Lecture outline gross anatomy of kidney
Learning Objectives
At the end of the lecture, students should be able to:
• Know the different parts of excretory system.
• Know the general overview of these excretory parts.
• Understand the structure of kidney
Human Urogenital System
Organisation of the ExcretorySystem
Kidneys
• Ureters
• Urinary bladder
• Urethra
Urogenital/ Excretory System Functions
Filtering of blood, Removal of wastes and metabolites
• Regulation of
– blood volume and composition
– concentration of blood solutes
– pH of extracellular fluid
– blood cell synthesis
• Synthesis of Vitamin D
• Reproduction and sexual function
Ureters and Urinary Bladder
Ureters
– Tubes through which urine flows from kidneys to urinary bladder
• Urinary bladder
– Stores urine
• Urethra
– Transports urine from bladder to outside of body
– Difference in length between males and females
– Sphincters
• Internal urinary
• External urinary
Ureters
• Superiorly
• Continuous with the renal pelvis
• Inferiorly
• Pass through the abdominal cavity, behind the peritoneum, infront of the psoas muscle, into the pelvic cavity
• Where they enter the posterior wall of the bladder
• 25-30 cm in length
Bladder
Urethra
• Extends from the base of the bladder to the outside world.
• Anatomical differences mean that male and female urethras are different.
– Female: 4cm long
– Male: 14cm long
Kidney
• Each kidney is 11cm in length
• 6cm in breadth
• 3cm in anterioposterior diameter
• Male 150gm
• Female 135gm.
• In thin person it may be palpable
• The right kidey is usually inferior because of liver.
• The hilus of left kidney is just above the transpyloric plane and that of right kidney is just below that (hilus is at
level of 1st LV).
Location and External Anatomy of Kidneys
• Location
– Lie behind peritoneum on posterior abdominal wall on either side of vertebral column
– Lumbar vertebrae and rib cage partially protect
– Right kidney slightly lower than left
• External Anatomy
– Renal capsule
• Surrounds each kidney
– Perirenal fat
• Engulfs renal capsule and acts as cushioning and source of energy
– Renal fascia
• Anchors kidneys to abdominal wall, separates from abdomen
– Hilum
• Renal artery and nerves enter and renal vein and ureter exit kidneys
Protection of the Kidneys
Surface anatomy of the Kidney
Kidney anatomy
Gross anatomy
• Renal sinus
• Surrounded by
renal
• Renal parenchyma
parenchyma
Kidney anatomy
Renal sinus:
• Contains blood & lymph vessels, nerves, urine-collecting structures
Kidney anatomy
Renal parenchyma:
• Glandular tissue
• Forms urine
• Two zones
– Outer cortex
– Inner medulla
Internal Structure of the
Kidney
Internal Anatomy of Kidneys
• Cortex: Outer area
– Renal columns
• Medulla: Inner area
– Renal pyramids
• Calyces
– Major: Converge to form pelvis
– Minor: Papillae extend
• Nephron: Functional unit of kidney
– Juxtamedullary
– Cortical
Internal Anatomy of Kidneys
• Renal corpuscle
– Bowman’s or Renal capsule
• Parietal layer
• Visceral layer
– Glomerulus
• Network of capillaries goes into another capillary bed called the peritubular Capillaries
- Arterioles
– Afferent
• Blood to glomerulus
– Efferent
• Drains not into veinule but another arteriole
• Tubules
– Proximal (convoluted) tubule
– Loops of Henle
• Descending limb
• Ascending limb
– Distal (convoluted) tubules
• Collecting ducts
Blood vessels servicing kidney
• Supplied by renal artery
– ~21% or cardiac output
– (mass in only ~ 0.4%)
Urine formation
Overview
• Blood plasma --urine
• Four steps
– Glomerular filtration
– Tubular reabsorption
– Tubular secretion
– Water conservation
References