1.9: Cardiovascular System
Learning Objectives
- Examine the anatomy of the heart
- Determine the main functions of the cardiovascular system
- Differentiate cardiovascular system medical terms and common abbreviations
- Recognize the medical specialties associated with the cardiovascular system
- Discover common diseases, disorders, and procedures related to the cardiovascular system
Cardiovascular System Word Parts
Click on prefixes, combining forms, and suffixes to reveal a list of word parts to memorize for the cardiovascular system.
Introduction to the Cardiovascular System
The cardiovascular system is made of three components: the heart, vessels, and blood. The heart is a fist-sized vital organ that has one job: to pump blood. If one assumes an average heart rate of 75 beats per minute, a human heart would beat approximately 108,000 times in one day, more than 39 million times in one year, and nearly 3 billion times during a 75-year lifespan. At rest, each of the major pumping chambers of the heart ejects approximately 70 mL of blood per contraction in an adult. This would be equal to 5.25 liters of blood per minute and approximately 14,000 liters per day. Over one year, that would equal 10,000,000 liters of blood sent through roughly 100,000 km of blood vessels. In order to understand how that happens, it is necessary to understand the anatomy and physiology of the heart.
Watch this video:
Media 9.1. The Heart, Part 1 – Under Pressure: Crash Course A&P #25 [Online video]. Copyright 2015 by CrashCourse .
Practice Medical Terms Related to the Cardiovascular System
Anatomy of the Heart
Location
The human heart is located within the thoracic cavity, between the lungs in the space known as the mediastinum . Figure 9.1 shows the position of the heart within the thoracic cavity. Within the mediastinum, the heart is separated from the other mediastinal structures by a tough membrane known as the pericardium, or pericardial sac, and sits in its own space called the pericardial cavity . The great vessels , which carry blood to and from the heart, are attached to the superior surface of the heart, which is called the base. The base of the heart is located at the level of the third costal cartilage. The inferior tip of the heart, the apex, lies just to the left of the sternum between the junction of the fourth and fifth ribs.
Concept Check
- On the diagram below (Figure 1), locate the mediastinum , the pericardial cavity , the base of the heart and the apex of the heart.
- Locate the largest vein in the body, the superior vena cava .
Membranes and Layers of the Heart Walls
The heart and the roots of the great vessels are surrounded by a membrane known as the pericardium or pericardial sac . The pericardium consists of two distinct sub layers:
- The sturdy outer fibrous pericardium is made of tough, dense connective tissue that protects the heart and holds it in position.
-
Separated by the
pericardial
cavity
and containing pericardial fluid the inner
serous
pericardium consists of two layers:
- the outer parietal pericardium , which is fused to the fibrous pericardium.
- the inner visceral pericardium , or epicardium , which is fused to the heart and forms the outer layer of the heart wall.
The walls of the heart consist of three layers:
- The outer epicardium , which is another name for the visceral pericardium mentioned above.
- The thick, middle myocardium , which is made of muscle tissue and gives the heart its ability to contract.
- The inner endocardium , which lines the heart chambers and is the main component of the heart valves.
Concept Check
- Look at Figure 9.2 below, and name the layers of the heart wall and surrounding membranes, starting with the innermost layer.
- As shown on the diagram, suggest why the myocardium layer is thicker than the endocardium layer.
Internal Structures of the Heart
The heart consists of four chambers:
- The upper chambers are the right and left atria (singular: atrium).
- The lower chambers are the right and left ventricles.
The interventricular septum is a muscular wall that separates the right and left ventricles. The interatrial septum separates the right and left atria.
The atrium and ventricle on each side of the heart are separated by an atrioventricular (AV) valve:
- The right AV valve, or tricuspid valve, separates the right atrium and right ventricle.
- The left AV valve, or bicuspid valve, separates the left ventricle and the left atrium. This valve is also called the mitral valve.
There are also two semilunar valves:
- The pulmonary valve separates the right ventricle from the pulmonary trunk.
- The aortic valve separates the left ventricle from the aorta.
Anatomy Labeling Activity
Physiology of the Heart
- Circulation through the heart: Blood is pumped by the heart in order to provide oxygen and nutrients to every cell in the body.
- The heart as an organ (coronary blood supply): The heart is an organ, made of cells and tissues which require their own blood supply.
- The heart’s electrical conduction system: The heart is able to independently generate and transmit instructions to the myocardium in order to make it contract and pump the blood.
1. Circulation Through the Heart: The Heart as a Pump
The heart pumps blood to two distinct but linked circulatory systems called the pulmonary and systemic circuits. The pulmonary circuit transports blood to and from the lungs, where it picks up oxygen and drops off carbon dioxide. The systemic circuit transports freshly oxygenated blood to virtually all of the tissues of the body and returns relatively deoxygenated blood and carbon dioxide to the heart to be sent back to the pulmonary circulation.
