Study Guide for PSB2000 Exam 2 Chapter 4 Study Hints It is always advisable to know the key terms introduced in each section The study hints listed here by chapter should help you focus on other important concepts for the exam Understand the breakdown of Central CNS vs Peripheral Nervous System PNS and the sub areas for PNS including the somatic nervous system motor for voluntary muscles and sensory and the autonomic nervous system controls involuntary muscles such as the heart intestines and other organs The autonomic nervous system breaks down further into the sympathetic fight or flight and parasympathetic vegetative systems Figure 4 1 is good for reviewing this material Central Nervous System brain and spinal cord Spinal cord communicates with all the sense organs and muscles except those of the head Peripheral Nervous System the nerves outside of the brain and spinal cord o o Somatic Nervous System the axons conveying messages from the sense organs to the CNS and from the CNS to the muscles o Autonomic Nervous System controls the heart the intestines an other organs Over the counter cold remedies exert most of their effects by blocking parasympathetic activity or increasing sympathetic activity The flow of sinus fluids is a parasympathetic response drugs that block the parasympathetic system inhibit sinus flow o The side effects of cold remedies stem from their sympathetic anti parasympathetic activities they inhibit salivation and digestion and increase heart rate Sympathetic expends energy prepares organs for vigorous activity consists of chains of ganglia just to the left and right of the spinal cord s central regions thoracic lumbar These ganglia are connected by axons to the spinal cord Increases heart rate breathing and decreases digestive activity Most of the postganglionic synapses use norepinephrine although a few including those that control the sweat glands use acetylcholine Parasympathetic conserves energy facilitates vegetative nonemergency responses Increases digestive activity Also known as craniosacral system because it consists the cranial nerves an nerves from the sacral spinal cord Unlike the sympathetic the parasympathetic ganglia are not arranged in a chain near the spinal cord o Long preganglionic axons extend from the spinal cord to parasympathetic ganglia close to each internal organ shorter postganglionic fibers then extend from the parasympathetic ganglia into the organs themselves o Parasympathetic ganglia act more independently than sympathetic because they are not linked together o Parasympathetic postganglionic axons release acetylcholine Dorsal toward back Ventral toward the stomach What is the difference between grey and white matter in the spinal cord Where are each found and why The H shaped gray matter in the center of the cord is densely packed with cell bodies and dendrites Many neurons of the spinal cord send axons from the gray matter to the brain or other parts of the spinal cord through the white matter which consists mostly of myelinated axons Each segment of the spinal cord sends sensory information to the brain and receives motor commands from the brain All the information passes through tracts of the axons in the spinal cord What is the Bell Magendie law Need to understand dorsal ventral orientation for this Pay particular attention to the following image which might appear on the exam Figure 4 3 Bell Magendie Law one of the first discoveries about the functions of the nervous system the entering dorsal roots axon bundles carry sensory information and the exiting ventral roots carry motor information The axons to and from the skin and muscles are the peripheral nervous system The cell bodies of the sensory neurons are in clusters of neurons outside of the spinal cord called the dorsal root ganglia o Ganglion cluster of neurons Outside of the CNS ganglion Inside of the CNS neuron Cell bodies of the motor neurons are inside the spinal cord Figure 4 3 the dorsal root on each side conveys sensory information to the spinal cord the ventral root conveys motor commands to the mucles What do our cranial nerves do for us in general To help out some I won t require you to be able to identify I XII on an diagram but you should be able to answer general questions about the names of the cranial nerves and whether they are for sensory or motor or both The major functions of each are in Table 4 4 or you can use the table with the mnemonics I provided in my PPT 1 Olfactory 2 Optic 3 Oculomotor 4 Trochlear 5 Trigeminal 6 Abducens 7 Facial 8 Vestibulocochlear 9 Glossopharyngeal 10 Vagus 11 Spinal Accessory 12 Hypoglossal Oh Oh Oh To Touch And Feel Very Good Vegas Slot Machines Some Say Marry Money But My Brother Says Bad Boys Marry Money Each cranial nerve originates in a nucleus that integrates the sensory information regulates the motor output or both Know the 3 main areas of the hindbrain medulla pons and the little brain cerebellum What are the main functions of the cerebellum The hindbrain contains the reticular formation and the raphe system Know the importance of these Hindbrain the posterior part of the brain consists of the medulla the pons and the cerebellum The medulla and pons the midbrain and certain central structures of the forebrain constitute the Medulla is just above the spinal cord and could be regarded as an enlarged extension of the spinal brainstem cord but located in the skull o Controls some vital reflexes including breathing heart rate vomiting salivation coughing sneezing through the cranial nerves which controls sensations from the head muscle movements in the head and much of the parasympathetic output to the organs o Damage to the medulla is frequently fatal and large doses of opiates are life threatening because they suppress activity of the medulla o Cranial nerve nuclei for nerves 5 12 are in the medulla and the pons Pons lies anterior and ventral to the medulla like the medulla it contains nuclei for several cranial nerves Term Latin for bridge many axons in the pons cross from one side of the brain to the other This is in fact the location where axons from each half of the brain cross to the opposite side of the spinal cord so that the left hemisphere controls the muscles of the right side of the body and the right hemisphere controls the left side Reticular formation has descending and ascending portions o Descending portion is one of several brain areas that control the motor areas of the spinal cord o
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