Ebook Anatomy and physiology for nurses at a glance: Part 2
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Ebook Anatomy and physiology for nurses at a glance: Part 2
The urinary system£882ChaptersThe kidney: microscopic 72The kidney: macroscopic 74The ureter, bladder and urethra 76Formation of urine 7871.■tmtomy an Ebook Anatomy and physiology for nurses at a glance: Part 2nd nỵradngy |br Niirws al a Glwe. I'm! Edition bn ỈVatc and Muralithiran Nair. © 2(115 ĩohn Wiley s Son*. Ltd. PuNiihcd 2015 by lohn Wiley St Son*, lid. Companion uxb««<: wwitaWglarKEbook Anatomy and physiology for nurses at a glance: Part 2
proximal convoluted tubule, loop of Henle, distal convoluted tubule and the collecting ducts. There are approximately over one million nephrons per kThe urinary system£882ChaptersThe kidney: microscopic 72The kidney: macroscopic 74The ureter, bladder and urethra 76Formation of urine 7871.■tmtomy an Ebook Anatomy and physiology for nurses at a glance: Part 2what is needed and excreting the rest as urine. A nephron eliminates wastes from the body, regulates blood volume and blood pressure, controls levels of electrolytes and metabolites and regulates hlood pH.Glomerular capsuleAlso known as glomerular capsule (Figure 31.2), this is a cuplike sac and is Ebook Anatomy and physiology for nurses at a glance: Part 2the first portion of the nephron. A Bowmans capsule is part of the filtration system in the kidneys, when blood reaches the kidneys for filtration, itEbook Anatomy and physiology for nurses at a glance: Part 2
enters the Bowmans capsule first, with the capsule separating the blood into two components: a filtrated blood product and a filtrate which is moved The urinary system£882ChaptersThe kidney: microscopic 72The kidney: macroscopic 74The ureter, bladder and urethra 76Formation of urine 7871.■tmtomy an Ebook Anatomy and physiology for nurses at a glance: Part 2 epithelial cells called podocytes while the parietal layer is lined with simple squamous epithelium, and it is in the Bowmans capsule dial the network of capillaries called the glomerulus is found.GlomerulusThe glomerulus consists ofa tight network of capillaries surrounded by podocytes. Podocytes Ebook Anatomy and physiology for nurses at a glance: Part 2have narrow cell processes that in turn give secondary extensions called pedicles (Figure 31.2). Podocytes completely surround the capillary network.Ebook Anatomy and physiology for nurses at a glance: Part 2
As blood flows though the glomerulus, waler and metabolic wastes are filtered through the capillary walls by the surrounding podos y tcs. Waler and waThe urinary system£882ChaptersThe kidney: microscopic 72The kidney: macroscopic 74The ureter, bladder and urethra 76Formation of urine 7871.■tmtomy an Ebook Anatomy and physiology for nurses at a glance: Part 2re 31.1). The surface of the epithelial cells of this segment of the nephron is covered with densely packed microvilli, lhe microvilli increase the surface area of the cells thus facilitating their resorptive function, ilte in-folded membranes forming the microvilli are the site of numerous sodium p Ebook Anatomy and physiology for nurses at a glance: Part 2umps. Reabsorption of salt, waler and glucose from the glomerular filtrate occurs in this sec tion of the tubule; al the same time certain substances,Ebook Anatomy and physiology for nurses at a glance: Part 2
including uric acid and drug metabolites, are actively transferred from the blood capillaries into the tubule for excretion. Loop of HenleIn the kidnThe urinary system£882ChaptersThe kidney: microscopic 72The kidney: macroscopic 74The ureter, bladder and urethra 76Formation of urine 7871.■tmtomy an Ebook Anatomy and physiology for nurses at a glance: Part 2nto two sections: the descending and the ascending loops (Figure 3l.l). The thin descending limb has low permeability to ions and urea, while being highly permeable to water. The loop has a sharp bend in the renal medulla going from descending to ascending thin limb.The thin ascending loop is imperm Ebook Anatomy and physiology for nurses at a glance: Part 2eable to water, but it is permeable to ions. Sodium (Na*), potassium (K*) and chloride (Cl) ions are reabsorbed from the urine by secondary active traEbook Anatomy and physiology for nurses at a glance: Part 2
ns port by a Na K-Q cotransporter. The electrical and concentration gradient drives more reabsorption of Na', as well as other cations such as magnesiThe urinary system£882ChaptersThe kidney: microscopic 72The kidney: macroscopic 74The ureter, bladder and urethra 76Formation of urine 7871.■tmtomy an Ebook Anatomy and physiology for nurses at a glance: Part 2es. These capillaries (vasa recta) also have a counter-current multiplier mechanism that prevents washout of solutes from the medulla, thereby maintaining the medullary concentration. As water isosmotically moved from the descending limb into the interslilium, it readily enters the vasa recta. The l Ebook Anatomy and physiology for nurses at a glance: Part 2ow blood flow through the vasa recta allows time tor osmotic equilibration, and can be altered by changing the resistance of the vessels' efferent artEbook Anatomy and physiology for nurses at a glance: Part 2
erioles.Distal convoluted tubuleA distal convoluted tubule is a twisted, lube-like structure of the nephron (Figure 31.1). The distal convoluted tubulThe urinary system£882ChaptersThe kidney: microscopic 72The kidney: macroscopic 74The ureter, bladder and urethra 76Formation of urine 7871.■tmtomy an Ebook Anatomy and physiology for nurses at a glance: Part 2ammonia, urea and certain drugs, out of the blood and into the urine. From the distal convoluted tubule, useful substances are returned to the blood, while waste products and toxins are added to the filtrate. Hydrogen ions are also pumped in. making the urine pl 1 more acidic. 1 he distal convoluted Ebook Anatomy and physiology for nurses at a glance: Part 2 tubule walls do not normally allow waler to pass through, but the hormone ADI 1 can open channels which allow waler to move out, concentrating the urEbook Anatomy and physiology for nurses at a glance: Part 2
ine.Collecting ductsFrom the distal convoluted tubule, filtrate drains into what are known as collecting ducts (Figure 31.1). These are tubes which reThe urinary system£882ChaptersThe kidney: microscopic 72The kidney: macroscopic 74The ureter, bladder and urethra 76Formation of urine 7871.■tmtomy an Ebook Anatomy and physiology for nurses at a glance: Part 2ration of urine produced by the kidneys. On leaving the colics ting ducts, urine enters a space known as the renal pelvis, from where it passes into the bladder and is expelled from the body during urination.rhe collecting duct system is under the control of ADI 1. In the absence of ADH. water in th Ebook Anatomy and physiology for nurses at a glance: Part 2e renal filtrate is allowed to enter the urine, promoting diuresis. When ADH is present, aquaporins aid reabsorption of water, thereby inhibiting diurEbook Anatomy and physiology for nurses at a glance: Part 2
esis.Q The kidney: macroscopicFigure 32.1 External layers of the kidneyftkiuKW I 7AiK ?. l< Maráự AmỉAkmMTtìỉ Cmt* pữ14ịFigure 32.2 Blood flow throughThe urinary system£882ChaptersThe kidney: microscopic 72The kidney: macroscopic 74The ureter, bladder and urethra 76Formation of urine 7871.■tmtomy anThe urinary system£882ChaptersThe kidney: microscopic 72The kidney: macroscopic 74The ureter, bladder and urethra 76Formation of urine 7871.■tmtomy anGọi ngay
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