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AP I Tst 3 Tissues of the Heart/Coronary cir

AP I Test 3 Tissues of the Heart Coronary circulation mar 4
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Pericardial Layers
-heart is enclosed in a double-walled sac called the pericardium
Parietal Pericardium (pericardial sac)
Visceral Pericardium (epicardium)
Parietal Pericardium
thick, fibrous layer-outer wall of the heart
-anchors to diaphram and major vessels
-won't allow the heart to overfill
Visceral Pericardium
thin layer
associated with myocardium
Myocardium
cardiac muscle between the epicardium and endocardium
-the thickest layer and performs the work of the heart
Pericardial cavity
between the parietal and visceral membranes
-contains fluid that lubricates the heart
-allows it to beat with minimal friction
Pericarditis
inflammation of the pericardium
-they grow in toward each other so then have limited space with higher pressure making it hard to lubricate
-causes painful hearbeat b/c of rubbing-friction rub with each heartbeat
Valves
has two or three fibrous, endothelial lined cusps
-prevent backflow (one way pump)
How are the valves opened and closed?
passively
-not muscular
What dictates the valves being opened and closed?
ventricular pressure
-they are pushed open and closed by changes in blood pressure that occur as the heart chambers contract and relax
Phases of the Cardiac cycle 1-Relaxed ventricle
Atrial pressure is greater than ventricle pressure
causing the AV vlaves to open and blood to flow into the ventricles
What happens after blood flows into the ventricles?
the ventricular pressure starts to rise above the atrial pressure
When semilunar -aortic valvews are closed how is the pressure aligned?
Pulmonary and aorta pressure is greater than the ventricular pressure
When the ventricles are contracted what happens?
the AV valves close
How is the pressure aligned when the AV valves are closed?
the ventricle pressure is greater than the atrial pressure
What happens when the ventricular pressure becomes greater than the pulmonary and aorta pressure?
it causes the semilunar valves to open
Isovolumetric contraction
this is when the ventricles are starting to contract and the AV valves are closed
-is called isovolumetric b/c even though the ventricles are contracting they do not eject blood yet and their is no change in their volume
-the ejection of blood will only begin when the ventricular pressure exceeds arterial pressure and forces the semilunar valves open
Chordae tendineae and Papillary muscle
-they are like strings on a parachute--what keeps the pressure from inverting is the strings applying down tension pressure on the edges
-these keep the heart from prolapsing
What does it mean if a heart prolapses?
-the valves bulge excessively into the atria or turn inside out like a windblown umbrella
you have a heart mumur
-which means blood is leaking the wrong direction
Septisemia
can hurt valves
bacterial infection that goes septic
-can disfigure the cusp of the valve and cause imperfection on seams and leak blood thru
-can cause congestive heart failure if it gets bad
Coronary circulation
the blood vessels of the heart wall
Where do the right and left coronary arteries originate?
the base of the aorta and branch into several arteries
What do the arteries that branch off do?
supply blood to myocardium
What are the only arteries to fill during diastole?
relaxed
-the R and L coronary arteries
What is hard on the vessels?
high systolic pressure-it damages them
bypass surgery involves these
Myocardial infarction
heart attack caused by a fatty deposit or blood clot building up plaques in a coronary artery
Ischemia
deficiency of blood flow to the cardiac muscle
-typically occurs when a partially blocked coronary artery constricts-produces lactic acid and stimulates pain
Ischemic tissue
receives limited blood flow
goes necrotic-decays
Anastomoses
connection of 2 arteries
they can supply the same tissue
-can provide some protection from myocardial infarction
-combine their blood flow to points farther downstream
-provide an alternate route called collateral circulation that can supply the heart tissue with blood if the primary route becomes obstructed---knees and joints also have these