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BSF SPRING BLOCK I Physio REVIEW
N/A
201
Physiology
Graduate
01/31/2012

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Cards

Term
Cardiac output from the left side of the heart is known as what?
Definition
Systemic blood flow
Term
Cardiac output from the right side of the heart is known as what?
Definition
Pulmonary blood flow
Term
Where is the site of highest resistance in the cardiovascular system?
Definition
Arterioles
Term
What arterioles contain alpha-1-adrenergic receptors?
Definition
Arterioles of the skin, splanchnic, and renal circulations
Term
What arterioles contain beta-1-adrenergic receptors?
Definition
Arterioles of skeletal muscles
Term
What part of the circulatory system has the largest total cross-sectional and surface area?
Definition
Capillaries
Term
What part of the circulatory system contains the highest proportion of the blood in the cardiovascular system?
Definition
Veins
Term
Are veins under low or high pressure?
Definition
Low pressure
Term
What type of receptors are found in veins?
Definition
Alpha-1-adrenergic receptors
Term
What is the equation for blood flow?
Definition
v = Q/A where Q = blood flow and A = area
Term
What is the equation for cardiac output/blood flow?
Definition
Q = (Change in Pressure)/(Total peripheral resistance)
Term
What pressure gradient drives blood flow?
Definition
Mean arterial pressure - Right artrial pressure
Term
Blood flow is inversely proportional to what?
Definition
Resistance of the blood vessels
Term
Resistance is directly proportional to what?
Definition
Viscosity of blood and length of the vessel
Term
Resistance is inversely proportional to what?
Definition
Fourth power of the vessel's radius
Term
How is parallel resistance calculated?
Definition
1/Rtotal = 1/Ra + 1/Rb + ...
Term
How is resistance in a series calculated?
Definition
Rtotal = Rartery + Rarterioles + Rcapillaries + etc.
Term
When an artery is added in parallel, what happens to the total resistance?
Definition
Decreases
Term
As blood flows through an organ in parallel, what happens to the pressure?
Definition
Decreases
Term
What predicts whether blood flow will be laminar or turbulent?
Definition
Reynold's number
Term
A larger Reynold's number predicts what?
Definition
Greater tendency for turbulence
Term
Turbulence in blood flow is responsible for what audible sound?
Definition
Bruits
Term
What increases the Reynold's number?
Definition
Decreased blood viscosity or increased blood velocity
Term
What describes a blood vessel's ability to stretch?
Definition
Capacitance/compliance
Term
Capacitance is inversely related to what?
Definition
Elastance
Term
How is capacitance/compliance calculated?
Definition
C = Volume/Pressure
Term
Where is capacitance greater?
Definition
Veins, allowing more blood volume
Term
Capacitance of arteries naturally decreases with what?
Definition
Age
Term
Where is blood pressure highest and lowest?
Definition
Aorta and venae cavae respectively
Term
Why does the largest decrease in pressure occur in arterioles?
Definition
Site of highest resistance
Term
What is normal mean aortic pressure?
Definition
100 mmHg
Term
What is normal arteriole pressure?
Definition
50 mmHg
Term
What is normal capillary pressure?
Definition
20 mmHg
Term
What is normal vena cava pressure?
Definition
4 mmHg
Term
How does arterial pressure fluctuate?
Definition
Pulsatile
Term
Where is arterial pressure highest during a cardiac cycle?
Definition
Systolic pressure
Term
When is systolic pressure measured?
Definition
After the heart contracts and blood is ejected into the arterial system
Term
Where is the arterial pressure lowest during a cardiac cycle?
Definition
Diastolic pressure
Term
When is diastolic pressure measured?
Definition
When the heart relaxes in diastole and blood is returning to the heart via veins
Term
The difference between systolic and diastolic pressure is known as what?
Definition
Pulse pressure
Term
What is the most important determinant of pulse pressure?
Definition
Stroke volume
Term
Why does pulse pressure increase to the same extent as the systolic pressure?
