3. Introduction to urine
Definition: Waste product that excreted by the
kidneys.
Major components of the urinary system include:
Kidneys – Urethra – Urinary bladder – Ureter.
Each Kidney composed of million functional structure
units known as nephrons.
4. The kidney composed of:
1. Glomerular capsule: also known as Boman’s capsule
and it contain the glomeruli.
2. Proximal tubules.
3. Loop of Henle: it contain Descending distal tubule
and Ascending distal tubule.
4. Collecting duct.
5. The Kidney and the Nephron
A. Renal Vein
B. Renal Artery
C. Ureter
D. Medulla
E. Renal Pelvis
F. Cortex
1. Ascending loop of Henle
2. Descending loop of
Henle
3. Peritubular capillaries
4. Proximal tubule
5. Glomerulus
6. Distal tubule
6.
7. Urine is regulated by three processes which are:
1. Filtration : Take place in the glomerulous.
2. Reabsorption: Take place in the tubules.
3. Secretion: from the small blood vessels around the
tubules.
11. Function of the urinary system:
1. Regulation of the water content in the body.
2. Excrete the waste products of metabolism.
3. Formation of Erythropoietin and vitD.
4. Maintain the PH of the blood (7.34 – 7.45).
5. Maintain the correct electrolytes balance in the
body
6. Reabsorption of certain substances of value to the
body such as glucose.
12. 7. Production of Renin which stimulate the production
of Aldosterone hormone.
Glomerular Filtration Rate (GFR):Rate or volume of
blood filtrated with in 1 minute in the glomeruli,
normally about 125ml/minute.
Renal Threshold: ability of the kidney to reabsorb
substance of value to the blood after filtrated ( Renal
threshold of glucose = 180 mg/dl).
13. Hormones Produced by the Kidney
Renin:
Released from juxtaglomerular apparatus when low blood flow or
low Na+. Renin leads to production of angiotensin II, which in turn
stimulate the secretion of aldosterone which leads to retention of
salt and water.
Erythropoietin:
Stimulates red blood cell development in bone marrow. Will
increase when blood oxygen low and anemia (low hemoglobin).
Vitamin D3:
Enzyme converts Vit D to active form 1,25(OH)2VitD. Involved in
calcium homeostasis.
14. Aldosterone:
Secreted by the adrenal glands in response to
angiotensin II or high potassium
Acts in distal nephron to increase resorption of Na+
and Cl- and the secretion of K+ and H+
ADH:
• High Na+ (blood is highly concentrated)
stimulates posterior pituitary to secrete ADH.
• ADH up regulates water channels on the collecting
ducts of the nephrons in the kidneys.
• This leads to increased water resorption and
decrease in Na concentration by dilution
15. What is Reabsorbed Where?
Proximal tubule - reabsorbs 65 % of filtered Na+
as well as Cl-, Ca2+, PO4, HCO3
-. 75-90% of H20.
Glucose, carbohydrates, amino acids, and small
proteins are also reabsorbed here.
Loop of Henle - reabsorbs 25% of filtered Na+.
Distal tubule - reabsorbs 8% of filtered Na+.
Reabsorbs HCO3-.
Collecting duct - reabsorbs the remaining 2% of
Na+ only if the hormone aldosterone is present.
H20 depending on hormone ADH.
16. Secretion
Proximal tubule – uric acid, bile salts, metabolites,
some drugs, some creatinine
Distal tubule – Most active secretion takes place here
including organic acids, K+, H+, drugs, Tamm-
Horsfall protein (main component of hyaline
casts).
17. Normal contents of the urine
Plasma Nephric
filtrate
Urine
Urea 0.03g/dl 0.03g/dl 1.8g/dl
Uric acid 0.004 g/dl 0.004g/dl 0.05g/dl
Glucose 0.1g/dl 0.1g/dl None
Amino acid 0.05g/dl 0.05g/dl None
Total
inorganic
salts
0.9g/dl 0.9g/dl 3.6 – 0.9g/dl
Protein 8g/dl None None
18. Urinanalysis
Urine can be analyzed by two ways:
1. Qualitative analysis.
2. Quantitative analysis.
Qualitative analysis include:
1. Macroscopical examination.
2. Microscopical examination.
The macroscopical examination also divided into:
19. 1. Physical examination.
2. Chemical examination.
Physical examination:
1. Volume: Normal range (1---2)L/day.
It depends on fluids intake, diets and physiological
condition.
Abnormality:
Polyuria: Increase urine volume more than 2L/day.
20. Causes:
1. DM. 2. Diabetes insipdus.
3. Chronic Renal Failure.
Oliguria: Decrease urine volume less than 1000ml/day
up to 500ml/day.
Causes:
1. Occur when GFR is reduced in case of acute
glomerular nephritis, ARF and nephrotic syndrome.
21. 2. When renal blood flow is reduced in case of
hypotension. Dehydration and cardiac disease.
Anuria: Volume of urine less than 100ml/day.
Occur in incompatible blood transfusion.
2. Appearance: normally is pale yellow due to certain
dye called urochrome.
Abnormality:
1. Colorless: polyuria.
22. 2. Deep yellow: Presence of urobilinogen in excess
amount.
3. Turbid: Presence of phosphate, albumin and
bacterial growth.
4. Red: Presence of Hb or RBCs.
5. Brown: presence in Black water fever and other
condition causing intravascular hemolysis.
6. White foams: : Presence of high conc. Of albumin.
23. 7. Yellow foam: Presence of high conc of bilirubin.
8. Milky: Presence of fat globules.
9. Black: Presence of hemogenstic acid.
10. Blue: Poison with dyes mainly hair dye.
3. Odor: Normally aromatic odor due to Presence of
organic acid.
May be change into ammonia odor in bacterial growth.
24. 4. PH: Normally slightly acidic (4.8—6.8).
Abnormality: Presence of PO4 and HCO3 in urine are
converted it into alkaline urine.
Presence of urate in high amount in urine lead to
acidity of it.
5. Specific Gravity: Density of the fluids compared
with the density of DW.
Normally (1.008---1.030).
