Cardiovascular Flashcards
Define the SA node
generates impulse, spindle shaped,20 mm long, 3 mm wide at the junction of superior vena cava and the RT. atrium, 1 mm below epicardium
The AV node is located …
1 mm below the RT. atrium endocardium, anterior to the ostium of the coronary sinus
Why AV node conduction is slow?
to allow the atria enough time to finish its contraction
what is the effect of sympathetic stimulation on AV node?
speeds up conduction and decrease refractory time.
* parasympathetic stim. has an opposite effect
Define the His-Purkinje system (ventricular conduction)
comprises His bundle, bundle branches & purkinje fibers altogther.. It has fast conduction speed. Made up of purkinje cells
The bundle branch is divided into ….. & ….
RBB (thin), & LBB (thick)
* LBB is further divided to ant. thin, and post. broad
What is the function of Purkinje fibers?
penetrate the ventricular myocardium to depolarize the muscle cells
The nexus (gap) in the …….. is used…..
intercalated discs
to low resistance electrical connection
The RMP for AV and SA node is …., while for the purkinje & cardiac muscle cells ….
- 70 mV (slow fibers)
- 90 mV (fast fibers)
- The inside is more negative with respect to the outside
Conduction speed depends on ….., …… & …..
protein content, diameter of the fiber, presence of gap junctions (e.g His-Purkinje system)
Automaticity is ….
ability to depolarize toward threshold automatically
* Cells with automaticity can function as pacemakers
Effective refractory period is …..
Relative refractory period is ……
- the interval during which AP can not be elicited no matter how strong the depolarizing stimulus
- The interval in which AP is elicited in response to a stimuli stronger than the needed to depolarize a resting cell
During AP, Ca enters the cell through …..
voltage gated L type Ca channels
* Ca leaves the myocell via Ca-Na exchange
At the Z line of the sarcomere, ….. extend to the interior of the myocardial fiber
T tubules (invagination of the sarcolemma)
What is the Ca induced Ca release?
The entry of Ca will cause the release of large amount of Ca from the sarcoplasmic reticulum, providing sufficient amount to initiate contraction.
* Still, it relies more on extracellular Ca than skeletal muscles
Sympathetic stim. and beta agonists increase ….. , so it increases the contraction force
the probability that a Ca channel is open which increase Ca influx
How is the myocardium relaxes?
- Stop Ca influx by closing the channels
- the endoplasmic reticulum actively reduces intracelluar Ca (ATPase activity)
- Troponin and tropomyosin restore their inhibitory configuration
Prolonged contraction is possible in cardiac muscle. T/F
False. unlike skeletal muscles, relaxation is part of the cardiac cycle
Skeletal muscles change in contractile force is due to ……
While for the cardiac muscle, is due to ….
change of number of fully activated fibers
change in contractility of all fibers
Atrial kick is ….. .
atrial systole (150 milisec)
* ECG P wave just before actual contraction
* EDV is max (120 mL), EDP is max (but below atrial)
* Left atrial pressure: a wave
* S4 is heard in pathologic condition
see p. 409
Mitral valve closure defines ….. . It occurs …… the tricuspid valve closure. Atrial pressure slightly ….. due to …..
the beginning of the isovolumetric contraction
before
increase c wave, bulging of the mitral into the left atrium
The loudest heart sound is …..
S1
Aortic valve opening marks ….. . It occurs …… the pulmonary valve
the beginning of the ventricular ejection
after (isovolumetric contraction is longer in the left ventricle)
V wave shows the ….
increase in atrial pressure due to refilling
* mitral is closed
Why aortic pressure rises fast?
because of the rapid ejection of blood into the aorta exceeds the drainage into the peripheral arteries
Ventricular diastole duration depends on …
HR
* But it has the longest duration in the cycle
Aortic valve closure defines ….. . It occurs …. the pulmonary valve closure
the beginning of the isovolumetric relaxation
before
The peak of the V wave occurs during …..
the isovolumetric relaxation
* Max atrial volume is reached
The incisura is caused by …
the rapid decrease of aortic pressure is interrupted by small pressure increase from elastic recoil
The S2 sound coincides with …..
