Test_ Portage Learning_ A&P 2 Module 1 _ Quizlet.

1. bring about a reaction to a stimulus. Muscle fibers are effectors in the somatic nervous system. 2. motor functions 3. composed of myelinated and un-myelinated nerve fibers. 4. To help an organism avoid injury, a reflex arc provides an immediate withdrawal from dangerous stimuli. The advantage of the reflex arc is production of a response by way of the spinal cord without the need to wait for processing by the brain. 5. contains millions of bipolar neuron receptor cells whose dendrite extends from the cell body to the surface of the epithelium where it terminates in a bulb from which arise many cilia called olfactory hairs. The olfactory hairs extend into a thin layer of mucus covering the surface of the epithelium in which airborne chemical substances dissolve in order to be detected. Several unmyelinated axons of olfactory neurons collect to form olfactory nerve fiber bundles which pass through the ethmoid bone in the roof of the nasal cavity and synapse with the olfactory nerve tract in the olfactory bulb. Why is smell classified as one of the chemical senses? What is an effector and what structures serve as effectors within the somatic nervous system? What is the function of the spinal cord and how does it accomplish this? What is the most important nerve of the cervical plexus and what structure does it supply? What does the frontal lobe control? What is the function of the temporal lobe? List the three major parts of the brain stem. What is the function of the pineal body? the auricle, the external acoustic canal (meatus) and the tympanic membrane (eardrum). The auricle directs sound waves into the external acoustic canal so that they can be detected. The external acoustic canal is the tunnel between the auricle and the eardrum which is lined with skin containing hairs and glands that secrete earwax which traps foreign materials. The inner end of the acoustic canal terminates at the tympanic membrane, a thin membrane of connective tissue whose vibration transmits sound energy to the middle ear. 7. its receptors are activated by airborne chemical substances dissolved in fluid on the nasal mucous membranes. 8. The central nervous system can send signals or impulses to and receive impulses from the peripheral nervous system. 9. Light passes into eye moving progressively through the cornea, aqueous humor, lens and vitreous humor to the surface of the retina which sends a signal through the optic nerve. 10. (1) sound waves passing into the external auditory canal and (2) causing the ear drum to vibrate which (3) transmits the vibrations to the ossicles which (4) push against fluid in the cochlear duct which (5) causes the hairs in the organ of Corti to move which (6) stimulates nearby neurons to (7) send impulses through the cochlear nerve to the brain.