Caracteristics of Blood Vessels
have thick walls,
no valves and
carry blood away
from the heart
link arteries to veins.
Their wall is only one cell thick
and this allows substances to
pass into and out of the blood.
• have thin walls,
• valves, and
• carry blood to the heart
http://www.youtube.com/watch?v=CjNKbL_-cwA Types of blood vessels
1.2 Parts of the Heart
It is a pump that pushes the blood into the arteries.
Is made of cardiac muscle, a special kind of muscle that never
Is divided into two sides by a wall called the septum.
It has got four chambers:
Atria: the two upper
atrium). They have thin
walls. They pump blood to
Ventricles: the two lower
chambers. They pump
blood out of the heart.
right ventricle, with
thin wall, pumps the
blood to the lungs .
left ventricle, with
thicker and stronger
wall, pumps the blood
to the body.
Tricuspid valve and bicuspid valve or mitral valve,
between atria and ventricles.
Semilunar valves (aortic valve and pulmonary
valve) between ventricles and arteries.
http://vimeo.com/5588613 ==> valves working
http://www.youtube.com/watch?v=jLTdgrhpDCg Cardiac Cycle, systole and diastole
1.3 The Blood
Every person has 4 to 5 litres of blood on average.
55% of the blood is plasma
45% consists of blood cells and platelets.
They defend the body from infection
http://www.youtube.com/watch?v=CRh_dAzXuoU blood cells
FUNCTIONS OF THE BLOOD
Oxygen and carbon dioxide
Keeping the normal temperature
of the body
Defence against disease
2. Blood circulation
Blood circulation in human being is double
It has two circuits (general and pulmonary)
The blood in the veins never mixes
with the blood in the arteries
The movement of blood through the heart
1. Blood from the body enters the right atrium through the vena cava.
The atria contract, the blood is pushed through the tricuspid
valve, into the right ventricle.
2. When the right ventricle contracts, the blood is pumped through the
semilunar valve into the pulmonary arteries.
3. Blood goes to the lungs.
In the lungs, the blood collects up oxygen and gets rid of its carbon
4. It then comes back to the heart in the pulmonary vein which enters the
When the atria contract, the blood is pushed through the bicuspid o
mitral valve into the left ventricle.
5. The ventricles contract and this pushes the blood through the semilunar
valve to the main artery of the body, aorta.
6. Blood is pushed out to all around the body.
The stages of heartbeat (cardiac cycle)
Diastole: heart chambers relax.
Systole: heart chambers contract.
4. Some illnesses of the circulatory system
Accumulation of substances (fats, calcium…) in the arteries, which causes them
to narrow and restricts the blood flow.
(a common form of arteriosclerosis in which fatty substances form a deposit of plaque on the inner lining ofarterial walls)
Blood clots formed in a blood vessel. It is especially dangerous in the brain
or in the heart
Heart attack and angina
Arteries which carry blood to the cardiac cells
Angina: narrowing or partial obstruction of the coronary arteries.
Heart attack: total obstruction of the coronary arteries