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60yr. old woman suffered a myocardial infarction. permanet damage to…
60yr. old woman suffered a myocardial infarction. permanet damage to papillary muscles, decrease in blood pressure
anatomy of the heart
function: transport system to supply blood, nutrients
4 chambers
2 receiving chambers
right atrium; receives blood returning from the systemic circuit
deoxygenated blood from cells of body
left atrium; receives returning blood from the pulmonary circuit
oxygenated blood from lungs
2 pumping chambers
right ventricle; pumps blood through pulmonary circuit
left ventricle; pumps blood through the systemic circuit
pericardium; double-walled sac with two layers
fibrous pericardium; protect, anchor heart to surrounding structures & prevent overfilling
parietal pericardium; lines internal surface of fibrous pericardium
visceral pericardium(epicardium); on external surface of heart
3 layers of the heart
epicardium; visceral pericardium
myocardium; circular and spiral bundles of contracting cardiac muscle cells
endocardium; innermost layer, lining of blood vessels. simple squamous epithelium. lines heart chambers & cardiac skeleton
3 veins emptied into right atrium
superior vena cava
returns blood from body regions above the diaphragm
inferior vena cava
returns blood from body regions below the diaphragm
coronary sinus
returns blood from coronary veins
4 veins emptied into left atrium; 4 pulmonary veins returning blood from lungs
interventricular septum; separates ventricles
interatrial septum; separates atria
coronary sulcus; encircles junction of atria & ventricles
anterior interventricular sulcus; "widowmaker"
pathway of blood
right side
superior vena cava, inferior vena cava, coronary sinus, right atrium, tricuspid valve, right ventricle, pulmonary semilunar valve, pulmonary trunk, pulmonary arteries, lungs
left side
4 pulmonary veins, left atrium, mitral valve, left ventricle, aortic semilunar valve, aorta, systemic circulation
role of valves; open & close in response to pressure change
atrioventricular valve (AV)
between atria & ventricle
prevent backflow into atria when ventricles contract
tricuspid valve
between right atrium & ventricle
mitral valve
between left atrium & ventricle
semilunar valve (SA)
prevent backflow from major arteries back into ventricles
pulmonary semilunar valve; between right ventricle & pulmonary trunk
aortic semilunar valve; between left ventricle & aorta
role of papillary muscles
anchor chordae tendineae to attached heart valves
contract when ventricles contract, closing valves during contraction
as ventricles contract, pressure rises & blood pushes on semilunar valve forcing to open
as ventricles relax, pressure falls & blood flows back from arteries filling cusps of SA and forcing closure
chordae tendineae; anchor cusps of AV valves to papillary muscles
hold valve flaps closed during ventricular contraction
prevent flaps from everting back into aorta
heart sounds; LUB-DUB
closing of heart valves
1st sound; closing of AV valve at beginning of ventricular systole
2nd sound; closing of SL valve at beginning of ventricular diastole
pause in-between is heart relaxation
different definitions
stroke volume
volume of blood pumped out by one ventricle with each beat
preload
stretching heart muscle just before contraction
afterload
pressure the ventricles must overcome to eject blood
heart rate concept
other factors affecting HR
age; fastest as fetus, declines w/ age
gender; faster on females
exercise; increase HR
body temp.; HR increases as body temp. increases
hormones
epinephrine & thyroxine increase HR
ions; must maintain constant
drugs; caffeine& cocaine
ANS
SNS activated by emotional or physical stressors
NE&EPI bind to nodal cells and increase HR
cardiac output
amount of blood pumped out by each ventricle in 1min.
HR accelerates & stroke vol. increases during exercise
mean arterial pressure
average pressure of blood circulating through a persons arteries during cardiac cycle
peripheral resistance
resistance of the arteries to blood flow
cardiac reserve
capacity to increase cardiac output above sea level
HR accelerates, stroke vol, increases
Frank-starling law
increase venous return stretches ventricles increasing contraction force
effects of failed mitral valve;
blood leaks into left atrium when left ventricle contract due to valve don't opening and closing properly
not enough blood pumped to the body
lead to heart failure & arrhythmias
direct effects
blood flow impaired
leads to patient being easily tired
muscle not receiving enough O2
indirect effects
heart pumped harder causing extra strain on left ventricle
irregular heartbeats
heart failure
her age & weight worsen her condition due to high blood pressure and extra strain on heart
her leaky valve causes a delay in her breathing slowing down blood circulation
caused her myocardial infarction
coronary arteries get blocked off
patient has DMII which interferes with the production of insulin
pancreas cannot produce insulin
causes high blood pressure
lack of energy and no cure
other systems affected
nervous system controls body temp., BP, HR, gastrointestinal activity
autonomic responses unstable , sets off stress hormones
sympathetic NS can cause hyperventilation if patient is aroused
respiratory system
increased pressure in heart can lead to congestion in lungs which causes heart failure
labored breathing slows down circulation to body
relationship between heart function and BP
BP is the force blood extorts on heart chambers which controls how fast or slow heart pumps blood
heart function and respiratory rate
body depends on O2 for life
w/o 02 blood could not be pumped throughout the body, therefore heart not beating