The document provides an overview of renal anatomy and physiology. It describes the key functions of the renal system as filtering waste from the blood and regulating fluid balance. The major structures include the kidneys, which filter blood and produce urine, the ureters which transport urine from the kidneys to the bladder, and the bladder which acts as a reservoir for urine storage. The kidneys contain nephrons, which are the functional filtering units. Blood enters the nephrons via the renal arteries and is filtered in the glomerulus. Urine is produced and drains through the renal tubules and collecting duct system.

1. Renal System Anatomy
& PHYSIOLOGY
DR. AMAR UL-ALA BUTT
CONSULTANT UROLOGIST
06-R-M-12967 (MOH 88/458)
BURAIDAH CENTRAL HOSPITAL(7/1)

2. Renal system summary
Functions:
1. Remove wastes from the body (urine)
2. Regulates fluid balance, maintains homeostasis
Structures:
 2 kidneys - filter blood, produce urine
 2 ureters - transport urine (kidneys to bladder)
 bladder - reservoir for urine
 urethra - transport of urine

3. Renal anatomy
 lies retroperitoneal, on
posterior abdominal wall
 lies from T12-L3 of vertebral
column, next to m. psoas
major
 superior parts are protected
by ribs 11, 12
 tilted: superior poles are
closer to midline than
inferior

4. KIDNEY FEATURES
2 Poles
– Upper
– Lower
2 Borders
– Lateral
– Medial – has hilum
2 Surfaces
– Anterior
– Posterior

5. RIGHT KIDNEY
ANTERIOR RELATIONS
Right suprarenal gland
Liver
Duodenum
Colon
Coils of small intestine

6. LEFT KIDNEY
ANTERIOR RELATIONS
Left suprarenal gland
Stomach
Spleen
Pancreas
Colon
Coils of small intestine

7. KIDNEY
POSTERIOR RELATIONS
Diaphragm
Psoas
major
Transversus
abdominis
Quadratus
lumborum
Last ribs
Ilioinguinal N
Iliohypo-
gastric N
Rt Lt

8. Renal anatomy
 R kidney lower than L
(due to R lobe of liver)
 ~ 12cm long x 5cm
wide x 2.5cm thick
 bean-shaped , reddish-
brown organs
 renal hilum
 kidney levels change
during respiration and
postural changes

10. External surface – 3 layers of tissue
1. renal fascia (outer)
– CT attaches kidney to
posterior abdominal wall –
flexible, allows kidney to
move with respiration
– covered by layer of fat
2. perirenal fat (middle layer)
– protective cushion
3. renal capsule (innermost)
– layer of collagen fibres -
barrier against
trauma, infection etc.
– kidney hangs suspended by
collagen fibres and packed
in soft cushion of adipose
tissue

11. Internal anatomy
outer cortex, inner medulla
 6-18 conical renal pyramids
 apex - renal papilla projects
into the renal sinus
renal columns
 extend from cortex inward
to renal sinus between
adjacent renal pyramids
 granular texture similar to
that of the cortex

12. Internal anatomy
 ureter enters renal sinus, it
expands to form a chamber
called - renal pelvis
 pelvis branches to form 2-3
major calyces
 branch further to form 6-8
minor calyces
 Each minor calyx surrounds
the papilla of a renal pyramid
 ducts within papilla connect to
wall of the calyx and discharge
urine produced in the cortex
and medulla
 Urine passes through the
calyces into the ureter

13. Left kidney: coronal section

14. KIDNEY BLOOD SUPPLY
IVC
Abdominal aorta
Renal A
Renal V

15. Blood supply to the kidney:
Renal arteries from abdominal aorta enter hilum and branch:
1. Interlobar arteries - pass through renal columns and reach junction
between medulla and cortex
2. Arcuate arteries run parallel with the base of the pyramids
3. Interlobular arteries move up into the cortex and branch to form
the afferent arteriole
The peritubular capillaries unite to form the interlobular veins, arcuate
vein, interlobar vein, renal vein
The renal vein exits at hilus and joins the IVC

16. Blood supply to kidney

17. Nephron
= Functional unit of the kidney, ~ 1.2 million nephrons per kidney!
Tubular components:
1. Glomerular (Bowman’s) capsule – double-walled cup
– simple squamous epithelium
2. Proximal convoluted tubule - coiled 1st section
– simple cuboidal epithelium with microvilli
3. Loop of Henle - hair-pin loop
– thin descending limb, thick ascending limb
4. Distal convoluted tubule - last section
– simple cuboidal epithelium
– specialised region - Juxta glomerular apparatus
Distal convoluted tubule opens into the collecting system
collecting ducts papillary ducts minor calyx…

18. Nephron

19. Vascular component of nephron
Made up of blood vessels:
1. Glomerulus - network of capillaries within Bowman’s capsule
2. Afferent arteriole - leading into glomerulus
3. Efferent arteriole - leading out of glomerulus
4. Peritubular capillaries - surrounding tubules
5. Vasa recta - specialised loops of blood vessels around long
Loop of Henle (juxtamedullary nephrons)

20. Nephrons: 85% are cortical, 15% are juxtamedullary

21. Renal corpuscle

22. Ureters Pyelogram (colour-enhanced)
 tubes that transport urine from
renal pelvis to bladder
 20-30 cm long
 muscular walls - peristaltic waves
force urine down to bladder
 retroperitoneal
 pressure in the bladder compresses
ureter, helps prevent backflow of
urine
 (physiological valve) - still allows
urine to flow into the bladder

