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Name __________________________
Wednesday, 11-30-16
Packet # 2 - 16
7th Science - ________
AIM: Define and describe the function of the urinary/excretory system.
Explain how the urinary and digestive systems work together.
Quote of the Day: “Always stay true to yourself and never let what
somebody else says distract you from your goals.” Michelle Obama
PPT – take notes in the spaces provided while discussing the PowerPoint
Excretory System
- Removes waste from the body
A major part of the excretory system is the urinary system
The urinary system removes liquid waste from the body through urination
Waste products in the blood are transported to the kidneys as urea
Urea is poisonous, so it must be removed from the body
Turn and Talk – what is a filter (display picture of coffee filter): key message: obstruct
the passage of something; keep something out
What happens in the kidney?
The kidney is the body’s main filter system; you have two of them!
The kidney receives all the blood; small filters called nephrons remove all the waste
(such as urea) that is remaining in the blood
The good parts of the blood are then sent back through the circulatory system to the rest
of the body
**CFU – blank screen – what systems are working together now? Urinary/circulatory.
How? Blood is filtered, bad parts are remove, good parts go back to circulatory system.
Urea, along with water and unwanted salt, then leaves the kidneys down small tubes
called ureters and is emptied into the bladder
The urea, salt, and water is known as urine
As more and more urine enters the bladder, it blows up like a balloon
As the bladder gets bigger, it sends signals to the brain that make you feel
uncomfortable and tell you to use the restroom
When your brain tells your bladder to release the urine, it exits the body through the
urethra
Turn and Talk - The urinary system finishes the process that another system started.
Which system?
The digestive system breaks down food for the nutrients the body needs, and then the
excretory system, which includes the urinary system, gets rid of waste.
Each system has its own set of organs, but they are connected through the processes
they perform.
The excretory system is responsible for removing waste from the body. Waste EXits the
body through the EXcretory system
It does this to help maintain homeostasis (stable internal environment) and prevents
damage to the body
Methods of the excretory system include sweating waste through the skin, exhaling
waste through the lungs, and removal of solid waste through the rectum & anus
One of the jobs of the excretory system is to remove solid waste
After nutrients have been absorbed in the small intestine and water absorbed in the large
intestine, all that remains is solid waste
The solid waste enters the rectum and leaves the anus as feces
In addition to the organs of the urinary system, the following organs work together to
form the excretory organ system
Skin: removes waste through sweat
Rectum: stores solid waste after it leaves the large intestine
Anus: the opening in which solid waste exits the body
Digestive and Excretory Systems


The digestive and excretory systems work closely together
After nutrients and water are absorbed by the small and large intestines of the
digestive system, the solid waste then enters the excretory system to exit through
the rectum and out the anus
Circulatory and Excretory (Urinary) Systems
Blood collects waste from throughout the body before passing through the kidneys of the
urinary system (remember, the urinary system is a part of the excretory system)
Clean blood then exits the kidneys while the waste (urea) moves through the urinary
system and exits the body through the urethra
Khan Academy Video, 4 minutes
https://www.khanacademy.org/partner-content/crash-course1/partner-topic-crash-coursebio-ecology/crash-course-biology/v/crash-course-biology-128?v=UU366tJPovg
Questions (start at 2:55 of video) – packed 4th minute of video, need to pause several
times.
1. The excretory system starts with the kidneys.
2. Kidneys filter a bunch of fluid out of your blood; 99% of it is reabsorbed, 1% is
sent out of the body in the form of urine.
3. On an average day, kidneys filter out about 180 liters of fluid from your blood.
Only 1.5 liters of that leaves the body as urine.