aortic valve closure (A2 then P2)
TP segment is recorded during ….
isovolumetric relaxation & rapid ventricular filling & diastasis
Mitral valve opening define the ….
beginning of the rapid ventricular filling
Y descent marks the …..
decrease in atrial pressure during the rapid ventricular filling
S3 coincides with …..
rapid ventricular filling
* normal in children, but pathologic in adults
Define diastasis
The period of slow ventricular filling. Duration depends on HR
* NOTE: during diastasis, atrial pressure and volume are slightly INCREASED due to pulmonary vein filling
Loud S1 can be heard during ….
sinus tachycardia (short PR interval)
Why the right and the left ventricles are asynchronous?
they don’t develop the same pressure before their valves open or close
Wide split of S2 is caused by …..
- RBB block
- ASD
- pulmonary stenosis & right ventricular overload
Paradoxical S2 splitting is caused by ….
LBB block
* duration of split will decrease on inspiration
S2 split widens on inspiration is ….., while the paradoxical S2 split ….. on inspiration
normal (physiologic)
shortens (P2 before A2)
Ventricular gallop is ….
S3 sound, heard during the rapid ventricular filling
- It is an indicator of heart failure in older patients. usual cause is mitral regurgitation
- S3 & S4 is better heard when the patient is in lateral decubitus position
Atrial gallop (kick) is never heard in …. . It frequently associated with ……
atrial fibrillation
decreased compliance or increased stiffness of the left ventricle, or aortic stenosis
* also called S4
Define CO and what is the normal value
The amount of blood pumped by any ventricle per minutes
normal is 4-8 L/min (resting)
* usually represented with the left ventricle
* Largely determined by venous return
Define the stroke volume SV
the volume of blood pumped per beat by the ventricle
- CO/HR
- or, difference between EDV & ESV
- SV average is about 70 mL
Cardiac index is …..
cardiac output divided by the body surface area
Ejection fraction EF is ….., and is considered the best ….
(SV/EDV) x 100%
- or is: (EDV - ESV) / EDV
- normal value is 55% - 80%
- The best clinical index of myocardial contractility
The best factors to assess the heart performance are …., …. & ….
- Preload: initial stretch of the heart muscle. The best index is EDV, then the radius of the ventricle
- Afterload: the pressure required to eject blood. The best index is aortic pressure
- Inotropic state (contractility): degree of activation of the myocardium
Positive inotropy agents include ….
catecholamines, beta-1 agonists, high concentration of Ca
Digitalis inhibit Na-Ca ATPase causing increased concentration of intracellular Ca
Negative inotropy agents include ….
Ca channel blocker, acidosis (blocks Ca channels), beta-1 receptor antagonists, alcohol, myocardial ischemia, Acetylcholine (effect in the atria only, not the ventricle)
Stroke volume is increased by ….. or …..
increasing preload, or decreasing afterload
Venodilators …… preload & afterload
decrease
Define blood flow and its types
blood flow (Q) is the amount of blood that passes a point in the circulation within a unit time (L/min or mL/min)
- Laminar: concentric layers, velocity zero at the wall, max at center. Flow occurs to a certain critical velocity
- Turbulent: chaotic flow, usually at high speed or making sharp turns. Occurs above critical velocity
For flow to occur, ….. is required
a pressure gradient
* pressure (P) is the force applied by the blood to the walls of vessels
Define systolic pressure and diastolic pressure
- Systolic: the highest pressure in the cycle. Occurs in early ventricular systole
- Diastole: The lowest pressure in the cardiac cycle, usually before the opening of the aortic valve
What is the effect of the following on the pressure curve:
- SV
- Rate of rise in ventricular pressure
- Arterial elasticity
- Blood viscosity
- higher SV leads to steeper pressure curve
- faster ejection means steeper curve
- Less compliance leads to steeper curve
- Higher viscosity means steeper curve
What is the mean arterial pressure ?
