By G. Uruk. Tulane University. 2018.
This online resource offers an extensive array of learning tools that are tailored to coincide with each chapter of the text discount levitra plus 400 mg overnight delivery. Learning Activities Among the activities awaiting you at the OLC are chapter quizzes best 400mg levitra plus, crossword puzzles, art labeling exercises, vocabulary flashcards, and animation-based activities. In addition, the OLC offers numerous case studies and clinical applications, cutting-edge online reference materials, and links to related anatomy and physiology Internet sites. Essential Study Partner This interactive study tool contains hundreds of animations and learning activities designed to help you grasp complex concepts. Interactive diagrams and quizzes make learning anatomy and physiology stimulating and fun. You can dissect the body layer by layer, or use a scroll bar to navigate up to a depth of 330 layers. You can also highlight a specific structure for an in-depth study or search by anatomical term to locate all instances of a structure. Other features include an alphabetized glossary and labeled structures for easy identification. Keep abreast of breaking news by clicking the latest scientific headlines from The New York Times or links to prominent journals in the Briefing Room. Visit the Student Center to ask a question on the discussion boards, brush up on test-taking tips, or perform job and internship searches. Conduct a virtual laboratory experiment at BioLabs, or head to The Quad to browse the vast array of rich, multimedia content specific to your course. History of Anatomy © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 History of Anatomy 1 Definition of the Science 2 Prescientific Period 2 Scientific Period 4 Clinical Case Study Answer 20 Chapter Summary 20 Review Activities 21 Clinical Case Study A 55-year-old women visits the village apothecary for her increasing shortness of breath. The physician, learning of the woman’s symptoms and finding swelling in her legs, makes the diagno- sis of dropsy and prescribes a course of therapy meant to rid the body of evil humors. He applies a dozen of his healthiest leeches to the woman’s legs and drains a pint of her blood by opening a vein in her arm. The ex- perience reinforces to the doctor the concept of evil humors and the effectiveness of bloodletting as a therapy. Current therapy for this condition is oral fluid restriction and medications that in- duce diuresis (increased urination) with the ultimate goal of decreasing fluid volume. It is no wonder that losing a pint of blood made this woman feel better in the short term. Unfortu- nately, repeated courses of this crude therapy left patients profoundly anemic (low red blood cell count) and actually worsened their heart failure. Throughout medical history, how has an accurate understanding of human anatomy and physiology led to better disease therapy? FIGURE: Blood letting was a technique of medical practice widely used for over two thousand years. History of Anatomy © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 2 Unit 1 Historical Perspective the structure of the body often has been stimulated by the desire DEFINITION OF THE SCIENCE of the medical profession to explain a body dysfunction. Various The science of human anatomy is concerned with the structural religions, on the other hand, have at one time or another stifled organization of the human body. The descriptive anatomical termi- the study of human anatomy through their restrictions on human nology is principally of Greek and Latin derivation. Over the centuries, peoples’ innate interest in their own bodies and physical capabilities has found various forms of ex- Objective 2 Distinguish between anatomy, physiology, and pression.
An atypical neuroleptic with intrinsic antimuscarinic activity reduces this possibility by counteracting the excitatory effects of released ACh as well as the inhibitory effects of DA (c) purchase 400mg levitra plus with visa. Thus the control of striatal neurons remains balanced than D2 receptors and remoxidpride (atypical) more active at D2 than 5-HT2A generic 400mg levitra plus. Also differences in the values for the dissociation constants between experimental studies (see later) make comparisons between D2 and 5-HT2A potency somewhat difficult. No neuroleptic has purely 5-HT2A antagonist activity and a pure 5-HT2A antagonist drug may not have neuroleptic activity. Risperidone, an atypical neuroleptic with some benefit against negative symptoms, is the most potent of all neuroleptics at 5-HT2A receptors (K1: 0. Some in vitro measurements show it to have up to 25 times more affinity for 5-HT2A than D2receptors and PET studies indicate that at therapeutic doses it displaces a 5-HT2 ligand in preference to a D2 one. Clozapine is also claimed to occupy over 80% of 5-HT2 and less than half this number of D2 receptors at clinical doses. Neuroleptics with 5-HT2 antagonist