- Blood that is carrying carbon dioxide and waste products from the body tissues is returned to the right atrium via the superior vena cava and the inferior vena cava .
- From the right atrium, the deoxygenated blood moves through the tricuspid valve into the right ventricle.
- The right ventricle pumps deoxygenated blood through the pulmonary valve into the pulmonary trunk , which splits into the right and left pulmonary arteries , leading toward the lungs. These arteries branch many times before reaching the pulmonary capillaries , where gas exchange occurs: carbon dioxide exits the blood, and oxygen enters. The pulmonary arteries are the only arteries in the postnatal body that carries deoxygenated blood. Did you notice that they are often colored blue on diagrams of the heart?
- Freshly oxygenated blood returns from the lungs to the left atrium via the pulmonary veins . These veins are the only postnatal veins in the body that carry highly oxygenated blood and are often colored red on heart images.
- From the left atrium, the blood moves through the mitral valve into the left ventricle.
- The left ventricle pumps blood through the aortic valve , into the aorta , delivering blood to all parts of the body.
Did you know?
The heart sounds heard through a stethoscope are the sounds of the four heart valves opening and closing at specific times during one cardiac cycle.
Concept Check
- On Figure 9.3 below, use your finger to trace the pathway of blood flowing through the right side of the heart, naming each of the following structures as you encounter them: Superior and inferior venae cavae, right atrium, tricuspid valve, right ventricle, pulmonary valve, right and left pulmonary arteries.
- Suggest what would happen if the aorta experienced a blockage or constriction.
Pulmonary Circuit
Blood exiting from the right ventricle flows into the pulmonary trunk, which bifurcates into the two pulmonary arteries. These vessels branch to supply blood to the pulmonary capillaries, where gas exchange occurs within the lung alveoli. Blood returns via the pulmonary veins to the left atrium.
Concept Check
On Figure 9.4 below, use your finger to trace the pathway of blood flowing through the left side of the heart, naming each of the following structures as you encounter them: right and left pulmonary veins, left atrium, mitral valve, left ventricle, aortic valve, aorta.
Cardiac Cycle
The process of pumping and circulating blood is active, coordinated, and rhythmic. Each heartbeat represents one cycle of the heart receiving blood and ejecting blood.
- Diastole is the portion of the cycle in which the heart is relaxed and the atria and ventricles are filling with blood. The AV valves are open so that blood can move from the atria to the ventricles.
- Systole is the portion of the cycle in which the heart contracts, AV valves slam shut, and the ventricles eject blood to the lungs and the body through the open semilunar valves. Once this phase ends, the semilunar valves close, in preparation for another filling phase.
2. The Heart as an Organ: The Coronary Blood Supply
Myocardial cells require their own blood supply to carry out their function of contracting and relaxing the heart in order to pump blood. Their own blood supply provides nutrients and oxygen and carries away carbon dioxide and waste. These functions are provided by the coronary arteries and coronary veins.
Concept Check
On the image below, locate the three main coronary arteries:
- Anterior interventricular artery (more commonly known as the left anterior descending artery, or LAD )
- Circumflex artery (Cx)
- Right coronary artery (RCA)
Follow the path of each of these three arteries to try to determine which parts of the myocardium each artery (along with its many smaller branches) supplies with blood.
3. The Heart’s Electrical Conduction System
In order for all parts of the heart to work together to beat regularly and effectively, the heart has its own electrical system, which initiates and conducts each heartbeat through the entire myocardium. Specialized groups of heart cells perform this function all on their own, without requiring messages from the central nervous system.
Watch this video:
Media 9.2. The Heart, Part 2 – Heart Throbs: Crash Course A&P #26 [Online video]. Copyright 2015 by CrashCourse .
Concept Check
On the image above, trace the electrical impulse generated by the heart’s pacemaker (the sinoatrial node , or SA node ) through the rest of the conduction system, including the atrioventricular (AV) node , the atrioventricular bundle (bundle of His) , the right and left bundle branches , and the Purkinje fibers .
We can detect and record the electrical activity of the heart’s conduction system using an electrocardiogram (ECG or EKG). Figure 9.7 shows the electrical impulse originating in the SA node (step 2) and traveling through the heart’s conduction system, allowing the heart to complete one cardiac cycle. Each waveform on the ECG tracing represents electricity moving through and affecting a different part of the heart. Did you notice that the AV valves close when the electrical impulse reaches the ventricles, just before systole occurs?
Practice Terms Related to the Cardiovascular System
Common Abbreviations for the Cardiovascular System
Many terms and phrases related to the cardiovascular system are abbreviated. Learn these common abbreviations by expanding the list below.
