THE CIRCULATORY SYSTEM

The Circulatory System

Nutrition lets us get substances we need like oxigen.

These substances have to be distributed throughout the body.

The blood carries these substances.

Blood vessels and the heart are the organs of the circulatory system. They take part in circulation.

Blood vesselsBlood vessels are tubes that carry

blood to every part of the body.• 1.- Arteries are the thickest

blood vessels.• 2.- Veins are thinner than

arteries. They carry blood from tissues to the heart.

• 3.- Capillaires are the thinnest blood vessels. Capillaires carry blood to the inside of the organs.

The Heart

• The HEART is the organ (muscle) that pumps blood to every part of the body.

• It beats constantly troughtout our whole life• It is located between the lungs (more to the

left than in the middle). Its size is like a closest fist.

• It is separated into two halves, right and left, by the SEPTUM (it prevents that the blood mix).

Each half is divided in two halves too:

1.- Upper chambers are called ATRIA

2.- Lower chambers are called VENTRICLES.

They are connected by a VALVE.

The valve lets the blood pass from the atrium to the ventricle of the same half.

The outside of the heart is dark red. It is covered with a very resistant tissue called PERICARDIUM

Blood circulationCirculation is the route blood takes to reach every part of

the body. The blood distributes oxygen and the substances we need to live.

Blood also picks up waste substances during this route.

The heart beats to pump the blood. It nec¡ver stops. The heart make two mouvements: SYSTOLE and DIASTOLE.

CIRCULATION has two phases: PULMONARY CIRCULATION and GENERAL CIRCULATION

Pulmonary circulationPulmonary circulation is the route blood takes between

the heart and the lungs

1.- The heart contracts (systole). The blood leaves the right ventricle of the heart. The pulmonary artery takes blood from the heart to the lungs. This blood is rich in CARBON DIOXIDE.

2.- The blood reaches the lungs. Gases are exchanged in the ALVEOLI. The blood releases carbon dioxide and gets oxigen.

3.- The blood rich in OXIGEN goes back to the heart. It enters the left atrium through the pulmonary veins. The heart relaxes (DIASTOLE). The blood is pumped from the lungs to the heart.

General CirculationGeneral Circulation is the route blood takes to

reach every part of the body. It works like this:

1.- Blood with oxygen coming from the lungs passes from the left atrium to the left ventricle. The blood leaves the heart from this ventricle through the aorta (artery).

2.- The blood travels to the aorta to thinner and thinner blood vessels. The blood reaches every organ in the body. The blood picks up nutritional substances when it travels through the small intestine. Then it carries these substances,as well as oxygen, to every part of the body. Waste substances are separated.

3.- The veins pick up waste substances. They take the blood to the heart. This blood enters the right atrium through the venae cavae.

4.- The blood goes from the right atrium to the right ventricle. The pulmonary circulation process starts again.

QUESTIONS:

Which organs form the circulatory system?

What is the function of each organ in the circulatory system?

Explain the diferrences between:

Atria and ventricles

Arteries and veins

Why must the heart beat constantly during our lifetime?

How are pulmonary circulation and general circulation different?

To learn more:

http://www.youtube.com/watch?v=D3ZDJgFDdk0

http://sln.fi.edu/biosci/systems/circulation.html. Circulatory System: The Life Pump

http://www.imcpl.org/kids/guides/health/circulatorysyst

www.neok12.com/Circulatory-System.htm