Definition
Diastolic pressure remains unchanged during ventricular systole
Term
Decreased capacitance would have what effect on the pulse pressure?
Definition
Increases
Term
The average arterial pressure with respect to time is known as what?
Definition
Mean arterial pressure
Term
How is mean arterial pressure approximately calculated?
Definition
Diastolic pressure plus 1/3 the pulse pressure
Term
Why is venous pressure so low?
Definition
High capacitance = large volumes at low pressure
Term
What is lower, venous pressure or atrial pressure?
Definition
Atrial pressure
Term
What is the order of waves on an on electrocardiogram (ECG)?
Definition
P -> Q -> R -> S -> T
Term
What represents atrial depolarization on an ECG?
Definition
P wave
Term
The PR interval in an ECG is the interval between the beginning of the P wave and the beginning of the Q wave and varies according to what?
Definition
Conduction velocity through the AV node
Term
What represents the depolarization of the ventricles on an ECG?
Definition
QRS complex
Term
The QT interval is the interval from the beginning of the Q wave to the end of the T wave and represents what?
Definition
Period of depolarization and repolarization of the ventricles
Term
The ST segment on a ECG is what?
Definition
Segment from the end of the S wave to the beginning of the T wave
Term
What does the ST segment on an ECG represent?
Definition
Period when the ventricles are depolarized
Term
What represents ventricular repolarization on an ECG?
Definition
T wave
Term
The resting membrane potential in cardiac APs is determined by the conductance of what?
Definition
K+
Term
An inward K+ current has what effect on cardiac membrane potential?
Definition
Depolarizes
Term
What is the resting membrane potential of ventricles, atria, and the Purkinje system?
Definition
-90mV
Term
What occurs during phase 0 of cardiac APs?
Definition
Upstroke via transient increase in Na+ conductance, depolarizes the membrane
Term
What occurs during phase 1 of cardiac APs?
Definition
Brief period of initial repolarization via outward current of K+ and decreased Na+ conductance
Term
When is the plateau of the AP of cardiac APs?
Definition
Phase 2
Term
What causes the plateau in phase 2 of cardiac APs?
Definition
Transient increase in Ca++ conductance, increased K+ conductance
Term
What occurs during phase 3 of cardiac APs?
Definition
Repolariztion, Ca++ conductance decreases and K+ conductance increases
Term
What occurs during phase 4 of cardiac APs?
Definition
Inward and outward K+ currents are equal, resting membrane potential approaches K+ equilibrium potential
Term
What is considered the pacemaker of the heart?
Definition
Sinoatrial (SA) node
Term
What is the intrinsic rate of SA action potential phase 4 depolarization from fastest to slowest?
Definition
SA > AV > His-Purkinje
Term
What occurs during phase 0 of SA action potential?
Definition
Upstroke via increased Ca++ conductance
Term
What occurs during phase 1 and 2 of SA node action potential?
Definition
Not present
Term
What occurs during phase 3 of SA node action potential?
Definition
Repolarization via increased K+ conductance
Term
What occurs during phase 4 of SA node action potential?
Definition
Slow depolarization via increased NA+ conductance and an inward Na+ current called If. If activated via repolarization during phase 3
Term
What causes the upstroke of the action potential in the AV node?
Definition
Inward Ca++ current
Term
The time required for excitation to spread throughout cardiac tissue is known as what?
Definition
Cardiac conduction velocity
Term
Conduction velocity is dependent on what?
Definition
Size of the inward current during upstroke
Term
Where is cardiac conduction velocity the fastest and slowest?
Definition
Purkinje system, AV node respectively
Term
Why is the conduction velocity slowest in the AV node?
Definition
Allows for ventricular filling before ventricular contraction
Term
What might be the result of increased AV node conduction velocity?
Definition
Compromised ventricular filling
Term
The ability of cardiac cells to initiate action potentials in response to inward depolarizing current is known as what?
Definition
Excitability
Term
What changes excitability over the course of an action potential?
