Week 7: Chp 28: Anatomy of the Heart Flashcards
What is the Heart?
a hollow, fist-sized organ
What is the location of the heart?
- located in the thoracic cavity between the lungs in a space called the mediastinum
- it lies behind the sternum and rests on the diaphragm
What is the heart contained in?
it is contained in a protective sac called the pericardium
The pericardium has 2 layers
- the outer layer, the pericardial sac or parietal pericardium
- the inner layer, the epicardium or visceral pericardium
Pericardial sac/ Parietal Pericardium
the outer layer of the pericardium
-a tough fibrous layer that turns inward at the base of the heart forming the inner layer, the epicardium
Epicardium/ Visceral Pericardium
the inner layer of the pericardium
-covers the heart surface
What is between the 2 layers of the Pericardium?
a pericardial cavity containing serous fluid that provides a lubricant that allows the heart to beat without friction
The heart muscle wall is composed of how many layers?
3 layers
- epicardium (thin, outer layer)
- myocardium (thick, middle layer)
- endocardium (thin, inner layer)
What is the muscular layer of the heart that is responsible for the mechanical, contractile function of the heart?
myocardium
What layer of the heart lines the interior of the heart and heart valves and is continuous with the inner layer, or endothelium, of the blood vessels?
endocardium
There are how many chambers within the heart?
4 chambers
- the right and left atria
- the right and left ventricles
Blood Flow Through the Chambers of the Heart
- The Right atrium receives deoxygenated blood from the systemic circulation through the great veins, the inferior and superior vena cava.
- Blood flows from RA to the Right Ventricle (RV)
- Blood is then delivered to the pulmonary circuit through the pulmonary artery
- Newly oxygenated blood is returned to the Left Atrium via the pulmonary vein
- Blood flows from the LA to the Left Ventricle (LV) and is then ejected into the aorta to the systemic circulation
How many valves are in the heart?
4 valves
- Atrioventricular (AV) valves; tricuspid and bicuspid/mitral valve
- Semilunar valves; pulmonary and aortic valves
Why is there a need for valves in the heart?
to facilitate a one-way flow
Atrioventricular (AV) valves and their location
between the atria and ventricles on the left and right sides of the heart
- The AV valve between the right atrium and right ventricle is the tricuspid valve
- The AV valve between the left atrium and left ventricle is the bicuspid/mitral valve
The Atrioventricular Valves Function
when open, the valves allow flow from the atria into the ventricle
-when the ventricles fill and the pressure within increases, the valves close to prevent retrograde flow back into the atria
Chordae Tendineae
fibrous chords that connect the valves to muscle to prevent the valves from budging or turning inside out during ventricular contraction
Semilunar Valves and their location
- between the ventricles and their respective arteries (Pulmonary and aortic valves)
- Pulmonary valve; between the right ventricle and pulmonary artery
- Aortic valve; between the left ventricle and the aorta
The Semilunar valves function
control the flow of blood between the ventricles and the pulmonary artery or aorta
The valves in the heart open and close in response to what?
changes in presssure
What happens to the AV valves when ventricles are relaxed during filling or diastole?
-The AV valves are open, allowing blood to flow into the ventricles
What happens to AV valves as the ventricles fill?
- The AV valves are forced upward and begin to close
- the pressure increase from ventricular contraction forces the AV valves fully closed, preventing backflow of blood into the atria
When does the Semilunar valves open?
when the increase in pressure from ventricular contraction exceeds the arterial pressure in the pulmonary circuit or aorta, the semilunar valves open, allowing blood to flow to the pulmonary or systemic circulation
