Neurohormone in earthworm is secreted by
a. Cerebral ganglia
b. Sub pharangeal ganglia
Circumphrayngeal ganglia
d. None
Answers
Answer:
A) cerebral ganglia
Explanation:
annelid nervous system:
In most annelids (segmented worms) such as the earthworm, two cerebral ganglia (bundles of nerve cells) form a primitive bilobed brain, from which sensory and motor nerve fibers lead to other areas of the body.
The most primitive annelids have a pair of ventral nerve cords joined by transverse connectives; the most advanced forms have the cords fused to form a single cord. A ganglionic swelling of the cord is found in each body segment, with the most anterior ganglion, the subpharyngeal ganglion, being the most prominent. Two to five pairs of lateral nerves leave each ganglion to innervate the body wall of that segment. A sub epidermal nerve plexus occurs over the whole body. Another plexus, called the enteric, stomodeal, or sympathetic system, is found in the wall of the gut.
Giant axons, usually few in number, travel the length of the cord. They may belong to one cell or be composed of many neurons. These axons are capable of very rapid conduction of impulses to the segmental muscles; their main function is to permit the worm to contract very rapidly as a defense against predators.
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Answer:
(A)- Cerebral Ganglia.
Explanation:
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