The Cardiovascular System The Heart and Related Blood Vessels.

The Cardiovascular System

The Heart and Related Blood Vessels

IntroductionIntroduction

The major function of the cardiovascular system is to transport substances throughout the body.

The heart and blood vessels are the major components of the cardiovascular system.


The nutrients and waste products of the body are transported through the blood vessels with a push from the heart.

The blood is connective tissue transported through the blood vessels which act as highways for the blood (vehicles).


Cardiology is the study of the heart and diseases associated with it.

The HeartThe Heart

The heart is located in the thoracic cavity behind the sternum.

The size of a persons heart is approximately the same size as their closed fist.

On average it weighs about 300g.

The HeartThe Heart

The base of the heart is the wide superior portion.

The apex is the inferior point.

The HeartThe Heart

The heart is covered by a sac made up of two layers.

1.) Serous Pericardium

2.) Fibrous Pericardium

The HeartThe Heart

The serous pericardium is made up of the visceral and parietal pericardium which are delicate layers of epithelial and connective tissue which aid in lubrication of the heart.

The HeartThe Heart

The fibrous pericardium is an outer tough layer of connective tissue that prevents the heart from over stretching.

The HeartThe Heart

The wall of the heart is composed of three layers:

1.) epicardium, outer most layer

2.) myocardium, middle layer made up of cardiac muscle(bulk of heart)

3.) endocardium, inner layer and smooth inner wall of heart

The HeartThe Heart

The heart is made up of four chambers.

The top chambers are atria.

The bottom chambers are ventricles.

The HeartThe Heart

The atria are broken up into the right and left atria which are separated by the interatrial septum.

The atria receive blood from veins.

They are very thin walled.

The HeartThe Heart

The ventricles are divided into the right and left ventricle which are separated by the interventricular septum.

Ventricles are responsible for pumping blood from the heart into arteries.

They have much thicker walls because of their active role in pumping blood.

The HeartThe Heart

The major blood vessels associated with the heart are veins and arteries.

Arteries carry blood away from the heart.

Veins carry blood to the heart.

Blood VesselsBlood Vessels

Arteries carry blood that is high in oxygen and low in carbon dioxide away from the heart.

- The aorta carries blood from the left ventricle to the body.

- The pulmonary arteries carry blood from the right ventricle to the lungs.

- The coronary arteries carry blood to the myocardium.


Veins carry blood that is high in carbon dioxide and low in oxygen into the heart.

- The superior vena cava brings blood from the head and upper limbs and the inferior vena cava brings blood from the trunk and lower limbs.

- The coronary sinus brings blood back from the myocardium.

- The pulmonary veins bring blood from the lungs into the left atrium.

Valves of the HeartValves of the Heart

The general function of heart valves is to prevent the back flow of blood.


Atrioventricular valves are valves within the heart that separate the atria and the ventricles.

The tricuspid valve lies between the right atrium and ventricle.

The bicuspid valve lies between the left atrium and ventricle.


These valves are opened and closed with the help of muscles called papillary muscles.

The valves are held in place by tendon like cords called chordae tendineae.


The semilunar valves are valves located near the end of the major blood vessels into and out of the heart.

The pulmonary semilunar valve is found in the pulmonary trunk.

The aortic semilunar valve is found in the aorta.


These valves can become damaged or diseased requiring them to be changed.

Heart Valves Heart Valve Surgery

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Pathway of BloodPathway of Blood

The general path taken by all blood is the same:

1.) The heart pumps oxygenated blood out of the left ventricle to aorta which branches out into arteries.

2.) The arteries are then branched and funneled into arterioles.


3.) The arterioles are then in turn branched out and funneled into capillaries which are located in the tissues of your body.

*This is where gas exchange occurs, which is the swapping of oxygen and carbon dioxide by the blood.

4.) The capillaries then begin to get larger and branch together into venules.


5.) The venules branch together into veins and the veins then come together to form the vena cava.

6.) The vena cava then enter the heart in the right atrium.


The pathway of blood through the heart and lungs is known as the pulmonary circuit.

1.) It begins in the right atrium with deoxygenated blood entering the heart.

2.) The tricuspid valve then opens and the blood rushes into the right ventricle


3.) The pulmonary semi-lunar valve opens the pulmonary trunk and the deoxygenated blood travels into the pulmonary arteries.

4.) The blood then gets funneled into the capillaries in the lungs, which run along side alveoli.

5.) The blood in the alveoli picks up oxygen from the walls of the lungs and the blood is transferred to the pulmonary veins.


6.) The pulmonary veins then take the oxygenated blood into the left atrium

7.) The tricuspid valve of the left atrium then opens and the blood is forced into the left ventricle.

8.) The aortic semi-lunar valve then opens and the left ventricle pumps the blood into the aorta which transports blood throughout the body.


The supply of blood for the heart is carried to the myocardium by the coronary artery and sinus.

1.) Coronary circulation begins in the ascending aorta with oxygenated blood.

2.) The blood travels down one of two paths the right or left coronary artery.


* The presence of multiple pathways for blood is common throughout the body, they are known as anastosomes.

3.) The capillaries within the myocardium then undergo gas exchange.

4.) The cardiac veins then transport blood to the coronary sinus which takes the blood back to the right atrium.

Heart Disorders and Diseases


Blood clots, fatty atherosclerotic plaques, and smooth muscle spasms within the coronary vessels lead to most heart problems.

