Basic Info

The Circulatory System

With every heartbeat, blood is sent throughout our body, distributing oxygen and to all of our cells. Each day, about 2,000 gallons of blood travel many times through almost 60,000 miles of blood vessels! The circulatory system delivers blood to all of the body.

The Systems

There are actually 2 systems inside of the circulatory system. The pulmonary circulation is a short system to the lungs and back, collecting the oxygen, and there is the systemic circulation, which distributes the oxygen through the body.

Blood

Blood keeps us alive. It contains millions of cells that, along with other things, fight infections and transport oxygen. There are 2 main kinds of blood cells. They are:

Red blood cells- Carry oxygen all over the body and remove carbon dioxide waste.

White blood cells- The army! White blood cells “fight” infections, clear away worn-out cells, and attack cells that are cancer causing.

The Heart

The heart it like a pump made out of muscle. Its main purpose is to propel blood to all the body. It has 4 different sections called chambers. On the bottom of the heart there are the left and right ventricles, which pump blood to the body. A muscular wall called the interventrical septum separates the two ventricles. There are also the left and right atriums, which receive blood from the body. Another muscular wall called the interatrial septum divides the two atriums, while the atrioventricular valves separate the ventricles and the atrium. Also, the tricuspid valve separates the right atrium from the right ventricle, and the mitral valve separates the left atrium and ventricle.

There are also two other valves that separate the ventricles and the blood vessels that carry blood leaving the heart. These valves are called the pulmonic valve, which separates the right ventricle from the pulmonary artery that leads to the lungs, and the aortic valve, which separates the left ventricle from the aorta, our body's biggest blood vessel.

The Hearts’ Beats

The heart usually beats from 60 to 100 times per minute, but can go much faster when necessary. It beats about 100,000 times a day, more than 30 million times per year, and about 2.5 billion times in a 70-year lifetime. The heart gets messages from the body that instructs when to pump more or less blood depending on a person's needs. When we're sleeping, the heart pumps barely enough to provide for the lower amounts of oxygen needed by our body at rest. When we're exercising or scared, the heart pumps faster to increase oxygen.

Blood Vessels

There are 3 types of blood vessels: arteries, veins and capillaries. Blood vessels that carry blood away to the lungs and body from the heart are called arteries. Blood vessels that carry the blood cells back to the heart are called veins. Capillaries link the arteries and veins.

Arteries

Some of the main arteries include:

The aorta, the largest artery and blood vessel, takes blood from the left ventricle, then goes down in front of the spinal column into the abdomen.

Two coronary arteries branch off at the beginning of the aorta that provides oxygen to the heart.

The pulmonary artery, carries oxygen-poor blood to the lungs from the right ventricle.

Arteries are the thickest blood vessels, because of their muscular walls that keep the blood moving. Arterial walls have three layers:

1. The endothelium is on the inside and provides a smooth lining for blood to flow over.

2. The media is the middle part of the artery, made up of a layer of muscle and elastic-like tissue.

3. The adventitia is the tough covering that protects the outside of the artery.

As they get farther from the heart, the arteries branch out into arterioles, which are smaller and less elastic.

Veins

Veins are not as muscular as arteries, but, unlike arteries, they do have valves that keep blood from flowing backward. Veins have the same three layers that arteries do, but are thinner and not as flexible. The two biggest veins are the superior and inferior vena cavae. The superior vena cavae takes blood back to the heart from the upper body.

The inferior vena cavae takes blood back from the lower body.

Capillaries

It's through the tiny capillaries that oxygen is delivered to the cells. Also, waste products such as carbon dioxide are also removed by the capillaries.

Through the Circulatory System

Part 1: Systemic Circulation

In the systemic circulation, blood travels out of the left ventricle, to the aorta, to every part of the body, and then back to the right atrium. The arteries, capillaries, and veins all have a part in systemic circulation. Once the aorta divides into plain arteries, blood flows to smaller arterioles and then to capillaries. While in the capillaries, the bloodstream delivers oxygen to the cells and picks up waste materials like carbon dioxide. Blood then goes back through the capillaries into venules, and then to larger veins until it reaches the vena cavae. Both vena cavae deliver this now oxygen- poor blood into the right atrium. Next, the blood exits into the right ventricle, ready to be pumped into the pulmonary circulation for more oxygen, and another trip.

Part 2: Pulmonary Circulation

In the pulmonary circulation, blood low in oxygen but high in carbon dioxide from the systemic circulation is pumped out the right ventricle into the pulmonary artery, which branches off in two directions. The right branch goes to the right lung, and the left branch goes to the left lung. In the lungs, the branches divide and divide into capillaries. Blood flows more slowly through tiny capillaries, allowing time for carbon dioxide to be exchanged with fresh oxygen between the capillary walls and the millions of alveoli, the tiny air sacs in the lungs. Oxygen jumps onto a molecule called hemoglobin in the red blood cells. The new oxygen- fresh blood leaves the lungs through the pulmonary veins and heads back to the left atrium, then fills the left ventricle so it can be pumped into the aorta and systemic circulation.

