The urinary system functions to remove waste from the blood, regulate fluid and electrolyte balance, and produce hormones. It is composed of the kidneys, ureters, urinary bladder, and urethra. The kidneys filter the blood to form urine, reabsorbing useful molecules while collecting waste to be excreted. Through intricate tubular transport, the nephron precisely regulates fluid and solute levels in the blood and produces concentrated urine for excretion.
5. A Kidney
Blood and waste enter
through renal artery
Filtered blood leaves
through renal vein
Excess water and toxic
waste leaves through ureter
as urine
14. Proximal Convoluted
Tubule
Reabsorbs: water, glucose,
amino acids, and sodium.
• 65% of Na+ is reabsorbed
• 65% of H2O is reabsorbed
• 90% of filtered bicarbonate (HCO3
-)
• 50% of Cl- and K+
15. Loop of Henle
Creates a gradient of increasing
sodium ion concentration towards
the end of the loop within the
interstitial fluid of the renal pyramid.
• 25% Na+ is reabsorbed in the loop
• 15% water is reabsorbed in the loop
• 40% K is reabsorbed in the loop
16. Distal Convoluted
Tubule
Under the influence of the hormone
aldosterone, reabsorbs sodium and
secretes potassium. Also regulates
pH by secreting hydrogen ion when
pH of the plasma is low.
• only 10% of the filtered NaCl and 20% of water
remains
17. Collecting Duct
Allows for the osmotic
reabsorption of water.
ADH (antidiuretic hormone)- makes
collecting ducts more permeable to
water-- produce concentrated urine
18. From the original 1800 g NaCl, only 10 g appears in the urine
Urine
Water- 95%
Nitrogenous waste:
• urea
• uric acid
• creatinine
Ions:
• sodium
• potassium
• sulfate
• phosphate
20. When bladder fills with 200 ml of
urine, stretch receptors transmit
impulses to the CNS and produce a
reflex contraction of the bladder
(PNS)
Diuresis (Micturition)
When is incontinence normal?
21. Why do doctors ask for
a urine sample?
Urinalysis
characteristics:
• smell- ammonia-like
• pH- 4.5-8, ave 6.0
• specific gravity– more than 1.0;
~1.001-1.030
• color- affected by what we eat: salty
foods, vitamins
22. odor- normal is ammonia-like
diabetes mellitus- smells fruity
or acetone like due to elevated
ketone levels
diabetes insupidus- yucky
asparagus---
Odor
23. Color- pigment is urochrome
Yellow color due to metabolic
breakdown of hemoglobin (by bile or
bile pigments)
Beets or rhubarb- might give a urine
pink or smoky color
Vitamins- vitamin C- bright yellow
Infection- cloudy
Color
24. Water: s.g. =
1g/liter;
Urine: s.g. ~
1.001 to 1.030
Specific Gravity
When urine has high
s.g.; form kidney stones
Diabetes insipidus- urine has
low s.g.; drinks excessive water;
injury or tumor in pituitary
25. pH- range 4.5-8 ave 6.0
vegetarian diet- urine is alkaline
protein rich and wheat diet-
urine is acidic
30. • Ketone
• RBC
• Hemoglobin
• Bile
• WBC
• Casts
Abnormal Constitutes of Urine
31. INQUIRY
1. List several functions of the kidneys.
2. What does the glomerulus do?
3. What are several constitutes you should not
find in urine?
4. What is specific gravity?
5. What two hormones effect fluid volume and
sodium concentration in the urine?
6. Where are the pyramids located in the
kidney?
7. What vessel directs blood into the
glomerulus?
8. Where does most selective reabsorption occur
in the nephron?
