BIO100 Chptr 15 Cardiovascular System Flashcards
angio-
angio-, vessel: angiotensin—substance that constricts blood vessels.
ather-
ather-, porridge: atherosclerosis—deposits of plaque in arteries.
brady-
brady-, slow: bradycardia—abnormally slow heartbeat.
diastol-
diastol-, dilation: diastolic pressure—blood pressure when the ventricle of the heart is relaxed.
edem-
edem-, swelling: edema—accumulation of fluids in the tissues that causes them to swell.
-gram
-gram, something written: electrocardiogram —recording of the electrical changes in the myocardium during a cardiac cycle.
lun-
lun-, moon: semilunar valve—valve with crescent-shaped flaps.
myo-
myo-, muscle: myocardium—muscle tissue within the wall of the heart.
papill-
papill-, nipple: papillary muscle—small mound of muscle projecting into a ventricle of the heart.
phleb-
phleb-, vein: phlebitis—inflammation of a vein.
scler-
scler-, hard: arteriosclerosis—loss of elasticity and hardening of a blood vessel wall.
syn-
syn-, together: syncytium—mass of merging cells that act together.
systol-
systol-, contraction: systolic pressure—blood pressure resulting from a single ventricular contraction.
tachy-
tachy-, rapid: tachycardia—abnormally fast heartbeat.
The term “cardiovascular” refers to
both the heart and the blood vessels.
.The pumping action of the heart moves blood through the body’s blood vessels. The blood vessels form two circuits. The pulmonary (pul′mo-ner″e) circuit sends oxygen-poor blood to the lungs to pick up oxygen and unload carbon dioxide. The systemic (sistem′ik) circuit sends oxygen-rich blood and nutrients to all body cells and removes wastes.
pulmonary (pul′mo-ner″e) circuit
sends oxygen-poor blood to the lungs to pick up oxygen and unload carbon dioxide.
systemic (sistem′ik) circuit
systemic (sistem′ik) circuit sends oxygen-rich blood and nutrients to all body cells and removes wastes.
The heart is
The heart is a hollow, cone-shaped, muscular pump. It is in the mediastinum of the thoracic cavity, superior to the diaphragm.
Size and Location of the Heart
Heart size varies with body size. An average adult’s heart is generally about 14 centimeters long and 9 centimeters wide.
The heart is bordered laterally by the lungs, posteriorly by the vertebral column, and anteriorly by the sternum and reference plates 10, 16, 21, and 22. The base of the heart, which attaches to several large blood vessels, lies beneath the second rib. The heart’s inferior end extends downward and to the left, terminating as a bluntly pointed apex at the level of the fifth intercostal space. Because of the heart’s location, it is possible to detect the apical heartbeat by feeling or listening to the chest wall between the fifth and sixth ribs, about 7.5 centimeters to the left of the midline.
Coverings of the Heart
pericardium (per″i-kar′de-um), or pericardial sac, is a covering that encloses the heart and the proximal ends of the large blood vessels to which it attaches. The pericardium consists of an outer fibrous bag, the fibrous pericardium, that surrounds a more delicate, double-layered serous membrane. The innermost layer of this serous membrane, the visceral pericardium (epicardium), covers the heart. At the base of the heart, the visceral pericardium turns back upon itself to become the parietal pericardium, which covers the inner surface of the fibrous pericardium
Wall of the Heart
The wall of the heart is composed of three distinct layers: an outer epicardium, a middle myocardium, and an inner endocardium
epicardium (ep″ĭ-kar′de-um)
which corresponds to the visceral pericardium, protects the heart by reducing friction. It is a serous membrane that consists of connective tissue covered by epithelium, and it includes capillaries and nerve fibers. The deeper portion of the epicardium typically contains adipose tissue, particularly along the paths of coronary arteries and cardiac veins that provide blood flow through the myocardium.
myocardium (mi″okar′de-um),
middle layer of the heart wall, or myocardium (mi″okar′de-um), is thick and consists largely of the cardiac muscle tissue that pumps blood out of the heart chambers. The muscle fibers lie in planes that are separated by connective tissues richly supplied with blood capillaries, lymph capillaries, and nerve fibers.
endocardium (en″dokar′de-um
The inner layer of the heart wall, or endocardium (en″dokar′de-um), consists of epithelium and underlying connective tissue that contains many elastic and collagen fibers. The endocardium also contains blood vessels and covers some specialized cardiac cells called Purkinje fibers, The Heart, Cardiac Conduction System.
