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Comparative Anatomy - Nervous System


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Comparative Anatomy - Nervous System

  1. 1. Nervous System
  2. 2. Composition and Functions: Divided into two parts (CNS and PNS) Responsible to perform: 1. receives stimuli from receptors 2. transmits information to effectors that respond to stimulation. 3. Regulates behavior by integrating incoming sensory information with stored information. 4. translating that into action by way of effectors. • Includes billions of nerve cells (NEURONS)
  3. 3. Neurons Neuron is the living nerve cell. It performs the specific function of the system. In this instance, is to transmit nerve impulses.
  4. 4. Neuron contains the following: CELL BODY - where nucleus and other organelles are located. PROTOPLASMIC PROCESS • Dendrite - conduct nerve impulses toward the cell body. • Axon - conducts nerve impulses away from the cell body. It is covered by tightly packed Schwann cells containing myelin as insulator
  5. 5. Type as to Number of Protoplasmic Process:
  6. 6. Types as to Functions 1. SENSORY NEURON - transmit impulses from sensory receptors of the sense organ to nerve center (CNS). 2. MOTOR NEURON - transmit impulses form the nerve center to the effectors (muscles or glands) 3. ADJUSTOR OR ASSOCIATIVE NEURON - connects sensory and motor neurons; located in nerve center, also called interneuron
  7. 7. Neuroglia • Composed of actively dividing cells supporting the neurons of the nervous tissue. There are several types of neuroglia based on function: 1. ASTROCYTES - connect neurons and capillaries. 2. MICROGLIA - dispose dead cells, bacteria, etc. 3. EPENDYMAL - line the fluid- filled cavities of CNS for protection. 4. OLIGODENDROCYTES - form the myelin sheath around the fibers. 5. SCHWANN CELLS and SATELLITE CELLS
  8. 8. Peripheral Nervous System Spinal Nerves • Dorsal & Ventral nerves arises from spinal cord • Dorsal roots has GANGLIONS • Dorsal & ventral roots connect spinal nerves to spinal cord • Spinal nerves through ramus communicanus  branches of spinal nerves 1. Dorsal ramus - supplies epaxial muscles and skin, dorsal part 2. Ventral ramus - supplies hypaxial muscles and skin, ventral part
  9. 9. Functional types of neurons in Spinal Nerves • Somatic afferent - sensory from general cutaneous receptors and proprioreceptors • Somatic efferent - motor to skeletal muscles • Visceral afferent - sensory from receptors in the viscera • Visceral efferent - motor to smooth, cardiac muscles and glands
  10. 10. Cranial Nerves Cranial nerves are classified in one of three general categories: 1) In series with dorsal roots of spinal nerves join the brainstem at a lateral (not ventral) level include mixed nerves - sensory and motor neurons includes nerves 0, V, VII, IX, X, XI 2) In series with ventral spinal nerves join the brainstem at the ventral level contain somatic motor fibers, and supply branchiometric muscles, (branchiometric nerves) includes nerves III, IV, VI, XII 3) No counterpart in spinal series because its nerves serve structures that are peculiar to the head (nose, eye, ear, lateral line system)sensory fibers includes nerves I, II, VII, VIII, IX Cranial Nerves • Terminal nerve: part of chemosensory system, such as for responding to olfactory pheromones. Absent in cyclostomes, birds, and humans. • Olfactory: runs from the olfactory epithelium to the olfactory bulb of the brain. • Optic: runs from the eye to the brain. Ganglion cells in the retina may cross over under the brain at the optic chiasma. • Oculomotor: supplies external ocular muscles (dorsal rectus, medial rectus, ventral rectus, ventral oblique). Has ciliary branch that passes to muscles of the iris and ciliary muscles.
  11. 11. Cranial Nerves (cont) • Facial:Serves muscles responsible for facial expression. • Statoacoustic or vestibulocochlear or auditory: serves the inner ear. The anterior branch serves the organ of equilibrium, while the posterior branch is responsible for equilibrium and hearing.I • Glossopharyngeal: associated with pharynx, taste buds and salivary gland. • Vagus: contains four branches that supply the branchiometric muscles of the 4 - 7 visceral arches (or their derivatives) • Accessory - spinal accessory nerves • Hypoglossal: serves hypobranchial muscles of the throat and tongue • Trochlear: supplies the dorsal oblique muscle of the eye. • Trigeminal: has three branches: opthalmic (serves the head region), maxillary (serves the upper jaw) and mandibular (serves the lower jaw). Where the branches intersect and cell bodies are found is called the semilunar ganglion. • Abducens: supplies the lateral oblique muscle of the eye.
  12. 12. Central Nervous System
  13. 13. Spinal Cord differentiation:
  14. 14. Development Structure and Evolution • Located in vertebral canal, anatomical beginning is the foramen magnum of the skull. • Length varies.  WITH TAIL - it extends to the caudal end of the vertebral column.  WITHOUT TAIL - it extens to about the lumbar region of the vertebral column. • Cross-section  Gray matter - nerve cell bodies.  White matter - nerve cell processes.
  15. 15. Brain Development
  16. 16. Forms and Function
  17. 17. Accessory Structures • Meninges - membranes which surround the brain and spinal cord.  Pia mater - innermost membrane  Arachnoid mater – Middle membrane  Dura mater - Outermost layer • Cerebrospinal Fluid - Is secreted by the choroid plexi. It protects the brain and cushions it from the skull. • Blood-brain barrier - Two epithelia which controls the flow of solutes from blood to brain. Prezi : bhgj/edit/#29_73668633
  18. 18. Members: Cabading, Brian Banta, Dyan Alyssa Hernaez, Chloe Idioma, Jusmine