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Cardiovascular System Anatomy and Physiology Study Guide for Nurses-columbia southern university

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HOME » NOTES » ANATOMY & PHYSIOLOGY » CARDIOVASCULAR SYSTEM ANATOMY AND PHYSIOLOGY

Cardiovascular System Anatomy and

Physiology

UPDATED ON FEBRUARY 11, 2021 BY MARIANNE BELLEZA, R.

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The almost continuous traffic into and out of a busy factory at rush hour occurs at a snails’ pace compared to the endless activity going on within our bodies. Like the bustling factory, the body must have a transportation system to carry its various cargos back and forth, and this is where the cardiovascular system steps in.

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  1. Functions of the Heart
  2. Anatomy of the Heart
    1. Heart Structure and Functions
    2. Layers of the Heart
    3. Chambers of the Heart
    4. Associated Great Vessels
    5. Heart Valves
    6. Cardiac Circulation Vessels
    7. Blood Vessels
    8. Tunics
    9. Major Arteries of the Systemic Circulation
    10. Major Veins of the Systemic Circulation
  3. Physiology of the Heart
    1. Intrinsic Conduction System of the Heart
    2. The Pathway of the Conduction System
    3. Cardiac Cycle and Heart Sounds
    4. Cardiac Output
    5. Physiology of Circulation
    6. Cardiovascular Vital Signs
    7. Blood Circulation Through the Heart

Weight. Approximately the size of a person’s fist, the hollow, cone-shaped heart weighs less than a pound. Mediastinum. Snugly enclosed within the inferior mediastinum, the medial cavity of the thorax, the heart is flanked on each side by the lungs. Apex. It’s more pointed apex is directed toward the left hip and rests on the diaphragm, approximately at the level of the fifth intercostal space. Base. Its broad posterosuperior aspect, or base, from which the great vessels of the body emerge, points toward the right shoulder and lies beneath the second rib. Pericardium. The heart is enclosed in a double-walled sac called the pericardium and is the outermost layer of the heart. Fibrous pericardium. The loosely fitting superficial part of this sac is referred to as the fibrous pericardium, which helps protect the heart and anchors it to surrounding structures such as the diaphragm and sternum. Serous pericardium. Deep to the fibrous pericardium is the slippery, two-layer serous pericardium, where its parietal layer lines the interior of the fibrous pericardium.

Layers of the Heart

The heart muscle has three layers and they are as follows:

Epicardium. The epicardium or the visceral and outermost layer is actually a part of the heart wall. Myocardium. The myocardium consists of thick bundles of cardiac muscle twisted and whirled into ringlike arrangements and it is the layer that actually contracts. Endocardium. The endocardium is the innermost layer of the heart and is a thin, glistening sheet of endothelium hat lines the heart chambers.

Chambers of the Heart

The heart has four hollow chambers, or cavities: two atria and two ventricles.

Receiving chambers. The two superior atria are primarily the receiving chambers, they play a lighter role in the pumping activity of the heart. Discharging chambers. The two inferior, thick-walled ventricles are the discharging chambers, or actual pumps of the heart wherein when they contract, blood is propelled out of the heart and into the circulation. Septum. The septum that divides the heart longitudinally is referred to as either the interventricular septum or the interatrial septum, depending on which chamber it separates.

Associated Great Vessels

The great blood vessels provide a pathway for the entire cardiac circulation to proceed.

Superior and inferior vena cava. The heart receives relatively oxygen-poor blood from the veins of the body through the large superior and inferior vena cava and pumps it through the pulmonary trunk. Pulmonary arteries. The pulmonary trunk splits into the right and left pulmonary arteries, which carry blood to the lungs, where oxygen is picked up and carbon dioxide is unloaded.

