Download The Urinary System - Health Science Program

The Urinary System
Urinary
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2 - Kidneys

2 - Ureters
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2 - Renal arteries

2 – Renal veins
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1 - Urinary bladder
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1 - Urethra
The Kidneys

Two bean shaped kidneys 4-6 ozs. each, found in the retroperitoneal cavity.

Filter wastes from blood, and maintain water & electrolyte balance.

Fist sized

Protected by adipose tissue and fibrous connective tissue
Structures of the kidney

Renal Pelvis: a basin like are in the central part of kidney
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Renal Cortex: outer layer of kidney containing nephrons

Nephrons are the functional units of the kidney.
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Medulla: Inner layer containing urine collecting tubules
Nephrons
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Each nephron forms urine by the processes of filtration, reabsorption and secretion

Each contains a glomerulus, which is a cluster of capillaries, surrounded by a membrane called the
Bowman’s capsule
The Ureters

Ureters- slender tube carries urine from renal pelvis to bladder.

15-18 in. long

Urine enters the tube every 10-30 seconds in spurts due to peristaltic activity

Ureteral orifice at bladder prevents reflux
The Bladder and Urethra
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Bladder- muscle sac that receives and stores urine.

Lined with ruggae

Stores 250 cc of urine

Urethra- slender tube carries urine from bladder outside body.

Female: 1-1.5 in. Male: 8 in. long
Main Function of the Urinary System

Remove urea (nitrogenous waste) from the blood stream so that it does not accumulate in the body
and become toxic

Urea: formed in liver from ammonia (from breakdown of simple proteins, amino acids, in the body
cells)

Urea carried by the blood stream to the kidneys for excretion.
Other functi
ons



Maintain proper balance of water, salts and acids
Example: Na and K which are electrolytes needed for proper functioning of muscle cells.
Kidneys can adjust what is excreted or held back

Kidneys also act as an endocrine organ as they secrete renin, which controls blood pressure

Help with calcium reabsorption in the intestines

Extract insulin and parathyroid hormone from the blood stream
How do kidneys produce urine?

Blood from the aorta branches into the Rt. And Lt. Renal artery

The arteries branch into arterioles throughout the renal cortex

Blood flow is slow and constant

If the blood flow diminishes the kidneys would produce renin, which stimulates contraction of the
arterioles, increased BP and blood flow will be restored!
Continued…

In each cortex, blood passes through the glomerulus and water, salt, sugar and urea are filtered out
of the bloodstream.

This waste is collected in the Bowmans Capsule and transported to the renal tubule.

In the renal tubule, reabsorption of needed substances and secretion of waste products is
completed.

It is now urine, 95% water and 5% waste substances .

The tubules lead to the renal pelvis, which narrows to the ureter, then the bladder and excreted out
of the urethra!

Sphincters hold urine until desire to urinate.
Urine

95% water

5% waste, toxins and salts

Clear, pale amber

1000cc – 2000cc excreted every 24 hours
Facts

The acid found in urine gives off that typical urine smell. In diabetics, urine may smell fruity due
to the presence of glucose.
Freshly made urine from the kidney is sterile but when it leaves the body, it is exposed to bacteria
present in the surrounding or on the skin.
A bacterial invasion leads to a breakdown on the salts in the urine to give off a foul-smelling odor.
If urine smells offensive the minute urination starts then there is already an infection in the urinary
tract.
Dysfunction of Kidneys

Renal Failure
-Complete inability to function properly.

Uremia
-Build-up of urea in the bloodstream.
-Eyes turn yellow.

Nephrotic Syndrome/ Nephrosis
-General group of Nephron dysfunctions…
-Edema:
Excessive fluid in body tissue.
-Hyperproteinuria:
Abnormally high blood protein levels.
-Hypoproteinuria:
Abnormally low blood protein levels.
-Hyperlipidemia:
Abnormally large amount of blood lipids.
Dysfunction of Kidneys

Nephroptosis/ Ptosis
-Downward displacement of a kidney’s.
-Can be caused by rapid weight loss.

Nephrolithiasis
-Presence of kidney stones.
-Named for the region the stone is located.


Urinary tract infection (UTI)
-An infection that usually begins in the bladder.
-Common in women due to shortened urethra and proximity to vagina/rectum
Hydronephrosis
-Blockage of urine flow cause kidneys to become enlarged and swollen.
-Can cause severe damage to Nephrons.