Lab 3 Flashcards
What is the difference between the vena cavae in human vs. sheep hearts?
The sheep has 3 vena cavae separated by 2 fat pads: The right anterior, stretching from the head towards the right atrium, the left anterior, streching from the head around the base of the heart to the RA, and the posterior, which comes from the tail end of the sheep
What is the difference between the pericardia in the sheep vs human hearts?
The sheep has no fibrous pericardium
What are 4 landmarks we can use to determine which angle we are looking at the heart from?
The pulmonary trunk is the most ventral vessel
The inverventricular sulcus runs diagonally downward in ventral view, but vertically on dorsal view
Both auricles point ventrally
The dorsal side is flat from a birds eye view
What are trabeculae?
Rods within the auricle of the heart
What is the thickness and pressure ratio for the ventricles
Left is 3x thicker than right, and pumps about 5x the pressure
What is the moderator band?
It looks similar to the chordae tendineae, but is made of muscle, not connective tissue.
It contains modified purkinje fibres, forming part of the heart’s conduction system
What is the fossa ovalis?
A thin membrane covering the foetal foramen ovalae
What is the ligamentum arteriosum?
A withered vessel called the ductus arteriosum running from the pulmonary trunk to the aorta, which used to carry blood from the pulmonary trunk to the aorta.
What would happen if the ductus arteriosum remained open after birth?
Blood would be forced from the aorta to the pulmonary trunk (due to the pressure gradient) resulting in more, higher pressure blood in the lungs and possible swelling
What is the foramen ovalis?
A hole in the inter-atrial septum, allowing blood to move from the right to left atrium, with a flap on the left side of the septum
How does the foramen ovalis close?
Increased pressure coming into the left atrium due to the pulmonary circuit being in use shuts the foramen ovalis. This eventually becomes sealed into the fossa ovalis
How does the ductus arteriosum close?
High concentrations of oxygen cause the smooth muscle surrounding the ductus to contract, causing it to constrict into the ligamentum.