Mean = 1/3 systolic + 2/3 diastolic
- MAP = CO * TPR
- Heart rate needs to be within normal 60-100
The major site of vascular resistance is ….
arterioles
* They account for the largest drop in blood pressure
Mean pressure …. as the distance increase from the aortic valve
declines
The ratio of mean blood pressure across a segment to the blood flow is called …..
resistance
R= delta P/Q
* can not be measured directly, but across a segement
Poiseuille’s law is …
R = (8 x viscosity x length) / π x r^4
* Q = (π x r4 x delta P) / 8 x viscosity x length
Blood viscosity depends on ….. & ……
hematocrit & protein content
* multiple myeloma & waldnestrom macroglobulinemia increases blood protein contents
The part in the circulation with the largest cross section is …
the capillaries
- v = Q/A
- They lack smooth muscles in their walls
Why large veins serve as capacitance vessels?
Because of their low pressure and high compliance
* may contain up to 75% of total blood at rest
Alpha receptors activation by the sympathetic system lead to ……
increase venous return
Central venous pressure at the right atrium is …
0 - 3 mmHg
* CVP is same as mean right atrial pressure
What are the factors maintaining venous return to the heart?
- venous valves
- Activity of skeletal muscles
- pump of inspiration
What is the reason for pressure waves in the Jugular vein?
lack of valves between the right atrium and the venae cavae
What is the difference between arterioles and metarterioles?
arterioles have a continuous smooth muscle coat.. While metarterioles have smooth muscle fibers at various points
What is the function of the precapillary sphincter??
regulate the blood flow from the arterioles into the capillary bed.
The pressure drop across arterioles and metarterioles is ….
the largest
* Their resistance account for 1/2 total vascualr resistance
The capillary wall consists of …..
a single layer of endothelium resting on a basement membrane
Post capillary venules have …. muscle coat
Collecting venules have ….. muscle coat
no
incomplete
What is the effect of sympathetic simulation of alpha & beta 2 receptors on capillaries?
- alpha: constriction
- beta 2: dilation
* humoral mechanisms also have an effect on the tone, and permeability
Lymph protein concentration is highest in ….
vessels draining the GIT
The rate of lymph flow is ….
120 mL/hr
The heart receives about ….. of the total cardiac output
5%
The coronary pressure gradient is the difference between …..
the coronary artery and the coronary sinus
Most coronary blood flow occurs during ….
diastole
* Increased HR can really compromise coronary blood flow
What is the effect of the following on coronary vascular resistance
- regional hypoxemia
- adenosine
- neural effect
- leads to vasodialtion (relaxation of precapillary sphincters)
- Most potent vasodilator, from ATP break down during increased activity
- Limited. Sympathetic stimulation leads to vasoconstriction, but the effect is overridden by the metabolic factors
The heart uses about ….. of the blood O2, and it derives its energy from oxidation of ….
75%
fatty acids
Alpha 1 activation leads to ….., beta 1 activation leads to …., while beta 2 activation leads to ….
- alpha 1: constriction of skin and splanchnic vessels
- beta 1: constriction of blood vessels, increase HR, AV conduction velocity & inotropy
- beta 2: vasodilation
see p.418
Baroreceptor are found in …. , and are activated through ….
heart, lungs, carotid sinus (IX) & aortic arch (X)
stretching caused by high pressure
* also called stretch receptor
* They are located in the adventitia of the vessels, and resemble GTO
Rate of firing of baroreceptors depends on …
- magnitude of stretch (mean arterial pressure)
- Rate of stretch (pulse pressure)
* pulse pressure is the difference between systolic and diastolic pressure (normal is 40)
What is the function of baroreceptors?
decrease fluctuations in blood pressure
- they function at a base rate when blood pressure is normal
- see p.419
Cardiopulmonary receptors are activated by …..
atrial filling and contraction
- located at junction of venae cavae and rt. atria, and the junction of pulmonary veins and left atria
- These are stretch receptors, and they do not respond directly to increase systemic BP
Activation of cardiopulmonary receptors leads to …..
