BIOL 221 Chapter 13 Lecture Outline The Urinary System

BIOL 221 Chapter 13 Lecture Outline The Urinary System Introduction • The urinary system can be broken down into 2 functional divisions o Urine forming Organs o Structures that transport urine from the kidneys for elimination from the body Kidneys • Kidneys: Pair of bean shaped organs located retroperitoneal against the posterior abdominal wall. The right kidney is about 2 cm lower than the left kidney. • The kidneys have 2 main functions o Primarily responsible for maintaining stability of ECF volume, electrolyte composition and osmolarity o Main route for eliminating potentially toxic metabolic wastes and foreign compounds from the body • There are two anatomically distinct regions in the kidneys o renal cortex: outer region o renal medulla: inner region made up of renal pyramids Nephron • Nephron: Functional unit of the kidney • There are 2 types of nephrons, distinguished by the location and length of their tubular components o Juxtamedullary nephrons o Cortical nephrons • Each nephron has 2 components o Tubular component o Vascular component Nephron – Vascular Component • The dominant part of the nephron’s vascular component is the glomerulus • Glomerulus: Ball-like tuft of capillaries that filters out water and solutes as blood passes through it • The flow of blood through the vascular component of the nephron follows the following path o Afferent arteriole o Glomerulus o Efferent arteriole o Peritubular capillaries/ Vasa recta Nephron – Tubular Component • The tubular component is a hollow, fluid-filled, continuous tube formed by a single layer of epithelial cells. It is divided into various segments based on differences in structure and function along its length. • The tubular component is made up of o Bowman’s (glomerular) Capsule o Proximal tubule 2 o Loop of Henele o Distal Tubule o Collecting duct Nephron • The formation of urine is the result of 3 basic renal processes