1. Aim: What is the excretory system, and how do the kidneys help maintain homeostasis?
Do Now:
Throwback! Homeostasis is the ability to maintain a stable internal environment.
What is one thing that humans do on a hot day to maintain their internal temperature of 37 degrees Celcius (98.6 degrees F)?
Sweat

2. Agenda Reminders Quiz tomorrow! (digestive and excretory systems)
Do Now/Hand Out Vacation HW (10)
Notes: Excretory System (18)
Finish Digestion demo (5)
Bacon Egg Cheese Worksheet (15)
Exit Slippage!!! (10)
Reminders
Quiz tomorrow! (digestive and excretory systems)
Your homework packet is due tomorrow

3. Match the system to a life function:
Process
Excretory System
8 Life Functions
Growth
Excretion
Nutrition
Reproduction
Respiration
Homeostasis
Synthesis
Transport
Suprise!
The excretory system gets rid of (excretes) metabolic waste that the cells produce

4. Hold up: Metabolism?! Four metabolic wastes:
This we breathe out
Metabolism is the total of all the chemical reactions in the body.
Excretion is when you get rid of waste products that were made in these chemical reactions.
From yesterday: is solid waste (feces [poop]) made in a chemical reaction?
NO! So poop isn’t excretion!
Four metabolic wastes:
1. CO2 (produced as a product of…
cellular respiration!)
2. Urea
3. Salts
4. Excess water
These we can’t breathe out

5. The Human Excretory System
The excretory system can be broken down into three main parts:
1. Kidneys
2. Ureters
3. Bladder

6. The Human Excretory System
The excretory system can be broken down into three main parts:
1. Kidneys
2. Ureters
3. Bladder

7. What if… One ureter got blocked? Could you still excrete urine?
Yes: Just only from
one kidney

8. Double-trouble question (it’s a two-parter!)
A: The ureter is part of the excretory system
B: If one is busted, the second will still make some urine

9. 1. Kidneys
The kidneys are the major organ of excretion and they maintains homeostasis in three main ways:
Removal of waste (urea) from the blood
Adjusts the amount of salts in the blood.
Adjusts the amount of water in the blood

10. Removing Urea
Urea is a toxic (poisonous!) compound that is produced when amino acids are broken down for energy
Urea is made by the liver
Makes urea, which goes into the blood
The kidneys filter that blood

11. Adjusting the amount of salts and water
We need some water and some salt, but too much is bad for us
The kidneys only take out enough salt and water to maintain homeostasis then excrete the rest in urine
Sweat also excretes salts and water
(Goldilocks style)

12. A Urine Example! From the Do Now… what do you do on a hot day? Sweat!
What two things are you losing in that sweat?
Water and salts
So do you have more or less water than usual?
Because you sweated it all out!
So your kidneys will maintain homeostasis by producing less urine
Because there is less water in the urine, the urine will be dark-colored and more concentrated.

13. What about on a cold day? You sweat less when you are cold
So you will have more water then usual
What do you think your pee will look like?
Pale and less concentrated!

14. ACTIVITY! Excretory System Demo

15. Worksheet! Dunkin Donuts #4: Bacon, Egg and Cheese Sandwich
What happens when you eat one?

16. Exit Slippage! Reminders: Work independently.
Remember to use scientific vocabulary that you learned today.
Reminders:
Quiz tomorrow! (digestive and excretory systems)
Your homework packet is due tomorrow

19. The original slides

20. Aim: What is the excretory system, and how do the kidneys help maintain homeostasis?
Do Now:

21. What is excretion? Excretion is one of the 8 life functions.
It means to remove metabolic waste.
Metabolic waste (urine/urea) is waste produced by the cells.

22. Why isn’t feces (poop) not considered excretion?
Feces is the leftover of undigested food.
The material in the feces originally entered through the mouth.
Waste from excretion comes from the cell.
It’s the waste product of the cell.

23. The Human Excretory System
The excretory system can be broken down into three main parts:
1. Kidney
2. Bladder
3. Ureter

25. The Kidneys
The kidneys is the major organ of excretion and it maintains homeostasis in three main ways:
Removal of waste (urea) from the blood
Adjustment of ions (salts) in the blood.
Adjustment of water content of the blood

26. The Kidneys as a Filter
The kidneys maintain homeostasis by acting like a filter for the body by sorting out the bad from the good.

27. Removal of urea Urea is produced in the liver
Unused amino acids can’t be stored in the body, so the liver breaks down the amino acids into fats and carbohydrates.
In the process of breaking down the amino acids, ammonia (a Toxic molecule) is produce as a waste product.
The liver then breaks the ammonia down into urea.
Urea is filtered out through the kidneys and passed out the body as urine and (sweat).

28. Adjustment of the ion content
Ions, such as sodium, are taken in by the body through food (salts).
Excess ions are removed through the kidneys.
Some of the ions are also lost through sweat.
Ions are important for the body, so the kidneys maintain a balance (homeostasis)

29. Adjustment of the water content
Water is taken into the body as food and drink and is lost in three ways
Urine
Sweat
Breath

30. Water
Water is needed to carryout most reactions in the body, however the body must maintain a balance (homeostasis) of water in the body.
The body loses water daily but how it loses it can change day to day.

31. A cold day
If it is cold outside, your body will sweat very little but you will urinate more frequently or a lot.
Because there is more water in it, the urine will be pale and less concentrated.

32. On a hot day
If it is a hot day, you will sweat a lot and you will urinate less or produce a little urine.
Because there is less water in the urine, the urine will be dark-colored and more concentrated.