The Urinary System
Zach, Casey, Jun
The Urinary System
• The function of the Urinary system is to
filter the blood and urine as well as help
regulate certain metabolic processes
through the kidneys.
• The urinary system also excretes the
waste, which is what is left over, so that
the body is not poisoned.
Structures
Of the Urinary System
The Kidneys
• Two within a person
• Filtration organs
• Adult Kidney is about 6x12x3 cm (WxHxL)
• Enclosed in tough, fibrous capsule
• Contains about 1 million nephrons
Ureters
• Two Ureters
• About 25 cm. long each
• Transport the liquids to the bladder
• Wall has three layers
• Inner – Mucous Coat
• Middle – Muscular Coat (smooth muscle fibers)
• Propels the urine
• Outer – Fibrous Coat (connective tissue)
The Bladder
• One bladder
• Holds the liquids filtered from the kidneys
• Hollow, distensible, and muscular
• Receives from the Ureters
• In the pelvic cavity
• Pressure from surrounding organs changes its shape
• On the inner floor consists a trigone
• Trigone has 3 opening of ureters
• Has a neck which is funnel-shaped on the anterior side
The Bladder (Cont.)
• Four layers
• Inner – Mucous Coat (Several thicknesses (which change with
the bladder as it expands and contracts) of transitional
epithelial cells)
• 2nd layer – Submucous Coat (Connective tissue and many
elastic fibers)
• 3rd Layer – Muscular Coat (Coarse bundles of smooth muscle
fibers and when together make the detrusor muscle which
surrounds the neck of the bladder forms an internal urethral
sphincter. Sustained contractions prevents the emptying of
the bladder)
• Outer – Serous Coat (Parietal Peritoneum (only on the upper
surface) and connective tissue (everywhere except the upper
surface))
Urethra
• Is a tube which excretes the fluids within the bladder to the
outside of the body
• Wall is lined with Mucous Membrane and a thick layer of
smooth muscle tissue
• Contains many mucous glands which are called urethral
glands secreting mucous into the urethral canal
Functions
Of the Urinary System
Urine Formation - Glomerular
Filtration
• Urine is formed beginning with
glomerular filtration. The force of
blood pressure forces the filtration
process to begin, but most of the
fluids from so are reabsorbed into the
blood stream. By the colloid osmotic
pressure of the plasma. The nephrons
use two capillaries to work through.
The first capillary bed is specialized to
filter, and instead of forming
interstitial fluid, the filtered fluid
(filtrate) moves into the renal tubule,
where much of it becomes urine.
Urine Formation – Tubular
Reabsorption
• Moves from the tubular fluid back in the blood within the
tubular capillary
• Kidney specifically reclaims the perfect amounts of
substances, such as water, electrolytes, and glucose which
the body requires.
Urine Formation – Tubular Secretion
• Substances which the body must eliminate, such as
hydrogen ions and some toxins, are removed even faster
than through filtration itself.
• Is the reverse process:
• Moving substances from the blood stream within
peritubular capillary into the renal tubule.
Blood Travel Within a Kidney
• Fluid flows though the renal corpuscle and within that it goes
through a cluster of blood capillaries called glomerulus
• The glomerulus capillaries filter the fluids coming through the
kidneys
• There is then a glomerular capsule which surrounds the
glomerulus and receives the fluid which the glomerulus filters
• This is near the proximal end of a renal tubule and the renal
tubule leads away from the glomerular capsule and becomes
highly coiled (this is called the proximal convoluted tubule)
• The proximal convoluted tubule dips down towards the pelvis,
becoming the descending limb of the nephron loop (also called
the “loop of Henle”)
Blood Travel Within a Kidney (Cont.)
• The tubule then curves up toward the renal corpuscle
forming the ascending limb of the nephron loop
• The ascending limb then returns to the region of the renal
corpuscle becoming highly coiled and renamed to the distal
convoluted tubule
• Then, the renal cortex is formed from a merging of several
nephrons which then turn into collecting ducts (which is not
part of a nephron)
• This then turns into the renal medulla and enlarges as the
other convoluted tubules join in
• This results in the tube emptying into a minor calyx through
an opening in the renal papilla
Smaller Units
Of the Urinary System
Nephron
• Consists of a Renal Corpuscle and a Renal Tubule
• Renal Corpuscle
• The renal corpuscle is a tightly coiled pack containing the
glomerulus
• The renal tubule is what the fluid flows through
Urine Composition
• The composition of urine reflects the amounts of water and
solutes that the kidneys must eliminate from the body or
retain in the internal environment to maintain homeostasis.
