The Circulatory System
What is the job of the Circulatory System?
The structure and function of arteries,capillaries, and veins
Arteries are blood vessels that carry oxygen rich blood AWAY from the heart. Remember, A A Arteries Away, A A Arteries Away, A A Arteries Away.
Capillaries are tiny blood vessels as thin or thinner than the hairs on your head. Capillaries connect arteries to veins. Food substances(nutrients), oxygen and wastes pass in and out of your blood through the capillary walls.
Veins carry blood back toward your heart.
The route of blood through the heart
Pathway of blood through the heart
1. Blood enters the right atrium from the superior and inferior venae cavae,
and the coronary sinus.
2. From right atrium, it goes through the tricuspid valve to the right ventricle.
3. From the right ventricle, it goes through the pulmonary semilunar valves to
the pulmonary trunk
4. From the pulmonary trunk it moves into the right and left pulmonary
arteries to the lungs.
5. From the lungs, oxygenated blood is returned to the heart through the
6. From the pulmonary veins, blood flows into the left atrium.
7. From the left atrium, blood flows through the bicuspid (mitral) valve into
the left ventricle.
8. From the left ventricle, it goes through the aortic semilunar valves into the
9. Blood is distributed to the rest of the body (systemic circulation) from the
Your blood is pumped by your heart and travels through thousands of miles of blood vessels right within your own body.Your blood carries nutrients, water, oxygen and waste products to and from your body cells. A young person has about a gallon of blood while an adult has about 5 quarts.Your blood is not just a red liquid but rather is made up of liquids, solids and small amounts of oxygen and carbon dioxide.
The composition of blood
Blood is made up of a number of types of cells:
Plasma: Plasma is a straw-coloured fluid in which blood cells are suspended. It is made up of approximately 90% water as well as electrolytes such as sodium and potassium and proteins.
Red Blood Cells: (Erythrocytes): The main function of red blood cells is to carry oxygen. RBC's contain a protein called Haemoglobin. This combines with oxygen to form Oxyhaemoglobin. Each RBC has a lifespan of approximately 120 days before it gets broken down by the spleen. New RBC's are manufactured in the bone marrow of most bones. There are approximately 4.5-5 million RBC's per micro-litre of blood.
White Blood Cells: (Leucocytes): There a number of types of white blood cells, although the function of all of them is to help fight disease and infection. They typically have a lifespan of a few days and there are only 5-10 thousand WBC's per micro-litre of blood.
Platelets: (Thrombocytes): Platelets are disc shaped cell fragments which are involved in clotting the blood to prevent the excess loss of body fluids.
2 major disorders that occur within the circulatory system
Ployarteritis nodosa -- PAN -- is a serious inflammatory disease of the small to medium sized arteries. Many body systems are involved, including the skin, central nervous system, heart, kidneys and intestinal tract. PAN is commonly associated with hepatitis B infection, but in most cases the cause for the illness is unknown. Symptoms of PAN are quite variable, although fever, night sweats, weight loss, fatigue, and muscle and joint aches are typical. Treatment of the disease depends on the extent of the illness, and which parts of the body are involved. Corticosteroids and other immunosuppressive drugs are often used.