GENERAL HISTOLOGY

OESOPHAGUS STOMACH

ECHINODERMS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
This structure is responsible for moving water in and out of the water vascular system.
A
ampullae
B
madreporite
C
ring canal
D
radial canals
Explanation: 

Detailed explanation-1: -The madreporite is a sieve-like, calcified plate that connects the system to the aquatic environment. Water enters through the madreporite and flows through a tube, called the stone canal, that connects to the circular ring canal surrounding the mouth.

Detailed explanation-2: -The system consists of a central ring canal and radial canals extending along each arm. Water circulates through these structures allowing for gas, nutrient, and waste exchange. A structure on top of the body, called the madreporite, regulates the amount of water in the water vascular system.

Detailed explanation-3: -The madreporite is a light-colored, calcerous opening used to filter water into the water vascular system of echinoderms. Acting as a pressure-equalizing valve, it is visible as a small red or yellow button-like structure (similar to a small wart) on the aboral surface of the central disk of a sea star.

Detailed explanation-4: -The madreporite is an essential part of the circulation system in echinoderms. Through this plate, which is also called a sieve plate, the echinoderm draws in seawater and expels water to fuel its vascular system. The madreporite functions like a trap door through which water can move in and out in a controlled manner.

Detailed explanation-5: -The madreporite is one of the most enigmatic organs of the echinoderms. It connects the internal cavity of the water-vascular system to the external seawater through its many pores which are lined with ciliated epithelium.

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