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.

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.

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

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.

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 heart1. Deoxygenated blood from the body comes into the right

atrium via the superior vena cava (vein) and the inferior vena cava (vein).

2. The deoxygenated blood passes through the tricuspid valve and moves into the right ventricle.

3. Deoxygenated blood leaves the right ventricle via the pulmonary valve and enters the pulmonary artery.

4. This blood enters the lungs and exchanges its CO2 for O2.

Left side of the heart1. Oxygenated blood from

the pulmonary vein enters the left atrium.

2. Oxygenated blood moves through the mitral valve (bicuspid) and into the left ventricle.

3. Oxygenated blood moves from the left ventricle through the aortic valve to the aorta.

4. Oxygenated blood is transported all over the body via the aorta.

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.

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.

Arteries and veins are made of three main layers.

1. Tunica adventitia outer layer

2. Tunica media smooth muscle layer

3. Tunica intima the inner layer

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.

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.

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.

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.

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.

Small Smallest Large

Vein Venules Capillaries Arterioles Artery

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.

The major surface veins are called the antecubital veins.

There are 3 major veins located in this area.

1. Median cubital vein 1st choice Large Tends not to move during

venipuncture

2.Cephalic vein 2nd choice More difficult to locate Sometimes moves Can be the only vein to palpate in obese patients3. Basilic vein 3rd choice Least anchored Located near the brachial artery If a needle is inserted too deep the artery could be punctured.

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

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

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.