A&P Flashcards
Where is the heart located ?
- Middle mediastinum
- Extends obliquely from 2nd to 5th rib
- Anterior to vertebrae
- Posterior to sternum
- Rests on diaphragm
What is the pericardium ?
A double walled sac containing a film of lubricating serous fluid
What are the roles of both layers of pericardium ?
Fibrous Pericardium
- Tough connective tissue protecting the heart which anchors to surrounding structures
- Prevents overfilling of the heart if fluid builds up in pericardial cavity (can inhibit effective pumping).
Serous Pericardium
- Parietal layer lines the internal surface of the fibrous pericardium
- Visceral layers lines external heart surface
Heart layers ?
Epicardium
-Visceral layer of serous pericardium
Myocardium
-Muscle of the heart and contractile layer
Endocardium
- Line heart chambers
- Prevents clotting of blood in heart
- Forms a barrier between 02 hungry myocardium and blood
About the parts of fibrous skeleton ?
Septums
- Flat sheets separating atriums, ventricles and left and right ides of heart
- Important for cardiac cycle as connective tissue is non conductive
Rings
- Rings around great vessel entrances and valves
- Stop stretching under pressure
What are the atriums and their roles ?
These are receiving chambers of the heart
Right atrium
- This is where the 3 veins drain into
- Superior VC
- Inferior VC
- Coronary Sinus
Left atrium
-Receives blood from the 4 pulmonary veins
What are the ventricles and their roles ?
These are muscular discharging chambers and are the hearts pumps
Right Ventricle
- Most of hearts anterior surface
- Thinner and responsible for pulmonary circulation
Left Ventricle
- Thick and responsible for systemic circulation via the aorta
- Most of hearts posterior surface
Explain the pathway of blood flow through the heart ?
- Right side of heart pumps blood through pulmonary circuit
- This blood gains 02 and loses c02 and enters the left side of the heart
- The left side of the heart pumps blood via the systemic circuit to all other bodily tissues and back to the right side
- This blood loses o2 and picks up c02 whilst going through systemic circuit
What is coronary circulation ?
- Circulation for the myocardium
- Arteries lie in the epicardium
What arteries supply the myocardium ?
The aorta branches into
Left CA
- Has 2 branches
- Anterior IV artery (supplies blood to IV septum & anterior walls of both ventricles
- Circumflex artery which supplies left atrium & posterior walls of left ventricle
Right CA
- Has 2 branches also
- Marginal artery which supplies the Myocardium lateral RHS of heart
- Posterior IV artery which supplies posterior ventricular walls and anastomoses w/ anterior IV artery
What veins are involved in venous drainage ?
Great, middle and small cardiac veins (empties into RA)
What is the reason for valves ?
Unidirectional flow of blood
What are the AV valves and their names ?
- Located at 2 AV junctions
- Prevents back flow into atria during contraction of ventricles
- Right AV = Tricuspid
- Left AV = Mitral or Bicuspid
What are the SL valves ?
- These valves guard the bases of the large arteries (Aorta and PA)
- These open under pressure from ventricles
