Cardiology

• Arrange the phases of the cardiac cycle in the correct sequence:

  1️⃣ Flow into atria

  2️⃣ Opening of A-V valves

  3️⃣ Atrial systole

  4️⃣ Ventricular systole

  5️⃣ Ventricular diastole
• What causes the first heart sound?

  Closing of AV valves
• The chambers of the heart empty completely during each cardiac cycle.

  False
• Stroke volume is the volume of blood pumped by each ventricle per beat.
• What is the ejection fraction in a healthy heart at rest?

  55-60%
• Systemic arterial pressure remains high throughout the cardiac cycle due to the elasticity of vessel walls.
• Cardiac output is defined as the volume of blood pumped per minute by each ventricle.
• What is the formula for cardiac output?

  Heart rate × Stroke volume
• Increased heart rate always leads to increased cardiac output.

  False
• End diastolic volume refers to the volume of blood in the ventricle at the end of diastole.
• What is another name for the Frank-Starling Mechanism?

  Starling’s Law of the Heart
• Increased end systolic volume leads to increased end diastolic volume.
• Summarize the steps of the Frank-Starling Mechanism in response to increased peripheral resistance:

  1️⃣ Decreased stroke volume

  2️⃣ Increased end systolic volume

  3️⃣ Increased end diastolic volume

  4️⃣ Increased stroke volume
• The phase where the atria contract is called systole
• An electrocardiogram is used to measure cardiac excitation
• Arrange the steps involved in cardiac excitation:

  1️⃣ Excitation-contraction coupling

  2️⃣ Propagation of the cardiac impulse

  3️⃣ Autonomic influence
• Excitable cells are surrounded by a plasma membrane, which regulates the passage of ions
• The plasma membrane is highly permeable to charged ions

  False
• Match the ion transport mechanism with its description:

  Ion Channels ↔️ Passive flow down gradients

  Ion Pumps ↔️ Active transport against gradients
• The resting membrane potential of a cardiac cell is approximately -85mV
• Voltage gating occurs when ion channel conductance changes in response to local changes in transmembrane potential
• Arrange the steps involved in excitation-contraction coupling:

  1️⃣ Calcium influx from L-type channels

  2️⃣ Ca2+ release from sarcoplasmic reticulum

  3️⃣ Ca2+ binds to Troponin-C

  4️⃣ Actin-myosin binding

  5️⃣ Contraction
• What does 'AS' represent in the heart cycle phases shown in the image?

  Atrial systole

  
• The phase where the atria relax is called atrial diastole

  
• What is the equation for cardiac output in terms of blood pressure and peripheral resistance?

  Cardiac Output = Blood pressure / Peripheral Resistance

  
• Cardiac Output is calculated by dividing Blood pressure by Peripheral Resistance.

  
• Free intracellular Ca2+ binds to Troponin-C to initiate contraction
• Current flows through gap junctions, which are specialized connections between cells
• What happens to cardiac output as peripheral resistance increases?

  Decreases

  
• What are the two states compared in the graph in terms of cardiac output and heart rate?

  Exercise and rest

  
• What is the systolic blood pressure in the aorta as shown in the image?

  120 mmHg

  
• The diastolic blood pressure in the aorta is 80 mmHg.

  
• What does the x-axis of the graph represent?

  End Diastolic Volume

  
• What is the mean blood pressure level in the right atrium in mm Hg?

  3

  
• What does the left diagram in the image show about blood flow in the aorta?

  Forward and backward flow

  
• The y-axis of the graph represents stroke volume or cardiac output

  
• The upper limit of normal blood pressure in the right atrium is 6

  
• Each gap junction is composed of two hemichannels called connexons
• Arrange the components of the cardiac excitation pathway in order:

  1️⃣ SA node

  2️⃣ Atria

  3️⃣ AV node

  4️⃣ Bundle of His

  5️⃣ Purkinje fibres

  6️⃣ Ventricles
• Pacemaker cells depolarize during phase 3