activity not only produce fewer EPSs but 5-HT2 antagonists reduce neuroleptic-induced EPSs. Fibres from 5-HT neurons in the raphe nucleus innervate and yet, despite the observed 5-HT2A receptor link with neuronal excitation, appear to inhibit DA neurons in the SN (A9). Thus antagonism of 5-HT released onto them would increase their firing and so reduce the likelihood of EPSs, although how 5-HT2A antagonists can SCHIZOPHRENIA 367 overcome the established motor side-effects of another neuroleptic is less clear if that compound has already caused a depolarising block of the neurons. The mechanism by which 5-HT2 antagonism could ameliorate schizophrenic symptoms and what effect 5-HT has on mesolimbic and mesocortical pathways through A10 neurons is even less certain. The probability that neuroleptics benefit from a particular balance of DA and 5-HT2A antagonism is developed later. The 5-HT3 receptor is found appropriately in mesocortical areas and while behavioural studies with their antagonists in rodents showed potential antipsychotic activity, they have proved ineffective in patients. They have been found to increase the extracellular concentration of DA in the frontal cortex of rats but diminish apomorphine-induced stereotypy (striatal effect). So they could be of some benefit, especially against negative symptoms, without causing EPSPs (see Chapter 9). Some, like chlorpromazine, block a1 postsynaptic receptors while clozapine (and risperidone) are as potent at a2 as D2 receptors. There is no evidence that either of these actions could influence striatal or mesolimbic function but NA is considered important for function of the prefrontal cortex and any increase in its release, achieved by blocking a2-mediated autoinhibition, might contribute to a reduction in negative symptoms and provide a further plus for clozapine (see Nutt et al. Centrally, however, most a2-receptors are found post- synaptically and their function, and the effect of blocking them, is uncertain. Glutamate Although there is no evidence that any of the neuroleptics have any significant effect on glutamate receptors, it will be of no surprise to learn that clozapine, but not pure D2 or 5-HT2 antagonists nor any typical neuroleptic, can overcome phencyclidine disruption of PPI in animals. Interestingly, the efficacy of clozapine (but not risperidone or olanzopine) is increased by the antiepileptic drug lamotrigine that has inhibition of glutamate release as one of its actions (see Chapter 16). Also glycine (and serine) have been shown to improve the negative symptoms by what is assumed (but not proven) to be a potentiation of NMDA receptor activity, but they can make positive symptoms worse. Profile of NT antagonism in neuroleptic action In deciphering the role of the different NTs, or more precisely their antagonists, in the antischizophrenic action of neuroleptic drugs it must be remembered that published binding data and calculated dissociation constants vary considerably, which, of course, affects correlation coefficients made with clinical activity. Factors to bear in mind are: (1) In vitro binding studies use different cell lines or membrane preparations and generally only yield the apparent dissociation constants for a number of antagonists obtained by comparative displacement of one labelled ligand. Unfortunately few 368 NEUROTRANSMITTERS, DRUGS AND BRAIN FUNCTION such ligands are specific for the receptor being analysed, i.
The Functional tern controlled by enteric neural cir- gastrointestinal motility discount levitra plus 400 mg with visa. Func- VA: Degnon Associates purchase 400 mg levitra plus free shipping, troenterology—From the basics to the tional Disorders of the Gut: A Hand- 2000;31–90. CHAPTER Gastrointestinal Secretion, Digestion, and Absorption 2727 Patrick Tso, Ph. CHAPTER OUTLINEGASTROINTESTINAL SECRETIONDIGESTION AND ABSORPTION OFSALIVARY SECRETION CARBOHYDRATESGASTRIC SECRETIONDIGESTION AND ABSORPTION OF LIPIDSPANCREATIC SECRETIONDIGESTION AND ABSORPTION OF PROTEINSBILIARY SECRETIONABSORPTION OF VITAMINSINTESTINAL SECRETIONELECTROLYTE AND MINERAL ABSORPTIONDIGESTION AND ABSORPTIONABSORPTION OF WATER KEY CONCEPTS 1. Pancreatic secretion neutralizes the acids in chyme and sorption of nutrients. Saliva assists in the swallowing of food, carbohydrate di- drates, fat, and protein. Secretin stimulates the pancreas to secrete a bicarbonate- bat pathogens. Pancreatic secretion is under neural and hormonal control nerves innervate the blood supply to the salivary glands. Bile salts play an important role in the intestinal absorption only increases saliva flow marginally. Carbohydrates, when digested, form maltose, maltotriose, food in the small intestine. The gastric mucosa contains surface mucous cells that se- zymes to monosaccharides and taken up by enterocytes. Lipids absorbed by enterocytes are packaged and secreted ach from the acid in the stomach cavity. Protein is digested to form amino acids, dipeptides, and