Diseases and Disorders of the Heart
Cardiomyopathy
The heart of a well-trained athlete can be considerably larger than the average person’s heart. This is because exercise results in an increase in muscle cells called hypertrophy . Hearts of athletes can pump blood more effectively at lower rates than those of non-athletes. However, when an enlarged heart is not the result of exercise, it may be due to hypertrophic cardiomyopathy . The cause of an abnormally enlarged heart muscle is unknown, but the condition is often undiagnosed and can cause sudden death in apparently otherwise healthy young people.
Other types of cardiomyopathy include:
- Dilated cardiomyopathy , which also has an unknown cause and is seen in people of any age. In this disorder, one of the ventricles of the heart is larger than normal.
- Arrhythmogenic cardiomyopathy , an inherited condition that results in irregular heart rhythms.
- Restrictive cardiomyopathy , which is a complication of other conditions which cause the myocardium to scar or stiffen (Centers for Disease Control and Prevention, 2019).
Cardiomyopathy may also be caused by myocardial infarctions, myocardial infections, pregnancy, alcohol or cocaine abuse, autoimmune and endocrine diseases. Because the myocardium is responsible for contracting and pumping blood, patients with cardiomyopathy experience impaired heart function which may lead to heart failure (Centers for Disease Control and Prevention, n.d.-a). To learn more, visit the Centers for Disease Control and Prevention’s web page on cardiomyopathy.
Heart Failure
Heart failure is defined as the inability of the heart to pump enough blood to meet the needs of the body. It is also called congestive heart failure (CHF). This condition causes swelling in the lower extremities and shortness of breath, due to a buildup of fluid in the lungs. It may be caused by cardiomyopathy, and it may lead to hypertension and heart valve disorders (Heart & Stroke, n.d.). To learn more, visit the American Heart Association’s web page on heart failure .
Valvular Heart Disease
The four heart valves open and close at specific times during the cardiac cycle, in order to ensure that blood flows in only one direction through the heart. This requires that these valves open and close completely. Infections such as rheumatic disease or bacterial endocarditis can affect the heart valves and result in scar tissue formation which interferes with valve function. Other causes of heart valve disease include congenitally malformed valves, autoimmune diseases, and other cardiovascular diseases such as aortic aneurysms and atherosclerosis (Centers for Disease Control and Prevention, n.d.-b).
Heart valve disease may be asymptomatic or cause dyspnea , arrhythmias , fatigue and other symptoms. It is often detected when a heart murmur is heard through a stethoscope (Centers for Disease Control and Prevention, n.d.-b).
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Mitral Valve
Prolapse
- The mitral (bicuspid) valve is diseased or malformed and is not able to close completely, allowing the regurgitation of blood back into the left atrium during systole. Because some of the blood goes back into the atrium, insufficient blood is pumped out of the ventricle into the systemic circulation. This inability to close properly and the resulting regurgitation may also be found in other heart valves (Centers for Disease Control and Prevention, n.d.-b).
-
Aortic Stenosis
- The aortic valve is narrowed and hardened, preventing it from opening fully and allowing sufficient blood to travel to the systemic circulation. Any heart valve can be stenosed, but this disorder most often affects the aortic valve (Centers for Disease Control and Prevention, n.d.-b).
Visit the Center for Disease Control and Prevention’s web page on valvular heart disease to learn more.
Aneurysms
An aneurysm is a defect in the wall of an artery in which the wall becomes thin and weak and starts to balloon out as blood pulses against the vessel wall. This can happen to any artery and even to the myocardial walls. Aneurysms sometimes occur in the portion of the aorta that is in the thorax (see Figure 9.8 ). If these aneurysms start to leak between layers of the vessel wall, the condition is known as aortic dissection. If an aortic or cardiac aneurysm bursts, there is sudden, massive internal bleeding (Centers for Disease Control and Prevention, n.d.-c).
People who smoke or have hypertension , hypercholesterolemia , and/or atherosclerosis have an increased risk of developing aneurysms. Having a family history of aneurysms or certain genetic diseases may also increase a person’s risk of developing an aneurysm.
Aneurysms can be asymptomatic and may be detected during diagnostic tests that are done for other reasons. They are sometimes repaired surgically and sometimes treated with medications such as antihypertensives (Centers for Disease Control and Prevention, n.d.-c; National Heart, Lung, and Blood Institute, n.d.). Visit the National Heart, Lung, and Blood Institute’s web page on aortic aneurysms to learn more.
Heart Defects
Fetal circulation is different from postnatal circulation. There are two extra openings in the fetal heart, the foramen ovale and the ductus arteriosus , which allow blood circulation that bypasses the immature fetal lungs. The fetal blood is reoxygenated by the mother’s lungs and transported between mother and fetus via the placenta. These two openings usually close around the time of birth.
