Heart

Question 1

How is the fish’s heart structured?

Answer 1

The fish’s heart is placed directly behind the gills and is divided in four compartments:
1. sinus
2. atrium
3. ventricle
4. bulbus
These four compartments are placed all in one row.
The circulation goes ventrally to front, and dorsally to back.

Question 2

What is meant for aorta switch?

Answer 2

With Aorta switch is intended the turn that the aorta do during development. It can curl right (solitus) or left (invesus), and this curl can affect the correct development of the heart:

• Solitus curl of great arteries ensures correct connection of valves with Ao and PA
• Inversus curl can be okay, but only when the whole heart develop inverted; if the heart develop in the usual way then the L-loop is fatal.

Question 3

How different is the fetal blood circulation compared to adult’s?

Answer 3

During fetal development, the lungs are not functional since they are filled with fluid and the fetus exchanges gas using the mother’s lungs, via the placenta. This lack of functional lungs allow the formation of two shunts, which function is to prevent the blood to flow through the lungs:

1. Foramen ovale, which separate the right and left atrium
2. Ductus arteriosus, which separate the pulmonary artery and the aorta.

Question 4

What is closed circulation? And open circulation? How do they relate to each other?

Answer 4

1. Open circulation:
   
   • no veins
   • blood reach the heart through the pericard
   • blood flows freely in lymph (haemolymph)
   • no coelom
2. Closed circulation:
   
   • blood contained in vessels
   • unidirectional circulation
   • veins and arteries

These two types of circulation are related to each other since the open circulation derive from the closed one.