Anatomy of the Heart and Blood Flow

Study Notes

Anatomy

The heart is a muscular organ located in the mediastinum, between the lungs.
It is roughly the size of a fist and is divided into four chambers: two atria and two ventricles.
The atria receive blood returning to the heart, and the ventricles pump blood out of the heart.
The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs.
The left side of the heart receives oxygenated blood from the lungs and pumps it to the body.
The heart valves regulate blood flow through the heart by opening and closing in response to pressure changes.
Four valves are present: mitral, tricuspid, pulmonary, and aortic.

Blood Flow

Deoxygenated blood enters the right atrium from the superior and inferior vena cava.
Blood flows from the right atrium to the right ventricle through the tricuspid valve.
The right ventricle pumps blood to the lungs through the pulmonary artery.
In the lungs, blood picks up oxygen and releases carbon dioxide.
Oxygenated blood returns to the left atrium through the pulmonary veins.
Blood flows from the left atrium to the left ventricle through the mitral valve.
The left ventricle pumps oxygenated blood to the body through the aorta.

Cardiac Cycle

The cardiac cycle is a sequence of events that occurs during one heartbeat.
It consists of two phases: systole (contraction) and diastole (relaxation).
Atrial systole occurs first, followed by ventricular systole.
During ventricular systole, the ventricles contract, pushing blood out of the heart.
During diastole, the heart chambers relax to allow them to fill with blood.
The cycle of contraction and relaxation is regulated by specialized cardiac cells that generate and conduct electrical impulses.

Conduction System

The heart's electrical impulses originate from the sinoatrial (SA) node, often called the pacemaker.
Electrical signals spread through the atria, causing them to contract.
The signals then travel to the atrioventricular (AV) node.
The AV node delays the signal to allow the atria to empty completely before the ventricles contract.
The signal travels through the bundle of His and Purkinje fibers, causing the ventricles to contract.
These electrical impulses are measured by an electrocardiogram (ECG or EKG).

Cardiac Output

Cardiac output (CO) is the volume of blood pumped by the heart per minute.
It is calculated by multiplying stroke volume (SV) by heart rate (HR).
Stroke volume is the amount of blood pumped in one heartbeat.
Heart rate is the number of heartbeats per minute.
Factors such as exercise, stress, and body temperature influence cardiac output.

Heart Sounds

Heart sounds are created by the closing of the heart valves.
Lub-dub is the typical sound heard with a stethoscope.
The first sound (lub) is associated with the closing of the mitral and tricuspid valves.
The second sound (dub) is associated with the closing of the pulmonary and aortic valves.
Abnormal heart sounds (murmurs) may indicate valve problems or other heart issues.

Blood Vessels

Arteries carry blood away from the heart.
Veins carry blood toward the heart.
Capillaries connect arteries and veins and facilitate exchange of gases and nutrients.
The aorta is the major artery leaving the heart, distributing oxygenated blood to the rest of the body.
The superior and inferior vena cava are major veins that return deoxygenated blood to the heart.

Heart Diseases

Coronary artery disease (CAD) involves the narrowing of the coronary arteries, reducing blood flow to the heart muscle.
Heart failure is the inability of the heart to pump enough blood to meet the body's needs.
Valve diseases involve problems with the heart valves, such as stenosis (narrowing) or regurgitation (leakage).
Arrhythmias are abnormal heart rhythms, which can be too fast, too slow, or irregular.
Congenital heart defects are present at birth and involve structural abnormalities in the heart.

Regulation of Heart Function

The autonomic nervous system regulates heart rate and strength of contraction.
The sympathetic nervous system accelerates heart rate and increases contractility.
The parasympathetic nervous system slows heart rate.
Hormones, such as adrenaline, also influence heart function.
Blood pressure and blood volume affect the workload of the heart.

Description

This quiz covers the anatomy of the heart, including its structure, chambers, and the flow of blood through the heart. Learn about the role of the heart valves and the process of oxygenation in the lungs. Test your knowledge on how blood circulates within the human body.