Septal defects are commonly first detected through auscultation . Unusual heart sounds may be detected because blood is not flowing and valves are not closing correctly. Medical imaging is ordered to confirm or rule out a diagnosis. In many cases, treatment may not be needed.
- Patent ductus arteriosus is a congenital condition in which the ductus arteriosus fails to close. If untreated, the condition can result in congestive heart failure.
-
Patent foramen ovale
is one type of atrial septal defect (ASD), due to a failure of the hole in the
interatrial septum
to close at birth.
- As much as 20 to 25% of the general population may have a patent foramen ovale. Most have the benign, asymptomatic version but in extreme cases, a surgical repair is required to close the opening permanently.
-
Tetralogy of Fallot
is a congenital condition that may also occur from exposure to unknown environmental factors; it occurs when there is an opening in the
interventricular septum
caused by blockage of the pulmonary trunk, normally at the pulmonary semilunar valve. This allows blood that is relatively low in oxygen from the right ventricle to flow into the left ventricle and mix with the blood that is relatively high in oxygen.
- Signs and symptoms include a distinct heart murmur, low blood oxygen percent saturation, dyspnea , polycythemia , clubbing of the fingers and toes, and in children, difficulty in feeding or failure to grow and develop.
- It is the most common cause of cyanosis following birth. Other heart defects may also accompany this condition, which is typically confirmed by echocardiography imaging.
- In the case of severe septal defects, including both tetralogy of fallot and patent foramen ovale, failure of the heart to develop properly can lead to a condition commonly known as a blue baby. Regardless of normal skin pigmentation, individuals with this condition have an insufficient supply of oxygenated blood, which leads to cyanosis , especially when active.
Diseases Related to Coronary Circulation
Coronary Artery Disease (CAD)
Coronary artery disease occurs when the buildup of plaque in the coronary arteries obstructs the flow of blood and decreases compliance of the vessels. This condition is called atherosclerosis . As the disease progresses and coronary blood vessels become more and more narrow, cells of the myocardium become ischemic which causes symptoms of angina pectoris , in some patients. If untreated, coronary artery disease can lead to myocardial infarction (MI).
The image below shows the blockage of coronary arteries on an angiogram .
CAD is progressive and chronic. Risk factors include smoking, family history, hypertension , obesity, diabetes, high alcohol consumption, lack of exercise, stress, and hyperlipidemia . Treatments may include medication, changes to diet and exercise, angioplasty with a balloon catheter, insertion of a stent, or coronary artery bypass graft (CABG).
- Angioplasty is a procedure in which the occlusion is mechanically widened with a balloon. A specialized catheter with an expandable tip is inserted into a blood vessel in the arm or leg, and then directed to the site of the occlusion. At this point, the balloon is inflated to compress the plaque material and to open the vessel to increase blood flow. Once the balloon is deflated and retracted, a stent consisting of a specialized mesh is typically inserted at the site of occlusion to reinforce the weakened and damaged walls and prevent re-occlusion.
- Coronary bypass surgery (Coronary artery bypass graft CABG) is a surgical procedure which grafts a replacement vessel obtained from another part of the body to bypass the occluded area.
Myocardial Infarction
Myocardial infarction (MI) is the medical term for a heart attack.
A MI normally results from a lack of blood flow to a region of the heart, resulting in death of the cardiac muscle cells. A MI often occurs when a coronary artery is blocked by the buildup of atherosclerotic plaque. It can also occur when a piece of an atherosclerotic plaque breaks off and travels through the coronary arterial system until it lodges in one of the smaller vessels. MIs may be triggered by excessive exercise, in which the partially occluded artery is no longer able to pump sufficient quantities of blood, or severe stress, which may induce spasm of the smooth muscle in the walls of the vessel.
In the case of acute MI (AMI) , there is often sudden pain beneath the sternum (retrosternal pain) called angina pectoris, often radiating down the left arm in males but not in female patients. Other common signs and symptoms include dyspnea , palpitations , nausea and vomiting, diaphoresis , anxiety, and syncope . Many of the symptoms are shared with other medical conditions, including anxiety attacks and simple indigestion, so differential diagnosis is critical.
An MI can be confirmed by examining the patient’s ECG .
Other diagnostic tests include:
- echocardiography .
- CT .
- MRI .
- Common blood tests indicating an MI include elevated levels of creatine kinase MB and cardiac troponin , both of which are released by damaged cardiac muscle cells.
MIs may induce dangerous heart rhythms and even cardiac arrest. Important risk factors for MI include coronary artery disease, age, smoking, high blood levels of LDL , low levels of HDL , hypertension , diabetes mellitus , obesity, lack of physical exercise, chronic kidney disease, excessive alcohol consumption, and use of illegal drugs.