Source:

http://www.kidshealth.org/parent/general/body_basics/heart.html


	Home	*The Circulatory System* With every heartbeat, blood is sent throughout our body, distributing oxygen and to all of our cells. Each day, about 2,000 gallons of blood travel many times through almost 60,000 miles of blood vessels! The circulatory system delivers blood to all of the body. *The Systems* There are actually 2 systems inside of the circulatory system. The pulmonary circulation is a short system to the lungs and back, collecting the oxygen, and there is the systemic circulation, which distributes the oxygen through the body. *Blood* Blood keeps us alive. It contains millions of cells that, along with other things, fight infections and transport oxygen. There are 2 main kinds of blood cells. They are: Red blood cells- Carry oxygen all over the body and remove carbon dioxide waste. White blood cells- The army! White blood cells “fight” infections, clear away worn-out cells, and attack cells that are cancer causing. *The Heart* The heart it like a pump made out of muscle. Its main purpose is to propel blood to all the body. It has 4 different sections called chambers. On the bottom of the heart there are the left and right ventricles, which pump blood to the body. A muscular wall called the interventrical septum separates the two ventricles. There are also the left and right atriums, which receive blood from the body. Another muscular wall called the interatrial septum divides the two atriums, while the atrioventricular valves separate the ventricles and the atrium. Also, the tricuspid valve separates the right atrium from the right ventricle, and the mitral valve separates the left atrium and ventricle. There are also two other valves that separate the ventricles and the blood vessels that carry blood leaving the heart. These valves are called the pulmonic valve, which separates the right ventricle from the pulmonary artery that leads to the lungs, and the aortic valve, which separates the left ventricle from the aorta, our body's biggest blood vessel. *The Hearts’ Beats* The heart usually beats from 60 to 100 times per minute, but can go much faster when necessary. It beats about 100,000 times a day, more than 30 million times per year, and about 2.5 billion times in a 70-year lifetime. The heart gets messages from the body that instructs when to pump more or less blood depending on a person's needs. When we're sleeping, the heart pumps barely enough to provide for the lower amounts of oxygen needed by our body at rest. When we're exercising or scared, the heart pumps faster to increase oxygen. *Blood Vessels* There are 3 types of blood vessels: arteries, veins and capillaries. Blood vessels that carry blood away to the lungs and body from the heart are called arteries. Blood vessels that carry the blood cells back to the heart are called veins. Capillaries link the arteries and veins. *Arteries* Some of the main arteries include: The aorta, the largest artery and blood vessel, takes blood from the left ventricle, then goes down in front of the spinal column into the abdomen. Two coronary arteries branch off at the beginning of the aorta that provides oxygen to the heart. The pulmonary artery, carries oxygen-poor blood to the lungs from the right ventricle. Arteries are the thickest blood vessels, because of their muscular walls that keep the blood moving. Arterial walls have three layers: 1. The endothelium is on the inside and provides a smooth lining for blood to flow over. 2. The media is the middle part of the artery, made up of a layer of muscle and elastic-like tissue. 3. The adventitia is the tough covering that protects the outside of the artery. As they get farther from the heart, the arteries branch out into arterioles, which are smaller and less elastic. *Veins* Veins are not as muscular as arteries, but, unlike arteries, they do have valves that keep blood from flowing backward. Veins have the same three layers that arteries do, but are thinner and not as flexible. The two biggest veins are the superior and inferior vena cavae. The superior vena cavae takes blood back to the heart from the upper body. The inferior vena cavae takes blood back from the lower body. *Capillaries* It's through the tiny capillaries that oxygen is delivered to the cells. Also, waste products such as carbon dioxide are also removed by the capillaries. *Through the Circulatory System* Part 1: Systemic Circulation In the systemic circulation, blood travels out of the left ventricle, to the aorta, to every part of the body, and then back to the right atrium. The arteries, capillaries, and veins all have a part in systemic circulation. Once the aorta divides into plain arteries, blood flows to smaller arterioles and then to capillaries. While in the capillaries, the bloodstream delivers oxygen to the cells and picks up waste materials like carbon dioxide. Blood then goes back through the capillaries into venules, and then to larger veins until it reaches the vena cavae. Both vena cavae deliver this now oxygen- poor blood into the right atrium. Next, the blood exits into the right ventricle, ready to be pumped into the pulmonary circulation for more oxygen, and another trip. Part 2: Pulmonary Circulation In the pulmonary circulation, blood low in oxygen but high in carbon dioxide from the systemic circulation is pumped out the right ventricle into the pulmonary artery, which branches off in two directions. The right branch goes to the right lung, and the left branch goes to the left lung. In the lungs, the branches divide and divide into capillaries. Blood flows more slowly through tiny capillaries, allowing time for carbon dioxide to be exchanged with fresh oxygen between the capillary walls and the millions of alveoli, the tiny air sacs in the lungs. Oxygen jumps onto a molecule called hemoglobin in the red blood cells. The new oxygen- fresh blood leaves the lungs through the pulmonary veins and heads back to the left atrium, then fills the left ventricle so it can be pumped into the aorta and systemic circulation. Source: http://www.kidshealth.org/parent/general/body_basics/heart.html
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