By Y. Candela. Mercyhurst College. 2018.
An abnormally low cardiac output lowers Vgas DL (P1 P2) the pulmonary capillary blood volume buy super levitra 80 mg mastercard, which decreases the alveolar capillary surface area and will cheap super levitra 80mg visa, in turn, decrease the diffusing capacity in otherwise normal lungs. GAS TRANSPORT BY THE BLOOD • Vgas The transport of O and CO by the blood, often referred DL 2 2 (P1 P2) to as gas transport, is an important step in the overall gas exchange process and is one of the important functions of FIGURE 21. These properties are combined into one term, lung diffusing capacity Oxygen Is Transported in Two Forms (DL), which can be measured in a human subject. DL is equal to the volume of gas transferred/min (gas) divided by the mean par- Oxygen is transported to the tissues in two forms: com- tial pressure gradient for the gas. Approximately 98% of the oxygen blood and oxygen capacity is 20 mL O2/dL blood, then the is carried by hemoglobin and the remaining 2% is carried blood is 80% saturated. The relation- ship between PO2, oxygen saturation, and oxygen content Dissolved O2 (mL/dL) is illustrated by the oxyhemoglobin equilibrium curve,an 0. The shape of the oxyhemoglobin equilibrium curve re- Binding Affinity of Hemoglobin for Oxygen. The globin molecule consists of four oxygen-binding heme sites plateau region of the curve is the loading phase, in which and a globular protein chain. When hemoglobin binds with oxygen is loaded onto hemoglobin to form oxyhemoglobin oxygen, it is called oxyhemoglobin (HbO2). The plateau region illustrates globin that does not bind with O2 is called deoxyhemoglo- how oxygen saturation and content remain fairly constant bin (Hb). Oxygen binds rapidly and reversibly to hemo- PAO were to rise from 100 to 120 mm Hg, hemoglobin 2 globin: O2 Hb HbO2. The amount of oxyhemoglo- would become only slightly more saturated (97 to 98%). In the pulmonary capillaries, where PO2 is high, the bly by hyperventilation. The steep unloading phase of the reaction is shifted to the right to form oxyhemoglobin. In curve allows large quantities of oxygen to be released or un- tissue capillaries, where PO2 is low, the reaction is shifted to loaded from hemoglobin in the tissue capillaries where a the left; oxygen is unloaded from hemoglobin and becomes lower capillary PO prevails. The maximum amount of oxygen that equilibrium curve enables oxygen to saturate hemoglobin can be carried by hemoglobin is called the oxygen carrying under high partial pressures in the lungs and to give up capacity—about 20 mL O2/dL blood in a healthy young large amounts of oxygen with small changes in PO at the 2 adult. The P —the PO at which 50% 50 2 bound to hemoglobin (whereas capacity is the amount that of the hemoglobin is saturated—provides a functional way can potentially be bound). The percentage saturation of to assess the binding affinity of hemoglobin for oxygen. A 50 bin content over capacity: high P signifies a decrease in hemoglobin’s affinity for 50 Hb O2 content oxygen and results in a rightward shift in the oxyhemoglo- SO2 100 (5) bin equilibrium curve, whereas a low P50 signifies the op- Hb O2 capacity posite and shifts the curve to the left. A shift in the P50 in Thus, the oxygen saturation is the ratio of the quantity either direction has the greatest effect on the steep phase of oxygen actually bound to the quantity that can be poten- and only a small effect on the loading of oxygen in the nor- tially bound. For example, if oxygen content is 16 mL O2/dL mal lung, because loading occurs at the plateau. The curve is S-shaped and O2 in physical solution can be divided into a plateau region and a steep region. CHAPTER 21 Gas Transfer and Transport 355 A carbon dioxide (high PCO2), all of which favor the unload- 100 ing of more oxygen to metabolically active muscles. Red blood cells contain 2,3-diphosphoglycerate (2,3- Shift to left DPG), an organic phosphate compound that also can affect 80 (P50 ↓) Shift to right affinity of hemoglobin for oxygen. In red cells, 2,3-DPG (P50 ↑) levels are much higher than in other cells because erythro- cytes lack mitochondria. An increase in 2,3-DPG facilitates 60 unloading of oxygen from the red cell at the tissue level Normal P50 (shifts the curve to the right). An increase in red cell 2,3- DPG occurs with exercise and with hypoxia (e.
