P5 Exam 1 notes - Cardiac Anatomy, Physiology and Function, Dysrhythmias

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lOMoARcPSD|20734855




P5 Exam 1 notes - Cardiac Anatomy, Physiology
and Function, Dysrhythmias

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CHAPTER 33

 Cardiovascular system
o Responsible for supplying oxygen to body organs and other tissues- PERFUSION
o Made up of the heart and blood vessels
o Any problem with the respiratory and hematologic systems requires the CV
system to work harder to meet perfusion needs
 Myocardium
o The heart muscle
 Pericardium
o Covering around the heart- PROTECTION
 Right atrium receives deoxygenated blood from the superior and inferior vena cava and
the coronary sinus
 Path of blood flow: Superior and inferior vena cava > Right atrium > tricuspid valve >
Right Ventricle > Pulmonic valve > Pulmonary artery > Lungs > Pulmonary veins > Left
atrium > Mitral valve > Left Ventricle > Aortic valve > Aorta > Body > Superior and
inferior vena cava




 AV valves
o Atrioventricular valves, separate atria from ventricles.
o Tricuspid: RA to RV.
o Mitral (bicuspid): LA to LV
 Semilunar valves
o Pulmonic: RV to pulmonary artery.
o Aortic: LV to aorta.
 Coronary arteries
o Originate on the aorta
o Feed the heart muscle

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o Left Main Coronary Artery (LMCA)
 Feeds the left side
 Two branches
 Left anterior descending (LAD)
 Left circumflex (LCX)
 Supplies the SA node in half of people
o Right coronary artery (RCA)
 Feeds the right side and inferior wall of the left side
 Supplies the SA nose in half of people
 Supplies the AV node in most people
o Mean arterial pressure (MAP)
 Must be at least 60 mmHg to maintain blood flow to the heart
 60-70 mmHg is needed to perfuse the major organs
 Diastole
o Relaxation and filling of the atria and ventricles
o 2/3 of the cardiac cycle
 Systole
o Contraction and emptying of the atria and ventricles
 Cardiac output
o Blood flow from the heart into systemic arterial circulation
o The amount of blood pumped from the left ventricle each minute
o CO= HR x SV
o Normally 4 to 7 LPM
o Cardiac index (=CO/BSA) is used to adjust for body size differences
 Heart rate
o The number of times the ventricles contract each minute
o Normal resting HR: 60-100bpm
o As HR increases, myocardial oxygen need increases
o Controlled by the autonomic nervous system
o Parasympathetic system slows the heart rate
o Sympathetic system increases the heart rate
 Stroke Volume
o The amount of blood ejected by the left ventricle with each contraction
o Influenced by HR, preload, afterload, and contractility
o Preload
 The amount of myocardial fiber stretch at the end of diastole, just before
contraction
 Results from the amount of blood within the ventricle at the end of
diastole
 Increase in volume stretches the fibers more, enhancing contraction and
improving stroke volume.
 Frank Starling Law
 Excessive filling may decrease CO

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o Afterload
 The pressure the ventricles must overcome to eject blood through
the semilunar valves into the peripheral blood vessels
 Directly related to the arterial blood pressure and the diameter of the
blood vessels
o Contractility
 The force of cardiac contraction independent of preload
 Decreased by hypoxia and acidemia
 Arterial System
o Primary function is to deliver oxygen and nutrients to tissues of the body
o Nutrients exchanged in the capillaries via osmosis, filtration, and diffusion
o Nutrients, chemicals, and body defense substances are distributed and
exchanged for cellular waste products
o Cellular wastes are transported to their excretory organs
o Blood shifted to and from skin to promote temperature regulation
 Blood Pressure
o The force of blood exerted against the vessel walls
o Greatest in the large blood vessels and decreases toward the capillaries
o Volume, ventricular contraction, and vascular tone are necessary to maintain
o Determined primarily by the volume of blood flow (CO) and the resistance in the
arteries
o Anything that increases CO or PVR increases the BP
o Systolic BP
 The amount of pressure/force generates by the left ventricle to distribute
blood into the aorta with each contraction
 A measure of how effectively the heart pumps
 An indicator of vascular tone
o Diastolic BP
 The amount of pressure against the arterial walls during relaxation
 Non-modifiable CVD risk factors
o Age, gender, ethnic origin, family Hx
 Modifiable CVD risk Factors
o Personal lifestyle habits- cigarette use, physical inactivity, obesity
 Major symptoms of CVD
o Chest pain or discomfort, dyspnea, fatigue, palpitations, weight gain, syncope,
extremity pain
 Assessment
o Pain or discomfort
o Dyspnea on exertion
o Orthopnea
 Dyspnea that appears when he or she lies flat
o Paroxysmal nocturnal dyspnea (PND)
 Develops after the patient has been laying down for several hours