Understanding Cardiac Function

Podcast

Play an AI-generated podcast conversation about this lesson

Download our mobile app to listen on the go

Get App

Questions and Answers

Within the hierarchy of blood vessel structure, which transition accurately depicts the diminishing luminal diameter observed as blood moves away from the heart?

Arteries → arterioles → capillaries → venules (correct)
Arterioles → arteries → venules → capillaries
Arterioles → arteries → capillaries → venules
Arteries → arterioles → venules → capillaries

The pulmonary artery carries oxygenated blood from the lungs to the left atrium.

False (B)

Describe the role of the hepatic portal vein in maintaining metabolic homeostasis, and name a specific class of molecules it transports.

The hepatic portal vein transports blood rich in nutrients and other molecules absorbed from the gastrointestinal tract directly to the liver. Examples of molecules transported by the hepatic portal vein include glucose, amino acids and lipids.

In cardiac myocytes, the influx of calcium ions into the cell during the plateau phase of the action potential is balanced primarily by the efflux of ______ ions to maintain electrical neutrality.

potassium Signup and view all the answers

Match the following components of the cardiac conduction system with their corresponding intrinsic firing rates:

Sinoatrial (SA) node = 60-100 beats per minute Atrioventricular (AV) node = 40-60 beats per minute Purkinje fibers = 20-40 beats per minute Signup and view all the answers

What is the functional implication of the disparity in muscle thickness between the left and right ventricles?

The left ventricle requires greater pressure to overcome the resistance of the systemic circulation, whereas the right ventricle only needs to overcome the lower resistance of the pulmonary circulation (A) Signup and view all the answers

The primary function of leukocytes within the cardiovascular system is to facilitate the transport of oxygen and carbon dioxide.

False (B) Signup and view all the answers

Describe the biophysical mechanism underlying the plateau phase observed in ventricular myocyte action potentials, explicitly detailing the ion channels involved and their temporal dynamics.

The plateau phase is primarily due to the influx of Ca2+ ions through L-type calcium channels, which is balanced by the efflux of K+ ions. This balance of ion movement prolongs the depolarization, creating the plateau. Signup and view all the answers

The Frank-Starling mechanism dictates that an increase in venous return leads to a corresponding increase in ______, thereby augmenting stroke volume.

end-diastolic volume Signup and view all the answers

A patient presents with a stenotic aortic valve, increasing afterload on the left ventricle. Which compensatory mechanism is most likely to occur initially to maintain cardiac output?

Ventricular hypertrophy to increase contractility (D) Signup and view all the answers

In parallel blood flow arrangements, alterations in the vascular resistance of one organ will invariably affect blood flow to all other organs.

False (B) Signup and view all the answers

Outline the steps involved in excitation-contraction coupling in cardiac muscle cells, focusing on the roles of calcium ions, ryanodine receptors (RyR), and the sarcoplasmic reticulum.

Excitation-contraction coupling begins with an action potential entering the cell, opening L-type Ca2+ channels in the T-tubules. The influx of Ca2+ triggers the opening of ryanodine receptors (RyR) on the sarcoplasmic reticulum. Ca2+ binds to troponin, initiating muscle contraction. Signup and view all the answers

The AV valves are open when atrial pressure is ______ than ventricular pressure, which allows blood to flow from the atria into the ventricles.

greater Signup and view all the answers

Match each numbered phase of the cardiac contractile cell action potential with its corresponding ionic event:

Phase 0 = Rapid Na+ influx Phase 2 = Ca2+ influx, K+ efflux Phase 3 = K+ efflux Signup and view all the answers

During isovolumetric ventricular relaxation, which statement accurately describes the state of the heart valves?

Both the atrioventricular and semilunar valves are closed. (A) Signup and view all the answers

The sinoatrial (SA) node is located in the interventricular septum near the tricuspid valve.

False (B) Signup and view all the answers

Explain how the unique biophysical properties of pacemaker cells, including the If 'funny' channels and T-type calcium channels, contribute to their autorhythmicity and the spontaneous generation of action potentials.

Pacemaker cells have If channels that open upon hyperpolarization, allowing Na+ influx, which then causes a gradual depolarization. Once -55mV is reached, T-type calcium channels open, depolarizing the cell to -40mV, thus a spontaneous action potential is generated. Signup and view all the answers

The QRS complex on an electrocardiogram (ECG) corresponds to the ______ of the ventricles.

depolarization Signup and view all the answers

Match the following structural components of cardiac muscle cells with their respective functions:

Intercalated discs = Facilitate rapid electrical communication between cells. T-tubules = Invaginations of the plasma membrane that conduct action potentials into the cell interior. Mitochondria = Provide ATP for the contractile process. Signup and view all the answers

Under conditions of extended strenuous exercise, what adaptation best enables the heart to maintain cardiac output despite a decrease in stroke volume due to reduced filling time during diastole?

Augmented contractility mediated by increased sympathetic stimulation (C) Signup and view all the answers

Flashcards

What is the heart?

A muscle-driven pump for blood movement throughout the body (7,200L/day).

What is the atria/atrium?

Receives blood from the vasculature.