Heart Diseases and Disorders

Heart Diseases and Disorders

Go to the following link:http://www.wisc-online.com/objects/OTA1604/OTA1604.swf

Make a list outlining the basic causes and severity of the four disorders found there.

Make predictions based on your knowledge of the heart on how easily these disorders can be treated.



Common heart disorders include:1.)An ischemia is a reduction of blood flow.

2.) Hypoxia is a reduced oxygen supply due to an ischemia.

3.) An angina pectoris is severe pain that accompanies an ischemia.

-A crushing pain radiating down the left arm.



4.) A myocardial infarction is a heart attack.- A heart attack is the death of a

portion of myocardium due to a thrombus (blood clot).

5.) Reperfusion damage occurs when oxygen deprived tissue has its blood supply regenerated, the formation of oxygen free radicals in the blood damages cardiac tissue.

Cardiac Conduction System (CSC)


There are specialized portions of cardiac muscle tissue that are autorhythmic or self exciting.

This autorhythmic property of portions of cardiac tissue is what generates the electrical signal causing the heart to beat.



The sinoatrial node is located in the right uppermost atrial wall.

- This node generates an electrical signal that is passed throughout atrial muscle fibers causing them to contract.

- This pacemaker generates an electrical signal 60 to 100 times per minute in a resting state.

Cardiac Conduction Systems (CSC)

Cardiac Conduction Systems (CSC)

The atrioventricular node (A-V Node) is located in the interatrial septum.

- It acts as a delay mechanism which allows for the ventricles to fill by holding up the electrical signal.



The atrioventricular bundle acts as the only electrical “transfer station” between the atria and ventricles.

The right and left bundle branches lead downward toward the apex of the heart allowing the electrical signal to propagate.



Throughout the heart the electrical signal makes contact with the muscle fibers due to the purkinje fibers, which are primarily responsible for the large scale contraction of the ventricles.

Electrical Signals of Beating Heart

Physiology of a Cardiac Muscle Contraction


The contractile fibers of the heart have a resting potential of -90mV and the opening of Na+ channels depolarizes them and drops the potential to -70mV.

This rapid depolarization causes the release of Ca2+ ions which are a part of the muscle contraction.



The K+ channels are then opened triggering a repolarization of the muscle fibers.

After the contraction is complete there is a refractory period in which no contraction can occur.

- This is the time that calcium, sodium and potassium levels are resupplied.

Electrocardiogram (ECG or EKG)

Electrocardiogram (ECG or EKG)

An ECG is a recording of the electrical changes that occur in the myocardium during the cardiac cycle.

There are three “waves” per heart beat.

ECG Tutorial

Electrocardiogram(ECG or EKG)


The first small upward wave is called the p wave.

- This wave represents atrial depolarization.



The QRS Complex is a grouping of waves consisting of a downward deflection followed by a large up sweep and ending as a small downward wave.

- This wave is the start of the ventricular contraction.



The t wave is the dome shaped upward deflection.

- This wave represents the repolarization of the ventricles.

Cardiac CycleCardiac Cycle

The cardiac cycle is made up of alternating contractions and relaxations.

- The contractions are known as systole.

- The relaxations are known as diastole.

- There is a systole and diastole for both atria and ventricles.

Cardiac CycleCardiac Cycle

When taking a blood pressure there are two numbers measured.

The first number is systole and the second is diastole.

The perfect healthy blood pressure is 120/80, these numbers are pressures calculated based on readings done with a blood pressure cuff.

Cardiac OutputCardiac Output

A persons cardiac output is the volume of blood pumped by each ventricle in one minute.

CO = heart rate stroke volume

Stroke volume is the amount of blood pumped out by a ventricle with each beat.

The normal CO is 5 liters.


Blood vessels are made up of three layers.

1.) tunica interna, is the inside layer of the vessel

2.) tunica media, is the middle layer

3.) tunica externa, is the outer layer


The tunica media is much thinner in the walls of veins than it is in arteries.

Artery walls are thicker so it is easier for oxygen and nutrients to diffuse out where they are supposed to.

BloodBlood

Blood is a liquid tissue that flows through the blood vessel.

Blood consists of plasma, blood cells and platelets

BloodBlood

In the average human man there are over 5,000,000 red blood cells (rbc) per cubic millimeter of blood.

In the average human woman there are over 4,500,000 rbc per cubic millimeter of blood.

BloodBlood

The primary function of rbcs is to carry oxygen which is picked up by and attached to the bloods hemoglobin.

Hemoglobin is a protein containing iron which is bright red in the presence of oxygen and burgundy without oxygen.

BloodBlood

The white blood cells of the body act as a line of defense in the blood.

They are macrophages which are responsible for attacking and destroying foreign bodies in the blood.

BloodBlood

There are far less wbcs in the blood, approximately 5000-9000 per mm3.

There are two types of wbcs:1.) granular, grainy exterior texture

2.) agranular, smooth exterior texture

The major difference between the two is the type of foreign bodies they are responsible for destroying.

BloodBlood

When a vessel opens to the outside the coagulation of the blood by the formation of a platelet plug occurs.

Platelets are small pieces of cellular material which originate by breaking off pieces of bone marrow.

BloodBlood

Plasma is the liquid in which all blood particles are suspended.

Plasma is where nutrients, salts and hormones are transported throughout the body.

The Cardiovascular System The Heart and Related Blood Vessels.

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