23. RIGHT URETER, RELATIONS
–Anteriorly
 Duodenum
 Terminal part of ileum
 Right colic & iliocolic vessels
 Right gonadal vessels
 Root of mesentry
–Posteriorly
 Right psoas major muscle
 Bifurcation of right common iliac A

24. LEFT URETER, RELATIONS
–Anteriorly
 Sigmoid colon
 Sigmoid mesocolon
 Left colic vessels
 Left gonadal vessels
–Posteriorly
 Left psoas major muscle
 Bifurcation of left common iliac A

25. URETER CONSTRICTIONS
1. Where it joins
the renal pelvis
2. Where it crosses
the pelvic brim
3. Where it pierces
the bladder wall

26. Bladder
 hollow muscular organ
 retroperitoneal, posterior to
pubic symphysis
 Capacity ~ 300-400 ml
(max = 1000 ml)
 empty: looks like a deflated
balloon, rugae
 full spherical rises above
abdominal cavity
 Males: anterior to rectum,
above prostate
 Females: inferior to uterus,
anterior to vagina

27. URINARY BLADDER FEATURES
Apex: points anteriorly---median umbilical
lig.
Base: (posterior surface)
Superior surface
2 Inferiolateral surfaces
Neck: rests on prostate

28. Support of bladder
 superior surfaces - peritoneum
 middle umbilical ligament -
superior border to umbilicus
 lateral umbilical ligaments -
sides of bladder to umbilicus
 At base, tough ligamentous
bands anchor bladder to pelvic
and pubic bones
Trigone : triangular area bounded
by openings of ureters and exit
to urethra
 cystitis - inflammation of the
bladder wall

29. Cross section of ureter & bladder
lined by transitional epithelium to
allow for stretch of wall
 lamina propria -
mucous membrane
– elastin fibres
 smooth muscle (m. detrusor)
– inner and outer longitudinal
– middle circular
 contraction compresses
bladder and expels contents
into urethra
 internal sphincter -
involuntary control

30. Urethra
Female ~ 4cm long
– opens to exterior between
clitoris and vaginal opening
Male ~ 20 cm long
– passes through prostate
gland
– pierces urogenital
diaphragm
– enters penis and extends
throughout length
– opens at urethral orifice

31. MALE URETHRA PARTS
Prostatic part:
– The widest part
– About 3 cm
Membranous part:
– In the urogenital diaphragm
– About 1.25 cm
Penile part:
– In the penis
– About 15 – 16 cm long

32. FUNCTIONS OF THE KIDNEY
1) Regulate the osmotic pressure (osmolality) of the
body fluids by excreting osmotically dilute or
concentrated urine.
2) Regulate the concentrations of numerous ions in
blood plasma, including Na, K, Ca, Mg, Cl,
bicarbonate (HCO3), phosphate, and sulfate.
3) Play an essential role in acid-base balance by
excreting H, when there is excess acid or HCO3,
when there is excess base.

33. FUNCTIONS OF THE KIDNEY
4) Regulate the volume of the ECF by controlling Na
and water excretion.
5) Help to regulate arterial blood pressure by adjusting
Na excretion and producing various substances
(e.g.,renin) that can affect blood pressure.
6) Eliminate the waste products of metabolism,
including urea (the main nitrogen-containing end-
product of protein metabolism in humans), uric acid
(an end-product of purine metabolism), and
creatinine (an end-product of muscle metabolism).

34. FUNCTIONS OF THE KIDNEY
7) Remove many drugs (e.g.penicillin) and foreign
or toxic compounds.
8) Are the major production sites of certain
hormones, including erythropoietin and 1,25-
dihydroxy vitamin D3
9) Degrade several polypeptide hormones, including
insulin, glucagon, and parathyroid hormone
10) Synthesize ammonia, which plays a role in acid-
base balance

35. FUNCTIONS OF THE
KIDNEY
11) Synthesize substances that affect renal blood
flow and Na excretion, including arachidonic
acid derivatives (prostaglandins, thromboxane
A2) and kallikrein (a proteolytic enzyme that
results in the production of kinins).
 When the kidneys fail, a host of problems
ensue. Dialysis and kidney transplantation
are commonly used treatments for advanced
(end-stage) renal failure

36. Bone Structure
Vitamin D
Activation
Calcium
Balance
Blood Formation
Erythropoietin
Synthesis
Cardiac Activity
Potassium
Balance
Regulation of Blood pH
Recovery of
Bicarbonate
Blood Pressure
Water Balance
Sodium
Removal
Metabolic
End Products
Removal of
Urea, Creatinine etc.
Functions of the Kidney
Manifold Tasks of the Kidney
Functions
Healthy Kidney

37. Functions of the Kidney
Filtration and Reabsorption
1500 l
blood per
day
through the
renal arteries
180 l
filtrate per day
in the glomeruli
60 l
urine per day
at the end of the
proximal tubules
20 l
urine per day
at the beginning of
the distal tubules
10 l
urine per day
at the end of the
distal tubules
1,5 l
urine per day
at the end of
the collecting
ducts
real removal:
1,5 l urine
Healthy Kidney

38. Micturition reflex:
Stretch receptors stimulated when filled to ~
220 ml
 afferent fibres to spinal cord
 motor neurons to sm in bladder wall
 contracts m. detrusor and increases
pressure
 need to relax both internal and external
sphincter - external under voluntary
control
 if external sphincter does not
relax, internal sphincter remains closed &
sm in bladder wall relaxes again
 Once volume exceeds 500 ml, micturition
reflex may generate enough P to open
internal sphincter
 leads to reflexive relaxation of external
sphincter

39. Thank you
All the best with your studies
ANY QUESTIONS