Urinary System chapter 15 Kidney Cortex Renal artery Renal vein Nephrons Aorta Cortex Inferior vena cava Medulla Renal pelvis Medulla Collecting duct Ureter Bladder Ureter Urethra a) The components of the urinary system. b) Internal structure of the kidney. c) The cortex and medulla of the kidney are composed of numerous nephrons. PLAY Animation—The Urinary System Figure 15.2

Functions of Renal Organs Table 15.2

Organs of the Urinary System Kidneys Cortex Renal Medulla Renal Pelvis

Urinary System Figure 15.2 Kidney Cortex Renal artery Renal vein Nephrons Aorta Cortex Inferior vena cava Medulla Renal pelvis Medulla Collecting duct Ureter Bladder Ureter Urethra a) The components of the urinary system. b) Internal structure of the kidney. c) The cortex and medulla of the kidney are composed of numerous nephrons. Figure 15.2

Organs of the Urinary System Urinary bladder Rectum Internal urethral sphincter Prostate gland Uterus Vagina External urethral sphincter Penis Rectum Urethra Testis a) The male b) The female Figure 15.3

Tubular and Vascular Nephron Components Figure 15.5

Nephrons: Produce Urine Bowman’s capsule/Glomerular capsule and Tubules Function Filter fluid and reabsorb needed substances Structures Glomerular capsule Proximal tubule Loop of Henle Distal tubule Collecting duct

Nephrons: Produce Urine Blood vessels associated with tubules Arterioles Afferent (toward glomerular capsule) Efferent (away from capsule) Capillaries Glomerular Peritubular Vasa recta

Formation of Urine Figure 15.6

Formation of Urine: Glomerular Filtration Filters fluid from capillaries into glomerular capsule Rate of filtration Resting rate under local chemical control Stress causes sympathetic nervous system to reduce blood flow to kidneys

Formation of Urine: Tubular Reabsorption Tubular reabsorption returns water and needed solutes to blood capillaries Sodium moved by active transport from tubule cells to interstitial fluid and diffuses to capillaries Chloride passively accompanies sodium (balanced charge) Water reabsorbed with salts Movement of sodium creates energy to transport glucose and amino acids into renal tubule then diffuses to the interstitial fluid

Tubular Secretion Tubular secretion removes other substances from blood Purpose Regulation of chemical levels in body Excretion of harmful chemicals Substances secreted Penicillin, cocaine, marijuana, pesticides, preservatives, hydrogen ions, ammonium, potassium

Concentration or Dilution of Urine: ADH Dilute urine Excreting excess water Mechanism Cycling of NaCl and urea create a concentration gradient in the medulla that allows water to diffuse from the renal tubules into the interstitial fluid and then into the blood capillaries

Formation of Dilute Urine Figure 15.10

Concentration or Dilution of Urine: ADH Concentrated urine Conserving water Mechanism Countercurrent exchange Increased ADH causes increased permeability to the collecting tubules and increased conservation of water

Formation of Concentrated Urine Figure 15.11

Urination Micturition reflex Internal urethral sphincter Smooth muscle External urethral sphincter Skeletal muscle

Kidney’s Role in Homeostasis Maintains water balance Adjusts blood volume and blood pressure Aldosterone, renin, ANH help maintain salt balance in order to control blood volume Maintains acid–base balance and blood pH Regulates red blood cell production via erythropoietin Activates an inactive form of vitamin D

Kidney’s Role in Homeostasis Figure 15.13

Kidney’s Role in Homeostasis Figure 15.15

Disorders of the Urinary System Kidney stones Crystallized minerals Block urine flow Urinary tract infections (UTI) Bacteria

Disorders of the Urinary System Acute and chronic renal failure Therapies Dialysis Kidney transplant