Kara Yeung, Angela Philip, Angel Oluwole-Rotimi
Excretory: Urinary System
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 Urinary System main components are kidneys, liver,
ureters, bladder and urethra
 Main purpose is excretion ( the process of eliminating wastes/
things the body has no use for)
Summary of work with other systems:
Nervous System:
 Bladder nerves make you feel you need to pee
 brain tell bladder muscles to squeeze and sphincters to loosen
when pee
Circulatory system
 blood needs to be pumped through the body to the kidneys so they can filter out unnecessary substances(ex.
water, acid, urea)
Endocrine system
 controls the system as it tells the kidneys what to do as your body finds what you need (ex. too little waterhormones go to make sure less urine leaves you/is made) -hormones tell your kidney’s how to act
 Also Adrenal gland is above kidneys-gives out adrenaline
Summary of the Liver’s Role in this System:
Filters blood and takes extra amino acids and turns them into other substances that could be beneficial but there’s a
byproduct - Urea, which is made from foods with protein (ex. Meat, poultry)
Urea (which our bodies DON’T need)- goes through bloodstream to kidneys where the Urinary system begins
Largest organ, right under diaphragm, top part of abdominal 'cavity', irregular
shape
Made of many different lobules (containing liver cells arranged in columns)- often
generalized to Let lobe & Right lobe
Lobules gets different blood flowing through it & filters it
Every lobule has a duct that takes waste (like bile) filtered out from blood and
combines with other ducts from the other lobules to make bigger ducts
How does the blood get there?- hepatic artery, portal veins take blood into the liver (by portal fissure)
Kidneys!
Kidneys: bean-shaped reddish colored organs which lie in the abdomen, just below the ribcage, approx. 10cm
Left kidney slightly superior to the right kidney (which sits under the liver)
Removes liquid waste (urea, uric acid and water) from body through filtering blood to make urine
Balances salts and salt levels, pH, calcium, body fluids and other substances in blood
Related to osmoregulation (keeps body fluids/salts in order) and homeostasis (keeps
correct blood pressure and pH level)
blood enters renal arteries and leaves through renal veins
Kidney has two layers: cortex ( outer) and medulla (inner)
medullary pyramids: conical structures in the medulla that contain the smallest unit
where urine is formed and blood composition is regulated called nephrons
Activity of nephron is subject to person’s choices, environment and hormones
Nephrons contain the Bowman’s capsule which surround a tight twisted knot of
capillaries called “glomerulus” that does exchange between blood vessel and nephron
Tubule system contains proximal tubule, loop of Henle, distal tubule, then collecting
duct
Tubule system is site of reabsorption and secretion based on substances needed by the body (like salts, glucose, amino
acids and water)
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Kara Yeung, Angela Philip, Angel Oluwole-Rotimi
Unwanted fluid from tubule to collecting duct are urine and two important nitrogen compounds: uric acid and urea
Ureters: two narrow tubes/ pipelines that take urine from kidneys to urinary bladder for storage and release
Muscles tighten + relax to push urine away from kidney
Bladder!
Bladder is a muscular sac that stores urine
Lined with layers of muscle tissue that expan an contract
Sphincter is circular muscle that keeps urine from leaking
Urethra is the tube that allows urine to exit the body
Nerves in the bladder signal the brain when you need to empty your
bladder
During urination, the brain sends a message to the bladder to tighten up
and to the sphincter to relax
As the sphincter relaxes, urine passes through the urethra and out of
the body
What’s in urine?
Water
Urea, waste produced when proteins are broken down
Urochrome, blood product that gives urine colour
Salts
Creatinine, waste product formed with regular breakdown of muscle
Byproducts of bile from the liver
Ammonia
Did you know!
 Adults pass about a quart and a half of urine each day, depending on the fluids and foods consumed and fluid
lost through perspiring and breathing
 The volume of urine formed at night is about half that formed in the daytime
 Normal urine is sterile; it is free of bacteria, viruses and fungi
 tissues of the bladder are isolated from urine and toxic substances by a coating that discourages bacteria from
attaching and growing on the bladder wall
 440 gallons of blood passes through your kidneys daily
 Urine is odorless:, bacteria in the air converts chemicals in urine to turn into other forms
 During wars in prehistoric times, urine was placed on wounds to destroy bacteria because of its antiseptic
qualities
 Only 40% of people smell the odor of urine
 Every 10-15 seconds – small quantities of urine empty into bladder
Questions:
1. What is the circulatory system's importance to the function of the Urinary (excretory) system?
2. What are 3 components of urine?
3. How do you know that you need to use the washroom? How does it happen?
4. What is the primary purpose of the urinary system?
5. What is the smallest unit in the kidney that does the real job? Where is it located and what does it do?