Download Kidneys


Urinary
System
Function
Kidneys
 Eliminate chemical/metabolic waste
 Nitrogenous wastes (byproducts of chemical reactions that are no
longer useful such as ammonia, urea, uric acid, creatinine)
 Control the volume and composition of body fluids
 Water/salt balance
Blood volume is closely associated with the salt balance of the body
 The more salt in the blood, the greater the volume of blood and the
greater the blood pressure
 The kidneys are involved in regulating blood pressure and also maintain
appropriate levels of certain ions in the blood

 Acid/base balance

The kidneys monitor and control blood pH through the excretion and
reabsorption of certain ions
Main organ of excretion (make urine)
 Principal job is the removal of urea and the regulation of water in the
bloodstream
 Convert Vitamin D to active form

Waste Products
 Urea
 End product of amino acid metabolism in body cells
 Water soluble
 Primary end product of the urinary system
 Ammonia
 End product of the deamination of amino groups
 Very toxic to tissues
 Converted to urea in the liver in land mammals
 Creatinine
 End product from creatinine phosphate in muscle
metabolism
Structures of the Urinary System
 Kidney
 Reddish brown organs
 Size of a bar of soap
 Located in the superior lumbar region; on either side of the
spinal column, anchored against the dorsal body wall by
connective tissue
 Responsible for excretion of urine and regulation of blood
volume and pH
Structures of the Urinary System
 Renal Vein
 Carries blood from the kidneys back to the heart
Structures of the Urinary System
 Renal Artery
 Carries blood into the kidney
Structures of the Urinary System
 Ureter
 Muscular tube
 Moves urine from the kidneys to the bladder through
peristalsis
Structures of the Urinary System
 Urinary Bladder
 Urine storage, can hold up to 600 to 1000 mL of urine
 Expands and contracts
 Stretch receptors indicate when it is full, signal notifies
the brain resulting in the desire to urinate
Structures of the Urinary System
 Urethra
 Tube that connects the
urinary bladder to the
outside
Kidneys
 Composed of over 1 million nephrons
 Produces urine
 Positioned so that urine flows into a collecting duct
with several nephrons entering the same collecting duct
Kidney Anatomy

Hilum

Renal Cortex

Renal pelvis

Calyces

Renal capsule

Adipose capsule

Renal Medulla



Medullary pyramids
Renal columns
Nephron
3 main regions of the
kidney
 Renal Cortex
 Renal Medulla
 Renal Pelvis
Renal Cortex
 Superficial
 (outer granulated
layer)
 Dips down in
between a
radially striated
or lined inner
layer
 Light in color
Renal Medulla
 Deep to the
renal cortex
 Darker in color
 Consists of
cone-shaped
tissue masses
called renal
pyramids
Renal Pelvis
 Central space or
cavity that is
continuous with the
ureter
 Collecting ducts
empty into this region
Hilum
 Medial indentation
 Point of entry for
renal artery and renal
nerves
 Point of exit for renal
vein and ureter
Calyces
 Form cup shaped area
 Enclose the tip of the
medullary pyramids
 Collect urine
Kidneys protected and stabilized
by connective tissue:
1. Renal capsule
– Encloses kidney
– Gives glistening appearance
2. Adipose capsule
– Fatty mass that helps hold kidney
in place
– Surrounds renal capsule
Medullary Pyramids
 Triangular regions
with a striped
appearance
Renal Columns
 Separate the
medullary pyramids
Blood Supply
• Kidneys receive
20–25% of total
cardiac output
Blood Flow
1.
Renal artery
2.
Segmental artery
3.
Lobar artery
4.
Interlobar artery
5.
Arcuate artery
6.
Interlobular artery
7.
Interlobular vein
8.
Arcuate vein
9.
Interlobar vein
10. Renal vein