Memmler s The Human Body in Health and Disease

Excretion Body systems work interdependently to maintain homeostasis by excretion • Urinary • Digestive • Respiratory • Integumentary Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Organs of the Urinary System • Two kidneys • Two ureters • Single urinary

Male urinary system, showing blood vessels. Zooming In: What vessel supplies blood to the

Kidney Activities • Excretion – Urea • Water balance maintenance • Body fluid acid–base regulation • Blood pressure regulation – Angiotensin – Aldosterone • Red blood cell production regulation Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Kidney Structure • Membranous renal capsule of fibrous connective tissue • Adipose capsule of fat • Fascia anchors kidney to peritoneum and abdominal wall • Retroperitoneal space • Right kidney lower than left to accommodate liver Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Blood Supply to the Kidney • Renal artery supplies blood • Nephrons are functional

Kidney Organization • Hilum • Renal cortex (outer portion) • Renal medulla (inner portion) – Renal pyramids • Renal pelvis – Calyces Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Longitudinal section through the kidney. Its internal structure is shown (left), along with an enlarged diagram of nephrons (right). Each kidney contains more than 1 million nephrons. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

The Nephron Functional kidney unit • Glomerular (Bowman) capsule – Glomerulus – Afferent arteriole • Peritubular capillaries • Proximal convoluted tubule (PCT) • Nephron loop (Loop of Henle) – Descending limb – Ascending limb • Distal convoluted tube (DCT) • Collecting duct Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

A nephron and its blood supply. The nephron regulates the proportions of water, waste, and other materials according to the body’s constantly changing needs. Materials that enter the nephron can be returned to the blood through the surrounding capillaries. Zooming In: Which of the two convoluted tubules is closer to the glomerular capsule? Which convoluted tubule is farther away? Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Formation of Urine • Glomerular filtration – Glomerular filtrate • Tubular reabsorption – Diffusion – Osmosis – Active transport • Tubular secretion • Countercurrent mechanism – Concentration of urine – Antidiuretic hormone (ADH) Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Summary of urine formation in a nephron. Copyright © 2009 Wolters Kluwer Health |

Control of Blood Pressure • Juxtaglomerular apparatus: Specialized cells that regulate kidney function • Triggered by low blood pressure – Secretes renin enzyme Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Structure of the juxtaglomerular (JG) apparatus. Note how the distal convoluted tubule contacts the afferent arteriole (right). Cells in these two structures make up the JG apparatus. Zooming In: The JG apparatus is made up of cells from which two structures? Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

The Ureters • Long, slender, muscular tubes – Epithelial cell lining – Involuntary muscle layer – Fibrous connective tissue coat • Entirely extraperitoneal • Extend from kidney to urinary bladder • Move urine by gravity and peristalsis Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

The Urinary Bladder Temporary reservoir for urine • Multiple layers • Mucous membrane – Transitional epithelium – Rugae – Connective tissue – Three-layered coat of involuntary muscle tissue – Incomplete coat of peritoneum • Trigone Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

The Urethra Tube that extends from the bladder to the outside • Male – Part of both reproductive and urinary systems • Female – Entirely separate from reproductive system Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Urination Process of expelling urine from bladder (micturition) • Involuntary control – Internal urethral sphincter • Voluntary control – External urethral sphincter Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

The Urine • 95% water, 5% dissolved solids and gases • p. H averages 6. 0 • Specific gravity measures amount of dissolved substances – Normal range 1. 002 to 1. 040 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Normal Constituents Dissolved solids normally found in urine • Nitrogenous waste products – Urea – Uric acid – Creatinine • Electrolytes – Sodium chloride – Sulfates – Phosphates • Pigment Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Abnormal Constituents Urinalysis is evaluation of urine • Glucose – Glycosuria • Albumin – Albuminuria • Blood – Hematuria • Ketones – Diabetes mellitus and starvation • White blood cells – Pyuria • Casts – Nephron disease Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Disorders of the Urinary System Portion of urinary system most prone to disorders is

Kidney Disorders Kidney disorders may be acute or chronic • Acute glomerulonephritis – Most common kidney disease • Pyelonephritis • Hydronephrosis • Polycystic kidney • Tumors • Kidney stones (calculi) • Renal failure – Leads to uremia, high levels of nitrogenous waste in the blood Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Renal Dialysis and Kidney Transplantation • Dialysis – Hemodialysis – Peritoneal dialysis • Kidney transplantation – Final option for treatment of kidney failure Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Disorders of the Ureters • Subdivision at renal pelvis • Constricted or abnormally narrow parts (strictures) • Renal ptosis • Ureterocele • Ureteral stones Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Bladder Disorders • Rupture • Cystitis – Interstitial cystitis • Tumors – 90% arise from epithelial lining – If bladder removed (cystectomy), ureters diverted to part of ileum in an ilial conduit • Urinary incontinence – Stress incontinence – Urge incontinence – Overflow incontinence – Enuresis Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Disorders of the Urethra • Congenital anomalies – Narrowing of opening or urethra itself – Presence of valve-like structure at junction of urethra and bladder – Hypospadias • Urethritis • Straddle injuries Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

The Effects of Aging • Loss of ability to concentrate urine • Decrease in number and size of nephrons • Increase in blood urea nitrogen (BUN) • Urinary infections • Prostate enlargement • Decreased bladder capacity • Incontinence Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins