The Cardiovascular System

The Cardiovascular System

Alabama Course of Study• Identifying structures and functions of the

Cardiovascular System.• Tracing the flow of blood through the body.• Identifying components of blood.• Describing blood cell formation.• Distinguishing among human blood groups.• Describing common Cardiovascular diseases

and disorders:– Myocardial Infarction– Mitral Valve Prolapse– Varicose Veins– Arteriosclerosis

Interesting Facts• The heart pumps 7,000 liters of blood through the body each

day, contracting some 2.5 billion times in an average lifetime.

• It contracts and relaxes some 70 or so times a minute at rest.• Average adult’s heart size is about 14 centimeters long and 9

centimeters wide.• Blood vessels strung together end to end could circle the

globe 2 ½ times.• The average 3 year old has 2 pints of blood in their body; the

average adult at least 5 times more.• A “heartbeat” is really the sound of the valves in the heart

closing as they push blood through its chambers making a “lubb dupp” sound.

Layers of the Heart• The wall of the heart is composed of 3 distinctive layers- an

outer epicardium, a middle myocardium, and an inner endocardium. Figure 13.3

• Epicardium- outer layer; protects the heart by reducing friction.

• Myocardium- thick middle layer; consists of cardiac muscle tissue that pumps blood out of the heart chambers.

• Endocardium- inner layer; consists of epithelium and connective tissue that contains many elastic and collagenous fibers. Continuous with the inner linings of blood vessels attached to the heart.

The Pericardium• The pericardium encloses the heart and

the proximal ends of the large blood vessels that it attaches to.

• Consists of an outer bag that surrounds a more delicate, double-layered sac

Parts of the Heart

Structure of the Heart• Internally, the heart is

divided into four hollow chambers.– Upper chambers: atria (have

thin walls and receive blood returning to the heart)

– Lower chambers: ventricles (receive blood from the atria and contract to force blood out of the heart into the arteries)

Structure of the Heart cont.

•Septum- partition that separates the right and left sides of the heart

• FYI: The Interatrial Septum (which separates the atria) is only present in the fetal period and is open during this period. It closes at the time of birth. The Interventrial Septum (which separates the ventricles) is supposed to be closed all the time but sometimes an opening is present at birth. This would be considered a Congenital heart disease.

Blood Vessels• Arteries are strong, elastic

vessels that are adapted for carrying blood away from the heart under high pressure.– As they divide and become

smaller, they become arterioles.

• Veins carry blood back to the atria and follow pathways that parallel those of the arteries.– Microscopic vessels that

continue from capillaries and merge to form veins are venules.

Table 13.2

• Aorta- largest blood vessel in the body; receives blood from the Left Ventricle and carries the oxygenated blood to every other part of the body

• Superior Vena Cava- returns blood back to the Right Atrium from the upper part of the body. It is one of the largest veins in the body.

• Inferior Vena Cava- returns blood back to the Right Atrium from the lower part of the body.

Blood Vessels cont.

Blood Vessels cont.

• Pulmonary Arteries- carries blood from the Right Ventricle to both of the lungs where the blood is oxygenated

• Pulmonary Veins- carries the oxygenated blood back to the Left Atrium in the heart.

Blood Vessels cont.• Capillaries are the smallest diameter blood

vessels.• Connect the smallest arterioles and venules• Have thin semipermeable walls in which

substances in the blood are exchanged for substances in the tissue fluid surrounding body cells

• Pulmonary Circuit- sends oxygen-depleted (deoxygenated) blood to the lungs to pick up oxygen and unload carbon dioxide.

• Systemic Circuit- sends oxygen-rich (oxygenated) blood and nutrients to all body cells and removes waste. Figure 13.1

Blue: Deoxygenated BloodRed: Oxygenated Blood

Blood

Interesting Facts

• Men have more blood than women. Men have 1.5 gallons compared to the 0.875 gallons of women.

• In the US, the most common ABO blood types are O (47%) and A (41%). Rarer are type B (9%) and type AB (3%).

Blood Cell Formation • Also called hematopoiesis• It begins in the yolk sac, which lies outside the

human embryo.• Blood cells are manufactured in the liver and

spleen, and still form in bone marrow later in development.

