NUR 239 Lecture Notes - Lecture 16: Collateral Circulation, Blood Vessel, Turbulence
21 May 2018
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Department
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NUR 239/Pathophysiology and Pharmacotherapeutics in Nursing I
Unit 3/Porth Chapter 17 and 18
Complete the following study guide and submit on Reggie Net by the due date on the Course Calendar
1
Key Terms (Porth Chapter 17 – Control of CV Function)
▪ Pulmonary Circulation: moves blood through the lungs and creates a link with the gas function of the
respiratory system
▪ Systemic Circulation: moves blood throughout all the other tissues of the body
▪ Hemodynamics: refers to the principles that govern the flow of blood in the vascular system
▪ Resistance: the opposition to flow caused by friction between the moving blood components and
stationary vessel wall
▪ Total Peripheral Vascular Resistance: in peripheral, the collective resistance of all the vessels in that part
of the circulation
▪ Viscosity: distance measurement; referring to the speed or linear movement per unit time of blood as it
flows through a vessel
▪ Flow: a volume measurement that is determined by the cross-sectional area of a vessel and the velocity of
the blow
▪ Turbulent flow: the laminar stream (blood components arranged in layers so that the plasma is adjacent to
the smooth, slippery endothelial lining of the blood vessel and the blood elements are in the axis of the
bloodstream) is disrupted and flow becomes mixed moving radially (cross) and axially (lengthwise)
▪ Distensibility: the ability of a blood vessel to be stretched and accommodate an increase volume of blood
▪ Vascular Compliance: refers to the total quantity of blood that can be stored in a given portion of the
circulation for each millimeter of mercury rise in pressure
▪ End-diastolic Volume: end of diastole, approx. 120 mL ventricles increase their volume
▪ End-systolic Volume: end of systole, approx. 50 mL of blood remains in the ventricles
▪ Stroke Volume: difference between the end-systolic volume and end-diastolic volumes (70mL)
▪ Cardiac Output: amount of blood the heart pumps each minute
▪ Stroke Volume: amount of blood pumped with each beat
▪ Preload: represents the volume work the heart; it is work or load imposed on the heart before contraction
begins; amount of blood that the heart must pump with each bear and represents the volume of blood
stretching the ventricular muscle fibers at the end of diastole
▪ Afterload: pressure or tension work of the heart; pressure that the heart must generate to move blood into
aorta; it is the work presented to the heart after contraction occurs
▪ Cardiac Contractility: refers to the ability of the heart to change its force of contraction without changing
its resting or diastolic length
▪ Microcirculation: consists of arterioles, capillaries, and venules; transports nutrients to the tissues and
removal of metabolites; organs and tissues regulate their blood flow based on metabolic needs; important
in tissues such as skeletal muscles and in the heart, or organs in which the metabolic activity and need for
blood flow vary
▪ Autoregulation of blood flow: local control mechanism that automatically adjusts tissue blood flow
independent of systemic factors
▪ Collateral Circulation: mechanism for the long-term regulation of local blood flow
Key Learning Objectives - Answer the follow questions (Chapter 17 - Control of CV Function):
▪ What is the main function of the circulatory system?
o Transport
▪ What is being transported by the circulatory system?
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o Consisting of the heart and blood vessels, it distributes oxygen and nutrients needed for metabolic
processes to the tissues, carries waste products from cellular metabolism to the kidneys and other
excretory organs for elimination, and circulates fluids, electrolytes, and hormones needed to
regulate body function
▪ Name the two parts of the circulatory system. Describe what each part does.
o Pulmonary (central) circulation → moves blood through the lungs and creates a link with the gas
function of the respiratory system
▪ Low arterial pressure
o Systemic (peripheral) circulation → moves blood throughout all the other tissues of the body
▪ High arterial pressure
▪ Look at figure 17.2. Where is the majority of blood at any given time?
o 4% in the left heart, 16% in the arteries and arterioles, 4% in capillaries, 64% in the venules and
veins, 4% in the right heart
o Capillaries: small, thin-walled vessels that link the arterial and venous sides of the circulation;
serving as an exchange system where transfer of gases, nutrients and wastes take place; smallest
size but has the largest surface area
o Venules and veins contain the largest amount of blood due to the distensible vessels that function
as a reservoir to collect blood from the capillaries and return it to the right heart
▪ Describe the layers of the heart.
o Pericardium: heart is enclosed in this loose-fitting sac; located between the lung in the mediastinal
space of the intrathoracic cavity; holds the heart fixed position in the thorax and providing
physical protection and barrier to infection
▪ Consists of a tough outer fibrous layer attached to the great vessels that enter and leave the
heart, the sternum, and the diaphragm, and thin fibrous layer that consists visceral and
parietal layer
o Myocardium: forms the walls of the atria and ventricles; muscle portion of the heart
o Endocardium: thin, three-layered membrane that lines the heart and covers the heart
▪ Inner most: lines the heart chambers
▪ Middle: consists of dense connective tissue with elastic fibers
▪ Outer: composed of irregularly arranged connective tissue cells that contain blood vessels
and branches of the conduction system and is continuous with the myocardium
▪ Describe the path a drop of blood would travel from the time it enters the heart from the superior/inferior
vena cava until it goes back out into systemic circulation (don’t forget the valves and vessels).
➢ Blood enters the right atrium from the superior and inferior vena cava, and the coronary sinus.
➢ From right atrium, it goes through the tricuspid valve to the right ventricle.
➢ From the right ventricle, it goes through the pulmonary semilunar valves to the pulmonary trunk
➢ From the pulmonary trunk it moves into the right and left pulmonary arteries to the lungs.
➢ From the lungs, oxygenated blood is returned to the heart through the pulmonary veins.
➢ From the pulmonary veins, blood flows into the left atrium.
➢ From the left atrium, blood flows through the bicuspid (mitral) valve into the left ventricle.
➢ From the left ventricle, it goes through the aortic semilunar valves into the ascending aorta.
➢ Blood is distributed to the rest of the body (systemic circulation) from the aorta.
▪ What unique characteristic does the heart muscle have that skeletal muscles do not? Contractions are
involuntary an d the duration of contraction is much longer, and the longitudinal arrangement of skeletal
muscle fibers differ from cardiac muscle cells that are arranged as interconnecting latticework with the
fibers dividing, recombining, and then dividing again
▪ The heart has a pacemaker to impulses and maintain a normal heart rate, what is the normal pacemaker
called and what is the normal rate? If this system fails describe the redundant backup systems in place to
sustain life.
o Natural pacemaker: SA Node
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Document Summary
Complete the following study guide and submit on reggie net by the due date on the course calendar. 120 ml ventricles increase their volume: end-systolic volume: end of systole, approx. Blood enters the right atrium from the superior and inferior vena cava, and the coronary sinus. From right atrium, it goes through the tricuspid valve to the right ventricle. From the right ventricle, it goes through the pulmonary semilunar valves to the pulmonary trunk. From the pulmonary trunk it moves into the right and left pulmonary arteries to the lungs. From the lungs, oxygenated blood is returned to the heart through the pulmonary veins. From the pulmonary veins, blood flows into the left atrium. From the left atrium, blood flows through the bicuspid (mitral) valve into the left ventricle. From the left ventricle, it goes through the aortic semilunar valves into the ascending aorta.
