Robaxin

By D. Lukjan. Union College. 2018.

The occipital lobe is located at the area located in front of the temporal lobe back or posterior portion of each hemi- and in the frontal cortex is called Broca’s sphere robaxin 500mg sale. It is the primary area for reception area purchase robaxin 500 mg on-line, which contributes to expressive and interpretation of visual stimuli. The thala- as expressing thoughts in a coordinated mus acts as a relay station that sorts, inter- way so that others may comprehend it. Language function is located in the left Below the thalamus is the hypothalamus, hemisphere of the cerebrum in most indi- which coordinates neural and endocrine viduals, whether they are right- or left- activities. An area located over the temporal internal environment and behaviors that 30 CHAPTER 2 CONDITIONS OF THE NERVOUS SYSTEM: PART I are important to survival, such as eating, ried by four major arteries, two carotid drinking, and reproduction. The ver- hypothalamus is the pituitary gland, an tebral arteries join to form the basilar endocrine gland that will be discussed in artery. A band of gray THE BRAIN matter called the hippocampus is involved in learning and long-term memory, help- Traumatic and Atraumatic ing to determine where important and rel- Brain Damage evant aspects of facts will be stored. The brain, like any other tissue, needs Beneath the occipital lobe of the cere- oxygen in order to function. The damage are dependent on: cerebellum also regulates and coordinates fine movements of the extremities, which • the cause of the damage have been initiated by the frontal lobe. Atraumatic (nontraumatic) brain dam- is the primary center of involuntary func- age caused by interference with oxy- tions. Control of vital organ functions gen reaching the brain (such as with such as regulation of heartbeat or respira- choking, carbon monoxide poison- tion occurs in the brain stem. Areas in the ing, or infection) or problems with- brain stem also regulate the diameter of in the brain itself (such as stroke, or blood vessels, consequently helping to structural problems within the brain control blood pressure. Reflex actions, or blood vessels in the brain) such as coughing and swallowing, are con- 2. The brain stem by an outside force that impacts the also contains scattered groups of cells, head hard enough to cause damage called the reticular formation, that are to the brain involved in the initiation and mainte- nance of wakefulness and alertness. Both atraumatic (nontraumatic) and trau- The brain requires both oxygen and matic brain damage are considered acquired nourishment in the form of glucose to brain injuries because they occur after birth function and survive. Oxygen and glucose and are not the result of genetic disorder, are transported to the brain by blood car- birth trauma, or degenerative disease. Conditions Affecting the Brain 31 Atraumatic Brain Damage bral thrombosis. Formation of the thrombus blocks blood flow to an Atraumatic brain damage, as just area of the brain. Because brain tissue explained, refers to conditions in which the needs the oxygen contained in blood brain has sustained damage due to condi- to survive, tissue that cannot obtain tions other than traumatic injury. This tissue death is called an or interference with blood and oxygen infarct. When a part pends on how large an area of the of the brain receives no oxygen (anoxia) brain has been deprived of blood sup- or too little oxygen (hypoxia), the tissue ply from the clot. Again, when the clot brain that then balloons out and can rup- occludes blood flow to a part of the ture), infections or inflammation of the brain, surrounding brain tissue dies. A third cause of stroke is hemorrhage, tions that deprive the brain of oxygen, which occurs because of rupture of a such as strangulation, near drowning, or blood vessel. When blood vessels are weakened because of dis- Stroke (Cerebral Vascular Accident) ease, such as with arteriosclerosis, or because of congenital weakness as Stroke, also known as cerebral vascular with an aneurysm, increased pressure accident, is a sudden alteration in brain may cause the blood vessel to burst. Stroke is usually the of oxygen, but also because the culmination of progressive disease that escaped blood compresses brain tis- has occurred over the course of many sue against the skull, causing further years. There are three as the result of stroke depends on: main causes of stroke: • the side of the brain affected 1. The most common cause is blocking • the specific area of the brain that has of a cerebral artery by a clot (throm- been damaged bus) that has formed inside the • the amount of damage that has artery, a condition referred to as cere- occurred 32 CHAPTER 2 CONDITIONS OF THE NERVOUS SYSTEM: PART I Often after stroke, in addition to the ini- tions. The organism recover, and function in these areas may also gains access to the cerebrospinal flu- be restored. Individuals with meningitis are usu- tions until months after the stroke as ally acutely ill, initially with fever and flu- occurred. Within a short period of At times, temporary blocking of the time they develop severe headache, neck cerebral arteries causes slight, temporary rigidity, and discomfort when exposed to neurological deficits. If the cause is bacterial in ori- are referred to as transient ischemic at- gin, prompt treatment with antibiotics tacks (TIAs). Although most individuals with meningitis recover Any infection of the brain or the mem- completely, some may have residual neu- branes that surround the brain and spinal rological deficits such as deafness, paraly- cord can cause serious neurological effects, sis, or cognitive difficulties.

