The Cardiovascular System, Lymphatic System & Blood

OBJECTIVES:

1. Describe the structure and function of the human heart.

2. Trace the flow of blood through the heart and body.

3. Distinguish between arteries, veins, and capillaries in terms of their structure and function.

4. Distinguish between pulmonary circulation and systemic circulation.

5. Summarize functions of the lymphatic system.

♥ Your heart is about the same size as your fist. ♥ An average adult body contains about five

quarts of blood. ♥ All the blood vessels in the body joined end to

end would stretch 62,000 miles or two and a half times around the earth.

♥ The heart circulates the body's blood supply about 1,000 times each day.

♥ The heart pumps the equivalent of 5,000 to 6,000 quarts of blood each day.

The Heart

♥ The Heart is cone-shaped

♥ About the size of a fist

♥ Located in the Thoracic Cavity between the Lungs directly behind the Sternum (Breastbone).

♥ Tilted so that the APEX (the pointed end) is oriented to the left.

♥ Locate the heart using a stethoscope

Structure of the Heart♥ The heart is enclosed in a protective

membrane sac called the PERICARDIUM♥ surrounds the heart and secretes a fluid that

reduces friction as the heart beats

Pericardium

Structure of the Heart

♥ Our Heart has FOUR CHAMBERS: ♥ UPPER CHAMBERS of the heart are the RIGHT

AND LEFT ATRIA (ATRIUM), ♥ RECEIVE BLOOD COMING INTO THE HEART.

♥ LOWER CHAMBERS are the RIGHT AND LEFT VENTRICLES♥ PUMP BLOOD OUT OF THE HEART.  The Left

Ventricle is the thickest chamber of the heart because it has to do most of the work to pump blood to all parts of the body.

How the Heart Works

RIGHT SIDE • Pumps flood from the

BODY INTO THE LUNGS, WHERE OXYGEN POOR BLOOD (DEOXYGENATED, USUALLY SHOWN IN BLUE) GIVES UP CARBON DIOXIDE AND PICKS UP OXYGEN

LEFT SIDE • Pumps OXYGEN RICH

BLOOD (OXYGENATED, USUALLY SHOWN IN RED) FROM THE LUNGS TO THE REST OF THE BODY EXCEPT THE LUNGS.

The Flow of Blood

Right Side♥ Blood enters right atrium

through the vena cava (passes through AV valve)

♥ Passes through tricuspid valve to right ventricle

♥ Blood transported to lungs via the pulmonary artery (through the pulmonary valve)

Left Side♥ Blood returns from the

lungs via the pulmonary vein (passes through AV valve)

♥ Enters the left atrium, passes through the bicuspid valve to the left ventricle

♥ Left ventricle pumps blood to the rest of the body through the aorta (passes through aortic valve)

♥ Blood vessels deliver the blood

Actual Heart

Valves

♥ THE GENERAL PURPOSE OF ALL VALVES IN THE CIRCULATORY SYSTEM IS TO PREVENT THE BACKFLOW OF BLOOD. 

♥ They also ensure that BLOOD FLOWS IN ONLY ONE DIRECTION.

BLOOD VESSELS  (ARTERIES, VEINS AND CAPILLARIES)

♥ The Circulatory System is known as a CLOSED SYSTEM because the blood is contained within either the heart or blood vessels at all times.

♥ The blood vessels keep the blood flowing in one direction.

♥ After the blood leaves the heart, it is pumped through a network of blood vessels to different parts of the body.

♥ The Blood Vessels that form this network and are part of the CIRCULATORY SYSTEM ARE THE ARTERIES, CAPILLARIES, AND VEINS.

ARTERIES AND ARTERIOLES (SMALL ARTERIES)

♥ Arteries carry blood from the HEART TO CAPILLARIES AND THE REST OF THE BODY. 

♥ The walls of arteries are generally THICKER than those of veins.

