Thorax Part 3 Flashcards
Name the structure.
Heart
Where is the heart placed?
Middle Mediastinum
Where is the heart contained?
Pericardium / Pericardial cavity
What is the pericardium?
Fibroserous sac surrounding heart and its great vessels
Describe the structure of the pericardium.
- Consists of 2 layers
- Fibrous
-
Serous (has 2 parts)
- Parietal – lines fibrous
- Visceral – adheres to heart
What are the steps of the cardiac cycle (7)?
- Atrial systole
- Isovolumetric contraction
- Ventricular ejection phase
- Reduced ejection
- Isovolumetric relaxation
- Rapid ventricular filling
- Reduced passive filling
What happens during atrial systole of the cardiac cycle?
- Prior to atrial systole, the blood will passively flow through the atrioventricular orifice into the ventricles through open atrioventricular valves (Mitral & tricuspid valves)
What happens during isovolumetric contraction of the cardiac cycle?
- Atrioventricular and semi-lunar valves are closed, as pressure is accumulating through isometric contraction
What happens during ventricular ejection phase of the cardiac cycle?
- Period at which the ventricular pressure exceeds aortic and pulmonary pressure (afterload), the semi-lunar (pulmonary & aortic) valves open, demarcating the initiation of this phase
What happens during reduced ejection phase of the cardiac cycle?
- Blood is ejected from the ventricles at a reducing rate, and ventricular pressure subsequently decreases simultaneously with volume reduction; aortic and pulmonary pressure eventually exceeds ventricular pressure, stimulating the closure of the semi-lunar valves
What happens during isovolumetric relaxation phase of the cardiac cycle?
- Early phase of ventricular diastole: Ventricular muscle relaxes, pressure on remaining blood within the ventricle begins to decrease
What happens during rapid ventricular filling phase of the cardiac cycle?
- Atrial pressure increases (ventricular pressure decreases via relaxation) to the extent that the atrioventricular valves open, enabling blood flow along the pressure gradient through the atrioventricular orifice into the ventricles
What happens during reduced passive filling phase of the cardiac cycle?
- Slow filling of the ventricles (Diastasis)
Name the branches of the aortic arch.
-
Brachiocephalic branch
- Right subclavian artery
- Right common carotid artery
- Left common carotid artery
- Left subclavian artery
Name the branches of the brachiocephalic vein.
- Right brachiocephalic vein
- Right subclavian vein
- Right internal jugular vein
- Left brachiocephalic vein
- Left internal jugular vein
- Left subclavian vein
Name the four cardiac valves.
- Right atrioventricular / tricuspid valve
- Left atrioventricular / bicuspid / mitral valve
- Pulmonary valve
- Aortic valve
How does the aortic valve differ from the pulmonary valve?
There is an opening for the right coronary artery.
Which artery supplies the cardiac muscles?
Coronary arteries
Describe the branching of the coronary arteries.
- Aorta
- Right coronary artery
-
Left coronary artery
- Anterior interventricular branch of the left coronary artery
- Circumflex branch of the left coronary artery
Which veins drain the cardiac muscles?
Coronary vein
Describe the branching of the coronary veins.
Cardiac veins drain into coronary sinus
Describe the SA node.
- Primary pacemaker cells located in wall of right atrium
- Rate: 60-100bpm
- Usually determines normal heart rhythm
What are the 3 latent pacemaker cells?
- AV node
- Bundle of His
- Purkinje fibers
Describe the AV node.
- Located at base of right atrium, near septum
- Rate: 40-60bpm