Question

Flow of hemolymph in Cockroach is
(a) Heart Ostia Perivisceral sinus Pericardial sinus Head Heart
(b) Heart Pericardial sinus Head Perivisceral sinus Ostia Heart
(c) Heart Head Perivisceral sinus Pericardial sinus Ostia Heart
(d) Heart Head Perivisceral sinus Ostia Pericardial sinus Heart

Answer 1

Hint: The flow of haemolymph is the flow of blood in cockroaches. The direction of the flow of hemolymph is posterior to anterior.

Complete Step by Step Answer:
In cockroaches, the blood from the heart gets pumped into the head from where it flows into the perivisceral sinus and perineural sinus. From here the alary muscles located on the dorsal diaphragm contract causing the blood flow from the perivisceral sinus into the pericardial sinus due to the increase in the volume of the pericardial sinus. Once the blood enters the pericardial sinus, alary muscles relax causing the volume of the pericardial sinus to decrease, thus all the blood is pushed into the heart. From here the blood gets pumped again by the heart into the head and the cycle repeats.

So, the correct answer is ‘Heart Head Perivisceral sinus Pericardial sinus Ostia Heart’.

Additional information: Let us now understand the anatomy of the body of a cockroach to get a more detailed understanding. The hemocoel (body cavity where blood flows) of cockroach is divided into 3 sinuses due to the presence of a ventral and dorsal diaphragm. The pericardial sinus is present above the dorsal diaphragm. The perivisceral sinus is present in between the dorsal and ventral diaphragm. The perineural sinus is present below the ventral diaphragm. This diagram will help us understand the structure better.

Note:
- In cockroaches, the heart is dorsal and the brain is ventral. Whereas in humans it is the opposite.
- Pericardial sinus is the sinus where the heart is present. In the perivisceral sinus, all the visceral organs are present which get directly bathed in the hemolymph. The perineural sinus is where the nerve cord is present.