Heart and Embryology Flashcards
What 2 pleura surround the heart?
-Visceral pericardium (epicardium)
-Parietal pericardium
List the 5 layers that are passed through if you move from the heart out towards the lungs
- Visceral pericardium
- Pericardial cavity
- Parietal pericardium
- Connective tissue layer
- Mediastinal pleura
In which species does the left coronary artery go down the subsinuosal groove?
Dogs and ruminants
In which species does the right coronary artery go down the subsinuosal groove?
Horses and pigs
Is the paraconal groove more cranial or caudal?
Cranial
Is the subsinuosal groove more cranial or caudal?
Caudal
What is a primary difference between the left ventricle and the right ventricle?
Left ventricle contains a much thicker muscular wall, while the right ventricle is made of thinner muscle
Why does the left ventricle contain more muscle than the right ventricle?
Because the left ventricle has to push blood systemically; the right ventricle only has to pump to the lungs
What is the ossa cordis?
A fibrous structure of the heart that supports the valves. Sometimes becomes ossified in cattle
What is the function of the septomarginal band?
Provides a conduit for conductive fibres so contraction is more even across muscles
Where is the SA Node located in the heart?
In the terminal crest (under the cranial vena cava)
What is the function of the intervenous tubercle?
Directs blood over the AV valve and into the right ventricle from the superior vena cava
What is the fossa ovales?
The remnant of the foramen ovale that closes once the animal is born
How would heart failure appear on a radiograph?
The heart would appear enlarged due to dilations in the atria
What are the 3 layers of a trilaminar embryo?
Ectoderm
Mesoderm
Endoderm
What are the 4 components of an early embryo heart?
Truncus arteriosus
Ventricle
Atria
Sinus venosus
What to the aortic arches eventually branch off of during development?
Truncus arteriosus
What are the steps of the division of the atrium?
Endocardial cushions begin to form, which then extend inward towards each other forming the atrio-ventricular canal. Once both sides meet each other, they form the septum intermedium and separate the right and left atrio-ventricular openings
What part of the heart is the sinus venosus incorporated into?
The right atrium. Contributes to the left coronary sinus in the adult heart
What structure forms the valve of the foramen ovale?
Septum primum
In what region do the aortic arches form?
Pharyngeal region
What happens to the 1st aortic arch as the others start developing?
It gets lost
What does aortic arch 3 form?
-Common carotids
-External carotids
-Internal carotids
What does aortic arch 4 form?
-Aorta
-Right and left subclavian arteries
-Brachiocephalic trunk
What does aortic arch 6 form?
-Pulmonary trunk
-Left and right pulmonary arteries
In dogs, what do the right and left subclavian arteries branch from?
Right: Brachiocephalic trunk
Left: Aorta
What do the carotids branch from in all species?
Brachiocephalic trunk
In cows and horses, what do the left and right subclavian arteries branch from?
Both branch from the Brachiocephalic trunk
What structure does the ductus arteriosus become in an adult?
Ligamentum arteriosum
What does the right recurrent laryngeal nerve loop under?
The right subclavian artery
What does the left recurrent laryngeal nerve loop under?
The ligamentum arteriosum
How would pathology of the heart affect the recurrent laryngeal nerves?
If the heart is enlarged, it would put pressure on the LEFT recurrent laryngeal nerve. The RIGHT recurrent laryngeal nerve would be unaffected as it is located cranial to the heart
What can happen if the heart fails to migrate during development?
Since the heart develops in the pharyngeal region, if it fails to migrate caudally then the animal can be born with their heart in their neck. This is not fatal, but it greatly reduces protection of the heart.
What structures are only present in a fetus?
Ductus venosus (liver)
Ductus arteriosus
Foramen ovale
Describe the path of blood through fetal circulation (sorry)
-Deoxygenated blood from body goes into right atrium and the right ventricle
-Pumped into pulmonary trunk, through ductus arteriosus, and into aorta to bypass the lungs
-Goes into umbilical arteries and to placenta for oxygen/nutrients/waste
Umbilical vein carries blood to liver in ductus venosus and back to heart
-Blood enters right atrium and goes through foramen ovale into left atrium
-Goes into left ventricle and pumped to body
What organs does the placenta function as for a fetus?
Lungs
GI tract
Kidneys
What occurs when the fetus is born?
-Umbilical arteries and vein closed off
–> this reduces pressure in caudal vena cava, increasing pressure in left atria and pushes foramen ovale closed
-Lungs expand and reduce circulatory resistance to blood flow in pulmonary circulation
-Muscles around ductus arteriosus constrict and close it, making it forms the ligamentum arteriosum
Why can it be normal to hear murmurs in neonates?
Because it takes some time for the ductus arteriosus and foramen ovale to fully close
