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Home , Renal medulla

Urinary System Excretory vs. – what is the difference? Urinary System – 3 functions

• Excretion • Remove nitrogenous wastes from the blood • Elimination • Micturition • Discharge of wastes to the environment • Maintains homeostasis of the plasma • Electrolyte balance • Water balance • Acid-base balance of blood Micturition Process that expels from the bladder • Stretch receptors activated as urine accumulates (at 150 mL); fullness continues to intensify contracts • Forces urine past the internal urethral sphincter • External urethral sphincter is under voluntary control until 600 mL Micturition reflex center • triggered by distension of the bladder • located in the spinal cord Neural and emotional factors may lead to incontinence • Inability to control voiding • Normal in infants until they learn to control external sphincter Automatic bladder • Complete loss of voluntary control over urination • Catheritization Urinary System • Pair of kidneys • Produce urine • Pair of • Use peristalsis to pass urine to bladder • • Temporarily stores the urine • • Sends urine to exterior • 8 in. males; 1.5 in. females Urinary System HW Check Urinary System HW Check

Kidneys

Characteristics • Reddish brown in color, bean shaped, smooth surface Location • Either side of vertebral column • Positioned retroperitoneally • Posterior wall of abdominal cavity • Near back muscles in a depression • Adipose and connective tissue Kidneys - Structure • Lateral side (convex) • Medial side (concave) • Medial depression (hilum) leads to Two distinct regions • (inner) • Renal columns • Renal pyramids • • Collecting Ducts • Pelvis • Renal (outer) • • Basin like area of ; joins the • PCT • DCT • Calyx Capsule • Extensions of the pelvis that drains the • Fibrous membrane apex of the pyramid surrounding the kidney • Renal Columns • Cortex like tissue that runs through the medulla

Kidneys - General Functions • Remove nitrogenous wastes from the blood to form urine • , reabsorption, secretion • Regulate metabolic processes • Maintains electrolyte and water balances • Maintains the acid-base balance of the blood • Secretes for blood cell formation • Use of • regulates blood pressure Renal Disease • Kidney transplant • result of end stage renal disease • Hemodialysis • Direct with blood • Peritoneal dialysis • Within abdominal cavity Kidney Vessels Renal arteries • supply kidneys with blood • enters at the hilum

Renal veins • carries blood from the kidneys back to the heart • Exits at hilum Kidney Vessels

or cortical radiate arteries

or cortical radiate veins “Functional unit of the kidney” • composed of a glomerulus • cluster of blood capillaries • surrounded by Bowman’s/glomerular capsule Renal Tubule • PCT, Loop of Henle, DCT • increase SA & efficiency of the kidney Urinary System HW Check Nephrons – Urine Formation

1. glomerular filtration (glomerulus to Bowman’s capsule) 2. tubular reabsorption (PCT and Loop of Henle) 3. tubular secretion (DCT ) Glomerular Filtration

Water and dissolved substances are filtered out of the glomerulus • Diffusion & active transport

Glomerular filtrate • Similar to plasma • mostly water, salt, , amino acids, and • Sent into the proximal convoluted tubule Rate of Filtration • Related to pressure • 125 mL/minute • 180,000 mL/24 hours (~45 gallons) • Most of the fluid is reabsorbed into the plasma

• Glomerulonephritis • Protein in urine and edema

• Shock • result of bp dropping • causes pressure in glomerulus to drop Regulation of Filtration Increases when excess fluid is present Decreases when fluid needs to be conserved Renin • acts with angiotensinogen  II • angiotensin II maintains sodium and water balances and blood pressure by vasoconstricting the • Also stimulates release of for Na to be reabsorbed

Too much renin results in hypertension • Ace inhibitor to inhibit angiotensin II Tubular Reabsorption Primarily in the proximal convoluted tubule • Contain dense microvilli

Substances are transported out of the filtrate and back into the blood

• Glucose, H2O, amino acids, albumin R ole of Na+ in transport of negative ions • chloride, phosphate, bicarbonate

Glucosuria glucose in the urine Indicator of possible diabetes Tubular Secretion • Certain substances leave the plasma and enter the renal tubule • H and K ions are usually added to filtrate • Occurs in the PCT and DCT • Increases some urinary excretions (begin at 3:45) http://www.bozemanscience.com/osmoregulation

• What organ do we use for osmoregulation?

