Urinary System How the Body Filters Blood Function

Urinary System How the Body Filters Blood

Function • Urinary System – Elimination of waste products • • Nitrogenous wastes Toxins Drugs Excess water

Regulation • Kidneys have four roles in maintaining blood composition – Excretion of nitrogen-containing wastes (previously discussed) – Maintaining water balance of the blood – Maintaining electrolyte balance of the blood – Ensuring proper blood p. H

Water Regulation – Antidiuretic hormone (ADH) • Prevents excessive water loss in urine – Aldosterone • Regulates sodium ion content of ECF • Promotes reabsorption of sodium ions

Functions of the Urinary System • Regulate aspects of homeostasis – Water balance – Electrolytes – Acid-base balance in the blood – Blood pressure – Red blood cell production – Activation of vitamin D

Organs of the Urinary System • • Kidneys Ureters Urinary bladder Urethra

Kidney Structures • Renal or medullary pyramids—triangular regions of tissue in the medulla • Renal columns—extensions of cortex-like material inward that separate the pyramids • Calyces—cup-shaped structures that funnel urine towards the renal pelvis

Regions of the Kidneys

Nephrons

Nephrons • The structural and functional units of the kidneys • Responsible forming urine • Main structures of the nephrons – Glomerulus – Renal tubule

Nephrons • Glomerulus – Knot of capillaries • Renal tubule extends from glomerular capsule and ends at the collecting duct – Glomerular (Bowman’s) capsule – Proximal convoluted tubule (PCT) – Loop of Henle – Distal convoluted tubule (DCT)

Where Does Filtrate Travel? 1. 2. 3. 4. 5. Bowman’s (Glomerular) capsule Proximal convoluted tubule Loop of Henle Distal convoluted tubule Collecting duct

Important Structures to pay attention to! • Renal Vein • Renal Artery • Renal Cortex

Renal Artery • An artery that is going TOWARDS the Kidney and sending blood AWAY from the heart. • Main Function is to carry oxygenated blood to the Kidney. • Interesting Condition- Stenosis. Narrowing of the Renal Artery, Causes major damage and high blood pressure.

Renal Vein • A vein or blood vessel that is carrying deoxygenated blood AWAY from the kidney and carrying blood TOWARDS the heart. • Main function- Recirculation of deoxygenated blood back to the heart. • The kidneys receive a lot of blood flow, about 25% of the total output of the heart, among the highest of any organ.

Thrombosis • Another condition- Caused by severe dehydration, or random clotting in the renal vein. • Can cause urine to have a red bloody look to it.

Renal Cortex • Forms a continuous smooth outer zone with a number of projections (cortical columns) that extend down between the pyramids. • In other words, the tissue of what the inner layer of the kidney is made out of.

Urine • Filtrate- the fluid that results from filtration occurring in the kidneys. Water is filtered out from other wastes – Includes: • • Water Glucose Ions Amino acids

Tubular Reabsorption • Materials not reabsorbed – Nitrogenous waste products • Urea—protein breakdown • Uric acid—nucleic acid breakdown • Creatine—associated with creatine metabolism in muscles

Characteristics of Urine • Solutes normally found in urine – Sodium and potassium ions – Urea, uric acid, creatine – Ammonia – Bicarbonate ions

Characteristics of Urine • Solutes NOT normally found in urine – Glucose – Blood proteins – Red blood cells – Hemoglobin – White blood cells (pus) – Bile

Ureters • Slender tubes attaching the kidney to the bladder – Continuous with the renal pelvis – Enter the posterior aspect of the bladder • Runs behind the peritoneum • Peristalsis aids gravity in urine transport

Urinary Bladder • Smooth, collapsible, muscular sac • Temporarily stores urine • Trigone—triangular region of the bladder base – Three openings • Two from the ureters • One to the urethra – In males, the prostate gland surrounds the neck of the bladder

Urethra • Function – Females—only carries urine – Males—carries urine and is a passageway for sperm cells