1. Excretory Systems semester-2 MBBS
Dr. Kumar K.V (14/2/2011)

2. Relationship of the Kidneys to Vertebra and Ribs

3. External Anatomy of Kidney
Paired kidney-bean-shaped organ
4-5 in long, 2-3 in wide, 1 in thick
Found just above the waist between the peritoneum & posterior wall of abdomen
retroperitoneal along with adrenal glands & ureters
Protected by 11th & 12th ribs with right kidney lower

4. Kidneys: Gross and Sectional Anatomy
Retroperitoneal
Anterior surface covered with peritoneum
Posterior surface against posterior abdominal wall
Superior pole: T-12
Inferior pole: L-3
Right kidney ~ 2cm lower than left
Adrenal gland on superior pole

5. Kidney Location
Lateral to vertebral column high on body wall, under floating ribs, in retro-peritoneal position (posterior to the parietal peritoneum)
The right kidney is slightly inferior to the left kidney in order to accommodate the liver
Surrounded by the renal capsule with a fat pad
12 x 6 x 3 cm
Bean shaped
Hilus – indentation
Retroperitoneal - between the body wall and peritoneum

6. Kidney External Anatomy
Average size – 12cm x 6cm x 3 cm
Weights 150 grams or 5 oz
Surrounded by three membranes (deep to superficial)
Renal capsule – fibrous barrier for kidneys.
Adipose capsule – fatty tissue designed for protection / stability.
Renal fascia – dense fibrous CTP anchors kidneys/ adrenals/ membrane 1 and 2 to surroundings.

7. Kidney - general information
Lie against posterior abdominal wall at level of T12-L3.
Right kidney is lower than left kidney due to the shape of the liver.
Lateral surface of kidney is convex while medial is concave.
Concave side has a cleft – Renal Hilus
Inside hilus is Renal sinus
Where kidneys receive renal vessels and nerves.

8. Kidneys: Gross and Sectional Anatomy
Surrounding tissues, from deep to superficial:
Fibrous capsule (renal capsule)
Dense irregular CT
Covers outer surface
Perinephric fat (adipose capsule)
Also called perirenal fat
Completely surrounds kidney
Cushioning and insulation
Renal fascia
Anchors kidney to posterior wall and peritoneum
Paranephric fat
Between renal fascia and peritoneum

10. External Anatomy of Kidney
Protective coverings of kidney
renal capsule---you will see in lab over sheep kidney
adipose surrounds that
layers of thin fascia hold everything against back body wall
peritoneum over all
Blood vessels & ureter enter hilus of kidney
Renal capsule = transparent membrane maintains organ shape
Adipose capsule that helps protect from trauma
Renal fascia = dense, irregular connective tissue that holds against back body wall

11. Kidney- External Anatomy
Lateral surface- convex
Medial is concave-
Renal Hilum
Opening to Kidney
Renal Sinus
Space within hilus
Kidneys receive blood vessels and nerves.

12. The Position of the Kidneys
Figure 26.2a, b

14. Figure 26.3 The Urinary System in Gross Dissection

15. Kidney Internal Anatomy I
Renal arteries and veins
Bring blood in and out of kidney
Renal cortex
Outer layer of Kidney
Renal medulla
Inner layer of Kidney
Nephron

16. Human Kidney

17. Kidneys: Gross and Sectional Anatomy
Minor calyx:
Funnel shaped
Receives renal papilla
8 to 15 per kidney, one per pyramid
Major calyx
Fusion of minor calyces
2 to 3 per kidney
Major calyces merge to form renal pelvis
Renal Lobe
Pyramid plus some cortical tissue
8 to 15 per kidney

18. a. Right renal vein enters IVC directly
Detailed Anatomy, cont …
2. Renal Veins
a. Right renal vein enters IVC directly
b. Left renal vein passes anterior to aorta, posterior to SMA, then into IVC
c. Venous pattern complex

19. Variations in Renal Veins
Note the duplication in the Left Renal Vein
Branches surround aorta

20. Origin of Renal, Gonadal Arteries
Note the right gonadal artery arising from the aorta, then branching to form the inferior capsular artery.
R and L Renal Arteries
Gonadal Arteries

21. d. R. renal artery courses from aorta posterior to IVC into hilus
Detailed Anatomy, cont …
d. R. renal artery courses from aorta posterior to IVC into hilus
e. Left renal artery course is from aorta directly to hilus
f. May see 2 or 3 pairs of renal arteries
g. Gonadal arteries:
1. may arise from renal artery usually arise from aorta

22. a. arise from abdominal aorta
Detailed Anatomy, cont …
C. Blood supply
1. Renal arteries:
a. arise from abdominal aorta
b. Divide into 2 or 3 branches before entering kidney
c. If 3 branches, may form:
1. “vascular fork”
2. may constrict ureter

24. Right Kidney: Relationships
Note:
Liver
Descending duodenum
Psoas muscle
Quadratus lumborum muscle
IVC

25. Left Kidney: Relationships
Note:
Tail of pancreas
Splenic flexure of colon
Aorta
Psoas and quadratus lumborum muscles

28. Anatomy of Urinary Bladder
Hollow, distensible muscular organ with capacity of mL
Trigone is smooth flat area bordered by 2 ureteral openings and one urethral opening

29. Location of Urinary Bladder
Posterior to pubic symphysis
In females is anterior to vagina & inferior to uterus
In males lies anterior to rectum

30. Urinary Tract – Urinary Bladder
The urinary bladder:
expandable, muscular container
serves as a reservoir for urine
positioned immediately superior and posterior to the pubic symphysis.
in females
the urinary bladder is in contact with the uterus posterosuperiorly and with the vagina posteroinferiorly.
in males
it is in contact with the rectum posterosuperiorly and is immediately superior to the prostate gland.
is a retroperitoneal organ.
when empty exhibits an upside-down pyramidal shape.
Filling with urine distends it superiorly until it assumes an oval shape.

