The heart is a hollow muscular organ that pumps blood through the cardiovascular system, delivering oxygen to sustain the body's systems. It begins developing in the third week as two endocardial tubes that fuse to form a primitive heart tube. Through looping and folding, the heart forms its four chambers and valves. The myocardium layer contains cardiac muscle cells that contract autonomously via electrical signals from the conduction system and the cardiac cycle to pump blood.

1. The Heart
By: Arielle Ramirez

2. 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

3. 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.

4. 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.

5. 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

6. 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

7. 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.

8. 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

9. 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

10. 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.

11. 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!