- Bainbridge reflex (when CVP is increased due to increased return)
- Decrease ADH (vasopressin)
- increase ANF release (reduces aldosterone, leads to increase Na excretion). Also increases GFR by constricting the efferent vessel
see p.419
PR segment represents ….
the depolarization of AV node, His-Purkinje fibers and bundles. Measured between the end of the P wave and start of QRS
* It is isoelectric (too small to be detected)
see p. 420 for full details on ECG
PR interval is ….
the time needed for the depolarizing impulse to travel from the SA node to the ventricles
Measured from beginning of P wave to the beginning of QRS
During the ST segment, all ventricular cells are ….
depolarized. Measured from the end of QRS to the start of T wave
* It is isoelectric
* elevations of depressions indicates pathologic conditions
The T wave represents ….
the repolarization of the ventricles
* Tall (tented) T waves indicates ischemia, infarction, hyperkalemia or CVA
The QT interval is prolonged in ……, and shortened in …
congestive heart failure, hypocalcemia
hypercalcemia & digitalis use
* Measured from the beginning of QRS to the end of T wave
RR interval represents
the length of the cardiac cycle
* from the beginning of one QRS to the next QRS
Normal sinus rhythm is originated in …. . Normal value is …..
SA node
- 60 - 100 /min
- Sinus tachycardia is over 100/min (exercise, fever, pain)
- Sinus bradycardia is below 60/min (athletes, SA dysfunction, infarction)
Sinus arrhythmia is identified by ….
different RR interval
* most common is the respiratory sinus arrhythmia
see p. 421
Arrhythmias could be due to …… or …..
disturbance in impulse origin, disturbance in impulse conduction
What are the types of AV block?
- First degree: delay in conduction from atria to ventricle. Long PR interval
- Second degree: Intermittent failure of conduction
- Third degree: Failure of any impulse to be conducted to the ventricles
In third degree AV block, the ventricles are depolarized by ….
It is characterized by ….., ….. & …..
- AV nodal impulse (Escape rhythm)
* Escape rhythm is characterized by wide pulse pressure & slow ventricular rate & prominent jugular pulsation (cannon A waves, due to atria contraction against closed tricuspid valve)
see p. 422
In BB block, the QRS interval is ….
prolonged
Ectopic beat is ….
beat originating outside the SA node
The pacemaker cells outside the SA node are ….
latent, because their rate of depolarization is slower than the SA node
* Escape (ectopic) rhythm is generated if these pacemakers are not depolarized within a certain period
In supra ventricular arrhythmias, QRS is ….
normal
Premature atrial contraction is ….
insertion of ectopic beat interrupting the next normal sinus rhythm
What is the difference between PSVT, atrial flutter & atrial fibrilation?
In the frequency of the stimulus PSVT 150-250 flutter 250-350 fibrilation 350-600 (multiple foci depolarizing the atria, and QRS is recorded at irregular interval) see p. 422
Saw tooth appearance is the characteristic of …
atrial flutter
also called F waves
Ventricualr arrhythmia is characterized by …..
bizarre QRS complex
PVC is ….
an ectopic beat in the ventricle before the next sinus rhythm.. Considered normal in healthy patients
* not conducted backwards through the AV node
What is the difference between the AIVR, VT & ventricular fibrillation?
AVIR: a normally latent pacemaker is activated, fires at a regular rate, 50-100/min
VT: 100-250/min
VF: over 250/min (no recognizable QRS, may be triggered by PVC during the vulnerable period at the end of ventricular repolarization)
Congestive heart failure occurs when ..
the heart is unable to deliver sufficient CO to meet the body demand
What are the initial causes of CHF?
- Increased afterload
- Increased preload (due to renal disease or over transfusion of fluids)
- Valvular disease: leads over loading of the ventricles
- Chronic tachycardia or bradyarrhythmia
- MI
What are the levels of the following in CHF
- ADH
- Aldosterone
- Catecholamines
- elevated
- elevated
- elevated in the body, but depleted in the myocardial tissue
What are the symptoms of CHF?