Definition
Refractory periods
Term
What reflects the time during which no action potential can be initiated regardless of how much inward current is supplied?
Definition
Absolute refractory period
Term
When does the absolute refractory period begin and end?
Definition
Upstroke to plateau
Term
The period during which a conducted action potential cannot be elicited is known as what?
Definition
Effective refractory period
Term
The period immediately after an absolute refractory period when repolarization is almost complete is known as what?
Definition
Relative refractory period
Term
What is required for an AP to be elicited during a relative refractory period?
Definition
More than usual inward current is required
Term
Where do chronotropic effects produce changes?
Definition
Heart rate
Term
A negative chronotropic effect elicits what change?
Definition
Decreases heart rate by decreasing the firing rate of the SA node, increases the PR interval. Positive chronotropic effects have the opposite response
Term
Vagal parasympathetic nerves send signals to all parts of the heart except the ventricles using what neurotransmitter?
Definition
Acetylcholine via muscarinic receptors
Term
How does parasympathetic innervation via the vagal nerve decrease heart rate?
Definition
Decreases rate of phase 4 depolarization
Term
What channels do parasympathetic negative chronotropic effects impact?
Definition
Decreases If channels to decreases inward Na+ current responsible for phase 4 depolarization in the SA node
Term
Sympathetic innervation has what effect on the circulatory system?
Definition
Increases heart rate, conduction velocity, and contractility via beta-1-adrenergic receptors, constricts vessels via alpha-1- adrenergic receptors
Term
How does parasympathetic vagal innervation decrease the conduction velocity through the AV node?
Definition
Decreased inward Ca++ current
Term
What neurotransmitter acts on beta-1 receptors?
Definition
Norepinepherine
Term
How does sympathetic innervation increase heart rate?
Definition
Increased If increases inward Na+ current to increase rate of phase 4 depolarization
Term
How does sympathetic innervation increase conduction velocity through the AV node?
Definition
Increased inward Ca++ current
Term
What maintains cell to cell cohesion in myocardial cells?
Definition
Intercalated disks
Term
What low resistance paths between cells allow for rapid electrical spread of action potentials?
Definition
Gap junctions
Term
How do T-tubules differ in myocardial cells vs in skeletal muscle?
Definition
Forms dyads with sarcoplasmic reticulum, well developed in ventricles but not atria
Term
The magnitude of tension that develops in cardiac muscle is proportional to what?
Definition
Intracellular Ca++
Term
What re-accumulates Ca++ to the sarcoplasmic reticulum in cardiac muscle?
Definition
Ca++ ATPase pump
Term
The intrinsic ability of cardiac muscle to develop force at a given muscle length is known as what?
Definition
Contractility or inotropism
Term
What can be used to estimate contractility?
Definition
Ejection fraction
Term
What factors increase contractility?
Definition
Increased heart rate, sympathetic stimulation, cardiac glycosides
Term
What is the positive staircase/Bowditch staircase principle?
Definition
Increased heart rate increases the force of contraction in a step-wise fashion as intracellular Ca++ increases cumulatively over several beats
Term
What is post-extrasystolic potentiation?
Definition
The concept that the beat that occurs after an extrasystolic beat has an increased force of contraction because "extra" Ca++ entered the cells during extrasystole
Term
How does sympathetic stimulation increase the activity of Ca++ pumps of the SR? How does this increase contractility?
Definition
Phosphorylation of phospholamban, more Ca++ is accumulated by SR and available for release in subsequent beats
Term
How does cardiac glycosides increase contractility?
Definition
Increases force of contraction by inhibiting Na+/K+ -ATPase pump, diminishes Na+/Ca++ gradient and increases intracellular Ca++
Term
How does parasympathetic stimulation via ACh muscarinic receptors decrease myocardial contractility?
Definition
Decreases inward Ca++ current during plateau of the cardiac cycle
Term
Pre-load is equivalent to what?
Definition
End-diastolic volume which is related to right atrial pressure
Term
What happens to end diastolic volume when venous return increases?
