Circulatory System Circulation of Blood
HUMAN HEART
INTRODUCTION
Heart, the most powerful organ in the circulatory system is conical, hollow & muscular organ, situated in middle mediastinum.
Heart, the most powerful organ in the circulatory system is conical, hollow & muscular organ, situated in middle mediastinum.
POSITION OF HEART
Heart lies in the
thoracic cavity between the lungs slightly towards left, enclosed with in
ribcage with the sternum in front & vertebral column behind.
SIZE & WEIGHT
The heart measures
about 3 ½ Inches & weighs about 300 gm in males & 250 gm in females.
MAIN FUNCTION OF HEART
Heart works
continuously like a muscular pump & pumps the blood to various parts of the
body to meet their nutritive requirements.
COVERING OF HEART PERICARDIUM
Heart is surrounded
by a double layered pericarcdium. The outer layer is called Fibrous pericardium
& inner layer is called as serous pericardium.
PERICARDIAL FLUID
Fluid is secreted
in b/w the two layers of pericardium which is known as pericardial fluid.
FUNCTION
Pericardial fluid acts as LUBRICANT & reduces friction b/w heart walls & surrounding tissues during beating of heart.
Pericardial fluid acts as LUBRICANT & reduces friction b/w heart walls & surrounding tissues during beating of heart.
STRUCTURE OF HEART
Human heart
consists of four chambers.
CHAMBERS OF HEART
1. RIGHT ATRIUM
Right Atrium is the
right upper chamber of heart & acts as thin walled low pressure pump.
OPENINGS (INLETS) OF RIGHT ATRIUM
1. Superior Vena
Cava
2. Anfenior Vena
Cava
3. Coronary Sinus
FUNCTION
It receives venous blood from the whole body & pump it to the right ventricle through the right atrioventricular (tricuspid opening) valve.
It receives venous blood from the whole body & pump it to the right ventricle through the right atrioventricular (tricuspid opening) valve.
2. LEFT ATRIUM
Left atrium is
upper triangular chamber which is present posteriorly. It also acts as low
pressure pump.
OPENINGS (INLETS) OF LEFT ATRIUM
Two pairs of
pulmonary veins.
FUNCTION
It receives oxygenated blood from the lungs through 4 pulmonary veins and pumps it to the left ventricle through the left atrioventricular orifice (mitral or bicuspid).
It receives oxygenated blood from the lungs through 4 pulmonary veins and pumps it to the left ventricle through the left atrioventricular orifice (mitral or bicuspid).
3. RIGHT VENTRICLE
Right ventricle is
the right lower chamber of heart, which is triangular in shape.
OPENINGS OF RIGHT VENTRICLE
§ Tricuspids valve
§ Pulmonary Aorta through pulmonary valve.
THICKNESS OF WALL
§ The wall of right ventricle is thinner than that of left
ventricle in a ratio of 1:3
SIZE OF CAVITY
Cavity of right
ventricle is broader than left because of thin muscular walls, and both of
these features are due to the fact that right ventricle has to pump the blood
into lungs only against low pressure system (i.e. pulmonary circulation).
FUNCTION
Right ventricle receives deoxygenated blood from right Atrium and pumps it to the lungs through pulmonary aorta for oxygenation.
Right ventricle receives deoxygenated blood from right Atrium and pumps it to the lungs through pulmonary aorta for oxygenation.
4. LEFT VENTRICLE
Left ventricle is
the most thick walled chamber and forms the apex of heart.
OPENING OF LEFT VENTRICLE
§ Bicuspid or Mitral valve
§ Systemic Aorta through aortic valve.
THICKNESS OF WALL
The walls of left
ventricle are 3 times thicker than those of right ventricle. Blood pressure is
6 times high.
SIZE OF CAVITY
The cavity of left
ventricle is narrower than the right ventricle because of more muscular walls.
It is due to the fact that left ventricle has to pump the blood to the entire
body against high pressure system (Systemic Circulation).
FUNCTION
It receives oxygenated blood from left atrium & pumps it into the aorta.
It receives oxygenated blood from left atrium & pumps it into the aorta.
INTERNAL STRUCTURE
OF VENTRLES
Interior of
ventricles show two parts
1. Rough in flowing
part
2. Smooth out
flowing part
1. ROUGH PART
TRABECULAE CARNEAE
Inflowing part of
each ventricle is rough due to presence of muscular ridges called as Trabeculae
carneae.
2. SMOOTH PART
Out flowing part of
each ventricle is smooth which gives origin to pulmonary trunk in right
ventricle & Ascending Aorta in left ventricle.
PAPILLARY MUSCLES
Papillary muscles
are the type of Trabeculae carneae being attached by their bases to ventricular
walls, & their apices are connected to, the cusps of valves through chorda
tendinae.
CHORDA TENDINAE:
These are delicate
fibrous chords, which connect the papillary muscles to the cusps of
Atriovertritcular valves.
FUNCTION
Chorda Tendinae don’t left the valves open back into the atria when the ventricles contract.
Chorda Tendinae don’t left the valves open back into the atria when the ventricles contract.
SEPTUM OF HEART
1. INTERATRIAL SEPTUM
Internally, the
right & left atria are separated by a vertical membranous septum called as
Interatrial septum.
2. INTERVENTRICULAR SEPTUM:
The right &
left verticals are also separated by a thick muscular septum called as
Interventricular septum.
3. ATRIOVENTRICULAR SEPTUM
Atria lie above
& behind the ventricles & are separated from ventricles by
Atrioven-tricular septum.
HEART VALVES
Heart possesses two
types of valves, which regulate the flow of blood with in the heart.
TYPES OF HEART VALVES
1. Atrioventricular
valves -> Bicuspid, Tricuspid
2. Semilunar vlaves
-> Aortic valve, Pulmonary valve
1. ATRIOVENTRICULAR VALVES
INTRODUCTION
Valves, which are present in b/w the Atria & ventricles are called Atrioventricular valves.
Valves, which are present in b/w the Atria & ventricles are called Atrioventricular valves.
TYPES OF ATRIOVENTRICULAR VALVES
They are of two
types.
1. Bicuspid or
Mitral
2. Tricuspid.
1. BICUSPID OR MITRAL VALVE
Blood flows from
left Atrium to the left ventricle through left atrioventricular on orifice,
which is guarded by bicuspid or Mitral valves.
CUSPS
It has tow (2) cusps so it is called as bicuspid.
It has tow (2) cusps so it is called as bicuspid.
2.TRICUSPID VALVE
Blood flows from
right Atrium to the Right ventricle through right Atrioventricular orifice,
which is guarded by Tricuspid.
CUSPS
It has 3 cusps so it is called as TRICUSPID.
It has 3 cusps so it is called as TRICUSPID.
2. SEMILUNAR VALVES
This is the second
category of heart valves, which guard the emergence of pulmonary & systemic
Aorta.
TYPES OF SEMILUNAR VALVES
It has Two Types:
1. Aortic Valve
2. Pulmonary Valve
1. AORTIC VALVE
This valve guards
the Aortic orifice in left ventricle
CUSPS
It consists of 3 Semilunar cusps.
It consists of 3 Semilunar cusps.
2. PULMONARY VALVE
This valve guards
the pulmonary orifice in right ventricle.
CUSPS
It also consists of 3 semi lunar cusps.
It also consists of 3 semi lunar cusps.
FUNCTIONS OF VALVES
Heart valves
maintain unidirectional flow of the blood & prevents its regurgitation in
the opposite direction.
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