Did you know?
It is estimated that between 22 and 64% of myocardial infarctions present without any symptoms.
Diseases of the (Electrical) Conduction System
Arrhythmia
The heart’s natural pacemaker, the sinoatrial (SA) node initiates an electrical impulse 60 to 90 times per minute in a resting adult. This impulse travels through the heart’s conduction system in order to ensure a smooth, coordinated pumping action. This electrical activity can be detected and recorded through the skin using an electrocardiograph . Arrhythmias may occur when the SA node fails to initiate an impulse, or when the conduction system fails to transmit that impulse through the heart.
In the event that the electrical activity of the heart is severely disrupted, cessation of electrical activity or fibrillation may occur. In fibrillation, the heart beats in a wild, uncontrolled manner, which prevents it from being able to pump effectively.
- Atrial fibrillation is a serious condition, but as long as the ventricles continue to pump blood, the patient’s life may not be in immediate danger.
- Ventricular fibrillation is a medical emergency that requires life support, because the ventricles are not effectively pumping blood, left untreated ventricular fibrillation may lead to brain death.
The most common treatment is defibrillation which uses special paddles to apply a charge to the heart from an external electrical source in an attempt to establish a normal sinus rhythm. A defibrillator effectively stops the heart so that the SA node can trigger a normal conduction cycle. External automated defibrillators (EADs ) are being placed in areas frequented by large numbers of people, such as schools, restaurants, and airports. These devices contain simple and direct verbal instructions that can be followed by non-medical personnel in an attempt to save a life.
Did you know?
Arrhythmia does not mean an absence of a heartbeat. That would be asystole, or flat line. Arrhythmia is defined as the absence of a regular rhythm, meaning that the heart rate is either too fast, too slow or just irregular.
Abnormal Heart Rates
Bradycardia is the condition in which resting adult heart rate drops below 60 beats per minute (bpm). A client exhibiting signs and symptoms such as weakness, fatigue, dizziness, syncope , chest discomfort, palpitations, or respiratory distress may indicate that the heart is not providing sufficient oxygenated blood to the tissues. If the patient is not exhibiting symptoms then bradycardia is not considered clinically significant. The term relative bradycardia may be used with a patient who has a heart rate in the normal range but is still suffering from these symptoms. Most patients remain asymptomatic as long as the heart rate remains above 50 bpm.
Tachycardia is the condition in which the resting rate is above 100 bpm. Tachycardia is not normal in a resting patient and may be detected in pregnant women or individuals experiencing extreme stress. Some individuals may remain asymptomatic , but when present, signs and symptoms may include dizziness, shortness of breath, rapid pulse, heart palpitations, chest pain, or syncope. Treatment depends upon the underlying cause but may include medications, ablation , implantable cardioverter defibrillators , or surgery.
Heart Block
A heart block refers to an interruption in the normal conduction pathway. Heart blocks are generally named after the part of the conduction system that is causing the problem. For example, bundle branch blocks occur within either the left or right atrioventricular bundle branches.
AV blocks are often described by degrees. A first-degree or partial block indicates a delay in conduction between the SA and AV nodes. A second-degree or incomplete block occurs when some impulses from the SA node reach the AV node and continue, while others do not. In the third-degree or complete block , there is no correlation between atrial activity and ventricular activity. This means that none of the impulses generated by the SA node get transmitted to the rest of the heart and the AV node must take over as the primary pacemaker, initiating contractions at 40 to 60 bpm, which is adequate to maintain consciousness.
In order to speed up the heart rate and restore full sinus rhythm , a cardiologist can implant an artificial pacemaker , which delivers electrical impulses to the heart muscle to ensure that the heart continues to contract and pump blood effectively. These artificial pacemakers are programmable by the cardiologists and can either provide stimulation temporarily upon demand or on a continuous basis. Some devices also contain built-in defibrillators.
Medical Terms in Context
Medical Specialties Related to the Cardiovascular System
Cardiologists and Thoracic Surgeons
Cardiologists are medical doctors that specialize in diagnosing and treating heart diseases. After completing medical school, cardiologists must complete at least six more years of training (Betts et al., 2013). Thoracic surgeons provide surgical treatments on the heart and other thoracic organs (National Cancer Institute, n.d.). For more information, visit the American College of Cardiology Foundation’s web page on cardiologists .
Cardiology Technologists
Cardiology technologists complete a college training program and perform diagnostic tests such as electrocardiography and stress testing, as well as pacemaker monitoring (Bureau of Labor Statistics, 2021). Please visit the Bureau of Labor Statistics’ web page on cardiology technologists for more information.