and chief cells secrete pepsinogen. Gastrin plays an important role in stimulating gastric acid ported in the blood. The acidity of gastric juice provides a barrier to microbial different mechanisms. Heme and nonheme iron is absorbed in the small intestine consists of three phases: cephalic, gastric, and intestinal. Most of the salt and water entering the intestinal tract, docrine cells, is a potent inhibitor of gastric acid secretion whether in the diet or in GI secretions, is absorbed in the and enhances insulin release. Some absorption occurs in the stomach, including that of medium-chain fatty acids and some drugs, but most digestion and absorption of nutrients takes place in the small intestine. Secretions from the sali- vary glands, stomach, pancreas, and liver aid in the diges- tion and absorption process and protect the GI mucosa from the harmful effects of noxious agents. This chapter discusses the relevant anatomy, mechanism, composition, and regulation of GI secretion and the role the GI tract plays in the absorption of carbohydrate, fat, protein, fat- soluble and water-soluble vitamins, electrolytes, bile salts, and water. GASTROINTESTINAL SECRETION Secretions of the GI tract share several common features. Secretions often empty into small ducts, which in turn empty into larger ducts, which empty into the lumen of the GI tract. Such a ductal system serves as a conduit for secretions from the salivary glands, pancreas, FIGURE 27. Physiology testinal cells, is involved in the formation of GI secretions. The acinus is a blind sac containing Salivary secretion is unique in that it is regulated almost ex- mainly pyramidal cells. Saliva is produced by a shaped myoepithelial cells surrounding the large pyramidal heterogeneous group of exocrine glands called the salivary cells.
Female sex hormones when dissolved in water buy levitra plus 400 mg low cost, forming a solution capable of conduct- promote the retention of fats order levitra plus 400 mg fast delivery, which are an important food re- ing electricity. An electrolyte is classified according to the ions it source for nursing a child. The three classes of electrolytes than lipids, there is a disparity between the percent of body fluids are acids, bases, and salts, all of which are important for normal between males and females. The functions of ions include the control of water movement through cells and the maintenance of normal acid-base (pH) balance. Ions are also essential for nerve and Water muscle function, and some ions serve as cofactors that are needed for optimal activity of enzymes. Symptoms of electrolyte Water is by far the most abundant compound found within cells imbalances range from muscle cramps and brittle bones to coma and in the extracellular environment. The three kinds of electrolytes are summa- within the body as a homogeneous mixture of two or more com- rized in table 3. In this condition, the water is the sol- vent, or the liquid portion of the solution, and the solutes are substances dissolved in the solution. Water is an almost universal Proteins solvent, meaning that almost all chemical compounds dissolve in it. In addition, it is also used to transport many solutes through Proteins are nitrogen-containing organic compounds composed the cell membrane of a cell or from one part of the cell to an- of amino acid subunits. Water is also important in maintaining a constant cellular that contains an amino group (—NH2) and a carboxyl group temperature, and thus a constant body temperature, because it (—COOH). There are 20 different types of amino acids that can absorbs and releases heat slowly. Another function of water protein to be constructed to function in very specific ways. They may exist by themselves or be conjugated (joined) with other compounds; for example, with nucleic acids (RNA or Dehydration is a condition in which fluid loss exceeds fluid in- DNA) to form nucleoproteins, with carbohydrates to form glyco- take, with a resultant decrease in the volume of intracellular and extracellular fluids. Rapid dehydration through vomiting, diar- proteins, or with lipids to form lipoproteins. Infants are especially vulnerable because body as structural or functional. They can die from dehydration resulting significantly to the structure of different tissues. Cytology © The McGraw−Hill Anatomy, Sixth Edition of the Body Companies, 2001 52 Unit 3 Microscopic Structure of the Body TABLE 3. Functional proteins assume a more active role in the Lipids, like carbohydrates, are composed of carbon, hydro- body, exerting some form of control of metabolism. Lipids, however, contain a smaller proportion clude enzymes and antibodies. Cellular growth, repair, and division depend stances within cells are summarized in table 3. Proteins, under certain conditions, may even be metabolized to supply cellular energy. List the four most abundant elements in the body and state Carbohydrates their relative percentages of body weight.