Question

The circulatory system in cockroach consists of
A. Heart, sinuses and alary muscle
B. Cardiac muscle, heart, blood vessels
C. Blood vessels, heart, atrium
D. Veins, heart and atrium

Answer 1

Hint: The circulatory system is an organ system which is involved in circulation of blood and in transportation of nutrients, hormones, carbon dioxide, etc. The circulatory system of cockroaches is of open type.

Complete answer:
Let us analyse the options and find the correct answer.
>Option A: In Cockroach, the heart is arranged mid-dorsally. It is pulsatile and consists of 13 segmentally arranged funnel-shaped chambers. There are 10 units or chambers that are arranged abdominally and 3 thoracic units.
The heart is enclosed in pericardial sinus, its wall has segmented bundles of alary muscles and a diaphragm.
Diaphragm divides the haemocoel into three sinuses:
a) Pericardial sinus (Dorsal) - It surrounds the heart, aorta and alary muscles.
b) Perivisceral sinus (middle)-containing alimentary canal.
c) Perineural sinus (ventral) - It encloses ventral nerve cord.

Haemolymph circulates by the contraction and relaxation of the heart assisted by alary muscles. It is devoid of respiratory pigment and hence does not assist in respiration. A pair of alary muscles are attached laterally to the walls of each chamber. Therefore, this is the correct option.
>Option B, C and D: The circulatory system of cockroaches consists of heart and no blood vessels except for aorta, therefore, it is an open circulatory system. Therefore, atrium and veins are also absent. Thus, this is the incorrect option.

Thus, the correct answer is option (A) Heart, sinuses and alary muscle.

Note:The heart beats at a rate of 100-200 per minute in a cockroach. A complete circulation site takes 20-30 minutes. A white substance, called fat body, occurs in the pericardial sinus. It plays an important role in the storage of food, Example: Albumen, fat and glycogen.