During adolescence 500 mg robaxin for sale, are present in the middle-ear chamber of each ear and however cheap 500mg robaxin otc, the number of bones decreases, as separate bones grad- serve to transmit sound impulses. The hyoid bone is located above the larynx total functioning of the skeletal system. The vertebral column (“backbone”) the skull called sutural (wormian) bones. Additional bones may consists of 26 individual bones separated by cartilaginous develop in tendons in response to stress as the tendons repeat- intervertebral discs. Bones formed this way are called wormian bone: from Ole Worm, Danish physician, 1588–1654 sesamoid: Gk. Skeletal System: © The McGraw−Hill Anatomy, Sixth Edition Introduction and the Axial Companies, 2001 Skeleton Chapter 6 Skeletal System: Introduction and the Axial Skeleton 133 Parietal bone Frontal bone Temporal bone Skull Occipital Zygomatic bone bone Maxilla Mandible Clavicle Pectoral Scapula girdle Costal cartilages Sternum Rib cage Ribs Humerus Vertebral column Ulna Ilium Pelvic girdle Os Pubis Sacrum coxae Coccyx Ischium Radius Carpal bones Metacarpal bones Phalanges Femur Patella Tibia Fibula Calcaneus Tarsal bones Creek Metatarsal bones Phalanges (a) (b) FIGURE 6. Skeletal System: © The McGraw−Hill Anatomy, Sixth Edition Introduction and the Axial Companies, 2001 Skeleton 134 Unit 4 Support and Movement are fused to form the sacrum, which is the attachment por- tion of the pelvic girdle. A few terminal vertebrae are fused FUNCTIONS to form the coccyx (“tailbone”). The rib cage forms the bony and cartilaginous The bones of the skeleton perform the mechanical functions of sup- framework of the thorax. It articulates posteriorly with the port, protection, and leverage for body movement and the meta- thoracic vertebrae and includes the 12 pairs of ribs, the bolic functions of hemopoiesis and storage of fat and minerals. Objective 2 Discuss the principal functions of the skeletal system and identify the body systems served by these functions. The com- The strength of bone comes from its inorganic components, of ponents of the appendicular skeleton are as follows: such durability that they resist decomposition even after death. The paired scapulae (“shoulder blades”) mans, has been determined from preserved skeletal remains. In fact, the term skeleton comes from a Greek word meaning is the axial component. It performs many body functions, including move the brachium (arm) and antebrachium (forearm). The skeleton forms a rigid framework to which bones, and the phalanges (“finger bones”) of the hand. The two ossa coxae (“hipbones”) are the of interest that the skeleton’s 206 bones support a mass of appendicular components of the pelvic girdle, and the muscles and organs that may weigh 5 times as much as the sacrum is the axial component. The pelvic girdle supports the weight of the brain and spinal cord; the rib cage protects the heart, body through the vertebral column and protects the viscera lungs, great vessels, liver, and spleen; and the pelvic girdle within the pelvic cavity. Each lower extremity contains a where blood cells are produced are protected within the proximal femur (“thighbone”) within the thigh, a tibia spongy bone tissue of certain bones. Bones serve as anchoring attachments metatarsal bones, and the phalanges (“toe bones”) of the for most skeletal muscles. It takes place in tissue Knowledge Check called red bone marrow located internally in some bones 1. In an infant, the spleen and liver produce red which are bones of the axial skeleton and which are bones blood cells, but as the bones mature, the bone marrow of the appendicular skeleton. Describe the locations and functions of the pectoral and ond by the red bone marrow to replace those that are worn pelvic girdles. Lipid is stored in the adipose tissue within the medullary cavity of certain bones. The adipose tissue and its lipid content are known as yellow bone marrow (fig. Skeletal System: © The McGraw−Hill Anatomy, Sixth Edition Introduction and the Axial Companies, 2001 Skeleton Chapter 6 Skeletal System: Introduction and the Axial Skeleton 135 In summary, the skeletal system is not an isolated body sys- tem. It is associated with the muscle system in storing calcium needed for muscular contraction and providing attachments for muscles as they span the movable joints. The skeletal system serves the circulatory system by producing blood cells in pro- tected sites. Directly or indirectly, the skeletal system supports and protects all of the systems of the body.