31. Urinary Bladder Located in pelvic cavity, posterior to pubic symphysis
3 layers
parietal peritoneum, superiorly; fibrous adventitia rest
muscularis: detrusor muscle, 3 layers of smooth muscle
mucosa: transitional epithelium
trigone: openings of ureters and urethra, triangular
rugae: relaxed bladder wrinkled, highly distensible
capacity: moderately full ml, max ml

34. Urinary Tract – Urinary Bladder
Trigone
posteroinferior triangular area of the urinary bladder wall
formed by imaginary lines
connect the two posterior ureteral openings
and the anterior urethral opening.
The trigone remains immovable as the urinary bladder fills and evacuates.
It functions as a funnel
directs urine into the urethra as the bladder wall contracts
four tunics
mucosa
submucosa
Muscularis: called the detrusor muscle
adventitia.
Internal urethral sphincter (smooth muscle)

35. Urinary Bladder Smooth, collapsible, muscular sac
Temporarily stores urine
Figure 15.6
Slide 15.21a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

36. Urinary Bladder Trigone – three openings Two from the ureters
One to the urethra
Figure 15.6
Slide 15.21b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

37. Urethra Release of urine is controlled by:
Internal urethral sphincter (involuntary)
External urethral sphincter (voluntary)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

38. Anatomy of Ureters 10 to 12 in long Varies in diameter from 1-10 mm
Extends from renal pelvis to bladder
Retroperitoneal
Enters posterior wall of bladder
Physiological valve only
bladder wall compresses arterial opening as it expands during filling
flow results from peristalsis, gravity & hydrostatic pressure

39. Urinary Tract : Ureters
long, fibromuscular tubes
conduct urine from the kidneys to the urinary bladder.
average 25 centimeters in length
retroperitoneal.
ureters originate at the renal pelvis
extend inferiorly to enter the posterolateral wall of the base of the urinary bladder.
wall is composed of three concentric tunics.
mucosa
muscularis
adventitia.

40. Urethra, Male
Male – cm
1. prostatic urethra – from base of bladder through prostate gland
2. membranous urethra – between prostate gland & base of penis
3. penile (spongy) urethra – traverses penis to orifice

41. Male Bladder and Urethra
18 cm long
Internal urethral sphincter
External urethral sphincter
3 regions
prostatic urethra receives semen
membranous urethra
passes through pelvic cavity
penile urethra

42. Urethra Fibromuscular tube conducts urine to the exterior of the body.
exits the urinary bladder through the urethral opening
at anteroinferior surface
conducts urine to the exterior of the body.
Tunica mucosa: is a protective mucous membrane
houses clusters of mucin-producing cells called urethral glands.
Tunica muscularis: primarily smooth muscle fibers
help propel urine to the outside of the body.
Two urethral sphincters:
Internal urethral sphincter
restrict the release of urine until the pressure within the urinary bladder is high enough
External urethral sphincter
and voluntary activities needed to release the urine are activated.

43. Anatomy of the Urethra Females Males
length of 1.5 in., orifice between clitoris & vagina
histology
transitional changing to nonkeratinized stratified squamous epithelium, lamina propria with elastic fibers & circular smooth muscle
Males
tube passes through prostate, UG diaphragm & penis
3 regions of urethra
prostatic urethra, membranous urethra & spongy urethra
circular smooth muscle forms internal urethral sphincter & UG diaphragm forms external urethral sphincter

44. Urethra, Female External urethral sphincter
– voluntary at pelvic floor
3-5 cm – from base of bladder to vestibule
UTIs (esp. E.coli)

45. Urethra: Gender Differences
Length
Females – 3–4 cm (1 inch)
Males – 20 cm (8 inches)
Location
Females – anterior to the vagina
Males – through the prostate and penis
Slide 15.24a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

46. Female Urethra 3 to 4 cm long External urethral orifice
between vaginal orifice and clitoris
Internal urethral sphinctermuscle, involuntary control

47. Male vs. Female
Fig 23.17

48. Urethra The internal urethral sphincter
involuntary (smooth muscle)
superior sphincter surrounding the neck of the bladder, where the urethra originates.
a circular thickening of the detrusor muscle
controlled by the autonomic nervous system
The external urethral sphincter
inferior to the internal urethral sphincter
formed by skeletal muscle fibers of the urogenital diaphragm.
a voluntary sphincter
controlled by the somatic nervous system
this is the muscle children learn to control when they become “toilet-trained”

49. Female Urethra Has a single function:
to transport urine from the urinary bladder to the vestibule, an external space immediately internal to the labia minora
3 to 5 centimeters long, and opens to the outside of the body at the external urethral orifice located in the female perineum.

50. Male Urethra Urinary and reproductive functions:
passageway for both urine and semen
Approximately 18 to 20 centimeters long.
Partitioned into three segments:
prostatic urethra is approximately 3 to 4 centimeters long and is the most dilatable portion of the urethra
extends through the prostate gland, immediately inferior to the male bladder, where multiple small prostatic ducts enter it
membranous urethra is the shortest and least dilatable portion
extends from the inferior surface of the prostate gland through the urogenital diaphragm
spongy urethra is the longest part (15 centimeters)
encased within a cylinder of erectile tissue in the penis called the corpus spongiosum
extends to the external urethral orifice

53. Disorders of Urinary System
Renal calculi
Urinary tract infections
Glomerular disease
Renal failure
Polycystic kidney disease