HUMAN HEART

HEART

Heat is a muscular organ that pumps blood throughouthe circulatory system.It is situated in between two lungs in the mediastinum. It is made up of four chambers, two atria and two ventricles.

RIGHT SIDE OF THE HEART

Right side of the heart has two chambers, right Atrium and right ventricle. Right atrium is a thin walled and low pressure chamber. It has got the pacemaker known as sinoatrial node that produces cardiac impulses

and atrioventricular node that conducts the impulses to the
ventricles. Right atrium receives venous (deoxygenated) blood via two large veins

1. Superior vena cava that returns venous blood from the head, neck and upper limbs

2. inferior vena cava that returns venous blood from lower parts of the body . Right atrium communicates with right ventricle through tricuspid valve. Wall of right ventricle is thick Venous blood from the right atrium enters the right ventricle through this valve.From the right ventricle, pulmonary artery arises. It carries the venous blood from right ventricle to lungs. In the lungs, the deoxygenated blood is oxygenated

LEFT SIDE OF THE HEART

Left side of the heart has two chambers, left atrium and left ventricle. Left atrium is a thin walled and low pressure chamber. It receives oxygenated blood from the lungs through pulmonary veins. This is the only exception in the body, where an artery carries venous blood and vein carries the arterial blood
Blood from left atrium enters the left ventricle through mitral valve (bicuspid valve). Wall of the left ventricle is very thick. Left ventricle pumps the arterial blood to different parts of the body through systemic aorta.

 SEPTA OF THE HEART

Right and left atria are separated from one another
by a fibrous septum called interatrial septum. Right and left ventricles are separated fro interventricular septum. The upper part of it is a membranous structure, whereas the lower parto is muscular in nature.

LAYERS OF WALL OF THE HEART

Heart is made up of three layers of tissues

1.Outer pericardium
2. Middle myocardium
3. Inner endocardium

VALVES OF THE HEART

there are four valves in human heart. Two valves are in between atria and the ventricles called atrioventricular valves. Other two are the semilunar valves, placed at he opening of blood vessels arising from ventricles, namely systemic aorta and pulmonary artery. Valves of the heart permit the flow of blood through heart in only one direction

Atrioventricular Valves

Left atrioventricular valve is otherwise known as mitral valve or bicuspid valve. It is formed by two valvular cusps or flaps (Fig. 89.3). Right atrioventricular valve is known as tricuspid valve and it is formed by three cusps Brim of the atrioventricular valves is attached to atrioventricular ring, which is the fibrous connection between the atria and ventricles. Cusps of the valves are attached to papillary muscles by means of chordae
tendineae. Papillary muscles arise from inner surface of the ventricles. Papillary muscles play an important role in closure of the cusps and in preventing the back flow of blood from ventricle to atria during ventricular contraction. Atrioventricular valves open only towards ventricles and prevent the backflow of blood into atria

Semilunar Valves

Semilunarvalves are present at the openings of systemic aorta and pulmonary artery and are known as aortic valve valve and pulmonary valve respectively. Because of the

ACTIONS OF THE HEART

Actions of the heart are classified into four types

1. Chronotropic action
2. Inotropic action
3. Dromotropic action
4. Bathmotropic action

2. CHRONOTROPIC ACTION

Chronotropic action is the frequency of heartbea heart rate. It is of two types

i.           Tachycardia or increase in heart rate
ii. Bradycardia or decrease in heart rate

ii.         INOTROPIC ACTION

Force of contraction of heart is called inotr
is of two types the positive inotropic action or increase in of contraction
i. P ". Negative inotropic action or decreas
force of contraction

DROMOTOTROPIC ACTION

is the conduction of impulse through heart. It is of two

i.           Positive
omotropic action dromotropic action or increase in the elocity of conduction
 dromotropic action or decrease in the
 
BLOOD VESSELS

Vessels of circulatory system are the aorta, arteries arteñioles, capillaries, venules, veins and venacavae Structural differences between different blood vessel

COMPLICATIONS IN BLOOD VESSELS

Aorta and Arteries

Arterial blood vessels are

highly susceptible for arteriosclerosis and atherosclerosis. Arteriosclerosis is disease of the arteries, associated with hardening, thickening and loss of elasticity in the wall of the vessels. Atherosclerosis is the disease marked by thenarrowing of lumen of arterial vessel due to deposition of cholesterol.

Arterioles

When the tone of the smooth

muscles in the arterioles increases, hypertension occurs

Capillaries

Permeability of the capillary membrane may increase resulting in shock or edema due to leakage of fluid,

proteins and other substances from blood

Vein

Inflammation of the wall of veins leads to the formation of intravascular clot called thrombosis. The clot gets dislodged, as thrombus. The thrombus travels through blood and causes embolism. Embolism obstructs the blood flow to vital organs such as brain, heart and lungs leading to many complications.

DIVISIONS OF CIRCULATION

Blood flows through two divisions of circulatory system:

Systemic circulation

 Pulmonary circulation

SYSTEMIC CIRCULATION

Systemic circulation is otherwise known as greater circulation.

Blood pumped from left ventricle passes through a series of blood vessels, arterial system

 PULMONARY CIRCULATION

Pulmonary circulation is otherwise called lesser circulation. Blood is pumped from right ventricle to lungs through pulmonary artery. Exchange of gases occurs between blood and alveoli of the lungs at pulmonar capillaries. Oxygenated blood returns to left atru through the pulmonary veins Thus, left side of the heart contains oxygenate arterial blood and the right side of the deoxygenated or venous blood

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Milan Tomic

Hi. I’m Designer of Blog Magic. I’m CEO/Founder of ThemeXpose. I’m Creative Art Director, Web Designer, UI/UX Designer, Interaction Designer, Industrial Designer, Web Developer, Business Enthusiast, StartUp Enthusiast, Speaker, Writer and Photographer. Inspired to make things looks better.

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