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Patho Ch. 22
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57
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Undergraduate 4
04/11/2012

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Term
layers of the heart
Definition
epicardium, myocardium, endocardium
Term
epicardium
Definition
visceral pericardium
Term
myocardium
Definition
muscle layer
Term
endocardium
Definition
inner, endothelial layer
Term
right atrium
Definition
thin-walled
reservoir for systemic venous blood
Term
right ventricle
Definition
propels blood into pulmonary circulation
low pressure
1/3 thickness of left ventricle
Term
left atrium
Definition
receives oxygenated blood from lungs
Term
left ventricle
Definition
high pressure
thick muscles
pressure exceeds right by five fold
forces blood into aorta
Term
atrioventricular valves
Definition
cusps attached to thin strands of fibrous tissue called chordae tendinea
Term
Where do chordae tendinea extend to?
Definition
papillary muscles
Term
semilunter valves (3 symmetrical cuplike cusps)
Definition
secured to fibrous ring
above cusps of aortic vavle are three outpouchings of the aortic wall called the sinuses of Valsalva
Term
Sinuses of Valsalve
Definition
opening to coronary arteries located within these outpouchings
Term
automaticity
Definition
ability to spontaneously generate impulses
Term
rhythmicity
Definition
regularity of impulse generation
Term
conductivity
Definition
ability to transmit impulses
Term
excitability
Definition
ability to response to stimulation
Term
sympathetic nervous system
Definition
increases both heart rate and force of cardiac contraction
sympathetic receptors are beta receptors
Term
depolarization
Definition
electrical excitation of heart
Term
repolarization
Definition
electrical recovery
Term
systole
Definition
muscle contraction
Term
diastole
Definition
muscle relaxation
Term
resting phase
Definition
-90 mV
sodium outside cell and potassium inside
negative cell inside and positive cell outside
Term
rapid depolarization
Definition
+30 mV
increased membrane permeability to sodium so inside becomes positive and outside becomes negative
Term
partial repolarization
Definition
small, abrupt change in ionic concentration and relative electrical change occurs
due to influx of chloride ions which reduces positive influence a little
Term
mid diastole phase of cardiac cycle
Definition
slow ventricular filling or "diastasis"
atrial and ventricular chambers are relaxed
Term
Late diastole phase of cardiac cycle
Definition
depolarization spreads through atria causing atria to contract, forcing blood into ventricles
Term
Early systole phase of cardiac cycle
Definition
depolarization spreads through ventricles causing AV valves to close which generated first heart sound
semilunar valves remain closed
Term
late systole phase of cardiac cycle
Definition
ventricular pressure exceeds pressures within vessels causing semilunar valves to open and ventricular ejection
Term
early diastole phase of cardiac cycle
Definition
repolarization spreads through ventricle and chambers relax
prsesure drops blow arterial pressures, causing semilunar valves to close which produces heart sound
pressure continues to drop causing AV valves to open allowing filling of ventricles
Term
P wave
Definition
represents atrial depolarization
Term
PR interval
Definition
time from onset of atrial activation to onset of ventricular activation
0.12 to 0.20 seconds
Term
QRS complex
Definition
represents ventricular depolarization
0.06 - 0.10 seconds
Term
ST segment
Definition
represents time between end of spread of the impulse through the ventricles and repolarization of ventricles
0.12 seconds
Term
T wave
Definition
represents ventricular repolarization
Term
QT interval
Definition
"electrical systole" of the ventricles
0.4 seconds
Term
cardiac output
Definition
quantity of blood ejected by each ventricle per minute
normally equals around 5 liters
Term
Cardiac Output equation
Definition
Cardiac Output(CO)= cardiac rate X stroke volume
Term
Caridac Output Volume
Definition
5040 mL
Term
Cardiac Rate Volume
Definition
72/min
Term
Stroke Volume Amount
Definition
70 ml
Term
Stroke Volume
Definition
ventricles fill during relaxation to an end diastocilic volume of 100 ml of blood
contraction typically forces about 2/3 of this volume into arterial blood vessels, leaving 30 ml in the ventricles at end of systole (end systolic volume or ESV)
Term
What are the 3 factors that infleuence ESV or SV?
Definition
preload, contractility, and afterload
Term
preload
Definition
refers to stretch of myocardial muscle initiated by return of venous blood to the heart
as increasing quanities of blood enter the atria, an associated rise in intra-atrial and intraventricular pressures should cause an increase in cardiac output
Term
contractility
Definition
alterations in strength of caridac muscle contraction caused by factors other than preload stretch
Term
What causes contractility to increase?
Definition
exposure to calcium, norepinephrine, or epinephrine and stiumalation by sympathetic nervous system
Term
What causes contractility to decrease?
Definition
acidosis, hypocalcemia, hyperkalemia, and parasympathetic neural stimualtion
Term
Afterload
Definition
amount of force that must be gerenated during systole to eject blood into aterial vessels
varies primarily as function of arterial blood pressure and ventricular radium
explains why myocardial work must increase under certain conditions if stroke volume is to be maintained (if rising arterial blood pressure poses resistance to exit if blood from heart, the cardiac muscle will have to exer great effort to sustain output)
Term
What are the three layers of the blood vessels?
Definition
tunic intima (innermost), tunica media (middle), and tunica externa or adventitia (outermost)
Term
What are arterial walls composed of?
Definition
elastic connective tissue, fibrous connective tissue, and smooth muscle
Term
Elastic arteries
Definition
have thick tunica media with more elastic fibers than smooth muscle
ex: aorta and pulmonary trunk
Term
Muscular arteries
Definition
contain more muscle fibers than elastic thus affected more by vasoconstriction/vasodilation
Term
arterioles
Definition
lumen diameteres of less than 0.5 mm and are composed almost entirely of smooth muscle
Term
What do the capillary walls contain?
Definition
simple squamous epithelium---only tunica intima
Term
pressure
Definition
force exerted on liquid (blood) per unit area
expressed as dynes per square centimeter, mm Hg, or torr
Term
resistance
Definition
opposition to force
in blood most resistance provided by diameter and length of blood vessels
resistance is inversely related to blood floow
flow varies inversely to viscosity of fluid
Term
neural control of total peripheral resistance
Definition
autonomic nervous system can regulate cardiac output and peripheral resistance
Term
vascular compliance
Definition
increase in volume a vessel can accommodate for a given increase in pressure
depends on ratio of elastic fibers to muscle fibers
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