Urinary System
By: Blake Rossman, David Barin, &
Gabe Watkins
Functions of the Urinary System
 The urinary system removes certain salts and
nitrogenous wastes.
 Helps maintain water and electrolyte concentrations
 Regulate certain metabolic processes by having
 Tubular ureters
 Saclike urinary bladder
 Tubular urethra
Functions and Locations of the Kidney
 Kidneys
 Reddish-brown, bean-shaped organ with a
smooth surface
 Lie on either side of the vertebral column
 Positioned retroperitoneally
 Behind the parietal peritoneum and
deep muscles in the back
 Connective tissue and masses of adipose
tissue surround the kidneys
Functions and Locations of the Kidney
Functions and Locations of the Kidney
 Primary role is to maintain homeostasis.
 Regulates the composition, volume and pH
of the extracellular fluid.
 Other important functions
 Secrete erythropoietin
 Have a role in the activation of vitaminD
 Secrete enzyme renin
Functions and Locations
Renal Blood Vessels
Renal Arteries
Basic blood supply to the
kidneys
Arise from the aorta
Functions and Locations of Nephrons
 Kidney has about 1 million nephrons.
 Each nephron consists of a
 renal corpuscle
 Renal tubule
 Renal Corpuscle is made of glomerulus
 Help filter fluids, the first step in urine formation
 Renal Tubule
 Fluid flows through on its way out of the body
Functions and Locations of
Nephrons
Urine Formation
 Glomerular filtration
 Filtration of plasma by the Glomerular capillaries
 Filtered fluid is reabsorbed in the bloodstream
 Colloid osmotic pressure of the plasma
 Tubular reabsorption
 Moves substances from the tubular fluid back to the blood
 Tubular secretion
 The reverse process, moves substances from the blood
within the peritubular capillary into the renal tubule
Urine Formation Continued
 Amount filtered at the glomerulus
-Amount reabsorbed by the tubule
+ Amount secreted by the tubule
= Amount excreted in the urine
Urine Formation
Urine Formation
Glomerular Filtration
 Similar to filtration at the
arteriolar ends of other
capillaries.
 Mostly water and the same
components as blood plasma
Filtration Pressure
 Hydrostatic pressure of blood forces
substances through the glomerular capillary
wall
 Net filtration pressure is the net pressure
forcing substances out of the glomerulus
 Normally positive
 Favoring filtration at the glomerulus
Urine elimination
 Urine forms in the Nephrons >Passes through
collecting ducts in renal papillae
 > calyces of kidneys
 > renal pelvis
 > ureter conveys it to the urinary bladder
 > urethra excretes urine
Functions and Locations of Major
Organs
 Ureters
 Help for urine elimination
 About a 25cm tube that extends downward behind the
parietal peritoneum and runs parallel to the vertebral
column.
 There are 3 layers. The inner (mucous coat), middle layer
(muscular coat), and outer layer (fibrous coat)
 The muscular walls of the ureters propel the urine
Functions and Locations of Major
Organs
 Urinary Bladder
 Stores urine and forces it into the urethra
 It is within the pelvic cavity, behind the symphysis pubis and
beneath the parietal peritoneum
 The internal floor of the bladder includes a triangular are
called the trigone
 Posteriorly at the base of the trigone, the openings are of the
ureters.
 Has 4 layers which are mucous coat, sub-mucous coat,
muscular coat, & serous coat.
 Can hold as much as 600 milliliters of urine before stimulating
pain receptors
Urinary Bladder
Micturition
 Micturition is urination or the process that expels urine from
the urinary bladder
 Detrusor, abdominal wall and pelvic floor muscles contract
 Stretch receptors stimulates triggering the micturition reflex
 Distension of the bladder wall as it fills with urine
 Micturition reflex center is in the spinal cord
 External sphincter is composed of skeletal muscle
 Under Conscious control
Diseases
 Cystitis- Inflammation of the urinary bladder
 More common in women because urethral pathway is
shorter;
 Ureteritis- Inflammation of the ureter
 Glomerulonephritis- the glomerular capillaries are
inflamed and become more permeable to proteins
 Automatic bladder- damage to the spinal cord above
the sacral region destroys voluntary control of urination
Thank You