The Heart By: Arielle Ramirez

The Heart is… an essential and

hollow muscular organ that pumps blood throughout the body to deliver oxygen via rhythmic contractions

part of the cardiovascular system

And Contributes and helps sustain all of the other bodily systems

Development of the Heart

The heart is one of the first functional organs to develop in babies. It begins to beat on day 21 of

human development. The heart derives from the

mesoderm embryonic germ layer. Initially, the heart is made up of

two endothelial tubes called endocardial tubes.

The endocardial tubes then fuse together to form a primitive heart tube.

Development of the Heart

The primitive heart tube then undergoes a series of looping/folding to form an asymmetrical heart.

The heart is considered to be fully developed around the 18th week of pregnancy.

Anatomy of the Heart

The heart is surrounded by a dense collagenous and fibrous sac to provide protection and support for the heart. The pericardial sac consists of: Parietal Pericardium: outer portion of the sac Pericardial cavity: space in between sac Visceral Pericardium: inner portion of the sac that lines the heart

The heart wall is made up of: Pericardium/Visceral Pericardium

Outer most layer Myocardium

Middle layer Endocardium

Inner most layer

Anatomy of the Heart

The myocardium layer contains cardiac muscle cells that wraps around the heart. Cardiac Muscle cells: Are considered to be autorhythmic cells (they can contract on their own) contain sarcomeres (contractile proteins) that contract to promote movement have only one nuclei connected by intercalated discs and desmosomes

Anatomy of the Heart

The heart is made up of 4 chambers and 4 valves:

Right Atrium: receives deoxygenated blood from the entire body via the superior and inferior vena cava

Right Ventricle: receives blood from the right atrium via the the tricuspid/ atrioventricular valve and pumps that blood out through the pulmonary valve and into the pulmonary artery

Left Atrium: receives oxygenated blood from the lungs via the pulmonary vein

Left Ventricle: receives oxygenated blood from the left atrium via the bicuspid valve and pumps that blood out to the rest of the body through the aortic valve and through the aortic artery.

Physiology of the Heart

The overall function of the heart is to contract and pump oxygenated blood to other tissues and organs so that they could function properly.

In order to do that, the heart undergoes two cycles/systems simultaneously: The Conduction System The Cardiac Cycle

The Cardiac Conduction System The conduction system consist of

specialized cardiac cells that send signals to the cardiac muscles to contract. The signals are initiated when the heart reaches a certain threshold potential.

The impulses then go through these specialized cardiac cells to promote contraction: Sino atria or SA node Atrioventricular or AV node Bundle of His Purkinje Fibers

The Cardiac Cycle

The cardiac cycle refers to what happens during a complete heart beat or when the heart diastoles (contracts), and systoles (relaxes).

The frequency of the cardiac cycle expresses heart rate.

Did you know……

The heart beats about 100,000 times a day. The heart is about the size of your two hands clasped

together. Each minute your heart pumps 1.5 gallons of blood. In 1893, the first successful open heart surgery was

conducted by a Chicago surgeon named Daniel Hale Williams

The heart is the essential organ of life!