• The composition varies due to diet
• Urine is normally around 95% water, and usually contains
urea and uric acid.
• Urine may also contain a trace of amino acids and some
electrolytes, which also depend on the diet.
Urea
• Urea is a byproduct of amino acid catabolism.
• Urea’s plasma concentration reflects the amount of protein
within the diet.
• About 50% is reabsorbed and the remainder is excreted in
urine.
• Urea enters the renal tubule by filtration.
Uric Acid
• Uric acid is produced by the metabolism.
• It is specifically the metabolism of certain organic bases and
nucleic acids.
• Uric acid is reabsorbed through active transport normally
present though glomerular filtration. A small amount is
secreted into the renal tubule and is excreted in urine.
Diseases
Of the Urinary System
Cystocele
• Cystocele is a hernia-like disorder in women which occurs
when the wall between the bladder and vagina weakens.
This causes the bladder to drop or sag into the vagina.
• Urine leakage
• Bladder not emptying completely
• When doing any act which increases pressure upon the
bladder, it is easy for urine to leak due to the opening to the
urethra stretching
Internal Cystitis
• Body miscommunicates pain from the colon to the bladder (have
pain in the bladder)
• Mostly women suffer from this disease
• Spicy foods, citrus and caffeine are a few of the foods causing
Internal Cystitis
• People feel the urge to urinate up to 50 times a day
• The nerves within the pelvic region are all bunched together (the
bladder, colon and prostate) into the same region of the spinal
cord near the tailbone
• When all are sending pain messages, the receptors get overloaded
causing the pain to be constantly on whereas normally it is only small,
short bursts of pain received
• Only way to treat is rectally with an anesthetic in a suppository
or gel, or perhaps an anesthetic patch applied to pelvic skin.
Kidney Stone
• Anyone can get kidney stones
• Men affected more than women
• It is a solid piece of combined material which is normally
found within the urine becoming highly concentrated
• The stone can stay in the kidney or move down the urinary
tract
• A small stone can move causing little to no pain whereas a
larger stone may get stuck along the urinary tract and can
block urine flow which could cause severe pain or bleeding
Kidney Stone (Cont.)
• People who have any of the following are at an increased risk of
gaining kidney stones:
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Hypercalciuria
Family history (of kidney stones)
Cystic kidney diseases
chronic inflammation of the bowel
hyperparathyroidism
renal tubular acidosis
Cystinuria
hyperuricosuria
hyperoxaluria
Gout
blockage of the urinary tract
a history of gastrointestinal tract surgery
Kidney Stone (Cont.)
• 4 Types
• Calcium Stones
• Most common
• Uric acid stones
• Form when the urine is stubbornly acidic
• Struvite stones
• Formed from kidney infections
• Cystine stones
• A genetic disorder, which causes cysteine to leak
through the kidneys and into the urine that forms
crystals that band together creating stones
Kidney Stone (Cont.)
• Two (of the three) ways listed can be used to remove
the kidney stone
• Shock wave lithotripsy
• Lithotripter (a machine) is used to crush the
stone
• Ureteroscopy
• A long tube-like instrument with an eyepiece
and basket is used to “fish” or grab the stone or
to break it with laser energy
• Having a healthy diet can help to prevent kidney
stones
End of Presentation
Thank you for staying awake!
Works Cited
"NewYork-Presbyterian. The University Hospital of Columbia
and Cornell." Cystocele. The New York Presbyterian, 30 Nov. 2008.
Web. 07 May 2013. <http://nyp.org/health/urologycystocel.html>.
"Strange New Source of Bladder Pain Discovered." Strange
New Source of Bladder Pain Discovered. LiveScience, 11 Sept.
2008. Web. 07 May 2013. <http://www.livescience.com/7563strange-source-bladder-pain-discovered.html>.
"National Kidney and Urologic DiseasesInformation
Clearinghouse (NKUDIC)." Kidney Stones in Adults. NIDDK, 28 Jan.
2013. Web. 07 May 2013.
<http://kidney.niddk.nih.gov/KUDiseases/pubs/stonesadults/index
.aspx>.
Navigation
Opening
Structures
Functions
Other
Diseases