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35 terms

Ch 19 The Circulatory System: The Heart Pt: 2

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p wave
Atrial depolarization
qrs complex
Ventricular depolarization
t wave
ventricular repolarization
cardic cycle
the series of physical events that transports blood through all four heart chambers during one heartbeat
pressure and resistance
flow is goverened by two main variable
sphygmomanometer
a pressure gauge for measuring blood pressure
pressure gradient
the amount of pressure change occurring over a given distance
auscultation
listening to sounds within the body (usually with a stethoscope)
first heart sound
heart sound that is produced by closure of the atrioventricular valves and that signals the beginning of systole; characterized as "lub" and usually loudest over the apex area of the heart
second heart sound
heart sound produced by closure of the semilunar valves; signals the ending of systole
third heart sound
ventricular filling sound. Occurs in early diastole during the rapid filling phase. Dull soft sound. Low pitched like distant thunder. Heard best at the apex w/ the bell held lightly w/ the person in the L lateral position. S3 is usually abnormal. Pathologic S3 is called ventricular gallop.
end diastolic volume
the amount of blood in each ventricle at the end of its relaxation period, about 130 mL
ventricular filling
What is the first phase of the cardiac cycle?
isovolumentric contraction
occurs b/w av valve closure and semilunar valve open; all 4 valves are closed momentarily; pressure gradient forces semilunar valves to open
ventricular ejection
Semilunar valves are open, blood is pushed from ventricles into aorta & pulmonary trunk
stroke volume
the volume of blood pumped out by a ventricle with each heartbeat
ejection fraction
measurement of the volume percentage of left ventricular contents ejected with each contraction
end systolic volume
the amount of blood remaining in each ventricle at the end of ventricular contraction, about 60 mL
isovolumetric relaxation
a brief interval during ventricular diastole when ventricular blood volume does not change because all four valves are closed
ascites
accumulation of serous fluid in peritoneal cavity
congestive heart failure
inability to pump enough blood to avoid congestion in the tissues
cardiac reserve
the difference between a person's maximum cardiac output and resting cardiac output
pulse
the rhythmic contraction and expansion of the arteries with each beat of the heart
tachycardia
abnormally rapid heartbeat (over 100 beats per minute)
bradycardia
slow heart rate, usually below 60 beats per minute
cardiac centers
centers of gray matter in the medulla oblongata
proprioceptors
sensory neurons that monitor position and movement of joints
baroreceptors
detect changes in blood pressure
chemoreceptors
stimulated by change in concentration of chemicals
chemoreflexes
Autonomic response to changes in blood chemistry, especially pH and concentrations of O2 and CO2. Initiated by chemoreceptors aortic bodies and carotid bodies. Adjust respiration to changes in blood chemistry. Also stimulates vasomotion. Hypoxemia, hypercapnia & acidosis induce vasoconstriction to increase LUNG perfusion!
baroreflexes
Autonomic negative feedback response to changes in blood pressure, detected by carotid sinuses. Input inhibits sympathetic cardiac and vasomotor neurons, reduces sympathetic tone, excites vagal fibers to the heart. Reduces heart rate and cardiac output, dilates arteries and veins and reduces blood pressure.
frank starling law of heart
this states that the greater the preload on cardiac muscle fibers before contraction, the stronger the force of contraction
contractility
ability of the cardiac muscle to shorten in response to an electrical impulse
afterload
the pressure that must be exceeded before ejection of blood from the ventricles can occur
coronary artery disease
narrowing of the coronary arteries due to plaque on the vessel walls