Saturday, May 5, 2012

Science Form 3 (Chapter 2) Blood Circulation and Transport

Introduction to function of Heart

The role of the heart is to pump oxygen-rich blood to every living cell in the body. In order to achieve its goal, it must continuously beat for a person’s entire lifespan. Because of its vital role, a non-beating heart always results in death. The human heart beats approximately 80,000 to 100,000 a day and pumps almost 2,000 gallons of blood. This means that in a person’s life lasting 70 to 90 years, the heart beats approximately two to three billion times and pumps 50 to 65 million gallons of blood. Because the heart is so essential for human sustenance, it is made up of a muscle different from skeletal muscle that allows it to constantly beat.

In order for the heart to deliver oxygenated blood to all cells, blood is pumped through arteries. Veins bring deoxygenated blood cells to the lungs, which then are oxygenated, and then sent back to heart. In this way, a continuous cycle is formed of the heart pumping oxygenated blood and deoxygenated blood out to their designated destinations, and therefore the heart maintains the circulatory system.

Systole: Stage when the ventricles of heart are contracting resulting in blood being pumped out to the lungs and the rest of the body.
- Thick, muscular walls of both ventricles contract.
- Pressure rises in both ventricles, causing the bicuspid and tricuspid valves to close. Therefore, blood is forced up the aorta and the pulmonary artery.
- The atria relax during this time. The left atrium receives blood from the pulmonary vein, and the right atrium from the vena cava.

Diastole: Stage when the ventricles of the heart are relaxed and not contracting. During this stage, the atria are filled with blood and pump blood into the ventricles.
- Thick, muscular walls of both ventricles relax.
- Pressure in both ventricles falls low enough for bicuspid valves to open.
- The atria contract, and blood is forced into the ventricles, expanding them. The blood pressure in the aorta is decreased, therefore the semi-lunar valves close.


Anonymous said...
This comment has been removed by a blog administrator.
huchong said...

thanks for sharing !
NFL Jerseys
tn chaussures

Ross said...

dsquared shoesdsquared shoes
dsquared jeansdsquared jeans
dsquared jeans 2011dsquared jeans 2011
dsquared shoes 2011dsquared shoes 2011
dsquared jeans womendsquared jeans women
asics shoes saleasics shoes sale
asics shoesasics shoes
asics running shoesasics running shoes
asics mexico 66asics mexico 66
onitsuka mexico 66onitsuka mexico 66
asics onitsuka mexico 66asics onitsuka mexico 66
asics whizzerasics whizzer
asics japanasics japan
asics ultimate 81asics ultimate 81
onitsuka coolidgeonitsuka coolidge
rotation 77rotation 77
asics topasics top
asics miniasics mini
asics olymposasics olympos
onitsuka kanuchionitsuka kanuchi
timberland bootstimberland boots

li said...

Sale Louboutin shoe store is up for many years.A man who wants to play its expertise, it must fit the social environment needs. If you need from the social environment, their expertise will lose value. Therefore, we have according to community needs, determine their own actions, better to show themselves. Louboutin Shoes Sale shoes wear can make you look more beautiful, more attractive feet.

Nike soccer cleats said...

Said was wonderful, really the best site! Liked by the way best described 2011 Nike soccer cleats

nike mercurial soccer cleats said...

Ah good exciting content! Will always come to our attention. To bring you good news-works perfect! So how is the Nike Football Cleats cleatschanged? the original Nike Speed boot!New products Nike Mercurial Vapor Superfly for us.the new Vapor football boots have undergone the same new paint work as the nike mercurial vapor superfly III and now feature the Nike Football Boots updated asymmetric.

luck said...

uggs clearance In cold climate, Ugg boots help to maintain your ft warm. They're a needed fashion accessory currently, Uggs Outlet equally stylish and comfortable. The obvious way to get cheap Ugg boots at a superb price tag should be to research for seasonal gross sales. These could be at outlets or at online web sites ugg boots clearance.