The endocardium lines all of the heart chambers and covers the structures, such as the heart valves, that project into them. This inner lining is also continuous with the inner linings (endothelium) of the blood vessels attached to the heart and throughout the cardiovascular system.
Heart Chambers and Valves
Internally the heart is divided into four hollow chambers, two on the left and two on the right.
- The upper chambers, called atria
- The lower chambers, the ventricles
auricles
Small, earlike projections called auricles extend anteriorly from the atria, slightly increasing atrial volume.
ventricles
The lower chambers, the ventricles, force the blood out of the heart into arteries.
atria
The upper chambers, called atria (sing., atrium), have thin walls and receive blood returning to the heart.
interatrial septum
separates the right from the left atrium
interventricular
septum separates the two ventricles
atrioventricular orifice
The atrium on each side communicates with its corresponding ventricle through an opening called the atrioventricular orifice (a″tre-o-ven-trik′u-lar ori-fis), which is guarded by an atrioventricular valve (AV valve).
atrioventricular (coronary) sulcus
of the heart demarcates the borders of the underlying atria from the ventricles. It is a continuous sulcus but it has been described as right and left parts in the following section for the purposes of description.
interventricular (anterior and posterior) sulci
mark the septum that separates the right and left ventricles
vena cavae, two large veins:
the superior vena cava and the inferior vena cava.
vena cavae, two large veins: the superior vena cava and the inferior vena cava. These veins return blood, which is low in oxygen, from tissues. A smaller vein, the coronary sinus, also drains venous blood into the right atrium from the myocardium of the heart.
large tricuspid valve (right atrioventricular valve)
guards the atrioventricular orifice between the right atrium and the right ventricle. It is composed of three leaflets, or cusps, as its name implies. This valve permits the blood to move from the right atrium into the right ventricle and prevents it from moving in the opposite direction.
chordae tendineae
attach to the cusps of the tricuspid valve on the ventricular side. These strings originate from small mounds of cardiac muscle tissue, the papillary muscles (pap′ĭ-ler″e mus′elz), that project inward from the walls of the ventricle (see fig. 15.7). The papillary muscles contract when the right ventricle contracts. As the tricuspid valve closes, these muscles pull on the chordae tendineae and prevent the cusps from swinging back (prolapsing) into the right atrium.
pulmonary trunk
A vessel that arises from the right ventricle of the heart, extends upward, and divides into the right and left pulmonary arteries that convey unaerated blood to the lungs.
pulmonary valve (pulmonary semilunar valve), which consists of three cusps
the pulmonic valve prevents regurgitation of deoxygenated blood from the pulmonary artery back to the right ventricle. It is a semilunar valve with 3 cusps, and it is located anterior, superior, and slightly to the left of the aortic valve. An image depicting the pulmonary valve can be seen below.
four pulmonary veins—two from the right lung and two from the left lung.
The left atrium receives the blood from the lungs through four pulmonary veins—two from the right lung and two from the left lung. The blood passes from the left atrium into the left ventricle through the atrioventricular orifice, which a valve guards. This valve consists of two leaflets and is named the mitral valve (shaped like a mitre, a type of headpiece), also called the bicuspid valve or left atrioventricular valve. It prevents the blood from flowing back into the left atrium from the left ventricle when the ventricle contracts.
mitral valve (shaped like a mitre, a type of headpiece), also called the bicuspid valve or left atrioventricular valve.
mitral valve (shaped like a mitre, a type of headpiece), also called the bicuspid valve or left atrioventricular valve. It prevents the blood from flowing back into the left atrium from the left ventricle when the ventricle contracts. As with the tricuspid valve, the papillary muscles and the chordae tendineae prevent the cusps of the mitral valve from swinging back (prolapsing) into the left atrium.
Mitral valve prolapse (MVP)
Improper closure of the valve between the heart’s upper and lower left chambers.
Mitral valve prolapse can develop at any age. It can run in families and may be linked to other conditions, such as infection and connective tissue disease.