Atrioventricular valves. Atrioventricular or AV valves are located between the atrial and ventricular chambers on each side, and they prevent backflow into the atria when the ventricles contract. Bicuspid valves. The left AV valve- the bicuspid or mitral valve, consists of two flaps, or cusps, of endocardium. Tricuspid valve. The right AV valve, the tricuspid valve, has three flaps. Semilunar valve. The second set of valves, the semilunar valves, guards the bases of the two large arteries leaving the ventricular chambers, thus they are known as the pulmonary and aortic semilunar valves.

Cardiac Circulation Vessels

Although the heart chambers are bathed with blood almost continuously, the blood contained in the heart does not nourish the myocardium.

Coronary arteries. The coronary arteries branch from the base of the aorta and encircle the heart in the coronary sulcus (atrioventricular groove) at the junction of the atria and ventricles, and these arteries are compressed when the ventricles are contracting and fill when the heart is relaxed. Cardiac veins. The myocardium is drained by several cardiac veins, which empty into an enlarged vessel on the posterior of the heart called the coronary sinus.

Blood Vessels

Blood circulates inside the blood vessels, which form a closed transport system, the so-called vascular system.

Arteries. As the heart beats, blood is propelled into large arteries leaving the heart. Arterioles. It then moves into successively smaller and smaller arteries and then into arterioles, which feed the capillary beds in the tissues. Veins. Capillary beds are drained by venules, which in turn empty into veins that finally empty into the great veins entering the heart.

Tunics

Except for the microscopic capillaries, the walls of the blood vessels have three coats or tunics.

The major branches of the aorta and the organs they serve are listed next in sequence from the heart.

Gonadal arteries. The gonadal arteries supply the gonads, and they are called ovarian arteries in females while in males they are testicular arteries. Lumbar arteries. The lumbar arteries are several pairs of arteries serving the heavy muscles of the abdomen and trunk walls. Inferior mesenteric artery. The inferior mesenteric artery is a small, unpaired artery supplying the second half of the large intestine. Common iliac arteries. The common iliac arteries are the final branches of the abdominal aorta.

Major Veins of the Systemic Circulation

Major veins converge on the venae cavae, which enter the right atrium of the heart.

Hepatic portal vein. The hepatic portal vein is a single vein that drains the digestive tract organs and carries this blood through the liver before it enters the systemic circulation. Hepatic veins. The hepatic veins drain the liver.

Physiology of the Heart

As the heart beats or contracts, the blood makes continuous round trips- into and out of the heart, through the rest of the body, and then back to the heart- only to be sent out again.

Intrinsic Conduction System of the Heart

The spontaneous contractions of the cardiac muscle cells occurs in a regular and continuous way, giving rhythm to the heart.

Cardiac muscle cells. Cardiac muscle cells can and do contract spontaneously and independently, even if all nervous connections are severed. Rhythms. Although cardiac muscles can beat independently, the muscle cells in the different areas of the heart have different rhythms. Intrinsic conduction system. The intrinsic conduction system, or the nodal system, that is built into the heart tissue sets the basic rhythm. Composition. The intrinsic conduction system is composed of a special tissue found nowhere else in the body; it is much like a cross between a muscle and nervous tissue. Function. This system causes heart muscle depolarization in only one direction- from the atria to the ventricles; it enforces a contraction rate of approximately 75 beats per minute on the heart, thus the heart beats as a coordinated unit. Sinoatrial (SA) node. The SA node has the highest rate of depolarization in the whole system, so it can start the beat and set the pace for the whole heart; thus the term “pacemaker“. Atrial contraction. From the SA node, the impulse spread through the atria to the AV node, and then the atria contract. Ventricular contraction. It then passes through the AV bundle, the bundle branches, and the Purkinje fibers, resulting in a “wringing” contraction of the ventricles that begins at the heart apex and moves toward the atria. Ejection. This contraction effectively ejects blood superiorly into the large arteries leaving the heart.

