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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
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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