by : Ms. Crizelda Liwanag

1. • Renal Anatomy
• Renal Blood Flow
• Renal Physiology
• Urine formation
– Glomerular Filtration
– Tubular Reabsorption
– Tubular Secretion

2. Renal Anatomy

3. kidney
What is the average weight of the kidney?
115-170 g
What is its average size?
11 cm in length, 6 cm in width, 3 cm thick
What is the rate of blood flow into the kidney via
the renal artery?
600 mL/min

4. kidney

5. Cortex
• Renal corpuscles
• Proximal tubules
• Distal tubules
Medulla
• Loop of Henle
• Vasa recta
• Collecting
tubules
2 regions of the kidney

6. What is the functional unit of the kidney?
of the kidney?
NEPHRON

7. Renal Blood Flow
3a
2
1
3b

8. Renal Blood Flow

10. 1 2
3a
4a
3b
5b
7b
4b
5a
6a
6b
8b

11. Renal Physiology
MAJOR FUNCTIONS
The Body’s Filters: removing toxins &
metabolic waste products
• Ultrafiltration
• Endocrine function
• Osmolarity regulation
• Volume regulation
• Acid-base regulation

12. ultrafiltration

13. ultrafiltration
Of the renal blood flow, how much is filtered
by the glomerulus?
125 mL/min
How many liters of blood is filtered by the
kidney each day?
180 liters
How much urine is produced per day?
1.5 liters

14. ultrafiltration
The kidneys possess extraordinary
mechanisms to reabsorb water while
removing metabolic waste by-products
and toxins.
How is kidney function measured?
GFR
Glomerular Filtration Rate

15. Endocrine function
1. Erythropoietin
2. Active form of vitamin D (1,25-
dihydroxy vitamin D3)
3. renin

16. Osmolarity regulation
ADH – synthesized in the hypothalamus &
released in the posterior pituitary in
response to an increase in osmolarity as
sensed by osmoreceptors in the anterior
hypothalamus

17. ↓BP ↓PLASMA VOL ↑OSMOLARITY
↓venous pressure ↓venous return ↓ atrial pressure
↑ ADH secretion
↑ tubular permeability to water
↑ water reabsorption
↓ water excretion ↓ urine volume ↑ urine osmolarity

18. Volume Regulation
Regulation of ECF volume thru the
• Renin-Angiotensin-Aldosterone (RAA)
pathway
• Atrial Natriuretic Factor (ANF)

19. ↓BP ↓PLASMA VOL ↓Na
↑ Renal symp nerves ↓ renal arterial pressure
↑ renin secretion (into afferent arteriole)
↑ plasma angiotensin (from adrenal cortex)
↑ aldosterone secretion
↑ tubular Na reabsorption ↓ Na excretion
↓ arterial pressure
ANF

20. Volume Regulation
Atrial Natriuretic Factor (ANF)
• Secreted by the cells in the atria of the
heart to inhibit Na+ reabsorption in the
kidneys
• Inhibits secretion of aldosterone which
stimulates Na+ reabsorption

21. Acid Base Regulation

22. Acid Base Regulation
• To excrete X’s alkali:
– Na2HPO4
– NaHCO3
• To excrete X’s acid:
– NH4Cl
– (NH4)2SO4
– NaH2PO4

23. What is the first step in urine formation?
GLOMERULAR FILTRATION

24. Glomerular Filtration
The filtration of a solute that is not
reabsorbed or secreted
Unit: mL/min
Affected by: hydrostatic & oncotic pressure,
Renin-angiotensin-aldosterone system,
structure

25. Glomerular Filtration
Substances retained:
• Blood cells
• Serum proteins
• Substances filtered:
• Water
• Smaller molecules
(MW: <70,000)
– Ions
– Amino acids
– Glucose
– Urea
– Creatinine
– Uric acid
– ammonia

26. Glomerular Filtration
• Approximately 20% of the volume of plasma
that passes through the glomerular tuft is
caught in Bowman’s space and is called the
glomerular filtrate.
• At this point, the filtrate is iso-osmotic with plasma and is
called an ultrafiltrate. (sp. gr. 1.010 +/-0.002 ; pH 7.4)

27. What barriers are there to
the passage of the filtrate?
• Endothelium (glomerular capillary)
• Basement membrane
– Lamina rara interna
– Lamina densa
– Lamina rara externa
• Podocytes (visceral layer)

29. Glomerular Filtration

30. Glomerular Filtration
• To pass through the filtration barrier:
– <4 nm in size
– Threshold

31. Glomerular Filtration

32. Tubular Reabsorption
• The movement of substances (by active or
passive transport)
– from the tubular ultrafiltrate into the
peritubular blood or the interstitium by the
renal tubular cells.

33. Tubular Reabsorption
Substances reabsorbed by active transport:
• Glucose, Amino acids, Salts (PCT)
• Chloride (LOH)
• Sodium (DCT)

34. Tubular Reabsorption
Substances reabsorbed by passive
transport:
• Water (all nephron parts except ascending
limb)
• Urea (PCT, ascending limb)
• Sodium (ascending limb)

35. Tubular Secretion
• The movement of substances (by active or
passive transport)
– from the peritubular blood or the interstitium
into the tubular ultrafiltrate by the renal tubular
cells
• To secrete substances the kidney is
unable to eliminate via ultrafiltration

36. Tubular Secretion
• Substances incompletely metabolized
– E.g. thiamine
• Substances not metabolized at all
– E.g. radiopaque contrast media / mannitol
• Substances not normally present
– Certain drugs

37. SUMMARY
• Close your notes...

39. •Glomerulus
FILTRATION: water (ADH not required)., Na+, Glucose, K+,
Cl-, Urea, Urate, Uric Acid, Proteins, Amino acids,
Bicarbonates, Creatinine, Phosphate, Inulin, PAH
REABSORPTION: --
SECRETION: --
•Proximal Tubule
Isotonic filtrate
FILTRATION: --
REABSORPTION: Water (ADH not required), Na+, Glucose,
K+, Cl-, Urea, Urate, Uric Acid, Proteins, Amino
acids, CO2

40. •Proximal Tubule
SECRETION: Creatinine, Hydrogen, PAH
•Loop of Henle
Hypertonic filtrate
REABSORPTION: Water, Na+, Cl-, Urate, Urea, CO2
SECRETION: --
•Distal Tubules
Area of dehydration (where ADH acts)
Iso or hypotonic filtrate; most common area of cast form’n
REABSORPTION: Water (ADH required), Na+, Cl-, Urate,
Urea, CO2
SECRETION: K+, Uric Acid, H+

41.  Collecting Duct
Hypertonic or Hypotonic filtrate
REABSORPTION: Water (ADH required), Na+, Cl-, Urate,
Urea, CO2
SECRETION: K+, H+