Biology urinary

1. The Urinary System
Department of
histology, cytology and
embryology
Kharkiv National
Medical University
Ukraine 2012
Lecture
for medical students

2. System Integration
food, water intake oxygen intake
elimination
of carbon
dioxide
Digestive System Respiratory System
Circulatory System
Urinary System
elimination of
excess water
salts, wastes
rapid transport
to and from all
living cells
elimination
of food
residues
nutrients,
water,
salts
carbon
dioxide
water
solutes
oxygen

3. The Urinary System
• Paired kidneys
• A ureter for
each kidney
• Urinary bladder
• Urethra

4. • ureters – muscular tubes connecting
renal pelvis to urinary bladder
• urinary bladder – distensible reservoir;
receives bilateral ureters and empties
via midline urethra
smooth muscle forms detrussor
muscle; specialized distally as
internal urethral sphincter

5. RENAL PARENCHYMA
• RENAL PYRAMIDS
–EXTENSIONS OF CORTEX (RENAL
COLUMNS) DIVIDE MEDULLA INTO 6 – 10
RENAL PYRAMIDS
–PYRAMID + OVERLYING CORTEX = LOBE
–POINT OF PYRAMID = PAPILLA
–PAPILLA NESTED IN CUP (MINOR CALYX)
–2 – 3 MINOR CALICES  MAJOR CALYX
–2 – 3 MAJOR CALICES  RENAL PELVIS
–RENAL PELVIS  URETER

6. KIDNEY FUNCTIONS
• FILTER BLOOD PLASMA, ELIMINATE WASTES
• REGULATE BLOOD VOLUME, PRESSURE
• REGULATE FLUID OSMOLARITY
• SECRETE RENIN
• SECRETE ERYTHROPOIETIN (EPO)
• REGULATE PCO2, ACID-BASE BALANCE
• SYNTHESIZE CALCITROL (VITAMIN D)
• DETOXIFY FREE RADICALS, DRUGS
• GLUCONEOGENESIS

7. Kidney Functions
• Regulation of blood ionic composition
• Regulation of blood pH
• Regulation of blood volume
• Regulation of blood pressure
• Maintenance of blood osmolarity
• Production of hormones
• Regulation of blood glucose levels
• Excretion of waste and foreign substances

8. Urinary System Function
• Removal of toxic waste products
• Regulation of blood volume
• Regulation of electrolyte balance
• Regulation of acid-base balance
• Regulation of fluids/electrolytes in
tissue fluid
• Production of erythropoietin*

9. 9

10. Cortex

11. NEPHRONS
• FUNCTIONAL UNITS OF KIDNEY
• ~1.2 MILLION PER KIDNEY
• THREE MAIN PARTS
–BLOOD VESSELS
–RENAL CORPUSCLE
–RENAL TUBULE

12. Nephron – functional unit of kidney

13. RENAL CORPUSCLE
• GLOMERULUS PLUS CAPSULE
• GLOMERULUS ENCLOSED IN TWO-
LAYERED GLOMERULAR CAPSULE
–“BOWMAN’S CAPSULE”
• FLUID FILTERS FROM GLOMERULAR
CAPILLARIES
–“GLOMERULAR FILTRATE”
• FLUID COLLECTS IN CAPSULAR SPACE
• FLUID FLOWS INTO RENAL TUBULE

14. RENAL TUBULE
• LEADS FROM GLOMERULAR CAPSULE
• ENDS AT TIP OF MEDULLARY PYRAMID
• ~3 CM LONG
• FOUR MAJOR REGIONS
–PROXIMAL CONVOLUTED TUBULE
–NEPHRON LOOP
–DISTAL CONVOLUTED TUBULE
–COLLECTING DUCT

15. URINE FORMATION
OVERVIEW
• BLOOD PLASMA  URINE
• FOUR STEPS
–GLOMERULAR FILTRATION
–TUBULAR REABSORPTION
–TUBULAR SECRETION
–WATER CONSERVATION

18. Renal Corpuscle

19. histology of urinary system 19
RENAL CORPUSCLE

20. III. Renal Corpuscle
Secondary processes interdigitate around glomerular
capillaries. The narrow space between processes is
the filtration slit.

21. Glomerulus & Podocyte

22. Structure
• consists of (1) glomerulus and (2) Bowman’s capsule
– glomerulus – tufts of capillaries; fed by afferent arteriole
and drains to efferent arteriole
– Bowman’s capsule – double-walled (visceral and
parietal) epithelial capsule
– ~ 200 micrometers diameter
– urinary pole – leads to proximal convoluted tubule;
route of filtrate
– vascular pole – site of afferent (incoming) and efferent
(outgoing) arterioles supplying glomerulus
Renal Corpuscle – site of filtration

24. EM structure of Glomerular Filtration Barrier

25. Proximal tubule cells

26. Structure
tubules formed by simple cuboidal epithelia
apical surface covered with microvilli creating LM
brush border
- increase surface area for ion absorption
 cells tightly bound to one another to seal off
intercellular space from lumen
- tight junctions and zonula adherens apically;
interdigitating plicae (folds) laterally
interdigitating basal processes contain numerous
mitochondria; creates LM basal striations; associated
with ion transport
Proximal convoluted tubule

28. • located within cortex
• approximately 1/3 as long as proximal
• contacts renal corpuscle at macula densa
to form juxtaglomerular apparatus
(below)
• morphology similar to straight portion
• function: ion exchange
Distal convoluted tubule

29. Distal convoluted (shorter)

31. Medulla

32. The thin limb of the loop of Henle

33. Histologically the ascending thick limb & the distal
convoluted tubules are the same

34. Collecting tubules

35. Collecting duct

36. Thin limbs of the loop of Henle

37. Cortical and Juxtamedullary Nephrons

38. 38histology of urinary system
Nephrons

40. Juxtaglomerular Apparatus

41. Juxtaglomerular apparatus

42. Juxtaglomerular apparatus

43. Ansa(loop)of Henle

44. Comparison of the tubule

45. • Start in cortex and descend through medulla
• as ducts coalesce and increase in size, cells of tubes
change from somewhat squamous to cuboidal to
columnar
• terminate at tip of renal pyramid where urine
enters into minor calyx
• distinguishable cell margins
• central nuclei with poorly staining cytoplasm
• At EM level many possess single cilium and sparse
microvilli
Collecting tubules / ducts

46. Histological structure of calyces, renal pelvis, ureter and
urinary bladder broadly similar
mucosa – lined by transitional epithelium over connect
tissue lamina propria
transitional epithelium – impermeable to water and
salts; distendable
lamina propria- dense irregular collagen fibers
muscularis – smooth muscle layer
bi-laminar: inner longitudinal and outer circular;
produce peristalsis
adventitia / serosa – connective tissue coat with or
without mesothelial covering
Ureter / Bladder

47. Ureter

50. Transitional epithelia changes depending
on how full the urinary bladder is

51. Dome cells

52. • fibromuscular tube connecting bladder to external
urethral orifice
• sexually dimorphic
males – terminal duct for both urinary and genital
systems
females – urinary system only
• lining – in both sexes grades from transitional
epithelium adjacent to bladder to stratified
squamous at orifice
males have stratified columnar or pseudostratified
columnar in middle portion
Urethra