Cardiovascular Perfusionists
Cardiovascular perfusionists complete a college training program and are responsible for operation of the heart-lung bypass machine during open heart surgery. They also monitor the patient’s vitals and administer medications (New York State Education Department, 2020). For more information, please read this job description from the American Board of Cardiovascular Perfusion (PDF) .
Cardiovascular System Vocabulary
Ablation : The removal or destruction of a body part or tissue or its function. Ablation may be performed by surgery, hormones, drugs, radiofrequency, heat, or other methods.
Aneurysm : Weakening of the wall of a blood vessel, causing it to thin and balloon out, and possibly eventually burst, resulting in internal bleeding.
Angina pectoris: Chest pain. It may be a symptom of coronary artery disease and myocardial infarction.
Angiogram : An x-ray or computer image (CT scan or MRI) of the blood vessels and blood flow in the body. A dye may be injected through a catheter (small tube) into an artery or vein to make the blood vessels easier to see.
Antihypertensives: A class of medications used to treat high blood pressure.
Arrhythmia : A deviation from the normal pattern of impulse conduction and contraction of the heart.
Asymptomatic : Having no signs or symptoms of disease.
Atherosclerosis : A hardening of the arteries that involves the accumulation of plaque.
Auscultation : Listening to the heart using a stethoscope.
Atrioventricular (AV) : The area of the heart where the atria and ventricles meet.
Atrioventricular (AV) valves : Mitral (bicuspid) valve that allows blood to flow from left atrium to left ventricle and tricuspid valve that allows blood to flow from right atrium to right ventricle.
Bradycardia : A condition in which the heart beats slower than 50 beats per minute.
Cardiac : Having to do with the heart.
Cardiac troponin : The regulatory protein for muscle contraction.
Cardiogenic : Originating from the heart.
Cardiologist : A physician who studies and treats diseases of the heart.
Cardiology : The study of the heart.
Cardiomegaly : Enlarged heart.
Cardiomyopathy : Disease of the heart muscle.
Compliance : The ability of the blood vessels to dilate and constrict as needed.
Computerized tomography (CT) : A noninvasive imaging technique that uses computers to analyze several cross-sectional X-rays in order to reveal minute details about structures in the body.
Congenital : Present at birth.
Creatine kinase MB : An enzyme that catalyzes the conversion of creatine to phosphocreatine, consuming ATP.
Cyanosis: A condition in which the oxygen supply is restricted, causing the skin to look blue.
Diabetes mellitus : A disease in which the body does not control the amount of glucose (a type of sugar) in the blood and the kidneys make a large amount of urine. This disease occurs when the body does not make enough insulin or does not use it the way it should.
Diaphoresis : Sweating.
Diastole : Period of time when the heart muscle is relaxed and the chambers fill with blood.
Ductus arteriosus : A temporary connection between pulmonary trunk and aorta in the fetal heart.
Dyspnea : Difficulty breathing.
Echocardiogram : A computer picture of the heart created by bouncing high-energy sound waves (ultrasound) off internal tissues or organs of the chest.
Echocardiography : A procedure that uses high-energy sound waves (ultrasound) to look at tissues and organs inside the chest.
Electrocardiogram (ECG/EKG) : The record of the heart’s function produced by the electrocardiograph.
Electrocardiograph : The instrument that generates an electrocardiogram (ECG); 10 electrodes are placed in standard locations on the patient’s skin to record heart function.
Electrocardiography : The science of recording the electrical activity of the heart.
Endocarditis : A condition in which the tissues lining the inside of the heart and the heart valves become inflamed.
Foramen ovale: An opening between right and left atria, which is normal in the fetal heart.
Great vessels: Include the superior vena cava, inferior vena cava, aorta and pulmonary trunk.
Heart murmur : An abnormal heart sound.
Heart rate : The number of times the heart beats within a certain time period, usually a minute.
High-density lipoprotein (HDL) : Often referred to as “good” cholesterol.
Hypercholesterolemia: Higher than normal levels of cholesterol in the blood.
Hyperlipidemia: Excessive fat in the blood.
Hypertension: Abnormally high blood pressure.
Implantable cardioverter defibrillators (ICD) : A small device placed by surgery in the chest or abdomen that is used to correct a heartbeat that is abnormal. Wires are passed through a vein to connect the device to the heart. When it detects abnormal heartbeats, it sends an electrical shock to the heart to restore the heartbeat to normal.
Inferior vena cava : One of the two largest veins in the body. It carries deoxygenated blood from the torso and legs back to the heart.
Interatrial septum : The wall separating the right and left atria.
Interventricular septum : The wall of myocardium that separates the right and left ventricles.
Ischemia : Lack of blood flow to body tissues.