• What is inside our kidneys?

• What happens on the descending side of the loop of Henle?

• What happens on the ascending side of the loop of Henle?

• What hormone regulates water reabsorption in the collecting duct?

• What is responsible for urine’s color? The Entire Process – This diagram will be VERY useful in Lab Components of Urine • Blood composition dependent on diet, cellular metabolism, and urine output • Urine content dependent on diet and exercise • 180 liters of blood filtered producing 1-1.8 liters of urine produced daily • 95% water, urea, uric acid, amino acids, electrolytes • 3 main components urea, uric acid, creatine Regulation of Urine Concentration ADH (antidiuretic hormone) released when concentration of water in the blood decreases • water retaining hormone; water leaves the collecting duct • If too low  polyuria Regulation of Urine Concentration Aldosterone • hormone that stimulates additional reabsorption of sodium from the collecting duct • Increases bp • Can be released in the presence of angiotensin II Urine Content Urine Production

Uric acid 1-1.8 liters/day • Nucleic acid catabolism Volume influenced by • 10% excreted • fluid intake • gout • environmental and body temp. Urea • emotional condition • Amino acid catabolism • respiratory rate • 50% reabsorbed

Water loss determined by kidneys depends on … • Evaporation of water from lungs or perspiration on skin Start Lab Turn in what you have finished before leaving Changes in Urine Production

Polyuria • excess production of urine • > 2.5 liters in 24 hours Oliguria • scanty amounts of urine • < 500 ml in 24 hours Anuria • absence of urine • < 70 ml in 24 hours Prostate Cancer Kidney Stones • uric acid, calcium, or magnesium • collecting ducts and renal pelvis • pain from ureter stretching • 60% pass on their own • Sound waves (lithotripsy) Cystitis •bladder infection •bacterial or from residual urine

More common in females – Why? Urinalysis • Reveal diseases • diabetes, glomerulonephritis, chronic UTI • Paper or plastic dipstick • Microscopic observations • Uric acid crystals – normal

Uric acid crystals are increased pathologically in urine in gout and in leukemia being treated with Begins with a visual observation chemotherapy Normal: • Pale to dark yellow • Clear • 750-2000 ml/24 hour Not normal but not disease • Turbidity • Excessive cellular material or protein • Red or red-brown color • Food dye • Increased RBC Urinalysis Dipstick screening: pH • 6 is normal • Range is 4.5 – 8.0 Protein Glucose Ketones • diabetes or starvation Nitrite • Presence of bacteria Microscopic Analysis: RBC • Should not be present • Could indicate: glomerular damage, tumors of the urinary tract, kidney trauma, urinary tract stones, renal infarcts, UTI infection

WBC There are white blood cells, bacteria and mucus present. • UTI infections The number of white blood cells could suggest the or associated presence of a urinary tract infection. If the white blood STI’s cells were not present, the bacteria could indicate a poorly collected or unpreserved specimen. Microscopic Analysis: Epithelial Cells (black arrows) • Present in small numbers • Indicates tubular degeneration

CASTS • Formed in or the collecting duct • RBC cast indicative of glomerulonephritis

• WBC cast indicative of end stage renal disease Microscopic Analysis: Crystals • Calcium oxalate (blue arrow) • Triple phosphate • Cystine • Severe liver diseases Calcium oxalate crystals (shown above blue arrow) can be present in urine when oxalate-rich foods such as tomatoes, spinach, garlic, oranges, and asparagus are ingested.