The roots of teeth fit into sockets robaxin 500 mg free shipping, called den- tal alveoli 500mg robaxin with visa, in the alveolar processes of the mandible and maxil- and fasten the tooth in its dental alveolus. Each socket is lined with a connective tissue periosteum, (gum) is the mucous membrane surrounding the alveolar specifically called the periodontal membrane. Digestive System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 Chapter 18 Digestive System 645 can be tasted. Saliva also contains starch-digesting enzymes and Enamel lubricating mucus, which aids swallowing. Saliva is secreted con- tinuously, but usually only in sufficient amounts to keep the mu- cous membranes of the oral cavity moist. Dentin Numerous minor salivary glands are located in the mucous membranes of the palatal region of the oral cavity. However, Dental pulp three pairs of salivary glands that lie outside the oral cavity pro- (in pulp cavity) duce most of the saliva, which is transported to the oral cavity via salivary ducts. The three major pairs of extrinsic salivary glands Gingiva are the parotid, submandibular, and sublingual glands (fig. It is positioned below and in front of the auricle of the membrane ear, between the skin and the masseter muscle. Saliva produced in the parotid gland drains through the parotid (Stensen’s) duct. Root The parotid duct parallels the zygomatic arch across the masseter canal Dental alveolus muscle, pierces the buccinator muscle, and empties into the oral Cementum cavity opposite the second upper molar. It is the parotid gland that becomes infected and swollen with the mumps. Root The submandibular gland lies inferior to the body of the mandible, about midway along the inner side of the jaw. Each sublingual gland contains several small sublingual ducts (Rivinus’ ducts) that empty into the floor of the mouth in an area posterior to the papilla of the submandibular duct. Enamel is composed Two types of secretory cells, serous and mucous cells, are primarily of calcium phosphate and is the hardest substance in the found in all salivary glands in various proportions (fig. Serous cells produce a watery fluid containing digestive enzymes; The pulp cavity contains the pulp, which is composed of connec- mucous cells secrete a thick, stringy mucus. Cuboidal epithelial tive tissue with blood vessels, lymph vessels, and nerves. Sympathetic impulses stimulate the receives nourishment through vessels traversing the apical fora- secretion of small amounts of viscous saliva. Proper nourishment is particularly important during embry- stimulation causes the secretion of large volumes of watery saliva. The diet of the mother should contain an Physiological responses of this type occur whenever a person abundance of calcium and vitamin D during pregnancy to ensure sees, smells, tastes, or even thinks about desirable food. Refluxed stomach acids also destroy tooth enamel and con- Pharynx stant vomiting, as in the eating disorder bulimia nervosa, contributes to the development of dental caries. The rate of tooth decay decreases after age 35, but then ing the oral and nasal cavities to the esophagus and larynx. Periodontal diseases result from plaque or tartar buildup at the gum line. This buildup pulls the pharynx has both digestive and respiratory functions. The sup- gum away from the teeth, allowing bacterial infections to develop. Saliva functions as a solvent in Wharton’s duct: from Thomas Wharton, English physician, 1614–73 cleansing the teeth and dissolving food molecules so that they Rivinus’ ducts: from August Quirinus Rivinus, German anatomist, 1652–1723 Van De Graaff: Human VI. Digestive System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 646 Unit 6 Maintenance of the Body Accessory salivary gland Tongue Accessory salivary gland Lingual frenulum Parotid gland Opening of submandibular duct Sublingual ducts Parotid duct Masseter muscle Sublingual gland Submandibular Submandibular gland duct Mandible (cut) FIGURE 18. Mucous cells Intralobular parotid duct Lumen of Seromucous submandibular acini intralobular duct Serous cells (a) (b) Mucous cells Serous cells Intralobular (c) sublingual duct FIGURE 18. Digestive System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 Chapter 18 Digestive System 647 TABLE 18. The right side has been cut away to illustrate the interior structures in the pharynx.

