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Learn about the urinary system, including kidney anatomy, nephron structure, urine formation, and regulatory processes. Explore how the system maintains homeostasis and eliminates waste products.
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Chapter 26, part 1 The Urinary System
Learning Objectives • Identify the components and functions of the urinary system • Describe the location and structural features of the kidneys • Describe the structure of a nephron, and outline the processes involved in the formation of urine • Describe the normal characteristics, composition, and solute concentrations of a representative urine sample
Learning Objectives • List and describe the factors that influence filtration pressure and the rate of filtrate formation • Identify the types of transport mechanisms found along the nephron • Describe how antidiuretic hormone and aldosterone levels influence the volume and concentration of urine
Functions of the urinary system • Excretion • The removal of organic waste products from body fluids • Elimination • The discharge of waste products into the environment • Homeostatic regulation of blood plasma • Regulating blood volume and pressure • Regulating plasma ion concentrations • Stabilizing blood pH • Conserving nutrients
Urinary system includes: • The kidneys • Produce urine • The ureters • The urinary bladder • Stores urine • The urethra
Figure 26.1 An introduction to the Urinary System Figure 26.1
The kidneys • Left kidney extends slightly more superiorly than right • Both kidneys and adrenal glands are retroperitoneal • Hilus • Entry for renal artery and renal nerves • Exit for renal veins and ureter
Figure 26.2 The Position of the Kidneys Figure 26.2a, b
Figure 26.3 The Urinary System in Gross Dissection Figure 26.3
Sectional anatomy of the kidneys • Superficial outer cortex and inner medulla • The medulla consists of 6-18 renal pyramids • The cortex is composed of roughly 1.25 million nephrons • Major and minor calyces along with the pelvis drain urine to the ureters
Figure 26.4 The Structure of the Kidney Figure 26.4a, b
Blood supply and innervation of the kidneys • Renal arteries branch repeated • Renal artery • Segmental artery • Interlobar artery • Arcuate artery • Interlobular artery • Afferent arterioles • Renal venules follow similar opposing pattern ending with renal veins
Figure 26.5 The Blood Supply to the Kidneys Figure 26.5a, b
Figure 26.5 The Blood Supply to the Kidneys Figure 26.5c, d
The nephron consists of a renal corpuscle and renal tubule • The renal corpuscle is composed of • Bowman’s capsule and the glomerulus • The renal tubule consists of • Proximal convoluted tubule (PCT) • Loop of Henle • Distal convoluted tubule (DCT)
Filtrate is produced at the renal corpuscle • Nephron empties tubular fluid into collecting system • Collecting ducts and papillary ducts
Figure 26.6 A Representative Nephron Figure 26.6
Nephron functions include: • Production of filtrate • Reabsorption of organic nutrients • Reabsorption of water and ions • Secretion of waste products into tubular fluid
Two types of nephron • Cortical nephrons • ~85% of all nephrons • Located in the cortex • Juxtamedullary nephrons • Closer to renal medulla • Loops of Henle extend deep into renal pyramids
Figure 26.7 Cortical and Juxtamedullary Nephrons Figure 26.7a
Figure 26.7 Cortical and Juxtamedullary Nephrons Figure 26.7b, c