Kanis JA super levitra 80 mg for sale, Gluer C-C (2000) An update on the diagnosis and ment of the activity of Paget’s disease of bone cheap super levitra 80mg without a prescription. Diffusion-weight- Technical report 843, World Health Organisation, Geneva, ed MR imaging of bone marrow: differentiation of benign ver- Switzerland, pp 5 sus pathologic compression fractures. Rauch F, Glorieux FH (2004) Osteogenesis imperfecta Lancet Radiology of osteoporosis. Rea JA, Steiger P, Blake GM, Fogelman I (1998) Optimizing Comparison of methods for the visualisation of prevalent ver- data acquisition and analysis of morphometric X-ray absorp- tebral fracture in osteoporosis. Smyth PP, Taylor CJ, Adams JE (1999) Vertebral shape: auto- fracture assessment using a semi-quantitative technique. Mughal M, Ward K Adams J (2004) Assessment of bone sta- Radiographics 16:335-348 tus in children by densitometric and quantitative ultrasound 80. Jergas M (2003) Conventional radiographs and basic quantita- techniques. Peh WC, Gilula LA (2003) Percutaneous vertebroplasty: indi- childhood and adolescence: An approach based on bone’s bio- cations, contraindications, and technique. Marshall D, Johnell O, Wedel H (1996) Meta-analysis of how 20:561-583 well measures of bone mineral density predict occurrence of 90. Semin plication to screening for postmenopausal osteoporosis (1994) Musculoskelet Radiol, 6(4):307-312 IDKD 2005 The Radiology of Hip and Knee Joint Prostheses I. Weissman2 1 Department of Radiology, Leiden University Medical Centre, Leiden, The Netherlands 2 Department of Radiology, Brigham & Women’s Hospital, Boston, MA, USA Introduction density polyethylene is radiolucent and cannot be readily visualized non-invasively. Currently, approximately 800,000 total Other Articulations hip arthroplasties are performed each year worldwide, with the USA accounting for more than 200,000 of them In an effort to decrease articular wear and the shedding. The most frequent causes of failure are loosening and of particles, which can cause loosening, other articular particle disease. Up to 20% of both the acetabular cup and the femoral head made of patients will need revision surgery over 20 postoperative alumina ceramic. Good to excellent results are Main Types of Devices Used expected in 95% of appropriately selected patients. Hip Currently Used Materials Unipolar: Usually a femoral component only (or a mod- ular femoral component). Used mainly in older patients Metal following a femoral-neck fracture in whom the acetabu- lum is relatively normal. A number of combinations are in current use, designed to be long-wearing and inert biologically. The principle Bipolar arthroplasty: Comprising both a fixed femoral alloys used are cobalt-chrome-molybdenum, cobalt- component and an acetabular component that moves chrome-tungsten and titanium-aluminium-vanadium. Thus, motion should occur The prosthesis may be inserted with cement (to trans- between the native acetabulum and the acetabular com- fer stress from the prosthesis to bone) or have a sin- ponent and between the femoral component and the ac- tered irregular (“porous”) coating, allowing bone in- etabular liner. Bone in-growth fixation of the femoral stem can be performed if necessary. Acetabular fixation is generally by This is the most commonly used device in patients with bone in-growth. Ultra-High-Molecular-Weight Polyethylene Hybrid total hip replacement: The acetabular compo- nent is fixed by bone in-growth while the femoral com- This hard, high-density material provides a low-friction ponent is cemented. Furthermore, it allows Customised: Following tumor resection or difficult revi- plastic deformity increasing congruity.
