Heart Lab Flashcards
Difference between human and sheep heart
- Sheep has 3 vena cava’s - left anterior (smaller)
- left posterior
- right anterior (larger))
What separates the 3 vena cava?
Fat pads
Left and right anterior vena cava drain:
Head and forelegs
Ventral view of sheep heart:
- Ventral interventricular sulcus is on 45 degree angle
- Aorta is to the sheep’s left (our right)
- pulmonary trunk is the most ventral
- ventral side is rounder than the flatter dorsal side due to the spine
- ligamentum arteriosum is only visible in ventral view
Dorsal view of sheep heart:
- Dorsal interventricular sulcus is straight
- More vessels in dorsal view
- flatter than ventral side
What colour is the atria?
Dark red
Great arteries appearance:
- Shrouded with fat
- Cream-coloured wall
- Pulmonary trunk is most ventral
What makes up the apex of the heart?
Left ventricle
Appearance of aorta
Large and white
Interaction between pulmonary trunk and aorta
They half twist around each other, reversing positions as they continue away from the heart
What is the ligamentum arteriosum?
- Remnant of ductus arteriosus
- Fibrous bridge
Brachiocephalic trunk:
Supplies the arm and the brain
Posterior vena cava drain:
Posterior of sheep
Cross-section of the base of the heart:
- Dorsal: Right ventricle opening and left ventricle opening
- Central: aorta
- Most-ventral: pulmonary trunk
Atria internal wall:
Smooth - allows for smooth laminar flow
Auricle internal wall:
Irregular due to bundles of muscle fibres crossing over like a woven basket.
They’re trabeculated
Function of trabeculae:
To aid contraction
What are the tendinous cords made of?
Fibrous connective tissue
What is in the RV but not in the LV?
Moderator band that crosses from the septum to the ventricular wall
What is the function of the moderator band:
Made of purkinje fibres, aids in conduction
When is the mitral valve open?
Ventricular filling and atrial contraction
When is the mitral valve closed?
Isovolumetric ventricular filling, ventricular ejection, and isovolumetric ventricular relaxation
Aortic valve open view
- Brachiocephalic trunk opening superior to valve flaps
- 3 valve cusps (semilunar shape)
- 2 coronary ostia (openings to coronary arteries) just behind valve flaps
Where do cardiac veins drain into
Left anterior vena cava
Fossa ovalis
- remnant structure of foreman ovale
- Between right and left atrium, interatrial septum
- translucent
What happens when the papillary muscles rupture?
Inlet valves can no longer close; as the tension the papillary muscle provided to keep the chordae teninae tight is gone so the flaps shoot upwards when ventricular pressure exceeds atrial pressure
What could cause a rupture of the papillary muscles?
- Myocardial infarction
- Bacterial or viral infection
- Ischemia
Why don’t the outlet valves need chordae tendinae?
No place to attach
They use their cup/pocket shape structure to be closed via the pressure of blood
Their shape gives strength
What did the foramen ovale do?
- Let blood flow from RA to LA because fetus had no need for pulmonary circuit as placenta of mother supplied oxygenated blood
- flap is on the left side
- in fetus the pressure is opposite
What did the ductus arteriosus do?
Allowed a shunt of blood to pass from the pulmonary trunk to the aorta, again because fetus has no need for pulmonary circuit.