Anatomy Flashcards
(24 cards)
Heart Muscle Wall Layers
Pericardium (Epicardium) - Outermost layer
Myocardium - Thickest Cardiac Muscle Layer
Endocardium - Innermost layer
Pericardium
Double walled membranous sac that encloses the heart.
- Prevents displacement of the heart during gravitational acceleration and deceleration.
- Serves as a physical barrier and protects the heart from infection and inflammation from the pleural space and lungs
- Contains nociceptors (pain) and mechanoreceptors to elicit reflex changes in BP & HR
Layers of Serous Pericardium
Parietal Pericardium - outermost layer
Visceral Pericardium - innermost layer
Separated by pericardial cavity
Pericardial fluid (10-30mL) provides lubrication for layers of pericardium allowing frictionless motion as heart beats.
Pericardial fluid secreted by serous membrane of Pericardium
Myocardium
Thickest layer - composed of Cardiac muscle cells
Varying degrees of thickness in each heart chamber
Endocardium
Innermost layer of myocardium
Internal lining comprised of simple squamous epithelial cells similar to that of arteries, veins and capillaries of the body creating a continuous, closed circulatory system
Chambers of the Heart
Left Atrium
Right Atrium
Left Ventricle
Right Ventricle
Heart Valves
RA - Tricuspid - RV
RV - Pulmonary Semilunar Valve - Pulmonary Trunk
LA - Mitral Valve - LV
LV - Aortic Semilunar Valve - Aorta
Flow of Blood Through Aorta
Ascending Aorta Right Coronary Artery Left Coronary Artery Brachiocephalic Artery -Right Subclavian Artery -Right Common Carotid Artery -Right Vertebral Artery Left Common Carotid Artery Left Subclavian Artery - Left Vertebral Artery
Major Arteries/Pulse Points
Carotid Brachial Radial Femoral Politeal Posterior Tibial Dorsalis Pedis
Coronary Circulation
Coronary Arteries
- Receive blood during ventricular diastole through openings in the aorta called coronary ostia.
- coronary veins carry blood away from cells and empty into RA through coronary sinus
Coronary Arteries
Left Coronary Artery
-Left Anterior Descending
- Left Circumflex
Right Coronary Artery
Left Coronary Artery
Splits in to LAD & LCX
Arises from single ostia behind left cusp of Aortic Semilunar Valve
Left Anterior Descending
Provides blood to L & R ventricles and much of inter-ventricular septum, travels down Anterior surface
Involved in Anterior (V3-V4) and Septal (V1-V2) MI
Left Circumflex
Supplies blood to Left Atrium and Lateral Wall of Left Ventricle. Often branches to Posterior surface of LA & LV
Involved in Lateral (Leads I aVL V5 - V6)
Right Coronary Artery
Originates from single ostia behind right aortic cusp, travels behind pulmonary artery and extends around right heart to posterior surface, where it branches to atrium and ventricle.
Three main branches are
-Conus (Supplies blood to upper RV)
- Right Marginal Branch (Travels RV to Apex)
- Posterior Descending branch (lies in posterior inter-ventricular sulcus and supplies smaller branches to both ventricles.
Involves in Inferior MI (Leads II, III, aVF)
Coronary Capillaries
At rest heart extracts 70-80% of O2 delivered to it and coronary blood flow is directly related to myocardial O2 consumption.
As myocardial O2 requirements increase so too must coronary blood flow (why GTN is used to reduce myocardial oxygen demand)
Coronary Veins
After passing through capillary network blood drains in to cardiac veins, mostly located in visceral pericardium.n Veins feed in to Great Cardiac Vein and coronary sinus (a cavity which acts like a vein) on posterior surface of the heart (between atria and ventricles), in the coronary sulcus. Deoxygenated blood enters directly in to RA.
Pulmonary Circulation
Facilitates gas exchange
Provides nutrients to lung tissues
Serves as a reservoir for LV
Serves as a filtering system - removes air, clots, other debris from circulation
Pulmonary Artery Pressure
15mmHg - Approx 1/5 that of MAP in aorta (95mmHg)
Arterioles
Divide at terminal bronchioles to form network of pulmonary capillaries around alveoli
Pulmonary Capillaries
Capillary walls consists of thin endothelial layer and thin basement membrane which often fuses with the basement membrane of the alveoli.
Therefore very little physical separation exists between blood in capillaries and gas in alveolus, allowing for exchange of gas and nutrients
Pulmonary Circulation Structures
Pulmonary Artery
Right & Left Pulmonary Artery
Pulmonary Capillaries
Left and Right Pulmonary Veins (2 each)
Blood Vessels
composed of 3 layers
tunica externa - outermost layer
tunica media - middle layer
tunica intima - innermost layer
Arterial wall composition
elastic connective tissue, fibrous connective tissue, smooth muscle