This impression is borne out to the extent that CNS stimulants robaxin 500 mg online, like amphetamine purchase 500 mg robaxin free shipping, increase release of noradrenaline and produce behavioural and EEG arousal, while reserpine, which reduces noradrena- line storage and hence release, causes psychomotor retardation. It is also supported by SLEEP AND WAKING 489 evidence that the firing rate of neurons projecting from the locus coeruleus is greater during waking (1±2 Hz) than during SWS (0. Furthermore, stimulation of the locus coeruleus in cats causes EEG desynchronisation and increases arousal, while a neurotoxic lesion of these neurons leads to EEG synchrony, increases SWS and reduces REM sleep. Because a reduction in the activity of noradrenergic neurons precedes the onset of sleep, this change in activity is thought to have a permissive role in sleep induction. How all these actions of noradrenaline are manifest is not clear and, unfortunately, most experiments in this area have been carried out on anaesthetised animals which, arguably, are not ideal for investigating mechanisms underlying arousal! One of the few investigations to have been carried out in unanaesthetised rats has shown that infusions of noradrenaline into the nucleus basalis of the medial septum increases waking (and the g-wave activity of the waking phase), but reduces the g-waves of SWS. These changes, which are thought to be mediated by activation of b-adrenoceptors, suggest that noradrenaline increases cholinergic influences on arousal, in the nucleus basalis, at least (Cape and Jones 1998). However, a fairly common side-effect of b-adrenoceptor antagonists, used clinically to relieve hypertension, is sleep disturbance which is expressed as nightmares, insomnia and increased waking. Clearly, these drugs must have additional actions either in other brain centres, or non-selective effects on other (possibly 5-HT1A) receptors that have quite different effects on arousal. It has even been suggested that b-blockers disrupt sleep patterns by inhibiting melatonin synthesis and release, but this is controversial. In contrast, a2-adrenoceptor agonists are well-known for their sedative effects. Since their activation of presynaptic a2-autoreceptors will reduce noradrenergic transmission, by depressing the firing of neurons in the locus coeruleus and release of noradrenaline from their terminals, this action is entirely consistent with the proposal that increased noradrenergic transmission increases arousal. Although this presynaptic action of a2-agonists would explain their sedative effects it must be borne in mind that many a2-adrenoceptors in the brain are in fact postsynaptic. Their role (if any) in sedation is unclear but it must be inferred that, if they make any contribution to sedation, then either a specific brain region or a specific a2-adrenoceptor subtype is involved. Another possible confounding factor is that many a2-adrenoceptor ligands have an imidazoline structure (see Chapter 8) and the recently discovered imidazoline receptors are also thought to influence the sleep cycle and arousal. Even less is known about the role of a1-adrenoceptors on arousal partly because most drugs acting at these receptors do not readily cross the blood±brain barrier. The role of noradrenergic neurons from the locus coeruleus on behaviour during the waking phase is rather controversial. It is doubtful that noradrenaline release is actually required for waking because animals with more than a 90% lesion of these neurons are still capable of staying awake, although they are rather subdued. Nevertheless, the single-unit activity of these neurons is increased by sensory stimuli ranging from those that cause physical discomfort (e. The evoked neuronal response typically shows a brief (phasic) burst of activity followed by a quiescent period of post-stimulus inhibition but this response, along with behavioural arousal, habituates on successive presentation of the stimulus. In fact, these neurons could serve all these purposes, thereby helping to protect the individual from threatening stimuli as well as directing attention to interesting, or salient environmental features (see also Chapter 8). Few studies have investigated the role in behaviour of noradrenergic neurons originating in the nuclei of the lateral tegmental area (see Chapter 8). However, what little evidence there is suggests that they respond primarily to unconditioned environ- mental stimuli but are capable of adaptive changes in their activity on repeated presentation of the stimulus. Because noradrenergic neurons arising in the lateral tegmental nuclei have numerous reciprocal connections with other brainstem nuclei involved in homeostasis (e. DOPAMINE The role of this neurotransmitter in the sleep±waking cycle has not received as much attention as that devoted to noradrenaline and interpretation of existing evidence is not straightforward. On the one hand, the firing rate of neurons projecting from the dopaminergic neurons in the ventral tegmental area does not vary across the sleep±waking cycle and, in any case, the dopaminergic innervation of the cortex is much more restricted than that of noradrenaline or 5-HT. On the other hand, drugs that modify dopaminergic transmission do affect arousal albeit in complex ways (see Gottesmann 1999). This action is thought to be due to activation of presynaptic D2-autoreceptors and some antagonists of this receptor increase waking state and reduce both non-REM and REM sleep. That a reduction in firing of dopaminergic neurons is associated with reduced arousal is consistent with evidence that local infusion of GABA into the dopaminergic ventral tegmental area also reduces waking. However, others have suggested that activation of postsynaptic D2-receptors in the dorsal striatum is responsible. By contrast, high doses of dopamine agonists increase arousal and cortical desyn- chronisation, possibly by activating postsynaptic D2-receptors.