Posts Tagged ‘RNA’

MICROSTRUCTURE The gastric wall consists of the major layers found elsewhere in the gut, i.e. mucosa, submucosa, muscularis externa and serosa, together with gastric vessels and nerves (Figs 65.15, 65.16). The microstructure reflects the functions of the stomach as an expandable muscular sac lined by secretory epithelium, although there are local structural and functional variations […]

CELL LINEAGES Haemopoietic stem cells Within the adult marrow there is a very small number (0.05% of haemopoietic cells) of self-renewing, pluripotent stem cells which are capable of giving rise to all blood cell types, including lymphocytes (Fig. 4.12). Although they cannot be identified morphologically in the marrow, they can be recognized in aspirates by […]

CHAPTER 3 – Nervous system The nervous system has two major divisions, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord and contains the majority of neuronal cell bodies. The PNS includes all nervous tissue outside the central nervous system and is subdivided into the cranial […]

NUCLEUS The nucleus (Figs 1.1, 1.2) is generally the largest intracellular structure and is usually spherical or ellipsoid in shape, with a diameter of 3–10 μm. Histological stains used to identify nuclei in tissue sections mainly detect the acidic molecules of deoxyribonucleic acid (DNA), which are largely confined to the nucleus. Nuclear membrane The nucleus […]

CYTOPLASM Compartments and functional organization The cytoplasm is highly concentrated, with about 200 mg/ml of proteins (about twice the concentration in blood) that must be precisely organized for correct molecular interactions to occur. It normally has extremely low levels of Ca2+, high K+ and low Na+ ions in comparison to extracellular fluid, differences which are […]

PLASMA MEMBRANE Cells are bounded by a distinct plasma membrane, which shares features with the system of internal membranes that compartmentalize the cytoplasm and surround the nucleus. They are all composed of lipids (mainly phospholipids, cholesterol and glycolipids) and proteins, in approximately equal ratios. Plasma membrane lipids form a layer two molecules thick, the lipid […]

Goldman: Cecil Medicine, 23rd ed. Copyright © 2007 Saunders, An Imprint of Elsevier LABORATORY EVALUATION OF SYSTEMIC INFLAMMATORY DISEASE   Among rheumatic diseases, some are characterized by severe systemic inflammation that can cause organ-threatening and life-threatening manifestations. These diseases can have arthritis as a component and presenting complaint, although the prominence of extra-articular manifestations, especially […]

Goldman: Cecil Medicine, 23rd ed. Copyright © 2007 Saunders, An Imprint of Elsevier Chapter 260 – HUMAN IMMUNODEFICIENCY VIRUS IN PREGNANCY Stephen A. Spector Epidemiology The World Health Organization and the Joint United Nations Programme on HIV/AIDS (UNAIDS) estimated that by the end of 2004 approximately 40 million people were living with human immunodeficiency virus (HIV) infection, including […]

Goldman: Cecil Medicine, 23rd ed. Copyright © 2007 Saunders, An Imprint of Elsevier Chapter 258 – MANAGEMENT OF NEOPLASTIC DISEASES DURING PREGNANCY Edward C. Grendys Jr. Epidemiology Although cancer is uncommon in a relative sense, it remains a leading cause of death in women of reproductive age ( Table 258-1 ). Overall cancer-related deaths account for 13% of mortality […]

Goldman: Cecil Medicine, 23rd ed. Copyright © 2007 Saunders, An Imprint of Elsevier THYROID-STIMULATING HORMONE Like the other glycoprotein hormones, TSH is a heterodimer composed of the common α subunit and the unique TSH β subunit. TSH is produced in thyrotroph cells. TSH is measured by highly sensitive immunoradiometric assays that use antisera directed toward […]

Goldman: Cecil Medicine, 23rd ed. Copyright © 2007 Saunders, An Imprint of Elsevier HOW HORMONES WORK Two classes of hormones operate via two distinct types of receptors ( Fig. 240-1 ). Peptide hormones are synthesized as parts of larger protein molecules and are processed to smaller proteins that are secreted. They act through receptors located […]

Goldman: Cecil Medicine, 23rd ed. Copyright © 2007 Saunders, An Imprint of Elsevier Chapter 237 – VITAMINS, TRACE MINERALS, AND OTHER MICRONUTRIENTS Joel B. Mason MICRONUTRIENTS IN NUTRITIONAL SCIENCE Dietary Requirements Micronutrients are a diverse array of dietary components necessary to sustain health. The physiologic roles of micronutrients are as varied as their composition; some micronutrients are used […]

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