Cardiovascular System Advanced

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Questions and Answers

Which features of arteries act to reduce the fluctuations in blood pressure caused by the heartbeat?

Collagen and smooth muscle

Tunica interna (endothelium)

Internal elastic membrane and smooth muscle (correct)

Diameter and length

What mechanism(s) are responsible for the movement of blood in the venous system of the LOWER limbs?

Gravity

One-way valves and venous compression caused by skeletal muscle action (correct)

One-way valves and venous compression caused by smooth muscle action

Suction effect of right atrial contraction

Which chambers of the heart are directly connected?

RA and LV; LA and RV

RA, RV and LV

RA and LA; RV and LV (correct)

RA and RV; LA and LV

Why is the left ventricle (LV) more muscular than the right ventricle (RV)?

Because the LV must overcome the total peripheral resistance of the much larger systemic circuit. Signup and view all the answers

What is the effect of neural inputs to the heart?

Change the rate of spontaneous contraction Signup and view all the answers

What molecular mechanism is responsible for the plateau phase of the action potential in cardiac muscle?

Slow opening Ca2+ channels Signup and view all the answers

What molecular mechanism is responsible for the spontaneous generation of action potentials in cardiac muscle?

Na+ leak channels Signup and view all the answers

What mechanism prevents tetanic contraction of cardiac muscle?

The absolute refractory period is as long as the duration of contraction Signup and view all the answers

Which of the following will increase the heart rate?

Increased Na+ leakage Signup and view all the answers

Which structures ensure the rapid and accurate spread of excitation through cardiac muscle?

The conducting system and gap junctions between individual cardiac muscle cells Signup and view all the answers

What would be the effect on the heart if the vagus nerve were cut?

Heart rate will increase Signup and view all the answers

The reduced oxygen level at high altitude will have which effect on cardiac activity?

Increased heart rate with reduced cardiac output Signup and view all the answers

During heavy exercise, if the heart rate were to exceed approximately 180 bpm, the pumping action of the heart would become inefficient. Why?

Because there is not enough time for the cardiac chambers to fill with blood Signup and view all the answers

What is the Bainbridge reflex?

Increase in venous return stretches the nodal cells, which increases the heart rate. Signup and view all the answers

Why does increased rigidity of blood vessels (arteriosclerosis) increase blood pressure?

Increased total peripheral resistance Signup and view all the answers

What may cause excessive turbulence in blood vessels?

Deformation of part of the blood vessel wall. Signup and view all the answers

Which of the following may increase blood viscosity?

Dehydration Signup and view all the answers

Which of the following responses to a change in blood volume directly involves the heart?

Increased venous return causes release of atrial natriuretic peptide (ANP), which reduces blood volume. Signup and view all the answers

Beta-blockers are drugs that reduce blood pressure. In the heart, they act as:

Antagonists of adrenaline and noradrenaline Signup and view all the answers

During the fight-or-flight response, sympathetic activity changes the distribution of blood as follows:

Increased blood flow to skeletal muscle and brain, reduced flow to skin and internal organs Signup and view all the answers

Study Notes

Cardiovascular System: Features of Arteries

Collagen and Smooth Muscle: Provides structural support and allows for vasoconstriction and vasodilation, which helps regulate blood pressure.
Internal Elastic Membrane: Allows the artery to stretch and recoil, absorbing pressure fluctuations from the heart.
Tunica Interna (Endothelium): Smooth surface reduces frictional resistance during blood flow.

Cardiovascular System: Venous Blood Flow

Gravity: Plays a role in returning blood from the upper body to the heart.
One-way Valves and Skeletal Muscle Action: Venous compression from muscle contractions propels blood upwards, while valves prevent backflow.

Cardiovascular System: Chambers of the Heart

Right Atrium (RA) & Right Ventricle (RV): Connected by the tricuspid valve, responsible for pulmonary circulation.
Left Atrium (LA) & Left Ventricle (LV): Connected by the mitral valve, responsible for systemic circulation.

