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Overview of excretory system of the body and structure of kidney.
Learning Objectives
At the end of the lecture, students should be able to:
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Know the different parts of excretory system.
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Know the general overview of these excretory parts.
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Understand the structure of kidney.
Human Urogenital System
Organisation of the ExcretorySystem
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Kidneys
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Ureters
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Urinary bladder
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Urethra
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Urogenital/ Excretory System Functions
Filtering of blood, Removal of wastes and metabolites
Regulation of
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blood volume and composition
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concentration of blood solutes
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pH of extracellular fluid
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blood cell synthesis
Synthesis of Vitamin D
Reproduction and sexual function
Urinary System Anatomy
Ureters and Urinary Bladder
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Ureters
– Tubes through which urine flows from kidneys to urinary bladder
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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
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Ureters
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Superiorly
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Inferiorly
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Continuous with the renal pelvis
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
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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).
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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
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Renal sinus
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Renal parenchyma
Kidney anatomy
Renal sinus:
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Surrounded by renal parenchyma
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Contains blood & lymph vessels, nerves, urine-collecting structures
Kidney anatomy
Renal parenchyma:
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Glandular tissue
Forms urine
Two zones
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Outer cortex
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Inner medulla
Internal Structure of the Kidney
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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
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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
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Tubules
– Proximal (convoluted) tubule
– Loops of Henle
• Descending limb
• Ascending limb
– Distal (convoluted) tubules
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Collecting ducts
Blood vessels servicing kidney
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Supplied by renal artery
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~21% or cardiac output
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(mass in only ~ 0.4%)
Urine formation
Overview
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Blood plasma -- urine
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Four steps
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Glomerular filtration
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Tubular reabsorption
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Tubular secretion
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Water conservation
References

Clinical oriented anatomy

KLM

6TH edition