The Circulatory System

1. The Circulatory System

2. The circulatory system • The circulatory system is made up of the heart, blood vessels, and the blood. • The circulatory system functions to transport waste products, oxygen, carbon dioxide, hormones, urea, and nutrients. • The circulatory system also plays a role in the body’s immune system.

3. The circulatory systemThe Heart • The circulatory system is made up of the heart, blood vessels, and blood. • Blood vessels include arteries, veins, and capillaries. • The heart is a two-pump system made of muscles that pushes blood through out the body. • One pump sends blood to the lungs and the other sends blood to the rest of the body.

4. The circulatory systemThe Heart • Pulmonary circulation  the blood that flows from the heart to the lungs • Systemic circulation  the blood that flows from the heart to the rest of the body

5. The circulatory systemThe Heart • The heart is located in the center of the chest and is surrounded by the pericardium. • The pericardium is a fluid-filled sac. • The heart has 3 layers. • The thin outer layer is the epicardium, which is home to the coronary arteries. • Coronary arteries give the heart its blood supply • The muscular middle layer is the myocardium. • The thin inner layer lining the heart is called the endocardium.

6. The circulatory systemThe Heart • The heart pumps around 5 liters of blood per minute and contracts an average of 70-75 times per minute. • The heart consists of 4 chambers. • Right side of the heart • Deoxygenated blood from the body comes into the right atrium via the superior vena cava (vein) and the inferior vena cava (vein). • The deoxygenated blood passes through the tricuspid valve and moves into the right ventricle. • Deoxygenated blood leaves the right ventricle via the pulmonary valve and enters the pulmonary artery. • This blood enters the lungs and exchanges its CO2 for O2.

7. The circulatory systemThe Heart • Left side of the heart • Oxygenated blood from the pulmonary vein enters the left atrium. • Oxygenated blood moves through the mitral valve (bicuspid) and into the left ventricle. • Oxygenated blood moves from the left ventricle through the aortic valve to the aorta. • Oxygenated blood is transported all over the body via the aorta.

8. The circulatory system • The peripheral circulation is make up of the pulmonary circulation and the systemic circulation. • Blood runs in a closed system through blood vessels and the four chambers of the heart. • The three main types of blood vessels in this closed system are arteries, veins, and capillaries.

9. The circulatory system • Blood is transferred to and from the lungs by the pulmonary artery, capillaries in the lungs, and the veins that drain those capillaries. • Blood is transferred to the body and back via the systemic circulation, which is made up of the aorta and systemic arteries and veins.

10. The circulatory system • Arteries and veins are made of three main layers. • Tunica adventitia  outer layer • Tunica media  smooth muscle layer • Tunica intima  the inner layer

11. The circulatory systemArteries • Arteries carry blood away from the heart. • Arteries = Away • Arteries carry oxygenated blood (except for the pulmonary artery) • Arteries are very elastic and are thick-walled. • Arteries do not have valves. • A pulse is taken from an artery. • The blood that comes out of an artery is usually bright red because it is oxygenated.

12. The circulatory systemArteries • The largest artery in the body is the aorta. • Smaller arteries branch off of the massive aorta. • Arterioles are the smallest arteries • Most of the time phlebotomists will not draw from arteries because they are under high pressure and are buried deeper in the body. • Arterial punctures are used to evaluate the body’s acid/base balance, O2 & CO2 concentration.

13. The circulatory systemVeins • Veins carry blood to the heart • Veins carry deoxygenated blood back to the heart (except for the pulmonary vein) • Veins have thin walls and are not very elastic. • Veins have valves to prevent backflow. • There is no pulse in a vein. • The blood that comes out of a vein is dark red because of its lack of oxygen. • Small veins are known a venules.

14. The circulatory systemVeins Veins • Venous blood is the most common specimen collected by the phlebotomist. • Veins are more accessible because they are closer to the skin’s surface.

15. The circulatory systemCapillaries • Capillaries are the smallest major blood vessels in the body. • They are one cell layer thick. • Capillaries are the site of gas exchange between the blood and body cells. • The cells get O2 and they give up CO2 and waste products. • At one end of a capillary is an arteriole and at the other is a venule. • Capillaries are the site of nutrients and waste product exchange between the blood and the tissue cells.

16. Arteries, Veins, & Capillaries Small Smallest Large Vein  Venules  Capillaries  Arterioles  Artery

17. Important Veins for Phlebotomists • The antecubital fossa of the upper extremities is the preferred site of venipuncture. • The antecubital fossa is the depressed area in front of the elbow. • This is the first area a phlebotomist should check because it is home to major arm veins that lie close to the surface. • Veins are easier to locate and puncture with a needle. • These veins are usually large enough to receive the needle and should be visible or palpable (able to touch) after application of the tourniquet.

18. Important Veins for Phlebotomists • The major surface veins are called the antecubital veins. • There are 3 major veins located in this area. • Median cubital vein • 1st choice • Large • Tends not to move during venipuncture

19. Important Veins for Phlebotomists • Cephalic vein  • 2nd choice • More difficult to locate • Sometimes moves • Can be the only vein to palpate in obese patients • Basilic vein  • 3rd choice • Least anchored • Located near the brachial artery • If a needle is inserted too deep the artery could be punctured.

20. Important Veins for Phlebotomists • Do not draw blood from an arm that has IV fluids running. • The fluid will alter the results of tests run on that blood. • Do not draw blood from an artificial fistula site (AV), used in dialysis. • There are some veins that should not be used for venipuncture. • Sclerosed veins • Tortuous veins • Thrombotic veins

21. Important Veins for Phlebotomists • Sclerosed veins • Veins that are hard and cordlike • Can be caused by disease, inflammation, chemotherapy, or repeated venipunctures. • Tortuous veins • Winding or crooked veins • Susceptible to infection • Blood flow is impaired so specimen may lead to erroneous (incorrect) results • Thrombotic veins • Veins that have clots

22. Important Veins for Phlebotomists • Veins of the back of the hand and wrist are acceptable for drawing blood. • NEVER draw from veins located on the underside of the wrist. • Legs, ankles, and foot veins are not to be used for routine venipuncture. • Taking blood from these sites can cause complications like phlebitis and thrombosis. • Each facility and doctor has a policy for drawing on legs, ankles, and feet. • All arteries are not to be used for venipuncture. • Arterial puncture is to be done by specialized personnel only.