Definition
Right atrial pressure increases due to increasing end-diastolic volume, stretches or lengthens ventricular muscle fibers
Term
Afterload in the left ventricle is equivalent to what?
Definition
Aortic pressure
Term
An increase in aortic pressure has what effect on afterload?
Definition
Increases afterload on the left ventricle
Term
Afterload for the right ventricle is equivalent to what?
Definition
Pulmonary artery pressure
Term
Increases in pulmonary artery pressure has what effect on afterload?
Definition
Increases afterload of the right ventricle
Term
What determines the maximum number of cross-bridges that can form between actin and myosin and in turn determines the maximum tension or force of contraction?
Definition
Sarcomere length
Term
Whe is velocity of contraction maximal?
Definition
When afterload is zero
Term
When is velocity of contraction decreased?
Definition
When afterload increases
Term
The principles that increases in stroke volume and cardiac output occur in response to an increase in venous return or end-diastolic volume is known as what?
Definition
Frank-Starling relationship
Term
The Frank-Starling relationship states that increases in end-diastolic volume cause an increase in what?
Definition
Ventricular fiber length which produces an increase in developed tension
Term
The Frank-Starling relationship matches cardiac output to what?
Definition
Venous return (greater venous return = greater cardiac output)
Term
Changes in contractility shift the Frank_starling curve in what direction?
Definition
Increased contractility = upward, decreased contractility = downward
Term
Ventricular pressure curves are constructed by combining what?
Definition
Systolic and diastolic pressure curves
Term
The relationship between diastolic pressure and diastolic volume in the ventricle is known as what?
Definition
Diastolic pressure curve
Term
The relationship between systolic pressure and systolic volume in the ventricle is known as what?
Definition
Systolic pressure curve
Term
Increased pre-load has what effect on the ventricular pressure loop graph?
Definition
Refers to an increase in end-diastolic volume and increases stroke volume basked on the Frank-Starling relationship
Term
Increased afterload has what effect on the ventricular pressure loop graph?
Definition
Refers to increased aortic pressure which results in decreased stroke volume as the ventricle ejects blood against a higher pressure
Term
What effect does increased contractility have on the ventricular pressure volume loop graph?
Definition
Increased stroke volume via a decrease in end-systolic volume
Term
Simultaneous plots of cardiac output and venous return as a function of right atrial pressure or end-diastolic volume is known as what?
Definition
Cardiac and vascular function curves
Term
Which part of the cardiac and vascular function curve depicts the Frank-Starling relationship for the ventricle?
Definition
Cardiac output/cardiac function curve
Term
The venous return/vascular function curve in a cardiac and vascular function plot depicts the relationship between venous return and what?
Definition
Right atrial pressure
Term
What is represented at the point where the vascular function curve on a cardiac and vascular function curve plot intersects the x-axis?
Definition
Mean systemic pressure
Term
Mean systemic pressure is equivalent to right atrial pressure at what point?
Definition
When there is no flow in the cardiovascular system
Term
What determines the slope of the venous return curve on a cardiac and vascular function curve plot?
Definition
Resistance of the arterioles
Term
What is represented at the point of intersection on a cardiac and vascular function curve plot?
Definition
Equilibrium or steady-state point where cardiac output equals venous return
Term
A clockwise rotation of the venous return curve indicates what?
Definition
Decrease in total peripheral resistance causing an increase in venous return to the heart
Term
A counterclockwise rotation of the venous return curve indicates what?
Definition
Increase in total peripheral resistance causing a decrease in venous return to the heart
Term
What effect does an increase in total peripheral resistance have on cardiac output and venous return?
Definition
Decreases both but right atrial pressure is unchanged. Increased TPR has the opposite effect
Term
The volume ejected from the ventricle in each beat is known as what?
Definition
Stroke volume
Term
How is stroke volume calculated?
Definition
End-diastolic volume - end-systolic volume
Term
What equation expresses cardiac output?
Definition
Cardiac output = stroke volume X heart rate
Term
The fraction of the end-diastolic volume ejected in each stroke volume is known as what?
