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Circulatory Lecture Outline/
Teacher Lecture Notes

Circulatory system job: transportation of oxygen to the cells. The oxygen bonds to the hemoglobin found in the blood and then is carried out to the cells.

Parts of the circulatory system:
Overall Structure 
- blood vessels consist of:
a) lumen - hollow center through which blood flows
b) tunics = coats that form the wall of a blood vessel

1. Arteries
         - arteries -> carry blood from heart to tissues
         - thick layer of smooth muscle
         - no exchange of gases
2. Arterioles
         - arteries divide into smaller arterioles
-> further branch into microscopic capillaries
         - arterioles play a key role in regulating blood flow from
arteries into capillaries
         - no exchange of gases
3. Capillaries
         - microscopic in size; connect arterioles and venules
         - site of exchange of gases, nutrients and wastes
between blood and tissue cells
         - flow of blood from arterioles to venules through
capillaries = microcirculation
         - capillary walls - made of endothelial cells only
-> very thin and porous
4. Venules
         - capillaries unite to form small venules, which in turn merge and form veins
         - no exchange of gases
5. Veins
         - veins -> carry blood from tissues back to heart
         - blood volume in rest -> 60 %  in systemic veins and venules
         - veins and venules = blood reservoirs
         - veins usually have valves, which prevent back flow of blood
         - compared to arteries, veins are thinner
         - blood pressure in veins is considerably lower than in arteries
veins: transports the blood to the heart this blood is lacking in oxygen. It is called deoxygenated blood and is typically colored as blue.

arteries: this transports blood from the heart and is rich in oxygen. It is called oxygenated blood and is typically colored as red.

capillaries: These are the bridges between the arteries and the veins. Their jobs are to take the oxygenated blood directly to the cell, and then pick up the deoxygenated blood and carry it to the veins.

Blood distribution
- 60 %  in systemic veins and venules
- 15 % in systemic arteries and arterioles
- 5 % in systemic capillaries
- hematology - study of blood, blood-forming tissues and the disorders associated with them
- blood = liquid connective tissue
- Functions:
1. transportation of gases, nutrients, wastes
2. regulation of homeostasis - temperature, pH, viscosity
3. protection - clotting mechanism protects against blood loss
                                - immune cells - protection against diseases
- exchange of material between blood and interstitial fluid
-> by osmosis, diffusion and bulk flow

Characteristics of blood:
- viscous (heavier and thicker than water)
- temperature: 38⁰C
- pH: 7.4
- volume: 4 - 6 liters (females - males) in humans
(approx. 8 % total body weight)

Circulatory Circle of Life

The job of the circulatory system is to move the oxygen out to the body, have the cell take that oxygen and then take the blood back up to the lungs to get more oxygen. It is done in the following fashion.

Heart:
The heart is basically shaped like a 4 pained window. There is a right side, and a left side. There is a top half and a bottom half. Each side has specific responsibilities and works with specific types of blood.

Right Atrium	Left Atrium
Right Ventricle	Left Atrium

The heart is set up like a football team.
You have receivers, quarterbacks (who push the blood) and running backs.

The atriums RECEIVE the blood.
The ventricles PUMP the blood out to specific parts of the body
and the veins and arteries are the running backs who carry the blood to where it needs to go.

Veins carry DEOXYGENATED blood. They carry blood TO the heart .
The primary blood vessels that carry the blood are called the upper and lower VENA CAVAS. One carries blood from the head region to the heart, the other carries blood from the body to the heart. This blood is designated as a blue color to show that it is LACKING oxygen.

Once the blood gets to the heart it is RECEIVED by the right atrium. The right atrium then allows the blood to go through a one-way valve to the right ventricle. Once in the right ventricle it is this “quarterback’s job “ to push (or pump) the blood out to the lungs.

The blood is pushed to the lungs out to the lungs by the right ventricle. It is carried to the LUNGS by the PULMONARY ARTERY. This is a major rule breaker.
What vessels carry what type of blood?
Veins carry DEOXYGENATED blood to the heart and that ARTERIES carry OXYGENATED blood away from the heart to the body.

But what type of blood do we have here???
Deoxygenated blood is being carried in an artery... on it’s way to the lungs.

Once it gets to the lungs, what’s going to happen??? The blood is going to get oxygenated. It’s going to become rich with oxygen. This is the blood that has to go out to the body. This is the blood that the body needs. This is the “red” blood of life. The blood get oxygen, becomes oxygenated and then heads back to the heart. It is carried to the heart by what kind of vessel?? What kind of vessels carry blood to the heart?? VEINS do. This is the second rule breaker. The PULMONARY VEIN carries OXYGENATED blood back to the heart.

This oxygenated blood is received in the LEFT ATRIUM. (remember the atriums as receivers.) It then goes through another one way valve to the LEFT VENTRICLE. If you look at a heart it is the side and part which has the greatest amount of muscle because of the quarter backing it must do! The LEFT VENTRICLE PUSHES the blood into the AORTA (which is the largest artery in the body). The AORTA then carries this OXYGEN rich blood out to the various parts of the body through the artery system. The blood is carried to the individual cells by the capillary bridges where the oxygenated blood leaves its oxygen and then is bridged to the veins.

The venous system works together and meets up with the VENA CAVA and back to the heart it goes, to start the circulatory circle of life again.