CARDIO-HEART

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Questions and Answers

During which phase of an action potential in cardiac muscle do Ca2+ channels remain open?

Plateau phase (correct)

Pacemaker potential

Repolarization phase

Depolarization phase

What is the primary role of the sinoatrial node in the heart?

It prevents backflow of blood.

It coordinates atrial contraction.

It serves as the heart's main pacemaker. (correct)

It stimulates increased cardiac output.

Which wave in an electrocardiogram (ECG) represents the depolarization of the ventricles?

T wave

QRS complex (correct)

R wave

P wave

What is the function of the AV node in the heart's electrical conduction system?

To delay the signal before it moves to the ventricles Signup and view all the answers

Which of the following best describes the cardiac cycle?

The contraction and relaxation phases of the heart Signup and view all the answers

What causes the prolonged action potential duration in cardiac muscle compared to skeletal muscle?

Sustained Ca2+ channel opening Signup and view all the answers

What does the T wave in an ECG indicate?

Ventricular repolarization Signup and view all the answers

Which component of the cardiac conduction system follows the AV node?

AV bundle Signup and view all the answers

What is the primary function of the systemic circuit?

Carries oxygen-rich blood from the heart to the body Signup and view all the answers

What opens into the aorta?

Left ventricle Signup and view all the answers

Which structure of the heart is primarily responsible for pumping blood to the body?

Left ventricle Signup and view all the answers

Which valves are involved in the blood flow from the left atrium to the left ventricle?

Bicuspid valve Signup and view all the answers

Which artery supplies blood to the right ventricle?

Right coronary artery Signup and view all the answers

Where do the coronary arteries originate?

From the base of the aorta above the aortic semilunar valve Signup and view all the answers

After entering the left atrium, blood is received from which vessels?

Pulmonary veins Signup and view all the answers

What is the nature of blood carried by the aorta?

Oxygen-rich, carbon dioxide-poor Signup and view all the answers

Which structure separates the right and left atria?

Interatrial septum Signup and view all the answers

What distinguishes the ventricles from the atria in terms of structure and function?

Ventricles are the pumping chambers with thick, strong walls. Signup and view all the answers

What is the primary function of the atrioventricular valves?

To ensure one-way blood flow between atria and ventricles. Signup and view all the answers

Which feature is characteristic of cardiac muscle tissue?

Cardiac muscle is striated and contains intercalated disks. Signup and view all the answers

Which phase of the cardiac cycle is characterized by the contraction of the ventricles?

Isovolumetric contraction Signup and view all the answers

What is the main purpose of the coronary sulcus in the heart?

To separate the atria from the ventricles. Signup and view all the answers

Which of the following statements about cardiac electrical conduction is true?

Purkinje fibers are responsible for carrying signals through the ventricles. Signup and view all the answers

What role do valves play in the heart's functioning?

They ensure unidirectional blood flow through the circulatory system. Signup and view all the answers

Study Notes

Cardiac Action Potentials

Depolarization: Sodium (Na+) and Calcium (Ca2+) channels open, allowing ions to enter the cell.
Plateau: Sodium (Na+) channels close, some Potassium (K+) channels open, and Calcium (Ca2+) channels remain open, prolonging the action potential.
Repolarization: Potassium (K+) channels are open, Calcium (Ca2+) channels close, allowing potassium to exit the cell.
Duration: Action potentials in cardiac muscle last significantly longer (200-500 msec) compared to skeletal muscle (2 msec) due to the plateau phase.

Cardiac Conduction System

Function: Conducts electrical impulses throughout the heart, coordinating the contraction of atria and ventricles.
Sinoatrial Node (SA Node): Located in the right atrium, initiates action potentials, acts as the heart's pacemaker, and contains a large number of Calcium (Ca2+) channels.

Path of Action Potential Through the Heart

SA node
AV node (Atrioventricular)
AV bundle
Right and Left Bundle Branches
Purkinje Fibers

Electrocardiogram (ECG/EKG)

Purpose: Records electrical activity of the heart, diagnoses cardiac abnormalities, and uses electrodes to measure electrical changes.
Components:
- P Wave: Depolarization of the atria.
- QRS Complex: Depolarization of the ventricles.
- T Wave: Repolarization of the ventricles.

Left Side of the Heart

Systemic Circuit: Carries oxygen-rich blood from the heart to the body.

Left Atrium

Receives oxygen-rich blood from the lungs through four pulmonary veins.

Left Ventricle

Pumps oxygen-rich blood to the aorta to the body.
Has a thicker wall and contracts more forcefully than the right ventricle to overcome higher pressure in the systemic circuit.

Aorta

Carries oxygen-rich blood from the left ventricle to the rest of the body.

Blood Flow Through the Heart

Right Atrium (RA)
Tricuspid Valve
Right Ventricle (RV)
Pulmonary Semilunar Valve
Pulmonary Trunk
Pulmonary Arteries
Lungs
Pulmonary Veins
Left Atrium (LA)
Bicuspid Valve
Left Ventricle (LV)
Aortic Semilunar Valve
Aorta
Body

Blood Supply to the Heart

Coronary Arteries: Branch directly from the aorta, supplying blood to the heart wall.
- Left Coronary Artery: Branches to supply the anterior heart wall and the left ventricle.
- Right Coronary Artery: Supplies the right ventricle.

Cardiac Muscle

Characteristics: Centrally located nucleus, branching cells, rich in mitochondria, striated with actin and myosin, uses Calcium (Ca2+) and ATP for contractions, and interconnected cells via intercalated disks.

Chambers and Blood Vessels

Chambers: Left Atrium (LA), Right Atrium (RA), Left Ventricle (LV), and Right Ventricle (RV).
Coronary Sulcus: Separates the atria from the ventricles.

Atria

Upper portion of the heart, holding chambers.
Small, thin-walled, and contract minimally to push blood into the ventricles.
Interatrial Septum: Separates the right and left atria.

Ventricles

Lower portion of the heart, pumping chambers
Thick, strong-walled, and contract forcefully to propel blood out of the heart
Interventricular Septum: Separates the right and left ventricles.

Heart Valves

Function: Ensure one-way blood flow through the heart.
Atrioventricular Valves (AV): Located between the atria and ventricles.
- Tricuspid Valve: Located between the right atrium (RA) and right ventricle (RV), has three cusps.

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