Of course 2.5 billion times refers to a person who has lived 100 years old! You're not their yet.
The pulmonary circuit receives O2 from the lungs, and releases CO2 from the blood.The systemic circuit releases O2 to the tissues , and receives CO2 produced by the cells.
The mediastinum contains many important structures, including the heart, pericardium, trachea, esophagus, along with blood vessels and nerves.
The fibrous pericardium is attached to the diaphragm, the sternum, and the vertebrae.The visceral layer is folded over at the great vessels, and gives rise to the parietal layer. Both layers are serous membranes, which means they secrete serous fluid.
Purkinje fibers are located along the endocardium. They initiate cardiac muscle contractions, which we’ll discuss in the next section.
Deoxygenated blood from systemic circulation enters the right atrium.The right ventricle pumps the blood into pulmonary circulation, towards the lungs.The left atrium receives oxygenated blood from pulmonary circulation.The left ventricle pumps the oxygenated blood into systemic circulation.
The superior diaphragm drains systemic circulation from regions above the diaphragm.The inferior diaphragm drains systemic circulation from regions below the diaphragm.
Notice the pulmonary trunk and pulmonary arteries are blue. The blue indicates deoxygenated blood in these illustrations. The coloring does NOT refer to arteries or veins.
The AV valves are open when blood fills the ventricles. The AV valves shut as the ventricles contract.
Semilunar valves are pushed open when the ventricles contract. As they relax, the weight of blood left in the aorta and pulmonary trunk pushes the valves shut.
Section 1, chapter 15: anatomy of the heart
Anatomy ∙ Physiology
Chapter 15, Section 1
FUNCTIONS OF THE
It pumps 7000L (1800 gallons) of blood through our body every day.
The heart contracts 2.5 billion times in a lifetime.
The heart is composed of two pumps
The systemic circuit carries
blood to the body
The pulmonary circuit carries
blood to the lungs
the heart is located within the mediastinum
It is about the size of a fist (14cm x 9cm)
2/3 of the heart is left of the midline
The heart is posterior to the sternum
attachment of major vessels
2nd intercostal space
Pointed inferior margin
5th intercostal space
The heart is surrounded by a pericardial membrane.
The fibrous pericardium forms a thick outer
layer of connective tissue.
The parietal pericardium is a serous
membrane attached directly to the fibrous
A visceral pericardium is a serous
membrane that forms the outer layer of the
The pericardial cavity contains serous fluid.
The wall of the heart contains 3 layers
The epicardium is also called the visceral
The myocardium contains a thick layer of cardiac
muscle, with blood vessels and nerves
The endocardium is a smooth layer of squamous
epithelium that lines the heart chambers and valves
The heart contains 4 chambers
The right atrium receives
blood from the body
The left atrium receives
blood from the lungs
The right ventricle pumps
blood towards the lungs
The left ventricle pumps
blood towards the body
A pocket on each atrium, called the auricle
increases the capacity of the atria.
blood enters the heart through the great veins
The superior vena cava
returns blood from the
upper body to the heart
Four pulmonary veins
return blood from the
lungs to the heart
The coronary sinus
returns blood from the
myocardium to the heart
The inferior vena cava
returns blood from the
lower body to the heart
Great arteries carry blood away from the heart
The aorta delivers oxygenated
blood to the systemic circulation
The pulmonary trunk* delivers
deoxygenated blood to the lungs
* The pulmonary trunk immediately
divides into a left and right pulmonary
Left and right AV valves prevent backflow into the atria.
*AV = atrioventricular
The tricuspid valve
guards the right AV
The bicuspid (mitral)
valve guards the left
AV valves are anchored to the ventricles by chordae tendineae
Chordae tendineae anchored to the
cusps papillary muscles
Papillary muscles contract to pull the
valves tightly shut
Mitral Valve Prolapse – cusp of the mitral valve protrudes into atrium.
Symptoms include: chest pain, heart palpitations, and fatigue.
Semilunar valves prevent backflow of blood into the ventricles
A pulmonary valve is located at
the base of the pulmonary trunk
An Aortic valve (not shown) is
located at the base of the aorta
Each cusp of a semilunar valve is
shaped like a crescent moon
path of blood through the right heart
1. Blood enters right atrium
through the SVC, IVC, and
2. It passes through the tricuspid
valve into the right ventricle
3. Blood is pumped from the right
ventricle, through the pulmonary
valve, and into the pulmonary
4. Blood passes into the
pulmonary arteries towards the
path of blood through the left heart
5. Oxygenated blood is returned to
the heart through 4 pulmonary
6. Blood enters the left atrium.
7. Blood passes through the
bicuspid valve into the left
8. The left ventricle pumps blood
through the aortic valve into the
9. Blood enters systemic
circulation to the tissues
throughout the body.