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Ahangari Test 3-2

Terms in this set (88)

Aorta
Carries oxygenated blood from left ventricle to body
Pulmonary artery
deoxygenated blood from right ventricle to lungs
Pulmonary Veins
4; carry oxygenated blood from lungs to heart
Superior and Inferior Vena Cava
Collect deoxygenated blood from body carry to right atrium
Layers of heart
pericardium, myocardium, endocardium
Left ventricle
largest and strongest chamber in your heart. Walls are only about a half-inch thick, but they have enough force to push blood through the aortic valve and into your body.
Papillary muscles
2 on left side; 3 on right
Tricuspid valve
regulates blood flow between the right atrium and right ventricle
Pulmonary valve
controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to your lungs to pick up oxygen.
Mitral valve
lets oxygen-rich blood from your lungs pass from the left atrium into the left ventricle.
Aortic valve
opens the way for oxygen-rich blood to pass from the left ventricle into the aorta, your body's largest artery, where it is delivered to the rest of your body.
Components of Vasculature
Arteries, Arterioles, Capillaries, Venules, Veins.
Arteries
deliver oxygenated blood to the tissues, thick-walled with extensive elastic tissue and smooth muscle, under high pressure(About 100mmgh).
stressed volume
The blood volume contained in the arteries
Arterioles
-are the smallest branches of the arteries, are the site of highest resistance in the cardiovascular system, have a smooth muscle wall that is extensively innervated by autonomic nerve fibers.
Arteriolar resistance
regulated by the autonomic nervous system (ANS)
Alpha1-Adrenergic receptors
found on the arterioles of the skin, splanchnic, and renal circulations.
Beta2-Adrenergic receptors
found on arterioles of skeletal muscle.
Capillaries
consist of a single layer of endothelial cells surrounded by basal lamina, are thin-walled,are the site of exchange of nutrients, water and gases.
Venules
formed from merged capillaries.
Veins
Are thin-walled. Are under low pressure. Have alpha-1 andrenergic receptors.
Contain the highest proportion of the blood in the cardiovascular system.
Veins.
Unstressed volume
blood volume contained in the veins
Velocity of blood flow
Affected by blood flow and cross-sectional area. V=Q/A
Blood flow
Affected by pressure gradient and resistance.
Q=P/R
Resistance
Poiseuille's equation R=8nl/r4. Depends on viscosity, length and radius.
Capacitance(compliance)
describes the distensibility of blood vessels. Is inversely related to elastance.Is much greater for veins than for arteries
C=V/P
Aorta, 100 mm Hg
Arterioles, 50 mm Hg
Capillaries, 20 mm Hg
Vena cava, 4 mm Hg
Mean pressure in the systemic circulation
Arterial pressure
Blood pressure (BP) is a force exerted by circulating blood on the walls of blood vessels. Is not constant during a cardiac cycle. It is pulsatile.
Systolic pressure
Highest arterial pressure during a cardiac cycle. Measured after the heart contracts and blood is ejected into the arterial system.(Contraction of ventricle)
Diastolic pressure
Lowest arterial pressure during a cardiac cycle.
Measured when the heart relaxed and blood is returning to the heart via the veins.(Relaxation of ventricle)
Pulse pressure
stroke volume most important determinant. Decreases in capacitance, such those that occur with the aging process, cause increases in this
Mean arterial pressure
Calculated approximately as diastolic pressure plus one-third of pulse pressure.
Venous system
Very low pressure; however high amounts of blood
elastance; compliance
The greater the amount of elastic tissue in a blood vessel, the higher the ______, and the lower the ______
Atrial pressure
Lower than venous pressure
Left atrial pressure is estimated by
the pulmonary wedge pressure
Hypertension
-Primary or essential hypertension is of unknown etiology and Secondary hypertension.
Angiotensin-converting enzyme (ACE) inhibitors
treat high BP; Captopril, Ramipril
Angiotensin || receptor blockers (ARBs)
treat high BP; Valsartan
Diuretics
treat high BP; Thiazide diuretics such as hydrochlorothiazide
Calcium channel blockers
treat high BP; Felodipine, Benidipine
Beta-adrenergic blocking agents
treat high BP; Propranolol-beta 1
P Wave
represents the wave of depolarization that spreads from the SA node throughout the atria, and is usually 0.08 to 0.1 seconds
Represents atrial depolarization on EKG
P Wave
Atrial repolarization on EKG
buried in the QRS complex
PR interval
onset of the P wave to the beginning of the QRS complex normally ranges from 0.12 to 0.20 seconds
This interval represents the time between the onset of atrial depolarization and the onset of ventricular depolarization.