Symptoms may include an irregular heartbeat, palpitations, and shortness of breath.
Most people don’t require treatment, but some cases may need medication or surgery.
aorta
the main artery of the body, supplying oxygenated blood to the circulatory system. In humans it passes over the heart from the left ventricle and runs down in front of the backbone.
aortic valve (aortic semilunar valve)
At the base of the aorta is an aortic valve (aortic semilunar valve) which consists of three cusps. It opens and allows blood to leave the left ventricle as it contracts. When the ventricular muscles relax, this valve closes and prevents blood from backing up into the left ventricle.
skeleton of the heart
The cardiac skeleton consists of four bands of dense connective tissue, as collagen, that encircle the bases of the pulmonary trunk, aorta, and heart valves. While not a “true” skeleton, it does provide structure and support for the heart, as well as isolate the atria from the ventricles.
Blood Flow Through the Heart
Blood low in oxygen (oxygen-poor blood) and high in carbon dioxide enters the right atrium through the venae cavae and the coronary sinus. As the right atrial wall contracts, the blood passes through the right atrioventricular orifice and enters the chamber of the right ventricle
Blood Supply to the Heart
The first two branches of the aorta, called the right and left coronary arteries, supply blood to the tissues of the heart. Their openings lie just superior to the aortic valve
Blood Supply to the Heart - posterior interventricular artery
which travels along the posterior interventricular sulcus and supplies the posterior walls of both ventricles, and a right marginal branch, which passes along the lower border of the heart. The right marginal branch supplies the walls of the right atrium and the right ventricle
Blood Supply to the Heart - One branch of the left coronary artery, the circumflex branch
One branch of the left coronary artery, the circumflex branch, following the atrioventricular sulcus between the left atrium and the left ventricle encircles the heart and travels posteriorly. Its branches supply blood to the walls of the left atrium and the left ventricle. Another branch of the left coronary artery, the anterior interventricular artery (or left anterior descending artery), lies in the anterior interventricular sulcus. Its branches supply the walls of both ventricles
collateral circulation
is the alternate circulation around a blocked artery or vein via another path, such as nearby minor vessels.
anastomoses
An anastomosis is a connection or opening between two things that are normally diverging or branching, such as between blood vessels, leaf veins, or streams.
thrombus or embolus -
A thrombus or embolus that partially blocks or narrows a coronary artery branch causes a decrease in blood flow called ischemia. This deprives myocardial cells of oxygen, producing a painful condition called angina pectoris. The pain usually happens during physical activity, when oxygen demand exceeds supply. Pain lessens with rest. Emotional disturbance may also trigger angina pectoris.
angina pectoris
is the medical term for chest pain or discomfort due to coronary heart disease.
ischemia
an inadequate blood supply to an organ or part of the body, especially the heart muscles.
Profuse perspiration (diaphoresis)
refers to excessive sweating for no apparent reason. Often, an underlying medical condition or a natural life event, such as menopause, cause this type of sweating. Sweat is the body’s natural way to control its temperature.
difficulty breathing (dyspnea)
Shortness of breath — known medically as dyspnea — is often described as an intense tightening in the chest, air hunger, difficulty breathing, breathlessness or a feeling of suffocation.
coronary thrombosis
is the formation of a blood clot inside a blood vessel of the heart. This blood clot restricts blood flow within the heart. It is associated with narrowing of blood vessels subsequent to clotting. The condition is considered as a type of ischaemic heart disease.
myocardial infarction (MI)
A blockage of blood flow to the heart muscle.
Called a heart attack
cardiac veins
Branches of the cardiac veins drain blood that has passed through the capillaries of the myocardium. Their paths roughly parallel those of the coronary arteries, these veins join the coronary sinus.
coronary sinus
the coronary sinus, which is an enlarged vein on the posterior surface of the heart in the atrioventricular sulcus. The coronary sinus empties into the right atrium. - the path of blood that supplies the tissues of the heart.
Cardiac Cycle
is the performance of the human heart from the ending of one heartbeat to the beginning of the next. It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following a period of robust contraction and pumping of blood, dubbed systole.
