Circulatory System (Part 1)
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Questions and Answers

What are the three main components of the circulatory system?

The three main components of the circulatory system are the heart, blood vessels, and blood.

As cells get larger, their surface area to volume ratio increases.

False

What is the evolutionary need for a circulatory system?

Cells need a circulatory system to deliver nutrients and oxygen to their interiors and remove waste products.

What are the two main types of circulatory systems?

<p>Open and Closed</p> Signup and view all the answers

What is hemolymph?

<p>Hemolymph is the fluid that circulates in the open circulatory system of some animals.</p> Signup and view all the answers

What is the difference between open and closed circulatory systems?

<p>In an open circulatory system, the blood is not contained within vessels. In a closed circulatory system, the blood is contained within vessels and is circulated by a heart.</p> Signup and view all the answers

What is the function of the endothelium?

<p>The endothelium is the inner lining of blood vessels. It mediates exchange between the blood and tissues, regulates blood vessel tone, and plays a role in blood clotting.</p> Signup and view all the answers

Blood is pumped around the body in vessels, which it never leaves, by a heart.

<p>True</p> Signup and view all the answers

What does the human circulatory system need?

<p>All of the above</p> Signup and view all the answers

What are the four chambers of the heart?

<p>The four chambers of the heart are the right atrium, right ventricle, left atrium, and left ventricle.</p> Signup and view all the answers

Which chamber of the heart receives deoxygenated blood from the body?

<p>Right atrium</p> Signup and view all the answers

What is the function of the AV valves?

<p>The AV valves prevent the backflow of blood from the ventricles to the atria during ventricular contraction.</p> Signup and view all the answers

What is the function of the semilunar valves?

<p>The semilunar valves prevent the backflow of blood from the aorta and pulmonary trunk to the ventricles during ventricular relaxation.</p> Signup and view all the answers

Which of the following accurately describes the human circulatory system?

<p>It is a closed system with two separate circuits: the pulmonary and systemic circulations.</p> Signup and view all the answers

What is the difference between the pulmonary and systemic circulations?

<p>The pulmonary circulation delivers deoxygenated blood from the heart to the lungs and returns oxygenated blood to the heart. The systemic circulation delivers oxygenated blood from the heart to the rest of the body and returns deoxygenated blood to the heart.</p> Signup and view all the answers

The pulmonary circulation has a lower pressure and higher flow compared to the systemic circulation.

<p>True</p> Signup and view all the answers

What is the primary function of the vascular system?

<p>All of the above</p> Signup and view all the answers

What are the four main types of blood vessels?

<p>The four main types of blood vessels are arteries, arterioles, veins, and venules.</p> Signup and view all the answers

Which type of blood vessel carries blood away from the heart?

<p>Arteries</p> Signup and view all the answers

Which type of blood vessel carries blood back to the heart?

<p>Veins</p> Signup and view all the answers

Match the following blood vessels with their respective functions:

<p>Arteries = Carry blood away from the heart Veins = Carry blood back to the heart Arterioles = Control blood flow into capillaries Venules = Collect blood from capillaries Capillaries = Site of exchange between blood and tissues</p> Signup and view all the answers

What is the function of the vascular smooth muscle cells?

<p>Vascular smooth muscle cells help regulate blood flow and pressure by contracting and relaxing the walls of blood vessels.</p> Signup and view all the answers

What is the primary cause of pulmonary hypertension?

<p>Abnormally high blood pressure in the pulmonary arteries.</p> Signup and view all the answers

Pulmonary hypertension is a common and treatable condition.

<p>False</p> Signup and view all the answers

What are the major risk factors for pulmonary hypertension?

<p>Risk factors for pulmonary hypertension include congenital heart defects, connective tissue disorders, HIV infection, and exposure to certain drugs.</p> Signup and view all the answers

What is the goal of pulmonary hypertension therapy?

<p>The goal of pulmonary hypertension therapy is to lower blood pressure in the pulmonary arteries and improve the function of the right ventricle.</p> Signup and view all the answers

What is the primary function of the heart's sinoatrial (SA) node?

<p>To regulate the rate of heartbeat.</p> Signup and view all the answers

The atrioventricular (AV) node slows down the electrical impulse from the SA node, allowing the atria to contract before the ventricles.

<p>True</p> Signup and view all the answers

What is the function of the Bundle of His?

<p>The Bundle of His conducts electrical impulses from the AV node to the ventricles.</p> Signup and view all the answers

What is the role of the Purkinje fibers?

<p>The Purkinje fibers rapidly distribute the electrical impulses throughout the ventricles, ensuring coordinated contraction.</p> Signup and view all the answers

What is excitation-contraction (EC) coupling?

<p>Excitation-contraction coupling is the series of events that link the action potential in a cardiomyocyte to the contraction of the muscle.</p> Signup and view all the answers

The action potential in a cardiomyocyte is similar to the action potential in a skeletal muscle cell.

<p>False</p> Signup and view all the answers

Why is a ventricular action potential different from a skeletal muscle action potential?

<p>The ventricular action potential has a longer plateau phase, which is due to the influx of calcium ions. This prolonged plateau phase is essential for sustained ventricular muscle contraction.</p> Signup and view all the answers

Which of the following structures are found at the sarcolemma of cardiomyocytes?