Cardiovascular System: Anatomy & Function

Left Ventricle Muscularity: The LV is thicker than the RV because it pumps blood against higher resistance across the entire body.
Right Ventricle (RV): Responsible for pumping deoxygenated blood to the lungs.
Left Ventricle (LV): Pumps oxygenated blood to the rest of the body.

Cardiovascular System: Neural Regulation

Sympathetic Nervous System: Stimulates heart rate and contractility.
Parasympathetic Nervous System: (Vagus nerve) Inhibits heart rate and force of contraction.
Atrial Natriuretic Peptide (ANP): Released from the heart, reduces blood volume and pressure.

Cardiovascular System: Cardiac Muscle Action Potential

Plateau Phase: Caused by slow opening calcium channels, which prolongs depolarization, allowing sustained contraction.
Spontaneous Depolarization: Driven by "funny" sodium leak channels, allowing rhythmic contraction.
Tetanic Contraction Prevention: Long absolute refractory period prevents summation of multiple action potentials, preventing tetany.

Cardiovascular System: Heart Rate Regulation

Increased Sodium Leakage: Leads to faster depolarization and increased heart rate.
Prolonged Plateau Phase: Increases the time for contraction and slows down heart rate.
Elevated Excitation Threshold: Difficult to trigger action potentials and decreases heart rate.

Cardiovascular System: Conduction System

Sinoatrial (SA) Node: The pacemaker of the heart.
Atrioventricular (AV) Node: Delays the signal slightly, allowing atrial contraction before ventricular contraction.
Gap Junctions: Allow direct electrical communication between cardiac muscle cells, ensuring coordinated contraction.

Cardiovascular System: Cardiac Output & Blood Pressure

Vagus Nerve Cutting: Increases heart rate.
High Altitude: Reduces oxygen levels, forcing the heart to beat faster and harder to maintain oxygenation.
Heart Rate Limit: The heart cannot beat too fast (over 180bpm) because the chambers don't have enough time to fill with blood, reducing efficiency.

Cardiovascular System: Blood Pressure Regulation

Bainbridge Reflex: Increased venous return stretches the heart, particularly the SA node, causing an increase in heart rate.
Arteriosclerosis: Stiffening of blood vessels increases total peripheral resistance, raising blood pressure.
Blood Vessel Turbulence: Caused by irregular flow, often due to narrowing or obstruction of blood vessels.

Cardiovascular System: Factors Affecting Blood Viscosity

Obesity: Can increase blood viscosity by altering lipid profiles.
Water Retention: Increases blood volume, potentially leading to thicker blood.
Dehydration: Reduces plasma volume, making blood thicker.
Increased Plasma Cholesterol: Results in larger blood cells and thicker overall blood.

Cardiovascular System: Blood Volume Regulation

Atrial Natriuretic Peptide (ANP): Released in response to increased blood volume, decreases blood pressure by reducing sodium reabsorption in the kidneys.
Glomerular Filtration Rate (GFR): Increased blood pressure increases filtration rate at the kidneys, removing excess fluid and reducing blood volume.
Aldosterone: Released in response to decreased blood pressure, causing sodium reabsorption in the kidneys, restoring blood volume.
Peripheral Vasoconstriction: Triggered by reduced blood pressure, narrowing blood vessels to increase resistance and raise blood pressure.

Cardiovascular System: Beta-blockers

Antagonists of Adrenaline and Noradrenaline: Reduce the effects of the sympathetic nervous system, slowing heart rate and decreasing blood pressure.

Cardiovascular System: Fight-or-Flight Response

Blood Redistribution: Sympathetic activity prioritizes blood flow to muscles and the brain, while reducing blood flow to skin and internal organs to maximize physical capabilities in a stressful situation.

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Description

This quiz covers the main features of arteries and veins, including their structural components and functions. It also explores the chambers of the heart and the mechanisms involved in blood flow. Test your knowledge of how these elements work together in the cardiovascular system.