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WorksheetsFIRST YEAR DAY 1
Total questions: 80
Worksheet time: 3600secs
A 55-year-old man with hypokalemia presents with palpitations. The physician explains that the resting membrane potential of his cardiac myocytes is altered. Which ion channel is primarily responsible for maintaining the resting membrane potential in cardiac muscle?
Fast Na+ channels
L-type Ca2+ channels
Inward rectifier K+ channels
T-type Ca2+ channels
A patient is diagnosed with a genetic mutation affecting "Intercalated Discs." Which functional property of the heart will be most directly impaired?
Ability to store calcium
Rapid spread of action potentials (Functional Syncytium)
Synthesis of ATP
Duration of the absolute refractory period
During a laboratory experiment, a cardiac muscle fiber is stimulated. Unlike skeletal muscle, cardiac muscle cannot be tetanized. This is due to:
Absence of T-tubules
Long absolute refractory period
Slow calcium sequestration
Presence of gap junctions
A 60-year-old woman is prescribed a Calcium Channel Blocker. In the plateau phase (Phase 2) of the ventricular action potential, which of the following occurs?
Rapid Na+ influx
Slow Ca2+ influx balanced by K+ efflux
Closure of all K+ channels
Maximum K+ permeability
In the mechanism of "Excitation-Contraction Coupling," the trigger for calcium release from the Sarcoplasmic Reticulum (SR) is:
Direct electrical stimulation of the SR
Influx of Ca2+ through L-type channels (Calcium-induced calcium release)
Entry of Na+ through fast channels
Binding of Acetylcholine to the sarcolemma
A patient has severe hypercalcemia. What effect would this have on the heart's contraction?
Spastic contraction
Flaccid paralysis
Increased heart rate
Prolonged AV nodal delay
The "Self-Excitation" of the SA node (Phase 4) is primarily caused by the gradual opening of which channels?
Fast Na+ channels
Funny (If) sodium channels and T-type Ca2+ channels
L-type Ca2+ channels
Inward rectifier K+ channels
A patient is given a drug that increases the permeability of the SA node to Potassium (K+). What is the expected clinical effect?
Tachycardia
Bradycardia (Hyperpolarization)
Increased contractility
Ventricular fibrillation
The "Relative Refractory Period" of the cardiac cycle is defined as the time when:
No stimulus, regardless of strength, can cause an action potential
A supra-normal stimulus can trigger a second action potential
The muscle is in Phase 0
Calcium is being pumped back into the SR
A researcher notes that cardiac muscle T-tubules are larger than those in skeletal muscle and are found at the Z-lines. This anatomical feature is important because:
It allows for anaerobic metabolism
It facilitates the entry of extracellular Ca2+ necessary for contraction
It houses the pacemaker cells
It prevents the heart from overstretching
On a pressure-volume loop, the "End-Diastolic Volume" (EDV) is measured just before which event?
Opening of the Aortic valve
Closing of the Mitral valve
Opening of the Mitral valve
Closing of the Aortic valve
A 70-year-old man has a Third Heart Sound (S3). In which phase of the cardiac cycle is this sound typically heard?
Isovolumetric contraction
Isovolumetric relaxation
Rapid ventricular filling
Atrial systole
During "Isovolumetric Contraction":
All valves are closed; ventricular pressure rises
Aortic valve is open; volume decreases
Mitral valve is open; volume increases
Ventricular pressure is lower than atrial pressure
The "c wave" in an atrial pressure tracing (JVP) corresponds to:
Atrial contraction
Ventricular contraction causing the AV valve to bulge into the atrium
Venous return filling the atrium
Opening of the Tricuspid valve
A patient has an End-Diastolic Volume of 120 mL and an End-Systolic Volume of 50 mL. What is the Stroke Volume?
170 mL
70 mL
50 mL
120 mL
A competitive athlete has a resting heart rate of 50 bpm and a stroke volume of 100 mL. What is the Cardiac Output?
5.0 L/min
7.0 L/min
10.0 L/min
2.5 L/min
The "First Heart Sound" (S1) is caused by:
Closure of Semilunar valves
Closure of AV valves
Blood hitting the ventricular wall
Turbulent flow in the Aorta
A "Fourth Heart Sound" (S4) is often heard in patients with stiff ventricles (hypertrophy). This sound occurs during:
Rapid filling phase
Diastasis
Atrial contraction
Ventricular ejection
The "v wave" of the atrial pressure curve is caused by:
Atrial systole
Slow flow of blood into the atria while AV valves are closed
Bulging of AV valves
Rapid emptying of atria
During the "Period of Ejection," ventricular pressure must exceed:
Atrial pressure
Aortic/Pulmonary pressure
Atmospheric pressure
Intrathoracic pressure
According to the Frank-Starling Mechanism, the heart pumps more blood when:
Afterload increases
More blood flows into the heart (Increased Preload)
Parasympathetic stimulation increases
Heart rate decreases
A patient is given a "Positive Inotropic" drug. This means the drug will:
Increase heart rate
Increase force of contraction
Increase conduction velocity
Increase the AV nodal delay
Stimulation of the Vagus nerve (Parasympathetic) primarily decreases heart rate by releasing Acetylcholine, which:
Increases Na+ permeability
Increases K+ permeability (Hyperpolarization)
Increases Ca2+ permeability
Decreases K+ permeability
A patient in the ICU has a core temperature of 40°C (104°F). What is the expected effect on the heart?