<p>All of the above</p> Signup and view all the answers

What is the function of gap junctions in cardiomyocytes?

<p>Gap junctions allow for rapid electrical communication between cardiomyocytes, which is essential for the coordinated contraction of the heart.</p> Signup and view all the answers

The depolarization phase of the cardiac action potential is primarily due to the influx of sodium ions, while the repolarization phase is primarily due to the efflux of potassium ions.

<p>True</p> Signup and view all the answers

Describe the events that occur during the plateau phase of the ventricular action potential.

<p>The plateau phase is caused by a balance between calcium ion influx and potassium ion efflux. This prolongs the depolarized state and allows for sustained ventricular contraction.</p> Signup and view all the answers

What is the main difference between the cardiac action potentials of the sinoatrial node and a ventricular cardiomyocyte?

<p>The sinoatrial node action potential is faster and has a shorter duration.</p> Signup and view all the answers

Study Notes

Human Physiology: The Circulatory System and Heart (Part 1)

  • The human circulatory system is essential for cell survival as it facilitates nutrient, waste, and gas exchange.
  • As cells grow larger, their surface area to volume ratio decreases. This reduces the efficiency of diffusion-based nutrient and waste exchange.
  • Multicellular organisms evolved closed circulatory systems with pumps to overcome the limitations of diffusion alone.
  • Open circulatory systems, such as those in insects and some mollusks, pump hemolymph, which is not confined to vessels. It bathes tissues directly. This system is less efficient than a closed circulatory system for larger, more complex organisms.
  • Closed circulatory systems, seen in vertebrates, utilize vessels to keep blood confined. Blood is pumped by a heart, never leaving the vessels. Exchange occurs across the vessel endothelium. Blood volume can be controlled via vessel contraction or relaxation for better regulation of flow.
  • Mammals have a closed circulatory system comprised of two circuits: pulmonary and systemic.
  • The pulmonary circuit circulates blood to the lungs to pick up oxygen and release carbon dioxide.
  • The systemic circuit circulates oxygenated blood to the body’s tissues and returns deoxygenated blood to the heart.
  • The human heart is a complex organ with several chambers and valves that regulate blood flow.
  • The heart's four chambers are the two atria and two ventricles. Atria receive blood, and ventricles pump blood out.
  • The heart has valves to ensure one-way blood flow, preventing backflow.
  • The electrical conduction system of the heart is a specialized network of cells that coordinates the heart's contractions. This system ensures that the heart contracts in a coordinated way.
  • The sinoatrial node (SA node) acts as the pacemaker of the heart.
  • The atrioventricular (AV) node delays the impulse, allowing the atria to contract completely before the ventricles contract.
  • The bundle of His and Purkinje fibers transmit the impulse throughout the ventricles, causing them to contract.
  • The heart relies on electrical signals to coordinate the contractions of the atria and ventricles. This ensures the heart functions as a pump.
  • Cardiac action potentials are electrical impulses that cause the heart muscle cells to contract. These potentials are triggered by changes in the permeability of the cell membrane to certain ions.
  • The series of events that link the action potential to contraction is termed excitation-contraction coupling.
  • Cardiomyocytes, specialized heart muscle cells, are interconnected via intercalated discs to facilitate rapid impulse conduction and synchronized contraction. These intercalated discs contain fascia adherens, desmosomes, and gap junctions.
  • The different phases of a cardiac action potential illustrate the ionic mechanisms involved in the cell’s electrical activity. Ions play a crucial role in conducting impulses.

Anatomy of the Human Heart

  • Main components and structures are shown.
  • The heart has multiple components, each with particular roles and functions in blood flow.

Pulmonary and Systemic Circulations

  • Two separate circuits enable blood flow throughout the body.
  • The pulmonary circuit transports deoxygenated blood to the lungs for oxygen uptake.
  • The systemic circuit delivers oxygenated blood and nutrients to body tissues, takes away waste products and returns deoxygenated blood to the heart.

Vascular System

  • The circulatory system comprises arteries, arterioles, capillaries, venules, and veins.
  • Arteries have thicker walls, supporting higher blood pressure, for quick transport.
  • Veins have thinner walls and valves, which help to move blood back to the heart against gravity.
  • Capillaries have thin walls to facilitate exchange between blood and tissues.

Cardiac Action Potentials

  • Electrical signals, called action potentials, are the driving force for cardiac muscle contraction.
  • Sinoatrial node (SA node) action potentials differ from ventricular action potentials in shape because of the differences in the ion channels involved in different cell types.

Excitation-Contraction Coupling

  • Describes the events connecting action potentials to muscle contraction in heart cells.
  • Release of calcium initiates the contraction process in the cardiomyocites.

Pulmonary Hypertension

  • A rare, life-threatening disorder characterized by abnormally elevated pulmonary pressures and right heart failure.
  • Vascular remodeling, causing distal vessel obliteration, often features in the disease.
  • Different factors can be associated with the onset and development of pulmonary hypertension.

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Description

Explore the vital functions of the human circulatory system in this quiz. Learn about the differences between open and closed circulatory systems, the role of the heart, and how nutrient and waste exchange occurs. Test your knowledge on how these systems support multicellular life.

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