The innermost layer of the body wall is formed by coelomic epithelium which is a thin membrane made up of single layer of cells (Fig. (b) Peripheral nervous system made up of nerves given out from the ganglia of the central nervous system. Although earthworm is a terrestrial animal, its respiration is more like that of a simple aquatic animal. The region next to the stomach is the intestine, which is a long, wide and thin- walled tube, extending from the 15th to the last segment, up to the anus. The nervous system is divisible into central, peripheral and autonomic nervous system (sympathetic nervous system). The neurosecretory system of the earthworm, Pheretima posthuma, has been studied by PF, PATh and PAVB bulk‐stained preparations and sections.There are three types (a, b and c) of neurosecretory cells in the cerebral ganglion, suboesophageal ganglion and the nerve cord ganglia.Axons of a‐ and b‐cells are observed in toto in the cerebral and the suboesophageal ganglions. The leaves or vegetable matters are seized by the pointed end of the mouth, the buccal chamber is everted and the food is drawn in by the suc­tion of the pharynx. The dorsal side of the body is brown in colour and can be distinguished from the ventral side which is lighter in colour. First pair arises just in front of setal ring while the other 2 pairs arise closely but behind setal ring. The nerves of the nerve cord, therefore, have both sensory and motor fibres, i.e., mixed. The body of earthworm consists of vari­ous apertures such as: It is a crescent-shaped aperture situated ventrally in the prostomium. Nervous system • The Peripheral nervous system a. The coelom opens to the exterior by dorsal pores and nephridiopores. The peritoneal epithelium is followed by longitudinal muscle fibres and circular muscle fibres. Likewise, its mid ventral part is formed of a pair of small and fused sub-pharyngeal ganglia. This test is Rated positive by 85% students preparing for Class 11.This MCQ test is related to Class 11 syllabus, prepared by Class 11 teachers. Charles D. Howell, The responses to light in the earthworm, Pheretima agrestis goto and Hatai, with special reference to the function of the nervous system, Journal of Experimental Zoology, 10.1002/jez.1400810205, 81, 2, (231-259), (2005). These are elongated cells, each having a broad, fan-like process attached to a narrow nucleated body. 1.95A). The outer­most layer of the gut wall is made up of tall and narrow cells derived from peritoneal epithelium. Digestive System. (a) Central nervous system comprising of a brain or supraoesophageal ganglion, sub-oesophageal ganglion, circumoesophageal connectives and the ventral nerve cord. The internal epithelium is formed of glandular and ciliated cells. Reproduction – some are unisexual or dioecious (Nereis) and some are bisexual or monoecious (earthworms and leeches). The outer covering of ventral nerve cord is called peritoneum. Body Wall 5. A pair of short and conical intestinal caeca is situated at the 26th segment. Their outer ends give out minute hair-like processes which help to receive stimuli. Conservation of water 3. Haemoglobin dissolved in the plas­ma of blood acts as a respiratory pigment, transporting oxygen to the body tissues. The nervous system in a human is made of the brain, spinal cord, sensory organs and all the neurons that serve as communication channels between the various organs of the body. Similar branches of motor fibers arise near the branches of the cord and form a synapse with them, running outward and ending in muscles. The large majority of the axon bundles called nerves are considered to belong to the PNS, even when the cell bodies of the neurons to which they belong reside within the brain or spinal cord. The septa are perfo­rated by numerous sphinctered oval or circu­lar apertures, through which communication is set up between adjacent coelomic cham­bers. The wall of the stomach is highly glandular, vascular and thrown into internal folds. The opposing sets of muscles are antagonized by an increase in the pressure of the coelomic fluid. 13. It consists of nerves arising from the central nervous system. The body of earthworm is elongated, narrow and cylindrical (Fig. The nervous system is metamerically segmented. organ of ingestion of food. Phylum – Arthropoda Its mid-dorsal part comprises of a pair of small and fused supra-pharyngeal ganglia, also called cerebral ganglia or brain. The stimuli from the skin are transmitted by sensory fibres to the nerve cord and the stimulus is transferred either to an association neuron first, or it may go to the muscles (effectors) which cause them to contract. 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