Heart Sounds
A heartbeat heard through a stethoscope sounds like “lubb-dupp.” These sounds are due to vibrations in the heart tissues produced as the blood flow is suddenly slowed with the contraction and relaxation of the heart chambers and with the closing of the valves.
- The first part of a heart sound (lubb) occurs during ventricular systole, when the AV valves close. The second part (dupp) occurs during ventricular diastole, when the pulmonary and aortic valves close.
Using a stethoscope, it is possible to hear sounds associated with the aortic and pulmonary valves
by listening from the second intercostal space on either side of the sternum. The aortic sound comes from the right, and the pulmonic sound from the left. The sound associated with the mitral valve can be heard from the fifth intercostal space at the nipple line on the left. The sound of the tricuspid valve can be heard at the fifth intercostal space just to the left of the sternum
endocarditis
is an infection of the endocardium, which is the inner lining of your heart chambers and heart valves. Endocarditis generally occurs when bacteria, fungi or other germs from another part of your body, such as your mouth, spread through your bloodstream and attach to damaged areas in your heart.
murmur
A heart murmur is an unusual sound heard between heartbeats. Murmurs sometimes sound like a whooshing or swishing noise. Murmurs may be harmless, also called innocent, or abnormal.
Cardiac Muscle Cells
Recall that cardiac muscle cells function like skeletal muscle cells, but the cardiac muscle cells connect in branching networks. The intercalated discs, which include gap junctions, join cardiac muscle cells, allowing action potentials to spread throughout a network of cells . As a result, cardiac muscle cells contract as a unit. They also have 1-2 nuclei
functional syncytium (funk′shun-al sin-sish′e-um).
A mass of merging cells that act as a unit - Two such structures are in the heart—in the atrial walls and in the ventricular walls. Portions of the heart’s fibrous skeleton separate these masses of cardiac muscle, except for a small area in the right atrial floor. In this region, specialized conduction fibers connect the atrial syncytium and the ventricular syncytium.
autorhythmic
able to initiate contraction itself without external nervous stimulation
cardiac conduction system
is a group of specialized cardiac muscle cells in the walls of the heart that send signals to the heart muscle causing it to contract. The main components of the cardiac conduction system are the SA node, AV node, bundle of His, bundle branches, and Purkinje fibers.
Purkinje fibers
are networks of fibers that receive conductive signals originating at the atrioventricular node (AVN), and simultaneously activate the left and right ventricles by directly stimulating the ventricular myocardium.
SA node (sinoatrial node or sinuatrial node)
SA node (sinoatrial node or sinuatrial node), which is a small, elongated mass of specialized cardiac muscle tissue just beneath the epicardium. It is in the right atrium near the opening of the superior vena cava, and its cells are continuous with those of the atrial syncytium.
an SA node reaches threshold and triggers an action potential on its own.
Action Potential at the SA Node. The prepotential is due to a slow influx of sodium ions until the threshold is reached followed by a rapid depolarization and repolarization. The prepotential accounts for the membrane reaching threshold and initiates the spontaneous depolarization and contraction of the cell.
The SA node is also called the pacemaker because it initiates the heart’s rhythmic contractions
The SA node is the heart’s natural pacemaker. The SA node consists of a cluster of cells that are situated in the upper part of the wall of the right atrium (the right upper chamber of the heart). The electrical impulses are generated there. The SA node is also called the sinus node.
internodal atrial muscle
It is a broad band of cardiac muscle that passes from the right atrium, between the superior vena cava and the ascending aorta. Bachmann’s bundle is, during normal sinus rhythm, the preferential path for electrical activation of the left atrium.
junctional fibers
(conducting fiber of heart) Located in Atria, they distribute the AP throughout the atria, then carry AP to the AV NODE. Bundle of H.I.S (AV Bundle) (conducting fibers of heart) Located in interventricular septum, they connect to the AV Node.
*P Wave. The P wave represents the depolarization of the left and right atrium and also corresponds to atrial contraction.
AV node (atrioventricular node)
which controls the heart rate, is one of the major elements in the cardiac conduction system. The AV node serves as an electrical relay station, slowing the electrical current sent by the sinoatrial (SA) node before the signal is permitted to pass down through to the ventricles.