Low-density lipoprotein (LDL) : Often referred to as ‘bad’ cholesterol.
Magnetic Resonance Imaging (MRI) : A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body.
Mitral valve: Located at the opening between the left atrium and left ventricle; also known as the bicuspid valve.
Myocardial infarction (MI) : Heart attack, caused by lack of blood flow and oxygen to the heart.
Myocarditis : A rare condition in which the heart muscle becomes thick and inflamed and may also become weak.
Occlusion : A blockage.
Pacemaker : An electronic device that is implanted in the body to monitor heart rate and rhythm. It gives the heart electrical stimulation when it does not beat normally.
Palpitations : A rapid or irregular heartbeat that a person can feel.
Pericardial fluid : Watery fluid produced in the serous and visceral pericardium surrounding the surface of the heart.
Pericarditis : Inflammation of the (sac) surrounding the heart.
Pericardiocentesis : Surgical puncture to aspirate fluid from the (sac) surrounding the heart.
Plaque : A fatty material including cholesterol, connective tissue, white blood cells, and some smooth muscle cells.
Polycythemia : A rare disorder in which the bone marrow produces an abnormally large amount of blood cells.
Pulmonary trunk: The very large artery referred to as a trunk, a term indicating that the vessel gives rise to several smaller arteries.
Roots of the great vessels : The part of each great vessel (aorta, pulmonary trunk, inferior vena cava, superior vena cava) that connects to the base of the heart.
Serous membrane : One of the thin membranes that cover the walls and organs in the thoracic and abdominopelvic cavities.
Sinus rhythm : The normal electrical pattern followed by contraction of the heart.
Sphygmomanometer : A blood pressure cuff attached to a measuring device.
Stethoscope : An instrument used to hear sounds produced by the heart, lungs, or other parts of the body.
Superior vena cava : One of two large veins in the body, which carries deoxygenated blood from the head and upper extremities back to the heart.
Syncope : Fainting.
Systole : Period of time when the heart muscle is contracting.
Tachycardia : A condition in which the resting rate is above 100 bpm.
Valvuloplasty : The widening of a stenosed heart valve using a balloon catheter.
Test Yourself
References
Bureau of Labor Statistics. (2021). Medical sonographers and cardiovascular technologists and technicians. In Occupational outlook handbook . U.S. Department of Labor. https://www.bls.gov/ooh/healthcare/diagnostic-medical-sonographers.htm
Centers for Disease Control and Prevention. (n.d.-a). Cardiomyopathy . CDC. https://www.cdc.gov/heartdisease/cardiomyopathy.htm
Centers for Disease Control and Prevention. (n.d.-b). Valvular heart disease . CDC. https://www.cdc.gov/heartdisease/valvular_disease.htm
Centers for Disease Control and Prevention. (n.d.-c). Aortic aneurysm . CDC. https://www.cdc.gov/heartdisease/aortic_aneurysm.htm
CrashCourse. (2015, July 6). The heart, part 1 – under pressure: Crash course A&P #25 [Video]. YouTube. https://youtu.be/X9ZZ6tcxArI
CrashCourse. (2015, July 13). The heart, part 2 – heart throbs: Crash course A&P #26 [Video]. YouTube. https://youtu.be/FLBMwcvOaEo
National Heart, Lung, and Blood Institute. (n.d.). Aortic aneurysm . National Institutes of Health, U.S. Department of Health and Human Services. https://www.nhlbi.nih.gov/health-topics/aneurysm
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Image Descriptions
Figure 9.1 image description: This diagram shows the location of the heart in the thorax (sagittal and anterior views). The sagittal view labels read (from top, clockwise): first rib, aortic arch, thoracic arch, esophagus, inferior vena cava, diaphragm, thymus, trachea. The anterior view labels read (from top, clockwise): mediastinum, arch of aorta, pulmonary trunk, left auricle, left lung, left ventricle, pericardial cavity, apex of heart, edge of parietal pericardium, diaphragm, edge of parietal pleura, ribs, right ventricle, right atrium, right auricle, right lung, superior vena cava. [Return to Figure 9.1].
Figure 9.2 image description: This image shows a magnified view of the structure of the heart wall. Labels read (from top, clockwise): pericardial cavity, fibrous pericardium, parietal layer of serous pericardium, epicardium (visceral layer of serous pericardium), myocardium, endocardium. [Return to Figure 9.2].
Figure 9.3 image description: This diagram shows the network of blood vessels in the lungs. Labels read (from top, clockwise (left-side of the body): aortic arch, pulmonary trunk, left lung, left pulmonary arteries, left pulmonary vein, pulmonary capillaries, descending aorta, (right side of body) inferior vena cava, right pulmonary veins, right pulmonary arteries, right lung, superior vena cava, ascending aorta. [Return to Figure 9.3].