- Dyspnea (usually on exertion, due to engorgement of lungs with fluid)
- Orthopnea (due to decrease ventilatory reserve and increased venous return to the right heart. Develops later in CHF). Patients use more pillows to sleep comfortably
- Paroxysmal nocturnal dyspnea
- Weight gain: not explained by diet, associated with water and sodium retention
What are the signs of CHF?
- Cardiomegaly: concentric (pressure hypertrophy, detected by increase voltage of QRS, not by xray) & eccentric (volume hypertrophy)
- Tachycardia (due to atrial fibrillation or PVC)
- Arterial pressure is high, low or normal
- Respiratory rate elevated
- Temperature may be low due to decrease CO
- Hepatomegaly & splenomegaly (due to right ventricular failure)
- Edema
- Pleural effusion: detected by xray and dullness on percussion
- Ascites
- Cyanosis: because of low CO, there is increased O2 extraction in capillaries
Define pulsus alternans
variation in blood pressure associated with alternating weak and strong left ventricular contractions
Define pulmonary rales
Wheezing sound during breathing, due to accumulation of fluid in the pulmonary space because of elevated pressure. Usually fluid is in the posterior bases of the lung
Define Kussmaul sign
Distension of the jugular vein during inspiration due to elevated CVP in heart failure
Anasarca is …..
edema involving the whole body
Cyanosis of CHF is treated with O2 administration. T/F
False.. It is unlike cyanosis associated with pulmonary disease
The ….. has higher blood flow velocity than the aorta because ….
the venae cava
because of the vessel is somewhat collapsed (has smaller cross section)
Laplace’s law is …..
wall tension = P x r / 2 x t
- P is pressure, r is radius, t is thickness of the wall
- Increased ventricle wall thickness will increase O2 demand (while coronary vessels will collapse due to narrowing, leading to hypoxia)
Why arterial constriction has less effect on mean systemic pressure?
because arteries have relatively small amount of blood
Total peripheral resistance is ……. (equation)
(MAP - CVP) / CO
The function of the fibrous pericardium is ….
preventing the heart from overdistending during diastole
- If it becomes laxed, this will lead to ventricular over filling
- If it becomes stiff (or the pericardium is filled with fluid) this leads to diastolic dysfunction and reduced SV
Phospholamban is ……
SERCA inhibitor (SER Ca pump inhibitor) * When phosphorylated by PKA, this will relieve the inhibition and increase contractility
Increased intrathoracic pressure leads to ….. venous compliance and …… venous return
increased, decreased
Coarctation of the aorta is …..
narrowing of the aorta at the area of ductus arteriosus (congenital) or due to any other reason
- Afterload is elevated.
- BP is different between arms and legs, left and right arm
The right vagus nerve innervate the ……, while the left vagus supply the ….
SA node
AV node
Bainbridge reflex is …… and is mediated by ….
increase HR due to increased CVP.
Mediated by CN X afferent, and the efferent effect is the slowing of the vagal input
* Helps prevent pulmonary edema
Carotid sinus syndrome is ……
fainting and due to excessive stimulation of the carotid sinus, which leads to increased vagal discharge
The response to sudden standing is ….
decrease parasympathetic input, increase sympathetic input, increase HR & CO, Vasoconstriction of alpha 1 receptors, leading to constriction of glomerular afferent, renin release, —–> aldosterone is released
What happens to MAP during exercise?
MAP increases
MAP = CO x TPR
* Because CO increases more than the TPR
HCT value for male ….., female is ……. .
HCT value is usually higher in the venous blood because of …..
44 - 46
40 - 42
chloride shift (leads to increase osmotic pressure inside the RBC, then RBC swelling)
* HCT = 3 x Hb
Cyanosis does not occur in severe anemia because …..
of low Hb
* Need > 5 g of deoxygenated Hb to appear
Bezold–Jarisch reflex in the heart is ……
bradycardia & hypopnea caused by hypotension detected by the carotid sinus, which leads to increase HR and contractility. However this response is opposed by the effect of the intraventricular baroreceptors which sense this stimuli and trigger paradoxical bradycardia and decrease contractility