AV bundle (atrioventricular bundle or bundle of His)
is a continuation of the specialised tissue of the AV node, and serves to transmit the electrical impulse from the AV node to the Purkinje fibres of the ventricles. … Left bundle branch - conducts the impulse to the Purkinje fibres of the left ventricle.
Electrocardiogram (ECG, EKG)
is a recording of the electrical changes in the myocardium during a cardiac cycle. (This pattern occurs as action potentials stimulate cardiac muscle cells to contract, but it is not the same as individual action potentials.) Because body fluids can conduct electrical currents, such changes can be detected on the surface of the body.
accelerator nerves
Sympathetic fibers reach the heart by means of the accelerator nerves, whose branches join the SA and AV nodes as well as other areas of the atrial and ventricular myocardium. The endings of these fibers secrete norepinephrine in response to series of action potentials. Norepinephrine increases the rate and force of myocardial contractions.
baroreceptor reflexes
The baroreflex or baroreceptor reflex is one of the body’s homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels.
cardioinhibitor reflex center
Cardioinhibitory syncope (CS) is a neurally mediated response causing bradycardia or asystole. This study reports on changes in blood pressure, heart rate variability (HRV), and ECG patterns before and after syncope with asystole.
cardioaccelerator reflex center.
stimulates cardiac function by regulating heart rate and stroke volume via sympathetic stimulation from the cardiac accelerator nerve. - Baroreceptors that detect stretch can also signal to the cardiovascular center to alter heart rate.
The most important ions that influence heart action are
potassium (K+) and calcium (Ca+2)
An excess of potassium ions in the blood (hyperkalemia)
An excess of potassium ions in the blood (hyperkalemia) decreases the rate and force of myocardial contractions. If the potassium ion concentration in the blood drops below normal (hypokalemia), the heart may develop a potentially life- threatening abnormal rhythm.
An excess of calcium ions in the blood (hypercalcemia)
An excess of calcium ions in the blood (hypercalcemia) increases heart action, which can result in dangerously extended heart contractions. Conversely, a low blood calcium concentration (hypocalcemia) depresses heart action. - arrhythmias, abnormal heart rhythms.
The blood vessels are organs of the cardiovascular system
They form a closed circuit of tubes that carries blood from the heart to the body cells and back again. These vessels include arteries, arterioles, capillaries, venules, and veins. The arteries and arterioles conduct blood away from the ventricles of the heart and lead to the capillaries, where substances are exchanged between blood and the body cells. Venules and veins return blood from the capillaries to the atria.
Arteries
Arteries are strong, elastic vessels adapted for transporting blood away from the heart under relatively high pressure. These vessels subdivide into progressively thinner tubes and eventually give rise to the finer, branched arterioles.
arterioles
a small branch of an artery leading into capillaries.
tunics - The wall of an artery consists of three distinct layers.
The wall of an artery consists of three distinct layers.
- The innermost tunic, tunica interna (intima), is composed of a layer of simple squamous epithelium, called endothelium, that rests on a connective tissue membrane rich in elastic and collagen fibers.
- The middle layer, tunica media, makes up the bulk of the arterial wall. It includes smooth muscle cells, which encircle the tube, and a thick layer of elastic connective tissue.
- The outer layer, tunica externa (adventitia), is relatively thin and chiefly consists of connective tissue with irregular elastic and collagen fibers.
platelets
a small colorless disk-shaped cell fragment without a nucleus, found in large numbers in blood and involved in clotting.
Arrhythmias
An arrhythmia is a problem with the rate or rhythm of your heartbeat. It means that your heart beats too quickly, too slowly, or with an irregular pattern. When the heart beats faster than normal, it is called tachycardia.
Altering Angiogenesis
Angiogenesis is the formation of new blood vessels, usually from the extension of preexisting vessels. Under the influence of vascular endothelial growth factor (VEGF), endothelial cells divide and assemble into the tubules that form capillaries as well as the innermost linings of larger blood vessels.
Vasomotor fibers
of, relating to, affecting, or being those nerves or the centers (as in the medulla and spinal cord) from which they arise that supply the muscle fibers of the walls of blood vessels, include sympathetic vasoconstrictors and parasympathetic vasodilators, and by their effect on vascular diameter regulate the amount of
