Human Anatomy & Physiology Urinary System Human Anatomy & Physiology

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 Ammonia Creatinine 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: Renal capsule Encloses kidney Gives glistening appearance 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 Renal artery Segmental artery Lobar artery Interlobar artery Arcuate artery Interlobular artery Interlobular vein Arcuate vein Interlobar vein Renal vein