Figure 9.4 image description: The top panel shows the human heart with the arteries and veins labeled (from top, clockwise): aorta, left pulmonary arteries, pulmonary trunk, left atrium, left pulmonary veins, aortic semilunar valve, mitral valve, left ventricle, inferior vena cava, right ventricle, tricuspid valve, right atrium, pulmonary semilunar valve, right pulmonary veins, right pulmonary arteries, superior vena cava. The bottom panel shows a rough map of the human circulatory system. Labels read (from top, clockwise): systemic capillaries of upper body, systemic arteries to upper body, pulmonary trunk, left atrium, left ventricle, systemic arteries to lower body, systemic capillaries of lower body, systemic veins from lower body, right ventricle, right atrium, pulmonary capillaries in lungs, systemic veins from upper body. [Return to Figure 9.4].
Figure 9.5 image description: The top panel of this figure shows the anterior view of the heart while the bottom panel shows the posterior view of the heart. The different blood vessels are labeled. Anterior view labels (from top of diagram, clockwise): left coronary artery, pulmonary trunk, circumflex artery, anterior interventricular artery, great cardiac vein, small cardiac vein, anterior cardiac veins, atrial arteries, right atrium, right coronary artery, ascending aorta, aortic arch. Posterior view labels (from top of diagram, clockwise): coronary sinus, small cardiac vein, right coronary artery, marginal artery, middle cardiac vein, posterior cardiac vein, posterior interventricular artery, marginal artery, great cardiac vein, circumflex artery. [Return to Figure 9.5].
Figure 9.6 image description: This image shows the anterior view of the frontal section of the heart with the major parts labeled. Labels read (from top of diagram, clockwise) arch of aorta, Bachman’s bundle, atrioventricular bundle (bundle of His), left ventricle, right and left bundle branches, Purkinje fibers, right ventricle, right atrium, posterior intermodal, middle intermodal, atrioventricular node, anterior intermodal, Sinoatrial node. [Return to Figure 9.6].
Figure 9.7 image description: This diagram shows the six different stages of heart contraction and relaxation along with the stages in the QT cycle. [Return to Figure 9.7].
Figure 9.8 image description: This diagram shows the arteries in the thoracic and abdominal cavity. Visceral branches of the thoracic aorta labels (from top): bronchial, esophageal, mediastinal, pericardial, thoracic aorta, aortic hiatus, celiac trunk, left gastric, splenic, common hepatic, superior mesenteric, abdominal aorta, inferior mesenteric, external iliac. Parietal (somatic) branches of thoracic aorta labels (from top): intercostal, superior phrenic, inferior phrenic, diaphragm, adrenal, renal, gonadal, lumbar, medial sacral, common iliac, internal iliac. [Return to Figure 9.8].
Figure 9.9 image description: This diagram shows the structure of the heart with different congenital defects. The top left panel shows patent foramen ovale (label reads foramen ovale fails to close), the top right panel shows coarctation of the aorta (label reads narrow segment of aorta), the bottom left panel shows patent ductus arteriosus (label reads Ductus arteriosus remains open) and the bottom right shows tetralogy of fallot (labels read aorta emerges from both ventricles, interventricular septal defect, enlarged right ventricle, stenosed pulmonary semilunar valve). [Return to Figure 9.9].
Figure 9.10 image description: An angiogram of atherosclerotic coronary arteries. The image shows blockages in the common trunk of the left coronary artery and circumflex artery. Blockages can cause ischemia, hypoxia, and myocardial infarction. [Return to Figure 9.10].
Figure 9.11 image description: In this image the QT cycle for different heart conditions are shown. From top to bottom, the arrhythmias shown are second-degree partial blocks (text reads: Note how half of the P waves are not followed by the QRS complex and T waves while the other half are. Question: what would you expect to happen to heart rate?), atrial fibrillation (text reads: Note the abnormal electric pattern prior to the QRS complexes. Also note how the frequency between the QRS complexes has increased. Question: What would you expect to happen to heart rate?), ventricular tachycardia (text reads: Note the unusual shape of the QRS complex, focusing on the S component. Question: What would you expect to happen to heart rate?), ventricular fibrillation (text reads: Note the total lack of normal electrical activity. Question: What would you expect to happen to heart rate?), and third degree block (text reads: Note that in a third-degree block some of the impulses initiated by the SA node do not reach the AV node while others do. Also note that the P waves are not followed by the QRS complex. Question: What would you expect to happen to heart rate?). [Return to Figure 9.11].
Unless otherwise indicated, this chapter contains material adapted from Anatomy and Physiology (on OpenStax ), by Betts et al. and is used under a CC BY 4.0 international license . Download and access this book for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction .