NERVOUS SYSTEM & SENSE ORGANS. Mrs. Ofelia Solano Saludar Department of Natural Sciences University of St. La Salle Bacolod City.
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Mrs. Ofelia Solano Saludar
Department of Natural Sciences University of St. La Salle Bacolod City
ORIGIN: ectoderm gives rise to the nervous system and nervous parts of sense organs
Billions of neurons, each of which establishes thousands of contacts with other nerve cells
Neurogliacells that support, nourish, & insulate neurons
Sensory receptors- integrates & stores information as memory
Motor receptors- response effectors
Parkinson’s Disease in humans is known to be caused by a decrease in dopamine (neurotransmitter) in the brain. Why not just inject patients with IV dopamine?
Ependymal cells – line the neurocoel and provide nutrients
Oligodendroglia – produce myelin in CNS which is white and speeds up nerve impulse transmission
Astrocytes – maintain blood brain barrier
Mesencephalon(midbrain)- forms the tectum which includes the optic lobes (receive fibers from retina) & auditory lobes (receive fibers from inner ear)
Epithalamus- dorsal part of diencephalon; gives rise to the pineal body (epiphyses) which functions as:
VENTRICLES- cavities containing cerebrospinal fluid (CSF) providing cushion, protection, nutrients
Optic nerve (II) - sensory ‘nerve’; sense of vision; a tract of the brain & not a true nerve
Trigeminal (V) - mixed nerve; sensory from skin of head & mouth (including teeth) & motor to muscles of 1st pharyngeal arch (muscles of jaw)
Facial (VII) - mixed nerve; sensory from lateral line of head, ampullae of Lorenzini, & taste buds; motor to muscles of hyoid arch
Auditory, acoustic or vestibulocochlear (VIII) - sensory from inner ear (balance & hearing)
Glossopharyngeal (IX) - mixed nerve; sensory from taste buds & lateral line; motor to muscles of 3rd arch
Vagus (X) - mixed nerve; sensory from & motor to heart, anterior digestive system, mouth, gill pouches 2 - 5, & lateral line
Accessory nerve (XI) - motor to derivatives of cucullaris muscle (cleidomastoid, sternomastoid, & trapezius); amniotes only
“Oh, Once One Takes The Anatomy Finals, AGood Vacation Appears Heavenly.”
Length varies among vertebrates:
Primitively, the dorsal & ventral roots remain separate, but in gnathostomes, they unite to form a spinal nerve
The ventral rami are united by cross-connections to form plexi from which the nerves to the appendicular muscles arise: Brachial plexus (anterior appendages), & the lumbosacral plexus (posterior appendages)
INNER EAR-invagination from the ectoderm
1-Inner hair cell, 2-Outer hair cells, 3-Tunnel of Corti, 4-Basilar membrane, 5-Reticular lamina, 6-Tectorial membrane, 7-Deiters' cells, 8-Space of Nuel, 9-Hensen's cells, & 10-Inner spiral sulcus
Beginning with amphibians, the MIDDLE EAR is added to inner ear, consisting of a chamber developed from the 1st gill pouch.
NEUROMAST ORGANS- receptors in skin of fishes & aquatic amphibians that detect water currents & ‘hear’ sounds