• Marrow-soft, netlike mass of connective tissue found within the medullary cavities of long bones, in the irregular spaces of spongy bone, and in the larger central canals of compact bone tissue.

• Two kinds of bone marrow:– Red marrow– Yellow marrow

Blood Cell Formation cont.• Red marrow: red because of oxygen-carrying

pigment, hemoglobin, in the red blood cells; occupies the cavities of most bones.– Primarily found in the spongy bone of the skull, ribs,

sternum, clavicles, vertebrae, and hipbones.• Yellow marrow: stores fat; it is not active in

blood cell production.– If the body needs more blood, yellow marrow can

become red marrow, which then reverts back to yellow marrow when there is enough or a surplus of blood.

Blood Components• Blood accounts for about 7-8% of our body

weight. Blood transports oxygen and nutrients to cells and gets rid of carbon dioxide and other waste products.

• Plays a vital roll in the immune system and in maintaining a relatively constant body temperature.

• Blood is a highly specialized tissue composed of many different components. The 4 most important ones are red blood cells, white blood cells, platelets, and plasma.

Blood Components cont.• Red Blood Cells (erythrocytes)- relatively

large microscopic cells without nuclei that make up 40-50% of the total blood volume

• RBC transfer oxygen from the lungs to all living tissues in the body and carry away carbon dioxide

• RBC are produced in bone marrow from stem cells at a rate of 2-3 million cells per second.

• Hemoglobin is the gas transporting protein molecules that make up 95% of a RBC. Each has about 270,000,000 iron-rich hemoglobin molecules.

• Anemic people generally have a deficiency in RBC.

• White Blood Cells (leukocytes)- Make up about 1% of blood volume.

• Most notably occur in the spleen, liver, and lymph glands.

• WBC’s called lymphocytes are the 1st responders for your immune system. Granulocytes and macrophages arrive and destroy alien cells and get rid of dead or dying blood cells.

• Individual WBC’s usually only last 18-36 hours before they are removed, though some live as much as a year.

Blood Components cont.

Blood Components cont.• Platelets (thrombocytes)- cells

that clot blood at the site of wounds

• They do this by adhering to the walls of blood vessels, thereby plugging the rupture in the vascular wall. They also release coagulating chemicals which cause clots to form in the blood that can plug up narrowed blood vessels.

• They stimulate the immune system.

• Are about 1/3 the size of RBC’s and have a lifespan of 9-10 days.

Blood Components cont.

• Plasma- relatively clear liquid protein and salt solution which carries the RBC’s, WBC’s, and platelets.

• 55% of your blood’s volume is made up of plasma and 95% of it consists of water.

• As the heart pumps blood to cells throughout the body, plasma brings nourishment to them and removes the waste products of metabolism.

• Plasma also contains blood clotting factors, sugars, lipids, vitamins, minerals, hormones, enzymes, antibodies, and other proteins.

Distinguishing Blood Types

• The discovery of blood groups– In 1901, the Austrian Karl Landsteiner

discovered human blood groups and blood transfusions became safer

– Mixing blood from 2 individuals can lead to blood clumping or agglutination. The clumped red cells can crack and cause toxic reaction.

• What are the different blood groups?– The differences in human blood are due to the

presence or absence of certain protein molecules and antigens and antibodies.

…Distinguishing Blood Types cont.• ABO blood grouping system

– According to the ABO blood typing system, there are 4 different kinds of blood types: A, B, AB, or O (null).

– Blood Group A• You have A antigens and B antibodies

– Blood Group B• You have B antigens and A antibodies

– Blood Group AB• You have both A and B antigens and no A or B

antibodies– Blood Group O

• You have neither A or B antigens and you have both A and B antibodies

…Distinguishing Blood Types cont.

• Rh factor blood grouping system– A person with Rh- blood does not have Rh

antibodies naturally in the blood plasma– A person with Rh- blood can develop Rh

antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies.

– A person with Rh+ blood can receive blood from a person with Rh- blood without any problems

BLOOD GROUP

CAN GIVE BLOOD TO

CAN RECEIVE BLOOD FROM

AB AB AB, A, B, O

A A and AB A and O

B B and AB B and O

O AB, A, B, O O