Ch 19 The Circulatory System: The Heart Pt: 2

Created by romallon 

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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

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