In the first meiotic division order super levitra 80 mg visa, the homologous chromosomes of a diploid parent cell are separated into two haploid daughter cells super levitra 80mg sale. In the second meiotic division, these chromatids are distributed to two new haploid daughter cells. The body of the flagellum contains numerous mitochondria spiraled around a Knowledge Check filamentous core. What are the functions of the seminiferous tubules, germi- ing movement. The maximum unassisted rate of spermatozoa move- nal epithelial cells, and interstitial cells? Discuss the effect of testosterone on the production of sperm Recent findings indicate that ejaculated spermatozoa (plural of cells and the development of secondary sex characteristics. Diagram a spermatozoon and its adjacent sustentacular cell of these sperm cells are defective, however, and are of no value. It is and explain the functions of sustentacular cells in the sem- not uncommon for them to have enlarged heads, dwarfed and mis- iniferous tubules. Male Reproductive © The McGraw−Hill Anatomy, Sixth Edition Development System Companies, 2001 706 Unit 7 Reproduction and Development Spermatogonia (46 chromosomes) Wall of seminiferous Primary tubule spermatocytes (46 chromosomes) Secondary spermatocytes (23 chromosomes) Spermatids (23 chromosomes) Sustentacular cell Lumen of seminiferous tubule Spermatozoa (23 chromosomes) (a) (b) Acrosome of head Head Body of flagellum Flagellum FIGURE 20. Spermatogonia undergo mitotic division to replace themselves and produce a daughter cell that will undergo meiotic division. Upon completion of the first meiotic division, the daughter cells are called secondary spermatocytes. No- tice that the four spermatids produced by the meiosis of a primary (c) spermatocyte are interconnected. Male Reproductive © The McGraw−Hill Anatomy, Sixth Edition Development System Companies, 2001 Chapter 20 Male Reproductive System 707 Pseudostratified ciliated columnar epithelium Smooth muscle Sperm in lumen of duct Connective tissue FIGURE 20. The tail is continuous with the beginning por- tion of the ductus deferens; both store spermatozoa to be discharged during ejaculation. The time required to produce ma- SPERMATIC DUCTS, ACCESSORY ture spermatozoa—from meiosis in the seminiferous tubules to storage in the ductus deferens—is approximately 2 months. From here, it penetrates the in- Objective 10 Describe the location and structure of each segment of the male duct system. The histological structure of the ductus deferens includes a Objective 12 Describe the location, structure, and functions layer of pseudostratified ciliated columnar epithelium in contact of the ejaculatory ducts, seminal vesicles, prostate, and with the tubular lumen and surrounded by three layers of tightly bulbourethral glands. Stimulation through these nerves causes peristaltic contractions of the muscular layer, Spermatic Ducts which propel the stored spermatozoa toward the ejaculatory duct. The spermatic ducts store spermatozoa and transport them from Much of the ductus deferens is located within a structure the testes to the urethra. The accessory reproductive glands pro- known as the spermatic cord (see figs. Male Reproductive © The McGraw−Hill Anatomy, Sixth Edition Development System Companies, 2001 708 Unit 7 Reproduction and Development Seminal crypt Smooth muscle FIGURE 20. Glandular epithelium plexus, nerves, the cremaster muscle, lymph vessels, and connec- tive tissue. The portion of the spermatic cord that passes anterior to the pubic bone can be easily palpated. This layer partitions the lumen pierces the capsule of the prostate on its posterior surface and into numerous intercommunicating spaces that are lined by pseu- continues through this gland (see fig. Both ejaculatory dostratified columnar and cuboidal secretory epithelia (referred ducts receive secretions from the seminal vesicles and then eject to as glandular epithelium).
As pathway come from the nucleus of the trape- shown in the stimulation diagram (red sym- zoid body and the ipsilateral cochlear nuclei; bols) (A) super levitra 80 mg fast delivery, the representation of the body however generic super levitra 80mg, most fibers originate from the runs obliquely from dorsolateral (leg region, contralateral cochlear nuclei. The efferent | ; arm region, –) to mediobasal (head re- fibers of the medial geniculate nucleus ex- gion, (! Controlled stimulation of the tend to the auditory cortex (D5), which lies ventral lateral nucleus (orange symbols) (B) in the transverse temporal gyri, or Heschl’s con- results also in involuntary sound produc- volutions (p. Sinceitdoesnotre- Lateral Geniculate Body (C) ceive any extrathalamic input, it must be This nucleus (C1) lies somewhat isolated at viewed as an integration nucleus. Afferent theventrocaudalaspectofthethalamusand fibers from the lateral geniculate nucleus is a relatively independent structure. It (collaterals of the optic fibers) and probably shows stratification into six cell layers also fibers from the medial geniculate nu- which are separated by the afferent fiber cleus enter the pulvinar. Crossed and un- There are reciprocal fiber connections be- crossed optic fibers terminate in a regular tween the pulvinar and the cortex of the arrangement (p. In the left lateral genicu- Hence, the pulvinar is not only integrated late body, the temporal half of the retina of into the optic and acoustic systems but is thelefteyeandthenasalhalfoftheretinaof also connected with the cortical areas im- the right eye are represented; in the right portant for language and symbolic thinking lateral geniculate body, the temporal half of (p. The fibers from the macula, which tion) of the pulvinar causes speech disorder in is the region of greatest visual acuity, termi- humans. The neurons of the lateral geniculate nu- cleus send their axons to the visual cortex, Kahle, Color Atlas