Physiology Cardiac Physiology Chapter

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Questions and Answers

What happens immediately after the aortic valve opens during cardiac muscle contraction?

Blood flows into the left atrium.

Ventricular pressure decreases.

Blood is ejected into the aorta. (correct)

Atrial pressure exceeds ventricular pressure.

During isovolumic relaxation, which of the following conditions is true?

The heart is actively contracting.

The aortic and AV valves are both closed. (correct)

Left atrial pressure exceeds both ventricular and aortic pressure.

Ventricular pressure remains constant.

What condition must be met for blood pressure to effectively reach the brain?

Vascular resistance must be minimized.

Abdominal pressure must be greater than heart pressure.

Oxygen levels in the blood must be elevated.

Pressure produced by the heart must be sufficient. (correct)

How does gravitational effect influence blood pressure in vessels located above the heart?

There is a decrease in pressure in vessels above the heart. Signup and view all the answers

What is the primary function of the circulation in the body?

To transport multiple gases and nutrients. Signup and view all the answers

What type of receptors do norepinephrine and epinephrine primarily bind to in cardiac muscle cells?

Beta1-adrenergic receptors Signup and view all the answers

Which neurotransmitter is released from parasympathetic neurons that influence heart activity?

Acetylcholine Signup and view all the answers

Which adrenergic receptor type is linked to the Gq protein in vascular smooth muscle cells?

Alpha1-adrenergic receptors Signup and view all the answers

What effect does the parasympathetic nervous system generally have on heart function?

Reduces heart rate Signup and view all the answers

Which of the following statements about the autonomic nervous system's control of the heart is correct?

Both sympathetic and parasympathetic systems modify rate and strength of contraction. Signup and view all the answers

What are the mechanoreceptors embedded in the walls of the aortic arch and carotid sinus called?

Baroreceptors Signup and view all the answers

What is the main effect of the baroreceptor reflex when blood pressure decreases significantly?

It minimizes the drop in blood pressure to a lesser extent. Signup and view all the answers

How quickly does the baroreceptor reflex respond to changes in blood pressure?

Within 1 second Signup and view all the answers

After a prolonged period of hypertension, how does the baroreceptor reflex adapt?

It regulates blood pressure around a new 'normal'. Signup and view all the answers

Which system does the CNS stimulate when responding to low blood pressure through the baroreceptor reflex?

The parasympathetic nervous system Signup and view all the answers

What is the main function of the atrial volume receptor reflex?

To regulate blood volume through the RAAS system Signup and view all the answers

How does an increase in blood volume affect renin release?

It results in a decrease in renin release Signup and view all the answers

What is the purpose of using the 12-lead ECG in clinical applications?

To provide standard comparisons for recognizing deviations from normal Signup and view all the answers

What occurs when blood volume decreases in relation to AVR action potential frequency?

AVR AP frequency decreases, triggering increased renin release and RAAS activation Signup and view all the answers

Which of the following describes the composition of ECG records?

They are graphical tracings of cardiac electrical potentials at the body surface Signup and view all the answers

What role does the right ventricle serve in the circulatory system?

Propels blood through the lungs Signup and view all the answers

Which component is part of the arterial system?

Arterioles Signup and view all the answers

What happens to blood as it passes through the pulmonary circulation?

It gains oxygen and loses carbon dioxide Signup and view all the answers

How do capillaries function within the vascular system?

Facilitate exchange of gases and nutrients Signup and view all the answers

What is the primary function of the left ventricle?

Propels blood to all other tissues Signup and view all the answers

What happens to the venous blood if the blood flow through capillaries is reduced?

It will contain more waste products Signup and view all the answers

Which of the following describes the correct pathway of the venous system?

Capillaries → venules → veins Signup and view all the answers

What does the arterial system transition into as it branches out?

Arterioles Signup and view all the answers

What role do voltage-gated K+ channels play during the repolarization plateau (phase 2)?

They remain open, allowing K+ to move out of the cell. Signup and view all the answers

During the final repolarization (phase 3), what happens to the voltage-gated Ca2+ channels?

They inactivate spontaneously after a brief opening. Signup and view all the answers

What primarily drives the net movement of K+ out of the cell during the repolarization phases?

Both electrical and concentration gradients Signup and view all the answers

What occurs to the voltage-gated Na+ channels during resting membrane potential (phase 4)?

They inactivate and prevent Na+ influx. Signup and view all the answers

What is the consequence of the increase in membrane permeability to Ca2+ during the repolarization plateau?

It opposes repolarization due to K+ efflux. Signup and view all the answers

What happens to K+ channels during the phases of cardiac action potentials?

They open, leading to a significant efflux of K+. Signup and view all the answers

What triggers the opening of voltage-gated Ca2+ channels during the repolarization plateau (phase 2)?