Definition
Ejection fraction, related to contractility
Term
What is the normal ejection fraction?
Definition
~55%
Term
The work the heart performs on each beat is known as what?
Definition
Stroke work
Term
How is stroke work calculated?
Definition
Aortic pressure X Stroke Volume
Term
What is the primary energy source for stroke work?
Definition
Fatty acids
Term
Cardiac oxygen consumption is directly related to what?
Definition
Amount of tension developed by the ventricles
Term
How is cardiac oxygen consumption increased?
Definition
Increased afterload, size of the heart, contractility, and heart rate
Term
What is the Fick principle?
Definition
Measures cardiac output via (O2 consumption)/(O2pulmonary vein - O2pulmonary artery)
Term
Filling of the ventricle by atrial systole causes which heart sound?
Definition
Fourth heart sound which is not audible in normal adults
Term
Which wave is atrial systole responsible for on an ECG?
Definition
P wave
Term
When does isovolumetric ventricular contraction occur on an ECG?
Definition
Onset of the QRS wave, represents electrical activation of the ventricles
Term
What wave on an ECG represents repolarization of the ventricles and marks the end of ventricular contraction?
Definition
Onset of T wave
Term
What point represents isovolumetric relaxation on an ECG?
Definition
End of T wave
Term
What causes the first heart sound?
Definition
Closure of the AV valves in isovolumetric ventricular contraction
Term
What causes the second heart sound?
Definition
Closure of the semilunar valves in isovolumetric ventricular relaxation
Term
What causes the third heart sound?
Definition
Ventricular filling, not normally audible in adults
Term
What kind of feedback system is the baroreceptor reflex?
Definition
Negative feedback system
Term
What is the function of the baroreceptor reflex?
Definition
Minute-to-minute regulation of arterial blood pressure
Term
Where are baroreceptors located?
Definition
As stretch receptors within walls of the carotid sinus and aortic arch
Term
What activates baroreceptors?
Definition
Decrease in atrial pressure in the carotid sinus, increase in atrial pressure in aortic arch
Term
What response by the ANS is elicited by baroreceptors when atria pressure decreases?
Definition
Decreased parasympathetic outflow to the heart, increased sympathetic outflow tot he heart and blood vessels
Term
What are the effects of the baroreceptor reflex?
Definition
Increased heart rate, contractility, and stroke volume, vasoconstriction of arterioles, vasoconstriction of veins, all in order to raise blood pressure
Term
What is the slower, hormonal mechanism designed to regulate blood pressure long term?
Definition
Renin-angiotensin-aldosterone system
Term
How does the renin-angiotensin aldosterone system regulate blood pressure?
Definition
Adjusts blood volume
Term
What does the enzyme renin activate after being secreted in response to a decrease in renal perfusion pressure?
Definition
Catalyzes the conversion of angiotensinogen to angiotensin I in plasma
Term
What converts angiotensin I to angiotensin II and where does this occur?
Definition
Angiotensin-converting enzyme (ACE) in the lungs
Term
What are the effects of ACE inhibitors?
Definition
Inhibits ACE to block the conversion of angiotensin I to II, decreases blood pressure
Term
What are the effects of angiotensin II?
Definition
Stimulates aldosterone secretion to increase Na+ reabsorption which water then follows, causes vasoconstriction of arterioles to increase total peripheral resistance and mean arterial pressure
Term
Chemoreceptors in the carotid and aortic bodies respond to what signals? What response is elicited?
Definition
Decreases in oxygen, produces vasoconstriction, increase in total peripheral resistance, and increases arterial pressure
Term
Vasopressin is involved in the regulation of blood pressure in response to what?
Definition
Hemorrhage via vasoconstriction and water reabsorption
Term
What does the atria release in response to an increase in atrial pressure? What are its effects?
Definition
Atrial natriuretic peptide, relaxes vascular smooth muscle, decreases total peripheral resistance, increases Na+ and water excretion
Term
The smooth muscle band at the junction of arterioles and capillaries is called what?
