Lesson 1 and lesson 2

Describe the composition of urine, including the common solutes found in urine.
1. 95% water
2. Urea main solute (50%) aka waste product from protein and amino acids from liver
3. Creatinine, uric acid, K, Na, hormones, vitamins, meds
State the normal volume for daily urine output.
1. 1200-1500 mL of day or 600-2000 mL
2. Depends on amount of fluid, non-renal fluid loss, anti-diuretic hormone ADH, need to excrete increased amounts of dissolved solids (glucose)
Define the following terms:
1. Oliguria- decrease in urine >400 mL bc of dehydration, diarrhea vomiting
2. Anuria- Cessation of urine flow bc of kidney damage or decreased blood flow
3. Polyuria- excessive urination bc of diabetes, adh suppressors, diuretics, caffeine, alcohol
4. Nocturia- Increased nightly urination
Describe the appropriate collection for a urine specimen including:
1. Container- wide mouthed and clear
2. Labeling- patient name, date and time collected, label on container not lid
3. volume needed for testing- 12 ml
4. transport and handling- needs to be tested within 2 hours of collection or refrigerated and stored properly if more than 2 hours
5. Preservative- Should preserve formed elements in sediment, be bactericidal (kills contaminants), not interfere with chemical testing, and inhibit urease
List the advantages of using urine preservatives.
1. Refrigeration- Easiest, decreases bacterial growth and metabolism
2. Thymol- Preserves glucose and sediments, inhibits bacteria and yeast
3. boric acid- Preserves protein and formed elements, inhibits bacteria for 24 hrs
4. formalin-Preserves sediments and formed elements
5. acetic acid- Bactericidal for aldosterone, catecholamines, metanephrines, etc
Describe the physical and chemical changes associated with unpreserved urine.
1. Can result in color change bc of altered solutes
2. Increased odor bc of bacterial growth
3. Decreased clarity bc of solute precipitation
4. False negative chemical results bc glucose and pH are removed
5. Microscopic changes- deterioration of RBCs, WBCs, and casts
Explain the following urine collection techniques:
1. random collection -Most common and collected any time
2. first morning void- Urine that’s been stored in bladder for > 8 hours and delivered within 2 hours of collection. Highly concentrated and useful for evaluating protein, chemicals, formed elements, and pregnancy testing
3. 2-hour- Collected before a meal and 2 hours after a eating to monitor insulin and diabetics
4. 12-hour or 24-hour timed- Bc solute concentration varies, urine collected for 12 or 24 hours with proper preservatives. Should end with an empty bladder. Mixed and aliquoted for testing
5. midstream clean catch-Catch urine to eliminate contamination. Patient is cleaned and midstream sample is collected “true elements”
6. catheterization-Urine collected through a catheter- helps avoid contamination for cultures and sensitivity testing
7. supra pubic aspiration- Needle through bladder for urine collection to help avoid contamination
8. pediatric collection bag-For babies and kids
List reasons for specimen rejection.

