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