Definition
Precapillary sphincter
Term
True capillaries lack smooth muscles and are defined as what?
Definition
Single layer of endothelial cells surrounded by a basement membrane
Term
What allows passage of water soluble substances in true capillaries?
Definition
Clefts/pores between endothelial cells
Term
What controls blood flow through capillaries?
Definition
Contraction and relaxation of the arterioles and precapillary sphincters
Term
How do lipid-soluble substances cross membranes of capillary endothelial cells?
Definition
Simple diffusion (ex. oxygen, carbon dioxide, etc.)
Term
Where are clefts/pores in endothelial capillary cells exceptionally tight or wide?
Definition
Tight in blood-brain barrier, wide in liver and intestines for passage of proteins (aka sinusoids)
Term
According to the starling equation, a positive J (fluid flow) means what in capillaries?
Definition
Net movement is out of the capillary
Term
What does K(f) represent in the Starling equation?
Definition
Filtration coefficent
Term
What does P(c) represent in the Starling equation?
Definition
Capillary hydrostatic pressure
Term
An increase in capillary hydrostatic pressure has what effect on the capillary?
Definition
Favors filtration out of the capillary
Term
What does P(i) represent in the Starling equation and what is its relationship with capillary filtration?
Definition
Interstitial fluid hydrostatic pressure, opposes filtration outof the capillary
Term
How is excess filtered fluid and filtered protein returned to the capillaries?
Definition
Via lymph
Term
What permits interstitial fluid to enter, but not leave, lymph vessels?
Definition
One-way flap valves
Term
What occurs when the volume of interstitial fluid exceeds the capacity of the lymphatics to return it to circulation?
Definition
Edema
Term
What are the effects of endothelium-derived relaxing factors (EDRF)?
Definition
Relaxation of vascular smooth muscle via production of cyclic guanosine monophasphate (cGMP)
Term
What is a well known endothelium-derived relaxing factor?
Definition
NO
Term
What organs exhibit autoregulation of blood flow?
Definition
Heart, brain, kidneys
Term
What is the definition of active hyperemia?
Definition
Blood flow to an organ is proportional to its metabolic activity
Term
What is reactive hyperemia?
Definition
An increase in blood flow to an organ that occurs after a period of occlusion of flow
Term
What basic principle guides the range of reactive hyperemia?
Definition
Longer periods of occlusion result in greater increases in blood flow above preocclusion levels
Term
What is the myogenic hypothesis of local control of blood flow based on?
Definition
Vascular smooth muscle contracts when it is stretched, explains autoregulation
Term
What is the metabolic hypothesis of local blood control of blood flow based on?
Definition
Tissue supply of oxygen is matched by tissue demand of oxygen via vasodilator metabolites, explains active hyperemia
Term
What vasoactive hormones cause arteriolar dilation and venous constriction?
Definition
Histamine, Bradykinin, Serotonin (arteriolar constriction only)
Term
Which vasoactive hormone causes local edema?
Definition
Histamine
Term
Which prostaglandins are vasodilators?
Definition
Prostacyclin and E-series prostaglandins
Term
What prostaglandins are vasoconstrictors?
Definition
F-series prostaglandins, thromboxane A(2)
Term
What controls coronary and cerebral circulation?
Definition
Local metabolic factors
Term
What are the most important metabolic factors in coronary circulation?
Definition
Hypoxia and adenosine
Term
What is the most important local vasodilator in cerebral circulation?
Definition
Carbon dioxide, an increase causes vasodilation to increase blood flow to the brain
Term
Why do vasoactive substances in the systemic circulation have little effect on cerebral circulation?
Definition
Blocked by blood brain barrier
Term
What sympathetic receptors are found in skeletal muscle blood vessels and what are their effects?
Definition
Alpha-1 = vasoconstriction, Beta-2 = vasodilation
Term
What are the local vasodilator substances in skeletal muscle?
Definition
Lactate, adenosine, K+
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