Circulatory System

It is the transport system that causes circulation of blood throughout body in a continuous circuit.

Sub Divisions 

There are two main divisions of circulatory system:

1. Systemic Circulation 

It is also called peripheral circulation.

Blood goes from Left Ventricle to Aorta to Arteries to Arterioles to Capillaries to Venules to Veins to Venae cava to Right atrium.

2. Pulmonary Circulation 

Blood goes from Right ventricle to Pulmonary arteries to Pulmonary arterioles to Pulmonary capillaries to Pulmonary venules and veins to Left atrium.



Organization

The cardiovascular system consist of two pumps and two circuits connected in series. When circuits are connected in series, flow must be equal in the two circuits.

Cardiac output is the output of either the left or right ventricle, and because of the series system, they are equal.

Functions Of Circulatory System

1. It supplies oxygen to tissues

2. It return carbon dioxide to lungs 

3. It regulate body temperature.

4. it maintain ionic concentration.

5. It regulate cell function.


Functional Part Of Circulation

1. Arteries

2. Arterioles

3. Capillaries

4. Venules

5. Veins


Arteries 

Arteries are the blood vessels that carry blood away from the heart.

The walls of arteries are strong and elastic.

It transport blood under high pressure in peripheral tissues.

It also serve as a high pressure reservoir to receive pulsatile output of blood from heart.

Arteries stretch as blood enter and they recoil to smaller size as blood flow out of them.

Arteries prevent arterial pressure from rising to high during systole.


Arterioles

Arterioles are smaller branches from arteries.

The walls of arterioles are strong and muscular.

Arterioles act as control valve through which blood is released into capillaries.


Capillaries

Capillaries are smallest blood vessels that connect arterioles and venules.

Capillaries have thin semi permeable membrane like walls.

They allow two way diffusion of gases, fluids, nutrients and hormones between flowing blood and interstitial fluid.


Venules

Venules are blood vessels that connect capillaries with veins.

Venules have thinner walls than arterioles.

They collect blood from capillaries.


Veins

Veins are blood vessels that carry blood toward heart.

Veins have thin muscular wall with valves in their lumen.

Veins transport blood from peripheral tissues back to heart.

Veins can dilate to store blood. Veins also regulate cardiac output.