Human Heart Anatomy and Circulation Quiz

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What is the focus of the next lecture after covering electrical activity in the heart?

Renal physiology

ECG and its diagnostic applications (correct)

Digestive physiology

Respiratory physiology

What is the function of the endogenous group of cells in the heart?

To regulate blood pressure

To produce the ECG pattern

To contract the cardiac muscles

To function as the normal pacemaker in non-pathological situations (correct)

What does the electrical axis of the heart indicate?

The general direction of electrical activity flow in the heart (correct)

The location of the endogenous pacemaker cells

The overall direction of blood flow in the heart

The site of implantable pacemakers

What will be covered in the next lecture after discussing the ECG?

Cardiovascular physiology Signup and view all the answers

What is the primary focus of today's lecture on cardiovascular physiology?

Electrical activity in the heart Signup and view all the answers

What is the purpose of an ECG in relation to the heart?

To diagnose disease or abnormal states Signup and view all the answers

What is the function of cardiac output?

To measure the amount of blood the heart puts out per unit of time Signup and view all the answers

Which equation represents the calculation for cardiac output?

$CO = HR imes SV$ Signup and view all the answers

What is the primary function of cardiovascular regulatory mechanisms?

To prevent blood pressure from falling too low Signup and view all the answers

Which factor can affect blood pressure?

Blood volume Signup and view all the answers

What is the function of peripheral resistance in the cardiovascular system?

To regulate the resistance to blood flow within the circulatory system Signup and view all the answers

What does stroke volume represent in the cardiovascular system?

The amount of blood pumped per beat Signup and view all the answers

What is the primary role of arterioles in the cardiovascular system?

To regulate the resistance to blood flow within the circulatory system Signup and view all the answers

How can adjustments in the cardiovascular system affect blood pressure levels?

By affecting heart rate, stroke volume, and peripheral resistance Signup and view all the answers

What is the main function of diuretics in treating high blood pressure?

To decrease fluid retention and reduce blood volume Signup and view all the answers

What is cardiac output a function of?

Heart rate, stroke volume, and peripheral resistance Signup and view all the answers

What does pulmonary mechanics primarily involve?

The pressure and volume changes associated with inspiration and expiration Signup and view all the answers

What is alveolar ventilation primarily modified by?

Changing breathing rate and tidal volume Signup and view all the answers

What causes the large upswing in depolarization during the cardiac action potential?

Opening of voltage-gated sodium channels Signup and view all the answers

What is the duration range of the cardiac action potential in contractile muscle cells?

250 to 300 milliseconds Signup and view all the answers

What causes the plateau phase during the cardiac action potential?

Opening of inward-rectifying potassium channels Signup and view all the answers

What is the resting membrane potential during the cardiac action potential in contractile muscle cells?

-90mV Signup and view all the answers

What leads to the large repolarization in phase 3 of the cardiac action potential?

Activation of delayed-rectifying potassium channels Signup and view all the answers

What process marks the beginning of repolarization during the cardiac action potential?

Phase 1 Signup and view all the answers

What closes during phase 1, trapping positively charged potassium in the cell?

Inward-rectifying potassium channels Signup and view all the answers

What leads to the elevated level of membrane potential during phase 2 of the cardiac action potential?

Activation of inward-rectifying potassium channels Signup and view all the answers

What marks phase 0 in the cardiac action potential?

The large upswing in depolarization caused by opening of voltage-gated sodium channels. Signup and view all the answers

What causes the wave of depolarization that stimulates the contractile muscle cells?

Large increase in sodium permeability and opening of voltage-gated sodium channels. Signup and view all the answers

What is the role of calcium during the cardiac action potential?

It contributes to the large upswing in depolarization. Signup and view all the answers

What are inward-rectifying potassium channels responsible for in phase 1?

Trapping positively charged potassium in the cell. Signup and view all the answers

What prevents the atria from contracting and pushing blood into the ventricles while the ventricles are also contracting?

The slight increase in resistance caused by the AV node Signup and view all the answers

Which part of the heart's conduction system is our endogenous pacemaker?

SA node Signup and view all the answers

What happens if the SA node fails as the pacemaker of the heart?

AV node takes over as pacemaker Signup and view all the answers

What is an ectopic pacemaker?

Any area functioning as a pacemaker that is not 'normal' Signup and view all the answers

What happens if the AV node becomes the pacemaker of the heart?

It can't spread electrical activity upwards because those muscles are in a refractory period Signup and view all the answers

Why are modern pacemakers computerized?

To sense heart rate and stimulate the heart as needed Signup and view all the answers

What is the equilibrium potential for sodium in pacemaker cells?

+60 mV Signup and view all the answers

Which ion moves to get the average membrane potential to be -94 mV in pacemaker cells?

Potassium ions Signup and view all the answers

What drives the depolarization in pacemaker cells?

Increased sodium permeability and decreased potassium permeability Signup and view all the answers

"Funny" channels, allowing both sodium and potassium through, open during which phase of the pacemaker potential/action potential?

(1) First phase Signup and view all the answers

What continues the depolarization after "funny" channels begin to close during the pacemaker potential/action potential?

T-type calcium channels begin to open. Signup and view all the answers

What happens after all of the ventricles depolarize during the action potential in pacemaker cells?

The heart contracts, from bottom to top. Signup and view all the answers

What is the function of the interventricular septum?

To separate the two ventricles Signup and view all the answers

Why does the left ventricle have substantially greater muscle than the right ventricle?

To pump blood to the systemic circulation, which has rather high resistance Signup and view all the answers

What is the primary role of the SA node in the heart's electrical conduction system?

To generate electrical activity causing the heart muscle to depolarize and contract Signup and view all the answers

Why is the slowing down of the wave of depolarization as it reaches the AV node important?

To allow the atria to finish contracting before the ventricles begin to contract Signup and view all the answers

What is the function of Purkinje fibers in the heart's conduction system?

To originate at the bottom of the heart and move upward into the contractile muscle Signup and view all the answers

What is the main function of cells within the heart's conduction pathway system?

To pass waves of depolarization onto the contractile cells Signup and view all the answers

What is responsible for rapidly transferring electrical activity between cardiac muscle cells?

Gap junctions Signup and view all the answers

Why is continual stretching of the heart undesirable?

It can lead ultimately to heart failure Signup and view all the answers

What is a function of desmosomes in the heart?

Help to resist stretching in the heart Signup and view all the answers

What is responsible for causing cardiac hypertrophy if stretched too far over a long period of time?

High blood pressure Signup and view all the answers

What is an important aspect of electrical conduction through internodal pathways in the atria?

Low resistance to current flow due to large cell size Signup and view all the answers

What is a distinguishing feature of pulmonary circulation compared to circulation throughout the rest of the body?

Having substantially less pressure and resistance during blood flow Signup and view all the answers