Mislabeled or unlabeled container
Contamination specimen
Not enough quantity
Improper transportation or preservative
Improper collection and storage
Light temp.
Differentiate parts of the urinary tract and their function:
1. Kidney- Filters blood and waste. Regulates electrolytes, chemical balance, and BP
2. Ureter- Connects kidney to bladder
3. Bladder- Stores urine
4. Urethra-Connects to bladder to outside body
Distinguish parts of the kidney and their function:
1. Medulla- Inner layer of kidney
2. renal pelvis- Funnel shaped structure at the indented part of the kidney. Receives urine from calyces and transfers to ureter
3. cortex-Site of plasma filtration
4. papilla-Located in medulla and has papillary ducts that empty into calyx
5. Nephron- Functional unit of kidney- important for formation and final composition of urine
Differentiate parts of the nephron and their function:
1. Glomerulus- Network of capillaries surrounded by the bowman’s capsule
2. Mesangium- Lies between the capillary endothelium and podocytes. The phagocytic and pinocytic cells form the tissues of the glomerulus
3. capillary endothelium- Supports filtration of plasma
4. basement membrane-Filtration barrier of glomerulus. Filters solute based on size
5. podocytes-Glomerular epithelial cells
6. bowman's capsule- Proximal end of renal tubule that surrounds the glomerulus
7. proximal convoluted tubule- adjacent to glomerulus. Convoluted tubule becomes straight as it enters medulla and becomes loop of Henle
8. thick and thin descending- Straight part of proximal convoluted tubule (goes down)
9. Loop of Henle- Tubular part of nephron that forms U shape. Has thick and thin descending and ascending limbs
10. distal convoluted tubule- Tubule that follows immediately after loop of Henle. After 2-3 loops it becomes the collection tubule/duct
11. thick and thin ascending- Straight part of distal convoluted tubule
12. collecting duct- Collection tank for several distal convoluted tubules. Final site of concentration of urine.
13. afferent arteriole- Renal artery that supplies blood to glomerulus
14. efferent arteriole- Where the blood leaves the glomerulus
15. peritubular capillaries- Capillaries that surround the tubules of the nephron
  1. Reabsorption of substances
16. vasa recta- Vascular network of capillaries that surround loop of henle
  1. Major exchange of water and salts
List the three processes of urine formation.
1. Plasma (glomerular) filtration
2. Reabsorption of certain components by renal tubules
3. Secretion of selective components by renal tubules
Explain the filtering process of the glomerulus.
1. Describe the three layers of the glomerulus-
  1. Capillary epithelium membrane- fenestrated contains open pore that increase permeability but don’t let large molecules with negative charges through
  2. Tri-layer basement membrane- restricts passage of large molecule
  3. Visceral epithelium of Bowman' s capsule- podocytes created filtration slits and it is covered with negative charge
Explain the Renin-Angiotensin-Aldosterone System (RAAS) and how it works to regulate sodium and blood pressure. Responds to changres in BP and plasma sodium concentration
1. Describe what happens in the body when there is increased or decreased sodium in the plasma.
  1. Low sodium in plasma- water retention decreased = decreased BV and BP
  2. Response- renin an enzyme is secreted in blood and produces Angiotensin 1. This hormone passes through the lungs. Angiotensin converting enzymes convert angiotensin 1 into 2 = blood flow corrected through
    1. vasodilation of afferent arterioles
    2. Constriction of efferent arterioles
    3. Reabsorption of sodium and release Aldosterone- triggers body to retain sodium and water
  3. High sodium in plasma- water retention increased
    1. Increased BV and BP
  4. Response- renin secretion inhibited and sodium excretion enhanced

Basically. Body will regulate secretion of renin if bp and Na drops

Compare and contrast active and passive reabsorption.
1. Active- Need carrier protein. Substances will reabsorb in
  1. proximal convoluted tubule- glucose, amino acids salt
  2. Loop of Henle- Chloride
  3. Distal convoluted tubule- sodium
2. Passive- needs no energy. Substance moves from low to high or high to low. Substances reabsorb passively in
  1. All parts of nephron except ascending loop of henle- water
  2. Proximal convoluted tubule- urea
  3. Ascending loop of henle- urea and Na
State the location(s) of the nephron where water is reabsorbed.
1. Distal convoluted tubule
2. Descending limb of loop of Henle
3. Collecting duct

Define renal threshold and maximal reabsorptive capacity.
1. Maximal reabsorptive capacity- when filtrate concentration is at its maximum and the substance spills into urine.
2. Renal threshold- maximum that is reached
List the final site of urine concentration.
1. The collecting duct
Explain the function of Antidiuretic Hormone (ADH) and it's affect on urine volume/concentration.
1. Antidiuretic hormone controls permeability of the cells of the collecting duct to water.
  1. Increased ADH- increased permeability to water = low volume of concentrated urine
  2. Decreased ADH- decreased permeability to water = high volume of diluted urine
  3. ^ body hydration = lower ADH = more urine volume
  4. Decreased body hydration = higher ADH = low volume of urine
2. AdH- body's water saver
3. Collecting duct is a pipe with water channels that open and close. ADH opens the holes so water leaks out of urine and goes back into blood = more yellow
4. No ADH holes stayed close so water goes into urine and out the body
State the normal pH of blood.
1. 7.35-7.45
Explain the three mechanisms for renal acid-base regulation.
1. Tubular secretion helps release waste products and secrete hydrogen ions to regulate acid-base balance
2. Kidneys slowest but strong.
3. First line of defense: Blood buffer system- When bicarbonate ions are filtered by the globulus and returned to the blood, the renal tubular cells need to secrete hydrogen ions into the plasma to prevent HCO3- loss in urine.
  1. Too much Acid (^ H+ ) Bicarbonate HCO3- will bind with H+ to neutralize the acid
  2. Too much base ( decrease H+) carbonic acid H2CO3 released H+ to neutralize the base
4. Pulmonary System- Lungs regulate CO2 in the blood which combines with H2O to form H2CO3. Faster breathing eliminates CO2 from the lungs and less h2co3 is formed= pH rises. Slower breathing reduces CO2 so pH falls
5. Renal system- Absorbs or exretes acid and bases. Kidney produces hco3- to make up the loss.
  1. When blood is acidic- kindey reabsorbs HCO3- and excretes H+
  2. When blood is alkaline, kidneys excrete HCO3- and retain H+
6. Ammonia buffer system- Kidney produces NH3 to bind to free H+ to form NH4 then excrete it = gets rid of excess acid