The Pathway of the Conduction System

The conduction system occurs systematically through:

SA node. The depolarization wave is initiated by the sinoatrial node. Atrial myocardium. The wave then successively passes through the atrial myocardium. Atrioventricular node. The depolarization wave then spreads to the AV node, and then the atria contract. AV bundle. It then passes rapidly through the AV bundle. Bundle branches and Purkinje fibers. The wave then continues on through the right and left bundle branches, and then to the Purkinje fibers in the ventricular walls, resulting in a contraction that ejects blood, leaving the heart.

Cardiac Cycle and Heart Sounds

anything that increases the volume or speed of venous return also increases stroke volume and force of contraction. Factors modifying basic heart rate most important external influence on heart rate is the activity of the autonomic nervous system, as well as physical factors (age, gender, exercise, and body temperature).

Physiology of Circulation

A fairly good indication of the efficiency of a person’s circulatory system can be obtained by taking arterial blood and blood pressure measurements.

Cardiovascular Vital Signs

Arterial pulse pressure and blood pressure measurements, along with those of respiratory rate and body temperature, are referred to collectively as vital signs in clinical settings.

Arterial pulse. The alternating expansion and recoil of an artery that occurs with each beat of the left ventricle creates a pressure wave-a pulse- that travels through the entire arterial system. Normal pulse rate. Normally, the pulse rate (pressure surges per minute) equals the heart rate, so the pulse averages 70 to 76 beats per minute in a normal resting person. Pressure points. There are several clinically important arterial pulse points, and these are the same points that are compressed to stop blood flow into distal tissues during hemorrhage, referred to as pressure points. Blood pressure. Blood pressure is the pressure the blood exerts against the inner walls of the blood vessels, and it is the force that keeps blood circulating continuously even between heartbeats. Blood pressure gradient. The pressure is highest in the large arteries and continues to drop throughout the systemic and pulmonary pathways, reaching either zero or negative pressure at the venae cavae. Measuring blood pressure. Because the heart alternately contracts and relaxes, the off- and-on flow of the blood into the arteries causes the blood pressure to rise and fall during each beat, thus, two arterial blood pressure measurements are usually made: systolic pressure (the pressure in the arteries at the peak of ventricular contraction) and diastolic pressure (the pressure when the ventricles are relaxing). Peripheral resistance. Peripheral resistance is the amount of friction the blood encounters as it flows through the blood vessels.

Neural factors. The parasympathetic division of the autonomic nervous system has little or no effect on blood pressure, but the sympathetic division has the major action of causing vasoconstriction or narrowing of the blood vessels, which increases blood pressure. Renal factors. The kidneys play a major role in regulating arterial blood pressure by altering blood volume, so when blood pressure increases beyond normal, the kidneys allow more water to leave the body in the urine, then blood volume decreases which in turn decreases blood pressure. Temperature. In general, cold has a vasoconstricting effect, while heat has a vasodilating effect. Chemicals. Epinephrine increases both heart rate and blood pressure; nicotine increases blood pressure by causing vasoconstriction; alcohol and histamine cause vasodilation and decreased blood pressure. Diet. Although medical opinions tend to change and are at odds from time to time, it is generally believed that a diet low in salt, saturated fats, and cholesterol help to prevent hypertension, or high blood pressure.

Blood Circulation Through the Heart

The right and left sides of the heart work together in achieving a smooth flowing blood circulation.

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Cardiovascular System Anatomy and Physiology Study Guide for Nurses-columbia southern university

コース: business law

30 ドキュメント
Students shared 30 documents in this course

大学: Kochi University

Was this document helpful?
3/7/23, 1:56 PM
Cardiovascular System Anatomy and Physiology: Study Guide for Nurses
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HOME » NOTES » ANATOMY & PHYSIOLOGY » CARDIOVASCULAR SYSTEM ANATOMY AND PHYSIOLOGY
Cardiovascular System Anatomy and
Physiology
UPDATED ON FEBRUARY 11, 2021 BY MARIANNE BELLEZA, R.N.
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