-shaped.
Has a mass of 250-350 grams- less than a pound.
Enclosed within the Mediastinum- the medial cavity of the thorax.
The heart extends obliquely for 12-14 cm (about 5 inches) from the second rib to the 5th
intercostal space- space between two ribs.
It rests on the superior surface of the diaphragm.
It lies anteriorly to the vertebral column and posteriorly to the sternum.
Two thirds of its mass lies to the left of the mid sternal line.
The lungs flunk the heart laterally and partially obscure it.
Its broad, flat base or posterior surface is about 9cm wide and is directed towards the
right shoulder.
Its apex point inferiorly towards the left hip.
Coverings of the heart
The heart is enclosed in a doubled- wall sac called pericardium.
Pericardium.(has 2 walls i. e fibrous pericardium and serous pericardium).
Fibrous pericardium.
Outermost, tough and dense connective tissue layer.
Functions:-
i. Protects the heart.
ii. Anchors it to surrounding structures.
iii. Prevent overfilling of the heart with blood.
Serous pericardium.
Thin and slippery.
Has two layers:-
, i. Parietal layer- outermost layer.
ii. Visceral layer- also called epicardium, which is an integral
part of heart wall.
Between the parietal and visceral layer is a cavity called pericardial
cavity- which contains a film of serous fluid that lubricates the
serous membranes allowing the heart to beat without friction.
Note:
Pericarditis-inflammation of the pericardium roughens the serous membrane surface
which causes the beating heart to rub against its pericardial sac, creating a cracking sound
called pericardial friction rub that can be heard by a stethoscope.
Layers of the heart wall
Compost of 3 layers:-
Epicardium-outermost. As we have noted, it is the visceral layer of the serous
pericardium. It’s often infiltrated with fat, especially in old people.
Myocardium-middle layer. Compost mainly of cardiac muscles and forms bulk
of heart. It’s the layer that contracts.
Endocardium-Innermost layer. Lines the heart chambers and covers the fibrous
skeleton of the valves. It’s continuous with the endothelial linings of the blood
vessels leaving and entering the heart.
Heart chambers
The heart has 4 chambers:-
o 2 superior atria(left and right)
o 2 inferior ventricles(left and right)
Interatrial septum divides the 2 atria.
Intraventricular septum divides the 2 ventricles.
Atria (receiving chambers):-
Receive blood returning to the heart from the circulation.
Blood enters the right atrium via 3 veins:-
i. Superior vena cava-returns blood from body regions
superior to the diaphragm.
ii. Inferior vena cava- returns blood from body regions
below the diaphragm.
iii. Coronary sinus- collects blood draining from the
myocardium.
(HESI/ TEAS/ATI)
Also known as the circulatory system.
Cardiopulmonary system.- Refers to cardiovascular system along with trachea, bronchi
and lungs.
Cardiovascular system is made up of;-
Heart
Blood vessels
Blood
HEART
About size of a fist
Hollow and cone-shaped.
Has a mass of 250-350 grams- less than a pound.
Enclosed within the Mediastinum- the medial cavity of the thorax.
The heart extends obliquely for 12-14 cm (about 5 inches) from the second rib to the 5th
intercostal space- space between two ribs.
It rests on the superior surface of the diaphragm.
It lies anteriorly to the vertebral column and posteriorly to the sternum.
Two thirds of its mass lies to the left of the mid sternal line.
The lungs flunk the heart laterally and partially obscure it.
Its broad, flat base or posterior surface is about 9cm wide and is directed towards the
right shoulder.
Its apex point inferiorly towards the left hip.
Coverings of the heart
The heart is enclosed in a doubled- wall sac called pericardium.
Pericardium.(has 2 walls i. e fibrous pericardium and serous pericardium).
Fibrous pericardium.
Outermost, tough and dense connective tissue layer.
Functions:-
i. Protects the heart.
ii. Anchors it to surrounding structures.
iii. Prevent overfilling of the heart with blood.
Serous pericardium.
Thin and slippery.
Has two layers:-
, i. Parietal layer- outermost layer.
ii. Visceral layer- also called epicardium, which is an integral
part of heart wall.
Between the parietal and visceral layer is a cavity called pericardial
cavity- which contains a film of serous fluid that lubricates the
serous membranes allowing the heart to beat without friction.
Note:
Pericarditis-inflammation of the pericardium roughens the serous membrane surface
which causes the beating heart to rub against its pericardial sac, creating a cracking sound
called pericardial friction rub that can be heard by a stethoscope.
Layers of the heart wall
Compost of 3 layers:-
Epicardium-outermost. As we have noted, it is the visceral layer of the serous
pericardium. It’s often infiltrated with fat, especially in old people.
Myocardium-middle layer. Compost mainly of cardiac muscles and forms bulk
of heart. It’s the layer that contracts.
Endocardium-Innermost layer. Lines the heart chambers and covers the fibrous
skeleton of the valves. It’s continuous with the endothelial linings of the blood
vessels leaving and entering the heart.
Heart chambers
The heart has 4 chambers:-
o 2 superior atria(left and right)
o 2 inferior ventricles(left and right)
Interatrial septum divides the 2 atria.
Intraventricular septum divides the 2 ventricles.
Atria (receiving chambers):-
Receive blood returning to the heart from the circulation.
Blood enters the right atrium via 3 veins:-
i. Superior vena cava-returns blood from body regions
superior to the diaphragm.
ii. Inferior vena cava- returns blood from body regions
below the diaphragm.
iii. Coronary sinus- collects blood draining from the
myocardium.