Decreased heart rate
Increased heart rate (Tachycardia)
Increased force of contraction
No effect
The Sympathetic nervous system increases heart rate and contractility by acting on which receptors in the heart?
Alpha-1 adrenergic
Beta-1 adrenergic
Muscarinic M2
Nicotinic
Severe Hyperkalemia (High K+) causes the heart to become:
Spastic and hyper-excitable
Flaccid and dilated
Extremely fast
Hypertrophied
"Chronotropic effect" refers specifically to changes in:
Force of contraction
Heart rate
Conduction velocity
Excitability
"Dromotropic effect" refers to changes in:
Heart rate
Force of contraction
Conduction velocity through the AV node
Blood pressure
Which of the following describes the effect of Digitalis (used in heart failure)?
Negative Inotropic
Positive Inotropic
Positive Chronotropic
Positive Dromotropic
Norepinephrine increases the force of contraction by:
Increasing inward Ca2+ current
Blocking Na+ channels
Opening K+ channels
Reducing ATP consumption
The total delay from the SA node to the ventricles is approximately 0.16 seconds. Where does the majority of this delay occur?
Internodal pathways
AV Node
Bundle of His
Purkinje fibers
What is the physiological significance of the "AV Nodal Delay"?
Allows ventricles to empty completely
Allows atria to empty blood into ventricles before ventricular contraction
Prevents the heart rate from getting too high
Increases the force of contraction
Which part of the conducting system has the fastest conduction velocity?
SA Node
AV Node
Purkinje fibers
Atrial muscle
If the SA node fails, the AV node usually takes over as the pacemaker. This is called a:
Sinus rhythm
Ectopic pacemaker
Ventricular escape
Heart block
The "Stokes-Adams Syndrome" occurs when:
The SA node is hyperactive
There is a sudden total AV block, causing a delay before ventricles start beating
The Purkinje fibers become the primary pacemaker of the whole heart
The patient has a resting tachycardia
Vagal stimulation can cause "Ventricular Escape." This occurs because:
Vagal fibers do not significantly innervate the ventricles
The Vagus nerve releases Norepinephrine in the ventricles
The ventricles have a faster natural rhythm than the SA node
The SA node becomes the permanent pacemaker
The pathway that conducts impulses from the Right Atrium to the Left Atrium is the:
Bundle of His
Anterior Internodal Pathway (Bachmann’s bundle)
Posterior Internodal Pathway
Purkinje system
In the heart, the "Pacemaker" is the part with the:
Longest refractory period
Fastest conduction velocity
Highest rate of spontaneous depolarization
Largest cells
Ectopic pacemakers can be caused by:
High Vagal tone
Localized ischemia or calcified plaques
Deep sleep
Excessive hydration
The conduction through the AV node is slow because:
The fibers are very large
There are fewer gap junctions between cells
The cells have many fast Na+ channels
The resting membrane potential is very negative
The "P wave" on a normal ECG represents:
Atrial repolarization
Atrial depolarization
Ventricular depolarization
Ventricular repolarization
A patient has a "PR Interval" of 0.25 seconds. This indicates:
Normal conduction
First-degree AV heart block
Tachycardia
Bundle branch block
The "QRS Complex" represents:
Ventricular depolarization
Atrial repolarization (masked)
Both A and B
Ventricular repolarization
Why is the "T wave" in a normal ECG usually upright (positive)?
Ventricles depolarize from base to apex
The last part of the ventricle to depolarize is the first to repolarize
The first part of the ventricle to depolarize is the last to repolarize
Repolarization is always positive
The "QT Interval" is a measure of:
Total duration of ventricular contraction
Atrial contraction time
AV nodal delay
Time between heartbeats
"Einthoven’s Law" states that if the ECG voltages are recorded simultaneously:
Lead I + Lead II = Lead III
Lead I + Lead III = Lead II
Lead II + Lead III = Lead I
Lead I = Lead II = Lead III
Standard Limb Lead II connects:
Right arm (-) and Left arm (+)
Right arm (-) and Left leg (+)
Left arm (-) and Left leg (+)
Right arm (+) and Left leg (-)
The "J point" on an ECG is:
The start of the P wave
The point where the QRS complex ends and the ST segment begins
The peak of the T wave
The midpoint of the PR interval
A "Current of Injury" is most commonly associated with:
Normal exercise
Myocardial Infarction or Ischemia
High salt intake
Sinus arrhythmia
In a patient with Acute Myocardial Infarction, the ST segment is typically:
Depressed
Elevated
Absent
Isoelectric
"Augmented Limb Lead aVR" usually shows a QRS complex that is:
Entirely positive
Entirely negative (Inverted)
Bi-phasic
Extremely tall
A "Mean Cardiac Axis" of -45 degrees (Left Axis Deviation) can be caused by:
Hypertrophy of the Right Ventricle
Hypertrophy of the Left Ventricle (e.g., Hypertension)
Tall, thin body build
Pregnancy
Right Axis Deviation (+120 degrees) is commonly seen in:
Left Bundle Branch Block
Pulmonary Valve Stenosis (Right Ventricular Hypertrophy)
Obesity
Aortic Regurgitation
Hyperkalemia (High K+) produces which characteristic ECG change?
