This uniquely readable, compact, and concise monograph lays a foundation of knowledge of the underlying concepts of normal cardiovascular function. Students welcome the book's broad overview as a practical partner or alternative to a more mechanistically oriented approach or an encyclopedic physiology text. Especially clear explanations, ample illustrations, a helpful glossary of terms, tutorials, and chapter-opening learning objectives provide superb guidance for self-directed learning and help fill the gap in many of today's abbreviated physiology blocks. A focus on well-established cardiovascular principles reflects recent, widely accepted cardiovascular research.
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The publisher is not responsible as a matter of product liability, negligence, or otherwise for any injury resulting from any material contained herein. This publication contains information relating to general principles of medical care that should not be construed as specific instructions for individual patients. Includes bibliographical references and index.
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Application of this informa- tion in a particular situation remains the professional responsibility of the practitioner; the clinical treatments described and recommended may not be considered absolute and universal recommendations. The authors, editors, and publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accordance with the current recommendations and practice at the time of publication.
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To purchase additional copies of this book, call our customer service department at or fax orders to International customers should call Atrial Systole Isovolumetric Contraction Rapid Ejection Reduced Ejection Isovolumetric Relaxation Rapid Filling Reduced Filling A or the kidneys. The circulation trans- with blood vessels. The pulmonary circulation is the eliminated in the urine. The systemic circulation is com- and for exchange of heat, which is a major by- prised of all the blood vessels within and out- product of cellular metabolism that must be side of organs excluding the lungs.
The right removed from the body. Blood flow through side of the heart comprises the right atrium the skin regulates heat loss from the body. The right atrium In summary, the ultimate purpose of the receives venous blood from the systemic cir- cardiovascular system is to facilitate exchange culation, and the right ventricle pumps it into of gases, fluid, electrolytes, large molecules, the pulmonary circulation where oxygen and and heat between cells and the outside envi- carbon dioxide are exchanged between the ronment.
The heart and vasculature ensure blood and alveolar gases. The left side of the that adequate blood flow is delivered to organs heart comprises the left atrium and the left so that this exchange can take place. The right side of the heart, pulmonary circulation, left side of the heart, and systemic circulation are arranged in series. Blood then flows from the left atrium into the left ventricle.
The left ventricle ejects Head the blood into the aorta, which then distrib- utes the blood to all the organs via the arterial system. Within the organs, the vasculature branches into smaller and smaller vessels, Lungs eventually forming capillaries, which are the primary site of exchange. Blood flow from the SVC capillaries enters veins, which return blood Aorta flow to the right atrium via large systemic veins the superior and inferior vena cava.
IVC As blood flows through organs, some of the fluid, along with electrolytes and small amounts of protein, leaves the circulation and Arms enters the tissue interstitium a process termed fluid filtration. The lymphatic vessels, which are closely associated with small blood vessels within the tissue, collect the excess fluid from Liver GI within the tissue interstitium and transport it back into the venous circulation by way of lymphatic ducts that empty into large veins subclavian veins above the right atrium.
Kidneys It is important to note the overall arrange- ment of the cardiovascular system. First, the right and left sides of the heart, which are sepa- rated by the pulmonary and systemic circula- Legs tions, are in series with each other see Fig. This via the hepatic artery parallel. The ejected per unit time of each side of the heart liver also receives blood from the aorta via the closely matches the output of the other so that hepatic artery.
Therefore, most of the liver circu- there are no major blood volume shifts between lation is in series with the intestinal circulation, the pulmonary and systemic circulations. Sec- while some of the liver circulation is in parallel ond, most of the major organ systems of the with the intestinal circulation see Chapter 7. Briefly, the parallel arrangement of that returns the blood to the heart. Therefore, major vascular beds prevents blood flow changes the circulations of most major organ systems are in one organ from significantly affecting blood in parallel as shown in Figure 1.
One major flow in other organs. In contrast, when vascular exception is the liver, which receives a large frac- beds are in series, blood flow changes in one tion of its blood supply from the venous circula- vascular bed significantly alter blood flow to tion of the intestinal tract that drains into the the other vascular bed. While this is true, it is more accurate to view the heart as a pump that receives blood from venous blood vessels at a low pressure, LV imparts energy to the blood raises it to a IVC higher pressure by contracting around the RV blood within the cardiac chambers, and then ejects the blood into the arterial blood vessels.
Venous blood returns to the right atrium RA via the supe- serves as a resistance network. Blood passes is determined by the arterial pressure minus the from the RA into the right ventricle RV , which venous pressure, divided by the vascular resistance ejects the blood into the pulmonary artery PA.