of Human Anatomy, Vol. Ventral Nuclei, Lateral and Medial Geniculate Bodies 187 B Responses of speech and sound following stimulation of the ven- tral lateral nucleus (according to Schaltenbrand, Spuler, Wahren and A Motor responses following stimu- Rümler) lation of the ventral lateral nu- cleus (according to Schaltenbrand, Spuler, Wahren and Rümler) 2 1 C Fiber connections of the lateral geniculate body 5 3 D Fiber connections of the medial 4 geniculate body Kahle, Color Atlas of Human Anatomy, Vol. During tinuously compensate for changes from the circular ciliary light to dark and from near to far. The meridional aperture and lens system must continu- muscle fibers pull the origins of the long ously adapt to the prevailing conditions. This relaxes both the requires a change in the curva- zonular fibers (), and the lens capsule, ture of the lens (), a change thus causing the lens to round off (). During The fiber tracts of the (adjustment for long dis- are less well known. As fixation of an object tances), the surface of the lens is only is the prerequisite of accommodation, the slightly curved, the lines of sight run paral- optic nerve is the. During arch runs propably via the visual cortex (adjustment for short (striate area) to the pretectal nuclei, distances), the surface of the lens is dis- possibly also via the superior colliculi (). At the same time, it introduces, on the same set of pages, the im- vous system; 2) to emphasize points of clinical relevance through use portant concept that CNS anatomy, both external and internal, is ori- of appropriate terminology and examples; and 3) to integrate neuro- ented differently in MRI or CT. It is the clinical orientation issue that anatomical and clinical information in a format that will meet the edu- will confront the student/clinician in the clinical setting. The goal of the sixth edition is to continue appropriate to introduce, and even stress, this view of the brain and this philosophy and to present structural information and concepts in spinal cord in the basic science years. These include, in the basic science setting should ﬂow as seamlessly as possible into the but are not limited to, new examples of general vessel arrangement in clinical setting. MRA, examples of speciﬁc vessels in MRI, and some additional exam- I have received many constructive suggestions and comments from ples of hemorrhage. This is especially the case for the modiﬁ- Fourth, additional examples of cranial nerves traversing the sub- cations made in Chapters 2, 5, 7, 8, and 9 in this new edition. In fact, the number of MRI showing cra- names of the individuals who have provided suggestions or comments nial nerves has been doubled.
Therefore super levitra 80 mg without prescription, these actions have significant direct impact buy super levitra 80 mg line, and, in addition, reset the bar for the rest of the health care marketplace. Introduction xi The rise of for-profit corporate medicine offered promise of numerous important advantages: 1. Funds for infrastructure investment, including the information technol- ogy in which health care lags far behind other industries. The potential to offer more consistent outcomes and systematic quality assurance. Scale to allow development of appropriate institutional and provider specialization. Institutional personnel who could free physicians from activities not directly related to patient care. The rationalization of a fragmented industry that would produce enhanced quality at lower cost. Instead, most cost savings have come from simply reducing payments to providers. Profit imperatives have led to greater selectivity in choosing which patients to service, rather than commitment to better processes for improved outcomes. Physicians have found it difficult to align their incentives with those of their employers, and employers have found it equally difficult to manage doctors. Patients, nominally the designated beneficiaries of these changes, seem the unhappiest of all. They have lost the unquestioned assurance that the physician is their advocate. Shifts in the marketplace may force them to find new doctors without warning or cause. Medical costs are again rising rapidly, and patients are being asked to pay an increasing share of their own medical bills (15). Only 44% of Americans express “a great deal of confidence” in medicine (16). More than 45 million Americans do not have health insurance, but physicians must provide care to all under legally and ethically defined circumstances. For the remainder of the population, a panoply of public and private health plans, not to mention laws and guidelines, regulate the provision of health care. THE INCREASING IMPACT OF LAW AND REGULATION ON MEDICAL PRACTICE The legal context of medical practice has changed significantly in recent years. The position of physicians within the US legal system is “neither as lofty nor as protected as it was previously” (13). There are xii Introduction new legal obligations, stricter liability laws, and increased competition. The definition of standard of care has evolved from the practices of competent physicians in the community (the locality rule) to national standards as articulated in the medical literature and practiced anywhere in the country. Contemporary concepts of informed consent are only 30 years old and are now based on fundamental principles of patient autonomy rather than physician judgment. Although health care as a right or a privilege may still be debated, our laws have increasingly defined the terms of access and the parameters of care. Increasingly, legal standards of care of have replaced medical stan- dards. In some cases this may be relatively explicit, such as indications for Cesarean section based more on the probability of liability than medi- cal judgment. Frequently, however, the replacement of medical judg- ment by courtroom standards is more subtle.