Session 6 Flashcards
Where is the heart located?
Middle mediastinum, protected by a fat layer
What is the position of the heart?
Oblique plane (horizontal)
What is the anterior side of the heart referred to as?
Superior surface
What is the posterior side of the heart referred to as?
Inferior or diaphragmatic surface
What forms the upper portion of the frontal view of the heart?
Ascending aorta and superior vena cava
What runs from the superior to inferior surface of the heart?
Anterior interventricular sulcus
What is the crux cordis?
Intersection of the posterior interventricular sulcus and atrioventricular sulcus
What are the three main functions of the heart?
- Electrical
- Mechanical
- Endocrine
What are the properties of myocardial cells?
- Automaticity
- Conductivity
- Excitability
- Extensibility
- Contractility
What is the composition of the cardiac skeleton?
Dense connective tissue within the atrioventricular septum
What are the functions of the cardiac skeleton?
- Attaches atrial and ventricular muscles
- Anchors 4 valves of the heart
- Electrically insulates the myocardium of the ventricles and atrium
What supports the heart valves?
- Right fibrous trigone
- Left fibrous trigone
- Tricuspid annulus
- Bicuspids annulus
- Aortic annulus
- Pulmonary annulus
How are cardiac muscle fibers connected?
Kept together by desmosomes
What is the arrangement of cardiac muscle fibers?
Spiral fashion with vortex at apex
What are the three layers of cardiac muscle?
- Epicardium: Outermost layer, rich blood supply
- Myocardium: Thickest middle layer, main role in contraction
- Endocardium: Smooth innermost lining of chambers and valves
What are the components of cardiac myocytes?
- 300-700 myofibrils with actin and myosin filaments
- Myofilaments arranged in Z lines
What happens during the contraction process of cardiac myocytes?
Myosin heads cross with actin filaments, overlap at dark band portion of sarcomere (A band)
What are the key structures involved in cardiac myocyte contraction?
- Transverse Tubules: Allow electrical impulses to enter cell
- Sarcoplasmic Reticulum: Regulates Ca++ concentration
- Mitochondria: Provide ATP
- Terminal Cisternae: Reserve Ca++
- Troponin: Composed of 3 proteins to regulate contraction
What is the location of the crux cordis?
Intersection of the posterior interventricular sulcus and atrioventricular sulcus
What is the strongest portion of the cardiac skeleton?
Right fibrous trigone
What is the role of transverse tubules in cardiac myocytes?
To allow electrical impulses to enter the cell
