Chapter4

Chapter4 - 4.1 Terminology to Describe the Nervous System...

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4.1 Terminology to Describe the Nervous System Central nervous system (CNS)- the brain and spinal cord Peripheral nervous system (PNS)- the nerves outside the brain and spinal cord o Somatic nervous system - the axons conveying messages from sense organs CNS muscles o Autonomic nervous system - controls heart, intestines, and other organs Has some of its cell bodies within the brain/spinal cord and some in clusters along the sides of the spinal cord Dorsal - towards the back o On a four-legged animal, top of the head is dorsal Ventral - towards the stomach o On a four-legged animal, the bottom of brain is ventral TABLE 4.1 The Spinal Cord Spinal cord - part of the CNS within the spinal column o Communicates with all the sense organs and muscles except for those of the head Bell-Magendie Law - the entering dorsal roots (axon bundles) carry sensory information, and then exiting ventral roots carry motor information o The axons from the skin and muscles are the PNS o dorsal root ganglia - cell bodies of sensory neurons in clusters of neurons outside the spinal cord white matter- consists mostly of myelinated axons o fat is white, therefore white matter gray matter The Autonomic Nervous System Autonomic nervous system consists of neurons that receive info from and send commands to the heart, intestine, and other organs o Has two parts: sympathetic and parasympathetic o Sympathetic Nervous System - a network of nerves that prepare the organs for vigorous activity, consists of chains of ganglia. Prepares body for “fight or flight”—increasing breathing and heart rate and decreasing digestive activity Ganglia and symp.ner.sys. are closely linked Sweat and adrenal glands, as wella s muscles that constrict blood vessels, and muscles that erect the hairs of skin have only sympathetic input o Parasympathetic Nervous System - facilitates vegetative, nonemergency responses aka craniosaral system b/c it consists of cranial nerves and form spinal cord know preganglionic (long) and postganglionic (short) axons postganglionic releases acetylcholine increases digestive and conserves energy, and decreases heart rate o Although they are opposite, both are constantly active to varying degrees, and many stimuli arouse parts of both systems The Hindbrain Hindbrain - the posterior part of the brain. Consists of: medulla, the pons, and cerebellum Brainstem - consists of medulla and pons, the midbrain, and certain structures of the forebrain
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Medulla - aka medulla oblongata- controls vital reflexes (breathing, heart rate, vomiting, salivation, coughing, and sneezing) o Just above the spinal cord and can be said to be an extension of the spinal cord but located in the skull o damage to medulla is life-threatening o Cranial nerves - control sensations from the head, muscle movements in the head, and much of the parasympathetic output to the organs—we have 12 pairs
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This note was uploaded on 10/24/2011 for the course PSB 2000 taught by Professor Glendenning during the Fall '08 term at FSU.

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Chapter4 - 4.1 Terminology to Describe the Nervous System...

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