Prominent U waves
Flat T waves
Tall, peaked (tented) T waves
Prolonged QT interval
Hypocalcemia (Low Ca2+) causes:
Shortening of the QT interval
Prolongation of the QT interval
Inversion of the P wave
Disappearance of the QRS complex
A 65-year-old man presents with crushing chest pain and ST elevation in leads V1-V4. Which part of the heart is affected?
Inferior wall
Anterior wall
Lateral wall
Posterior wall
A patient with "Atrial Fibrillation" will lack which wave on the ECG?
QRS complex
T wave
P wave
U wave
During "Angina Pectoris" (Ischemia), the ECG often shows:
ST segment depression
Tall peaked T waves
Delta waves
Absence of QRS
In a "Third-Degree (Complete) Heart Block":
Every P wave is followed by a QRS
The PR interval is simply prolonged
There is no relationship between P waves and QRS complexes
The QRS complex is always narrow
"Wolff-Parkinson-White Syndrome" is characterized by a short PR interval and a slurred upstroke of the QRS called a:
Gamma wave
Delta wave
Epsilon wave
J wave
A patient has "Hypokalemia." The ECG is likely to show:
Peaked T waves
Flattened T waves and U waves
Shortened QT interval
Left axis deviation
The "Bainbridge Reflex" is triggered by increased pressure in the atria and results in:
Decreased heart rate
Increased heart rate
Decreased contractility
Bronchoconstriction
During a massive hemorrhage, the "Baroreceptor Reflex" causes:
Increased Vagal tone
Increased Sympathetic output and Tachycardia
Vasodilation
Decreased stroke volume
A 40-year-old male with "Pheochromocytoma" (adrenaline-secreting tumor) would have:
Negative inotropic effect
Positive chronotropic and inotropic effects
Dromotropic inhibition
Bradycardia
"Cardiac Tamponade" (fluid in the pericardium) causes:
Increased Cardiac Output
Decreased End-Diastolic Volume and low Stroke Volume
Hypertension
Bradycardia
Left-sided Heart Failure typically leads to:
Peripheral edema (swollen legs)
Pulmonary edema (fluid in lungs)
Jugular venous distension
Splenomegaly
The drug Atropine blocks Muscarinic receptors. It is used to treat:
Tachycardia
Bradycardia
Hypertension
High fever
"Ventricular Fibrillation" is fatal because:
The heart rate is too slow
There is no coordinated contraction; Cardiac Output is zero
The blood pressure is too high
The valves are stuck open
A patient has "Aortic Stenosis." During systole, you would expect to hear:
A systolic murmur
A diastolic murmur
Only S1 and S2
No heart sounds
In "Mitral Regurgitation," blood flows back into the:
Left Ventricle during diastole
Left Atrium during systole
Right Atrium during systole
Aorta during diastole
Which blood vessels act as the "Primary Resistance Vessels" determining blood pressure?
Large Arteries
Arterioles
Capillaries
Veins
"Capillaries" lack which of the following layers?
Endothelium
Tunica Media (Smooth muscle)
Basement membrane
All of the above
"Sinusoids" are found in which organ?
Brain
Liver
Heart
Skin
The "Tunica Adventitia" of large vessels contains small blood vessels that supply the vessel wall itself, called:
Arterioles
Vaso vasorum
Lymphatics
Venules
Veins are known as "Capacitance Vessels" because:
They have high pressure
They can hold large volumes of blood (60% of total blood)
They have very thick walls
They are the site of gas exchange
Which type of capillary has "pores" and is found in the kidneys and small intestine?
Continuous
Fenestrated
Discontinuous
Sinusoidal
The "Blood-Brain Barrier" is formed by which type of capillary?
Fenestrated
Continuous with tight junctions
Sinusoidal
Open
"Edema" (swelling) can be caused by:
Decreased capillary hydrostatic pressure
Increased plasma colloid osmotic pressure
Decreased plasma proteins (Albumin)
Lymphatic drainage increase
The velocity of blood flow is slowest in the:
Aorta
Arterioles
Capillaries (due to largest total cross-sectional area)
Vena cava
"Angiotensin II" is a powerful:
Vasodilator
Vasoconstrictor
Inotropic agent
Chronotropic agent