♥ The smooth muscle cells and elastic fibers that make up the walls help make arteries tough and flexible.  This enables arteries to withstand the high pressure of blood as it is pumped from the heart. The force that blood exerts on the walls of blood vessels is known as BLOOD PRESSURE.

♥ EXCEPT FOR THE PULMONARY ARTERIES, ALL ARTERIES CARRY OXYGEN-RICH BLOOD.

AORTA

♥ The artery that carries Oxygen-Rich blood from the LEFT VENTRICLE to all parts of the body, EXCEPT THE LUNGS, is the AORTA.

♥ THE AORTA WITH A DIAMETER OF 2.5 cm, IS THE LARGEST ARTERY IN THE BODY.

♥ As the Aorta travels away from the heart, it branches into smaller arteries so that all parts of the body are supplied.

♥ THE SMALLEST ARTERIES ARE CALLED ARTERIOLES

CAPILLARIES

♥ ARTERIOLES BRANCH INTO NETWORKS OF VERY SMALL BLOOD VESSELS CALLED CAPILLARIES.

♥ IT IS IN THE THIN-WALLED (ONE-CELL IN THICKNESS) THAT THE REAL WORK OF THE CIRCULATORY SYSTEM IS DONE.

♥ The walls of the capillaries consist of only one layer of cells, making it easy for Oxygen and Nutrients to DIFFUSE FROM THE BLOOD INTO THE TISSUE.

♥ Forces of diffusion drive CO2 and waste products from the tissue into the capillaries.

♥ Capillaries are extremely NARROW; Blood cells moving through them must pass in single file.

VEINS ♥ THE FLOW OF BLOOD MOVES FROM CAPILLARIES

INTO THE VEINS. ♥ Veins form a system that COLLECTS blood from every part

of the body and CARRIES it back to the HEART. ♥ The smallest veins are called VENULES. ♥ LIKE ARTERIES, VEINS ARE LINED WITH SMOOTH

MUSCLE.  Vein walls are thinner and less elastic than arteries.  Veins though are more FLEXIBLE and are able to stretch out readily.

♥ Large veins contain valves that maintain the one direction flow of blood.  This is important where blood must flow against the force of gravity.

♥ The flow of blood in veins is help by contractions of skeleton muscles, especially those in the legs and arms.  When muscles contract they squeeze against veins and help force blood toward the heart.

Normal Valves

When Valves Fail: Varicose Veins

Patterns of Circulation

• THE PULMONARY CIRCULATION carries blood between the heart and the lungs– BEGINS AT THE RIGHT VENTRICLE AND ENDS AT THE

LEFT ATRIUM. 

• THE SYSTEMIC CIRCULATION supplies each major organ with blood including the heart– STARTS AT THE LEFT VENTRICLE AND ENDS AT THE

ATRIUM, CARRIES BLOOD TO THE REST OF THE BODY. 

• The heart receives its supply of blood from a PAIR of CORONARY ARTERIES leading from the Aorta. 

• When things go wrong…

Lymphatic System

• As blood circulates throughout the body, fluid from the blood LEAKS into tissue.

• A NETWORK OF VESSELS KNOWN AS THE LYMPHATIC SYSTEM COLLECTS THE FLUID AND RETURNS IT TO THE CIRCULATORY SYSTEM.

• The loss fluid is known as LYMPH, a transparent yellowish fluid, and is collected in lymphatic capillaries and moves to larger lymph vessels. 

Lymphatic System cont…

• The lymphatic system has no pump like the heart, lymph must be moved through vessels by the squeezing of skeletal muscles.

• Lymph vessels pass through small bean-shaped enlargements (organs) called LYMPH NODES, which act as filters and produce special white blood cells called LYMPHOCYTES that are specialized to fight infection.

