Heart Anatomy and Function Quiz

Study Notes

Heart Anatomy and Function

The heart is composed of cardiac muscle tissue and is found in most animals, including domestic species.
Its primary function is to pump blood through the blood vessels of the circulatory system.

Heart Chambers

Humans, mammals, and birds have four heart chambers:
- Right Atrium: Receives deoxygenated blood from the body's veins (superior and inferior vena cava).
- Right Ventricle: Receives blood from the right atrium via the tricuspid valve (right atrioventricular [AV] valve) and pumps it through the pulmonary valve into the pulmonary circuit for oxygenation.
- Left Atrium: Receives oxygenated blood from the lungs.
- Left Ventricle: Receives oxygenated blood from the left atrium via the bicuspid valve (left atrioventricular [AV] valve) and pumps it through the aortic valve into the systemic circuit.

Mediastinum

The mediastinum is the central compartment of the thoracic cavity where the heart and major vessels are situated, along with the esophagus, trachea, and thymus.
It extends from the sternum (ventrally) to the vertebrae (dorsally).

Heart Structure

Apex: The tapered caudal (inferior) portion of the heart.
Base: The wider cranial (superior) portion of the heart.
Pericardium: A fluid-filled sac that surrounds and supports the heart within the thoracic cavity.
- Fibrous Pericardium: Dense and loose connective tissue that forms the outer (parietal) layer.
- Serous Pericardium: Epithelial tissue that forms the inner (visceral) layer.
- Pericardial Cavity: The fluid-filled space between the fibrous and serous pericardium.

Cardiac Muscle Tissue

Epicardium: Serous membrane that forms the innermost layer of the pericardium and the outermost layer of the heart.
Myocardium: The thickest and middlemost muscular layer of the heart wall.
Endocardium: The innermost layer of epithelial tissue that lines the chambers of the heart.

Cardiomyocytes

Cardiomyocytes are cardiac muscle cells that make up most of the cells in the myocardium.
Unlike skeletal myofibers, they are small, mononucleated cells.
They are connected by intercalated disks, which function as a unified syncytium.
- A syncytium allows for synchronized contraction of cardiac tissue in a wave-like pattern, facilitating the heart's pumping function.

Myofibrils

Myofibrils are bundles of myofilaments arranged in parallel within each cardiomyocyte.
The myofilaments are organized into sarcomeres, which gives cardiac muscle its striated appearance, similar to skeletal muscle.

Blood Flow Through the Heart

Deoxygenated Blood: Enters the right atrium via the superior and inferior vena cava and is then pumped into the right ventricle through the tricuspid valve. The contraction of the right ventricle pumps the blood through the pulmonary valve into the pulmonary circuit.
Oxygenation: In the pulmonary circuit, blood passes through the lungs, where carbon dioxide (CO2) is removed and oxygen (O2) is added.
Oxygenated Blood: Returns to the heart through the pulmonary veins into the left atrium. This blood is then pumped into the left ventricle through the bicuspid valve. The contraction of the left ventricle pumps oxygenated blood through the aortic valve into the ascending aorta.
Systemic Circuit: Blood travels through the arteries (ascending aorta) to deliver oxygen and nutrients to the brain and other tissues.

Heart Valves

Heart valves are essential for maintaining unidirectional blood flow.
Semilunar Valves: Open during ventricular contraction and close during ventricular relaxation.
- Aortic Valve: Located between the left ventricle and the ascending aorta.
- Pulmonary Valve: Located between the right ventricle and the pulmonary arteries.
Atrioventricular Valves: Open during ventricular relaxation and close during ventricular contraction.
- Mitral/Bicuspid valve: Located between the left atrium and the left ventricle.
- Tricuspid Valve: Located between the right atrium and the right ventricle.

Description

Test your knowledge on the anatomy and function of the heart with this quiz. Covering important aspects like heart chambers and the role of the mediastinum, you'll explore the circulatory system's key player. Perfect for students of biology or anyone interested in human anatomy.