Cardiovascular/ Cieculatory System

Kardia ( latin word ) means Heart & Vasculum ( latin word ) means Vessele. So Cardiovascular system consists of Heart & Blood Vessele. So Cardiovascular system consists of Heart & Blood vessels. Cardiovascular system also known as Blood Circulatory System (as it circulates blood in the body).

Definition: The circulatory system is an organ system that moves nutrients, gases & wastes to & from cells, helps fight diseases & helps stabilize body temperature & pG to maintain homeostasis (equilibrium).

Organs of Cardiovascular system:
1, Heart
2, Blood vessels
3, Blood

Heart: It is a central pumping station which circulates blood to/from body by contraction & dilation. Heart receives blood by coronary blood vessel.

Blood Vessels: A tube carrying blood away from or toward the heart. Blood vessels are the means by which blood circulates throughout the body. Blood vessels are of two types – Artery & vein.

Artery: Carry blood (oxygenated blood) away from the heart except pulmonary artery. Pulmonary artery carries deoxygenated blood from heart to lung. Artery divides into small branches – arterioles, leading into many smaller vessels – capillaries.

Vein: Conveying blood (deoxygenated blood) toward the heart except pulmonary vein. Pulmonary vein carries oxygenated blood from lung to heart. Vein divides into small branches – venule, leading into many smaller vessels – capillaries.

Capillary: an extremely narrow blood vessel. Capillaries form networks in most tissues; they are supplied with blood by arterioles & drained by cenules. The vessel wall is only one cell thick, which enables exchange of oxygen, carbon dioxide, water, salts, etc. between the blood & the tissues.

In capillary blood supply O2 to the tissue & receive CO2 from the tissue. This blood is known as deoxygenated blood. This deoxygenated blood goes to the heart through vein & then to lung through pulmonary artery. In lung this blood (deoxygenated blood) expelled out CO2 & receive O2 (become oxygenated). This oxygenated blood goes to heart through pulmonary vein. Then this blood ( oxygenated blood) become circulates to the body through artery. In this way exchange of gases (oxygen & carbon dioxide) by the blood takes place in capillary.

Blood: Blood is a liquid connective tissue consists of blood plasma & blood cells.

Blood plasma (55%) consist of –

Water (90%), Mineral salt, Plasma protein, Food stuff, Gases in solution, Waste Products, Antibodies & antitoxins, Hormones from ductless glands, Enzymes, etc.

Blood cells (45%) consists of-
1, Red Blood Cell (RBC)
2, White Blood Cell (WBC)
3, Platelets

Red Blood Cell (RBC) – also known as erythrocyte containing the pigment “hemoglobin”, The principal function of which is the transport of oxygen ( as oxyhemoglobin). Oxyhemoglobin is a bright red substance formed after combines reversibly with oxygen. RBC is produced in red bone marrow of spongy bone.

White Blood Cell (WBC) – also known as leukocyte produced in red bone marrow of lymph node & spleen. It involved in protecting the body against foreign substances & in antibody production. Thus it plays an important role in body immune system.

Platelets – also known as thrombocyte plays an important role in blood coagulation.

Functions of blood:
1, It transport gases (O2 & C2), nutrients, hormones, enzymes, vitamins, etc.
2. Regulates body temperature, blood pressure, water & electrolytes balance.
3, Prevent hemorrhage (bleeding).

Blood Pressured:
It is the lateral pressure exerted by the blood to the vessel wall while flowing through it Blood

Pressure is of the following types:

1, Systolic blood pressure- maximum pressure during systole (contraction of heart)

Normal range: 100 – 140 mmHg

2, Diastolic blood pressure- minimum pressure during diastole (dilation of heart).
Normal range: 60 – 90 mmHg

Types of Circulatory system:
There are mainly three types of circulation occurs in human body & these are:

1, Systemic circulation- is the portion of the cardiovascular system which carries oxygenated blood away from the heart, to the body, & returns deoxygenated blood back to the heart.

2. Pulmonary circulation- is the portion of the cardiovascular system which carries oxygen- depleted blood away from the heart, to the lungs, & returns oxygenated blood back to the heart.

3, Coronary circulation- It provides a blood supply to the heart.


Blood flow in the body:

In capillary level blood receive CO2 from the tissue. This blood is called deoxygenated blood This deoxygenated blood drain to Heart (Right Atrium) through Capillary, Venule & vein. From Right Atrium blood goes to Right Ventricle of the Heart. Then this deoxygenated blood goes to Lung from Right Ventricle through pulmonary artery. In Lung this blood (deoxygenated blood) expelled out CO2 & receive O2 (become oxygenated) This oxygenated blood goes to Heart (Left Atrium) through pulmonary vein. From Left Atrium blood goes to Left Ventricle. Then this blood (oxygenated blood) become circulates to the tissues of the body from Left Ventricle of the Heart through Artery, Arteriole & Capillary. This oxygenated blood becomes deoxygenated after using by the tissues of the body. Again this deoxygenated blood goes to Lung for oxygenation & circulates in the body by the above way.

Common Diseases:

1, Hypercholesterolemia (hyperlipidaemia) – Raised cholesterol above normal limit in blood

1, Hypertension – Raised & sustained BP above normal limit is called hypertension.

3, Myocardial Infarction: Necrosis of heart muscle due to short supply of blood.

4, Ischemic Heart disease: Deficiency of blood supply in the heart.

5, Angina: Severe heart pain due to ischemia (inadequate blood flow to the heart).

 

Atherosclerosis:

Fatty deposits, celled plaque, may accumulate on the interior surface of the coronary arteries. This is particularly common in people who have high levels of cholesterol in their blood. Plaque deposits reduce the bore of the coronary arteries and thus the amount of blood they can carry.

So limit the blood supply to the heart that during times of stress the heart muscle is so deprived of oxygen that the pain of angina is created.

Trigger the formation of a clot causing a coronary thrombosis. this stops the flow of blood through the vessel and the capillary network it supplies causing a heart attack. The portion of the heart muscle deprived of oxygen dies quickly of oxygen starvation. If the area is not too large, the undamaged part of the heart can, in time, compensate for the damage.

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