Heart Anatomy - Lecture 7 Flashcards
Where is the heart located?
○ In the thorax between the lungs
○ Lies between ribs 2-5 to the left of the midline
○ Apex lies in the 5th intercoastal space in the midclavicular line
What is the pericardium?
Composed of an outer fibrous layer and an inner serous pericardium
What is the fibrous pericardium
○ Inelastic, made of dense connective tissue
○ Fuses with the diaphragm inferiorly and superiorly with the great vessels
○ Prevents overfilling of the heart and anchors it in position
What is serous pericardium?
○ Double layered serous membrane - made up of parietal and visceral layers
What is the parietal layer?
Lines the inner surface of the fibrous pericardium
What is the visceral layer?
○ Epicardium
○ Adheres to the surface of the heart
○ Vessels run through this layer
○ Varying amounts of fat
What is the pericardial cavity?
○ Potential space between parietal and visceral layers
○ Contains pericardial fluid
○ Prevents friction
What are the three layers of the heart wall?
○ Endocardium: inner layer - endothelium
○ Myocardium: middle layer - cardiac muscle
○ Epicardium: outer layer - visceral pericardium
What are the great vessels in the right atrium?
○ Superior vena cava - carries deoxygenated blood from the upper body
○ Inferior vena cava - carries deoxygenated blood from the lower limbs and abdomen
What are the great vessels in the left atrium?
Pulmonary veins - carries oxygenated blood from the lungs
What are the great vessels in the right ventricle?
○ Pulmonary trunk - carries deoxygenated blood towards the lungs
○ Pulmonary arteries - divisions of the pulmonary trunk and carries deoxygenated blood to the lungs
What are the great vessels in the left ventricle?
Aorta - carries oxygenated blood to the rest of the body
What is trabeculae carnae?
○ Found in the ventricles
○ Meaty ridges
What are pectinate muscles?
○ Found in the atria
○ Smaller ridges
What is the fibrous skeleton of the heart?
○ Composed of bands of fibrous connective tissue between the atria and ventricles
○ Electrically separates the atria from the ventricles
○ Encircles the pulmonary trunk and aorta
○ Heart valves are suspended from it
What is the function of the heart valves?
Prevent backflow of blood
What are the two types of heart valves?
○ Atrioventricular (AV) valves
○ Semilunar valves
What are the two AV valves and where are they located?
○ Tricuspid valve - located between the right atrium and right ventricle
○ Bicuspid/mitral valve - located between the left atrium and left ventricle
What are the two semilunar valves and where are they located?
○ Pulmonary valve - located between the right ventricle and pulmonary trunk
○ Aortic valve - located between the left ventricle and aorta
How are the AV valves opened?
Opened by blood flowing from the atria to the ventricles
How are the AV valves anchored?
Anchored by chordae tendinae to papillary muscles
What is the function of the papillary muscles?
○ Prevents eversion of valves
○ Prevents backflow of blood into the atria
When are the AV valves open?
When ventricular pressure is less than atrial pressure
When are AV valves closed?
When ventricular pressure is greater than atrial pressure
How are the semilunar valves opened?
Opened by the force of blood as the ventricles contract
How are the semilunar valves closed?
○ Blood flows backwards in the aorta and pulmonary trunk during ventricular relaxation
○ Blood pools in the cusps pushing the valves shut
○ This prevents backflow of blood into the ventricles
What is coronary circulation?
The coronary circulation is the system of vessels that supply the heart muscle with blood
How much blood does the heart receive per minute?
The heart receives 250ml/min of blood
When is blood delivered to the myocardium?
During ventricular relaxation
Name the two main coronary arteries
○ Left coronary artery
○ Right coronary artery
What are the branches of the LCA?
○ Anterior interventricular
○ Circumflex
What are the branches of the RCA?
○ Marginal artery
○ Posterior interventricular
Which veins drain into the coronary sinus?
The great, middle and small cardiac veins
Where does the coronary sinus empty into?
Right atrium
Which veins drain directly into the right atrium?
Anterior cardiac veins
What is angiography used for?
Angiography is used to examine the patency (openess) of the coronary vessels
What is the cardiac conducting system?
Network of non-contractile cells that initiate electrical impulses that coordinate effective heart contraction
What are the key components of the cardiac conducting system?
○ Sinoatrial (SA) node
○ Atrioventricular (AV) node
○ AV bundle (bundle of His)
○ Right & left bundle branches
○ Purkinje fibres
Why is foetal circulation different from normal circulation?
○ Receives oxygen and nutrients from the placenta via the umbilical vein
○ It needs to bypass the non-functional lungs
What are the three circulatory shortcuts in foetal circulation?
○ Foramen ovale.
○ Ductus arteriosus.
○ Ductus venosus
What is the function of the foramen ovale?
○ Connects the right and left atria
○ Bypasses the right ventricle and pulmonary system
What is the function of the ductus arteriosus?
○ Connects the pulmonary trunk to the arch of the aorta
○ Bypasses pulmonary system and left side of the heart
What is the function of the ductus venosus?
○ Connects the umbilical vein to the inferior vena cava
○ Bypasses the liver
What happens to the foetal circulation at birth?
○ Lungs expand -> blood rushes into the pulmonary circulation -> O2 levels rise -> ductus arteriosus constricts
○ Left atrial pressure increases -> foramen ovale closes
○ The umbilical cord is tied -> umbilical vessels close ->
ductus venosus fibroses
What are the adult remnants of foetal structures?
○ Ductus venosus -> ligamentum venosum
○ Foramen ovale -> fossa ovalis
○ Ductus arteriosus -> ligamentum arteriosum
