Chapter 20: The Heart Flashcards
The heart
A hollow muscular pumping organ within the thoracic cavity.
It is a dual pump:
Pulmonary circuit - the right side which pumps blood to the lungs.
Systemic circuit - the left side which pumps blood to the rest of the body.
Arteries
Vessels which take blood away from the heart
Mostly carries O2 rich blood
Veins
Vessels which take blood towards the heart.
Most carries deoxygenated blood
Capillaries
Microscopic vessels which exchanges materials between the blood and tissues.
What is the heart enclosed by
Pericardium:
- Fibrous pericardium - dense CT
- Serous pericardium - parietal (lines the cavity wall) and visceral (lines the surface of the heart)
What is visceral pericardium also referred as?
Epicardium
What are the 3 layers of the hearts wall?
- Outer epicardium - simple squamous epithelium and CT
- Middle myocardium - consists of cardiac muscle arrange in bundles
- Inner endocardium - thin layer of simple squamous cells and thin layer of CT.
What are the 4 chambers of the heart?
2 atriums - the 2 uppermost blood collecting chambers. Has thin walls.
2 ventricles - the 2 lowermost blood pumping chambers. Has thick walls.
Why is the left ventricle wall 3x as thick as the right ventricle wall?
A thicker wall means a more powerful pump, and blood has to travel further to the rest of the body from the left ventricle.
The right ventricle just pumps blood a short distance to the lungs.
Heart valves
Consists of 2 or 3 fibrous flaps of tissue (cusps) covered with endocardium.
These valves keep the one-way flow of blood (prevent back flow)
Atrioventricular (AV) valves
Located between an atrium and ventricle.
2 of them:
1. Tricuspid valve - located between the right atrium and right ventricle (contains 3 flaps)
- Bicuspid valve - located between the left atrium and left ventricle (contains 2 flaps)
Chordae tendineae
Papillary muscles which connect the edges of the AV valves to the ventricle wall
Semilunar (SL) valves
- Pulmonary SL valve - located between the right ventricle and pulmonary trunk
- Aortic SL valve - located between the left ventricle and aorta
What is the pathway of pulmonary circulation?
Right atrium -> right ventricle -> pulmonary trunk -> pulmonary arteries -> lung capillaries (blood released CO2 and picke up O2) -> pulmonary veins -> left atrium
What is the pathway of systematic circulation of blood
Left atrium -> left ventricle -> aorta -> arteries in body -> body capillaries (blood releases O2 and picks up CO2) -> veins in body -> superior or inferior vena cava -> right atrium