One millimeter of mercury is the pressure exerted by a 1-mm vertical col- ventricle. As the left ventricle contracts and umn of mercury 1 mm Hg is the equivalent ejects blood into the systemic arterial system, of 1.
Vascular a relatively high pressure is generated resistance is determined by the size of blood to mm Hg maximal or systolic pressure. Details of the pumping The right atrium receives systemic venous action of the heart are found in Chapter 4. This venous return usually expressed in terms of its cardiac out- then passes through the right atrium and fills put, which is the amount of blood ejected the right ventricle; atrial contraction also with each contraction i.
Right multiplied by the heart rate. Any factor that ventricular contraction ejects blood from alters heart rate or stroke volume will alter the the right ventricle into the pulmonary artery.
The heart rate is determined This generates a maximal pressure systolic by specialized cells within the heart that act pressure that ranges from 20 to 30 mm Hg as electrical pacemakers, and their activity is within the pulmonary artery. As the blood increased or decreased by autonomic nerves passes through the pulmonary circulation, the and hormones see Chapter 2.
The action blood pressure falls to about 10 mm Hg. The potentials generated by these pacemaker left atrium receives the pulmonary venous cells are conducted throughout the heart and blood, which then flows passively into the trigger contraction of cardiac myocytes see left ventricle; atrial contraction provides a Chapter 3. This results in ventricular con- small amount of additional filling of the left traction and ejection of blood. Furthermore, mones see Chapters 3, 4, and 6.
The heart synthesizes ovascular changes that can lead to hyperten- several hormones. One of these hormones, sion or exacerbate heart failure. In summary, atrial natriuretic peptide, plays an impor- organ function is dependent on the circula- tant role in the regulation of blood volume tion of blood, and cardiovascular function is and blood pressure see Chapter 6.
Sensory dependent on the function of organs. The cardiovascular system must be able to Vascular System adapt to changing conditions and demands of the body. For example, when a person exer- Blood vessels constrict and dilate to regulate cises, increased metabolic activity of contract- arterial blood pressure, alter blood flow within ing skeletal muscle requires large increases organs, regulate capillary blood pressure, in nutrient supply particularly oxygen and and distribute blood volume within the body.
To meet this about by activation of vascular smooth muscle demand, blood vessels within the exercising within the vascular wall by autonomic nerves, muscle dilate to increase blood flow; however, metabolic and biochemical signals from out- blood flow can only be increased if the arterial side of the blood vessel, and vasoactive sub- pressure is maintained.
Arterial pressure is stances released by endothelial cells that line maintained during exercise by increasing car- the blood vessels see Chapters 3, 5, and 6. The If these changes were not to occur, arterial endothelium lining blood vessels produces blood pressure would fall precipitously dur- substances that modulate hemostasis blood ing exercise, thereby limiting organ perfusion clotting and inflammatory responses see and exercise capacity. Therefore, a coordi- Chapter 3.
Another example of adapta- and Organ Function tion occurs when a person stands up. Gravi- Cardiovascular function is closely linked to tational forces cause blood to pool in the legs the function of other organs. For example, the when a person assumes an upright body pos- brain not only receives blood flow to support ture see Chapter 5. In the absence of regu- its metabolism but also acts as a control center latory mechanisms, this pooling will lead to for regulating cardiovascular function.
A sec- a fall in cardiac output and arterial pressure, ond example of the interdependence between which can cause a person to faint because organ function and the circulation is the kid- of reduced blood flow to the brain.
To pre- ney. The kidneys excrete varying amounts of vent this from happening, coordinated reflex sodium, water, and other molecules to main- responses increase heart rate and constrict tain fluid and electrolyte homeostasis. Blood blood vessels to maintain a normal arterial passing through the kidneys is filtered, and blood pressure when a person stands.
As described in ume. This control is accomplished by changes Chapter 6, neural and hormonal neurohu- in autonomic nerve activity to the heart and moral mechanisms regulating cardiovascular vasculature, as well as by changes in circulat- function are under the control of pressure sen- ing hormones that influence cardiac, vascular, sors located in arteries and veins i.
A decrease in arterial pressure from This textbook emphasizes our current knowl- its normal operating point elicits a rapid baro- edge of cellular physiology as well as the receptor reflex that stimulates the heart to classical biophysical concepts that have been increase cardiac output and constricts blood used for decades to describe cardiac and vas- vessels to restore arterial pressure Fig. Chapter 2 describes the elec- These cardiovascular adjustments occur trical activity within the heart, both at the through rapid changes in autonomic nerve cellular and whole organ level.
Chapter 3 activity particularly through sympathetic builds a foundation of cellular physiology by nerves to the heart and vasculature.
Welcome to Cardiovascular Physiology Concepts
Cardiovascular Physiology Concepts
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