• The fluid is returned to the circulatory system at an opening in a vein located under the left clavicle, or collarbone, just below the shoulder

Blood

The fluid component of the cardiovascular system

(liquid connective tissue)

Objectives

1. List the components of blood.

2. Distinguish between red blood cells, white blood cells, and platelets in terms of their structure and function.

3. Summarize the process of blood clotting.

4. Explain what determine the compatibility of blood types for transfusion.

Major functions of blood

• Transportation of dissolved gasses, nutrients, hormones and metabolic wastes

• Regulation of the pH and ion composition of interstitial fluids

• Restriction of fluid loss at injury sites

• Defense against toxins and pathogens

• Stabilization of body temperature

Plasma

• Approximately 55 percent of blood in made up of a fluid portion called PLASMA.

• Plasma is the straw-colored liquid portion of blood and is 90% water and 10 percent dissolved fats, salts, sugars, and proteins called PLASMA PROTEINS.

Other Components of Blood

• THE CELLULAR PORTION OF BLOOD MAKE UP THE OTHER 45 % &  INCLUDES SEVERAL TYPES OF HIGHLY SPECIALIZED CELLS AND CELL FRAGMENTS

• THEY ARE RED BLOOD CELLS (RBC), WHITE BLOOD CELLS (WBC), AND PLATELETS.

• Hematocrit – percentage of whole blood volume contributed by formed elements

Formed Elements

b. UAA, AAG

Red Blood Cells (erythrocytes)

• RBC are the most numerous.• One microliter of blood contains approx. 5 million

RBCs. • RBC are BICONCAVE, or shaped so that they are

narrower in the center than along the edges. • RBC are produced from cells in the Bone Marrow,

they are gradually filled with HEMOGLOBIN which forces out the nucleus and other organelles.

• Mature RBC do not have a Cell Nucleus and Organelles.  The Mature RBC becomes little more than a membrane sac containing Hemoglobin.

RBC Structure

Hemoglobin• Binds and transports oxygen and CO2

• Each RBC contains about 280 million hemoglobin molecules

• Each RBC can potentially carry more than a billion oxygen molecules at a time.

Hemoglobin Structure

Hemoglobin is the iron-containing protein that gives RBC the ability to carry oxygen.  Hemoglobin gives the RBC their color.

RBC origin and production• Red blood cells are formed in the bone marrow

(erythropoiesis) and released into the bloodstream

• RBC stay in circulation for about 120 days before they are destroyed by special WBC in the liver and spleen. 

• RBC in your body are dying and being replace at a rate of about 2 million per second.

• Blood doping – athletes inject RBCs that were removed at an earlier date more

oxygen to muscles

White Blood Cells (leukocytes)

• WBCs defend body against invasion by pathogens / they remove toxins, wastes, and abnormal or damaged cells

• WBCs have nuclei and other organelles but lack hemoglobin and are much bigger than RBCs

• Outnumbered by RBC almost 500 to 1. • WBC are produced in the Red Bone Marrow, The

Lymph Nodes, and the Spleen.  • They are larger than RBC, almost Colorless, and do

NOT Contain Hemoglobin. • WBC have a nucleus and can live for many months or

years.

WBC

• THE MAIN FUNCTION OF WBC IS TO PROTECT THE BODY AGAINST INVASION BY FOREIGN CELLS OR SUBSTANCES.

• WBC called PHAGOCYTES can destroy bacteria and foreign cells by phagocytosis (engulfed and digested)

• Some produce special proteins called ANTIBODIES, and some release special chemicals that help the body fight off disease and resist infection.

• Doctors are able to detect the presence of infection by counting the number of WBC in the blood.  When a person has an infection, the number of WBC can Double.

Platelets (thrombocytes)• Platelets are NOT Cells; they are tiny

fragments of other cells that were formed in the bone marrow.

• Platelets are small membrane bound cell fragments that contain enzymes and other substances important to the process of clotting

• Form a “platelet plug” (patch in blood vessel) that combines with plasma proteins to form blood clots

• Lifespan of only 7-10 days, then recycled by the spleen

Platelet origin and production

• Platelets are made in the bone marrow, then enter the bloodstream

• The rate of platelet production is stimulated by a peptide hormone (TPO)

Blood Smear

plateletplatelet

WBCWBC

RBCRBC

When you turn 18,