The Urinary System kidneys and nephron- structure and fx Pages 511-516

The Urinary System URINE for a great time today!!!

Functions of the Urinary System © 2015 Pearson Education, Inc. Functions of the Urinary System Elimination of waste products which include: Nitrogenous wastes Toxins Drugs Regulation of homeostatic factors such as: Water, acid/base, electrolyte balance BP RBC mfr Vitamin D activation

Organs of the Urinary System © 2015 Pearson Education, Inc. Organs of the Urinary System Kidneys (contain the nephron) Ureters Urinary bladder Urethra

Figure 15.1a Organs of the urinary system. Hepatic veins (cut) Inferior vena cava Renal artery Adrenal gland Renal hilum Aorta Renal vein Kidney Iliac crest Ureter Rectum (cut) Uterus (part of female reproductive system) Urinary bladder Urethra (a)

Kidneys Location and structure against the dorsal body wall © 2015 Pearson Education, Inc. Kidneys Location and structure against the dorsal body wall at the level of the T12 to L3 vertebrae right kidney is slightly lower than the left It is crowded by the liver renal hilum medial indentation where structures enter or exit the kidney (ureters, renal blood vessels, and nerves) An adrenal gland sits atop each kidney

Figure 15.1b Organs of the urinary system. 12th rib (b)

Kidneys Protective tissue structures: (from deep to superficial) © 2015 Pearson Education, Inc. Kidneys Protective tissue structures: (from deep to superficial) Enclosed by a fibrous connective tissue capsule Lies directly on the kidney Protects from infection Perirenal fat capsule surrounds the kidney and cushions against blows Renal fascia is the outermost capsule anchors the kidney and adrenal gland to surroundings Pararenal fat capsule surrounds renal fascia

Kidneys Three kidney regions © 2015 Pearson Education, Inc. Kidneys Three kidney regions Renal cortex—outer region Renal medulla—deeper region Renal (medullary) pyramids—triangular regions of tissue Renal columns—extensions of cortex-like material separate the pyramids Renal pelvis—medial region; flat, funnel-shaped tube Calyces—extensions of the renal pelvis enclose the renal pyramids collect urine and send it to the renal pelvis>ureter>urinary bladder Nephrons comprise the bulk of cortex and medulla and are made of specialized endothelial and/or epithelial tissues

Figure 15.2a Internal anatomy of the kidney. Longitudinal section of the right kidney Renal cortex Renal column Major calyx Minor calyx Renal pyramid (a)

Figure 15.2b Internal anatomy of the kidney. Cortical radiate vein Cortical radiate artery Renal cortex Arcuate vein Arcuate artery Renal column Interlobar vein Interlobar artery Segmental arteries Renal vein Renal artery Minor calyx Renal pelvis Major calyx Renal pyramid Ureter Fibrous capsule (b)

© 2015 Pearson Education, Inc. Blood Supply One-quarter of the total blood supply of the body passes through the kidneys each minute The abdominal aorta supplies the renal artery Renal artery provides each kidney with arterial blood supply Renal artery divides into smaller vessels Renal vein Smaller vessels get bigger to supply renal vein Renal vein returns blood to the inferior vena cava

Figure 15.2b Internal anatomy of the kidney. Cortical radiate vein Cortical radiate artery Renal cortex Arcuate vein Arcuate artery Renal column Interlobar vein Interlobar artery Segmental arteries Renal vein Renal artery Minor calyx Renal pelvis Major calyx Renal pyramid Ureter Fibrous capsule (b)

Nephrons – structural & functional unit of the kidney © 2015 Pearson Education, Inc. Nephrons – structural & functional unit of the kidney Responsible for forming urine Two main structures of a nephron: Renal corpuscle – includes: glomerulus, Bowman’s capsule, podocytes Renal tubule – includes: proximal convoluted tubule Loop of Henle distal convoluted tubule

Figure 15.3a Structure of the nephron. Cortical nephron Fibrous capsule Renal cortex Collecting duct Renal medulla Proximal convoluted tubule Renal cortex Renal pelvis Glomerulus Juxtamedullary nephron Ureter Distal convoluted tubule Nephron loop Renal medulla (a)

Nephrons 2 locations for nephrons: Cortical nephrons © 2015 Pearson Education, Inc. Nephrons 2 locations for nephrons: Cortical nephrons Located entirely in the cortex Include most nephrons Juxtamedullary nephrons Found at the boundary of the cortex and medulla Nephron loop dips deep into the medulla

Figure 15.3a Structure of the nephron. Cortical nephron Fibrous capsule Renal cortex Collecting duct Renal medulla Proximal convoluted tubule Renal cortex Renal pelvis Glomerulus Juxtamedullary nephron Ureter Distal convoluted tubule Nephron loop Renal medulla (a)

Nephrons Each nephron has two capillary beds: Glomerulus © 2015 Pearson Education, Inc. Nephrons Each nephron has two capillary beds: Glomerulus fed and drained by the afferent/efferent arterioles High pressure - for filtration Peritubular capillaries Drains the glomerulus Low pressure and porous - for absorption

Figure 15.3c Structure of the nephron. Glomerular capsular space PCT Glomerular capillary covered by podocytes Efferent arteriole Afferent arteriole (c)

Figure 15.3d Structure of the nephron. Filtration slits Podocyte cell body Foot processes (d)

Figure 15.3b Structure of the nephron. Proximal convoluted tubule (PCT) Peritubular capillaries Glomerular capillaries Distal convoluted tubule (DCT) Glomerular (Bowman’s) capsule Efferent arteriole Afferent arteriole Cells of the juxtaglomerular apparatus Cortical radiate artery Arcuate artery Arcuate vein Cortical radiate vein Collecting duct Nephron loop (b)