Thorax anatomy 1 Flashcards
What is the shape of the heart?
The general shape and orientation of the heart are that of a pyramid that has fallen over and is resting on one of its sides. Placed in the thoracic cavity, the apex of this pyramid projects forward, downward, and to the left, whereas the base is opposite the apex and faces in a posterior direction. The sides of the pyramid consist of:
- A diaphragmatic (inferior) surface on which the pyramid rests,
- an anterior (sternocostal) surface oriented anteriorly,
- a right pulmonary surface,
- a left pulmonary surface.
Where do the two coronary arteries arise from?
the aortic sinuses in the initial portion of the ascending aorta and supply the muscle and other tissues of the heart.
Where does the returning venous blood pass through?
through cardiac veins, most of which empty into the coronary sinus. This large venous structure is located in the coronary sulcus on the posterior surface of the heart between the left atrium and left ventricle
Where does the coronary sinus empty?
into the right atrium between the opening of the inferior vena cava and the right atrioventricular orific
What are the components of the cardiac conduction system?
- the sinu-atrial node
- the atrioventricular node
- the atrioventricular bundle with its right and left bundle branches
- The subendocardial plexus of conduction cells (the Purkinje fibers).
How is the conduction system protected?
-The unique distribution pattern of the cardiac conduction system establishes an important unidirectional pathway of excitation/contraction. -Throughout its course, large branches of the conduction system are insulated from the surrounding myocardium by connective tissue. -This tends to decrease inappropriate stimulation and contraction of cardiac muscle fibers.
Describe the conduction pathway in the heart
- The number of functional contacts between the conduction pathway and cardiac musculature greatly increases in the subendocardial network
- Thus, a unidirectional wave of excitation and contraction is established, which moves from the papillary muscles and apex of the ventricles to the arterial outflow tracts.
How does coronary artery disease affect the cardiac conduction system?
-The cardiac conduction system can be affected by coronary artery disease. -The normal rhythm may be disturbed if the blood supply to the coronary conduction system is disrupted. -If a dysrhythmia affects the heart rate or the order in which the chambers contract, heart failure and death may ensue.
Where is the heart?
In the middle mediastinum
What is the heart contained within?
pericardial sac
What is the pericardial sac?
a double-layered sac with fibrous and serous parts 1. Serous : parietal (lines fibrous pericardium) and visceral part (adherent to heart itself) 2. Fibrous
What are the two parts of the serous?
- Partietal: lines fibrous 2. Visceral - adheres to heart
What are the two pumps in the heart?
- One pump delivers poorly oxygenated blood to the lungs, where it’s oxygenated and returned to the heart
- Second pump delivers highly oxygenated blood to the rest of the body.
What are the two circulations called?
These two circulations are called the pulmonary and systemic circulations
Where does blood from the left ventricle leave?
via the aorta and travels to the head, neck, and through the rest of the body
How does deoxygenated blood return?
To right atrium through superum vena cava or inferior vena cava
Where does blood from the right atrium go?
blood enters the right ventricle, from where it exits the heart into the pulmonary trunk, and then into either the left pulmonary artery or the right pulmonary artery where it goes to lungs for gas exchange to occur
Where does blood from the lungs go?
returns from the lungs via the pulmonary veins into the left atrium.
Where does the aorta emerge from?
The left ventricle
What are the three main branches emerging from the aortic arch?
- brachiocephalic trunk: further subdivides to give a right common carotid artery and a right subclavian artery. 2. left common carotid artery 3. left subclavian artery
What does the brachiocephalic trunk supply?
upper limb and the head and neck on the right side.
Where is venous return from the systemic circulation?
Via two brachiocephalic veins
How are the brachiocephalic veins formed?
the union of an internal jugular vein in the neck and a subclavian vein.
What are the two atrioventricular valves in the heart?
- Mitral (left) 2. Tricspid (right)
What are the small attachment of tendons?
-the chordae tendineae which anchor the cusps into the wall of the ventricle -these are the papillary muscles
What are the two openings within the aortic wall?
two openings for coronary arteries which supply the heart muscle itself with highly oxygenated blood.
What is the anterior interventircular branch?
One of the main branches of the left coronary artery is the branch that descends in between the left and right ventricles
What does the circumflex branch do?
goes behind and down the posterior surface of the heart
Where is the main drainage vessel for the coronary veins?
Coronary Sinus
What does the conducting system of the heart composed of?
The conducting system of the heart is composed of collections of cardiac cells and interconnecting fiber bundles which initiate electrical impulses and rapidly conduct them through the heart, consists of the sinoatrial node, the atrioventricular node, the atrioventricular bundle or bundle of His, and the purkinje fibers.