The attainment of threshold potential Signup and view all the answers

What is the primary mechanism by which the resting membrane potential is restored at phase 4?

Return to resting membrane permeabilities and concentrations Signup and view all the answers

Study Notes

Physiology (0603302)

Course: Physiology
Chapter: Cardiac Physiology
Semester: Summer 2023/2024
Instructor: Dr. Mohammad A. Abedal-Majed
Institution: The University of Jordan, School of Agriculture

Cardiac Physiology Resources

Video (327): How does human circulatory system work – 3D animation - YouTube
Video (328): Human Heart Anatomy And Physiology | How Human Heart works? (3D Animation) - YouTube
Video (335): Circulatory System and Pathway of Blood Through the Heart - YouTube

Blood Flow

The diagram illustrates the flow of blood through the heart, lungs, and body.
Pulmonary circulation describes the blood flow through the lungs to pick up oxygen.
Systemic circulation describes the blood flow through the body delivering oxygen.
The heart's four chambers are labeled and their functions summarized.

Vascular System

Pulmonary Circulation (low pressure): Poorly oxygenated blood travels from the right ventricle to the lungs via pulmonary arteries. Highly oxygenated blood returns to the left atrium via pulmonary veins.
Systemic Circulation (high pressure): Highly oxygenated blood leaves the left ventricle via the aorta and travels to the body tissues. Poorly oxygenated blood returns to the right atrium via the vena cava.

Functional Components of the Circulatory System

Pump (heart): Pumps blood throughout the body.
Distributing (arterial): Carries blood away from the heart.
Collecting (venous): Carries blood back to the heart.
Exchange (capillary beds): Allows for gas and nutrient exchange between blood and tissues.

1) The Pumps

Right Ventricle: Pumps blood through the lungs. Acquires oxygen from inhaled air and releases carbon dioxide from the blood.
Left Ventricle: Pumps blood to all other tissues in the body, delivering oxygen and nutrients. Receives carbon dioxide and other waste products from the tissues.

2) Distributing (arterial) and Collecting (venous) Tubes

Arterial system branches from the aorta and pulmonary artery progressively into smaller vessels to reach capillaries.
Venous system empties into vena cava and pulmonary vein. It joins small vessels to become progressively larger. Capillaries transition to venules, then veins.

3) Exchange System (Capillary Beds)

Blood flow through capillaries supports exchange of materials (O2, CO2, nutrients, and waste products) between the blood and tissues.
Changes in cellular metabolism will result in different compositions of venous blood compared to the reference point.

Cardiac Output

Cardiac output (CO) = Stroke Volume (SV) x Heart Rate (HR)
Stroke volume (SV) is the amount of blood pumped per beat. Average: 70 ml/beat.
Heart rate (HR) is the number of heart beats per minute. Average: 70 beats/minute.
Cardiac output is approximately 5 liters/minute at rest.

Heart Valves

Atrioventricular (AV) valves (mitral and tricuspid): Regulate blood flow from atria to ventricles. Open during atrial contraction, close during ventricular contraction.
Semilunar valves (aortic and pulmonic): Regulate blood flow from ventricles into the aorta and pulmonary arteries. Open during ventricular contraction, closes during ventricular relaxation.

Electrical Activity of Cardiac Muscle Cells

Specialized muscle cells in the SA node spontaneously depolarize, generating an action potential.
This action potential spreads to other cells, causing coordinated heart contraction.
Pacemaker cells establish the inherent heart rate without neural signals, modulated by the sympathetic and parasympathetic nervous systems..

Cardiac Action Potentials

Cardiac action potentials have a longer duration (100-250 milliseconds) compared to skeletal muscle potentials (1–2 milliseconds) due to the role of Ca2+ channels.

Regulation of Blood Pressure

Sympathetic Nervous System: Releases norepinephrine and epinephrine to increase heart rate, contractile force, and vasoconstriction.
Parasympathetic Nervous System: Releases acetylcholine to decrease heart rate and vasoconstriction.
Blood vessels play a critical role in blood pressure regulation.

Baroreceptor Reflex

Baroreceptors (mechanoreceptors) are embedded in the aortic arch & carotid sinus.
Changes in blood pressure (blood volume) are sensed, modifying autonomic activity (sympathetic & parasympathetic) thereby to maintain a stable blood pressure.

Atrial Volume Receptor Reflex

Atrial volume receptors are mechanoreceptors in the atrial walls that sense changes in atrial stretch/distention, allowing for regulation of blood volume.

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Description

Explore the intricacies of cardiac physiology in this quiz, focusing on blood flow, the anatomy of the heart, and the circulatory system. Designed for summer semester students at The University of Jordan, this quiz will test your understanding of how the heart works. Dive into the mechanisms of pulmonary and systemic circulation.