PR interval
If the P-R interval is >0.2 sec
there is an AV conduction block.
QRS complex
Duration normally 0.06 to 0.1 seconds. This relatively short duration indicates that ventricular depolarization normally occurs very rapidly.
If the QRS complex is prolonged (> 0.1 sec)
conduction is impaired within the ventricles. This can occur with bundle branch blocks or whenever a ventricular foci (abnormal pacemaker site) becomes the pacemaker driving the ventricle.
Ectopic foci
are abnormal pacemaker sites within the heart (outside of the SA node) that display automaticity.
conducted over slower pathways within the heart, thereby increasing the time for depolarization and the duration of the QRS complex.
ectopic foci nearly always results in
ST segment
Segment from the end of the S wave to the beginning of the T wave. Represents the period when the ventricles completely are depolarized.
ventricular ischemia or hypoxia
ST segment can become either depressed or elevated under these conditions
T wave
represents ventricular repolarization and is longer in duration than depolarization
a small positive U wave may be seen following the T wave
represents the last remnants of ventricular repolarization
inverted or prominent U waves
indicates underlying pathology or conditions affecting repolarization.
QT interval
interval from the beginning of the Q wave to the end of the T wave. Range from 0.2 to 0.4 seconds
Q-T interval represents
the time for both ventricular depolarization and repolarization to occur, and therefore roughly estimates the duration of an average ventricular action potential.
Prolonged Q-T intervals
can be diagnostic for susceptibility to certain types of tachyarrhythmias.
Ventricles, atria and the Purkinje system
have stable resting membrane potentials of about 90mV. Action potential are of long duration, especially in Purkinje fibers, where they last 300 msec.
Phase 0.(Ventricles, atria and the Purkinje system)
upstroke of the action potential caused by a transient increase in Na+ conductance. This increase results in an inward Na+ current that depolarizes the membrane
At the peak of the action potential/ Phase 0 (Ventricles, atria and the Purkinje system)
the membrane potential approaches the Na+ equilibrium potential.
Phase 1(Ventricles, atria and the Purkinje system)
brief period of initial repolarization
Initial repolarization/ Phase 1(Ventricles, atria and the Purkinje system)
caused by an outward current, in part because of the movement of K+ ions out of the cell and in part because of a decrease in Na+ conductance.
Phase 2(Ventricles, atria and the Purkinje system)
Plateau of the action potential
Caused by a transient increase in Ca2+ conductance, which results in an inward Ca2+ current, and by an increase in K+ conductance.(Ventricles, atria and the Purkinje system)
Phase 2
Phase 3 (Ventricles, atria and the Purkinje system)
repolarization. Ca2+ conductance decreases, and K+ conductance increases and therefore predominates.
High K+ conductance results in a large outward K+ current (Ik) which hyperpolarizes the membrane back toward the K+ equilibrium potential.
Phase 3(Ventricles, atria and the Purkinje system)
Phase 4(Ventricles, atria and the Purkinje system)
resting membrane potential.
Period during which inward and outward current (Ik1) are equal and the membrane potential approaches the K= equilibrium potential.
Phase 4 (Ventricles, atria and the Purkinje system)
Sinoatrial node
normally the pacemaker of the heart. Has an unstable resting potential.
Phase 0 (SA node)
upstroke of the action potential. Different then ventricle and purkinje fibers.
Caused by an increase in Ca2+ conductance.
Phase 0(SA node)
Phase 3
repolarization (phase?)
Caused by an increase in K+ conductance.(SA Node)
Phase 3(SA Node)
Phase 4
slow depolarization. Accounts for the pacemaker activity of the SA node (automaticity)
Phase 4
Caused by an increase in Na+ conductance, which results in an inward Na+ current called If (SA Node)
Phases 1 and 2(SA node)
not present in the SA node action potential.
AV node
Upstroke of the action potential in the ______ is the result of an inward Ca+ current (like in the SA node).
Conduction velocity
reflects the time required for excitation to spread throughout cardiac tissue.
Depends on the size of the inward current during the upstroke of the action potential.
Conduction velocity
Conduction velocity
Fastest in Purkinje system slowest in AV node
Absolute refractory period (ARP)
No action potential can be initiated.
Excitability
ability of cardiac cells to initiate action potentials in response to inward, depolarizing current.
Effective refractory period (ERP)
effective means that a conducted
action potential cannot be generated
Relative refractory period (RRP)
Action potential can be elicited but more than the usual inward current is required
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