Unit B Lesson B12 Excretion
Completion requirements
Lesson B12: Human Systems: Excretion
Video Lesson
How does the human body remove harmful waste substances? Watch this video to learn about the human excretory system.
Lesson B12: Human Systems: Excretion
Figure B.3.12.1 – The kidneys are located on the left and right sides of the lower back.
Figure B.3.12.2– A diet high in meat and dairy products can lead to kidney stones forming.
Figure B.3.12.3– Kidney stones block urine from leaving the body and cause lower back pain.
Reading and Materials for This Lesson
Science in Action 8
Reading: Pages 141–145
Materials:
No additional materials are needed for this lesson.
Kidney Stones
Kidney stones are solid crystals that grow in the kidneys. Sometimes urine forms a saturated solution that cannot dissolve any more minerals or wastes. In this situation, solid wastes can precipitate out of urine and collect to form a kidney stone.
Saturated urine can form in several ways. When the body has low water levels, the kidneys do not release water into urine. Less water solvent in urine creates a more saturated solution. Uric acid is a waste produced when the body breaks down animal proteins. People who eat a lot of dairy and meat products produce a lot of uric acid. Their kidneys filter out more uric acid solute into urine, which increases the saturation of the urine solution.
Kidney stones are sometimes very tiny and pass out of the urinary tract without pain. However, some kidney stones grow large enough to block the ureters leading out of the kidneys. This is a very painful condition as urine backs up in the kidneys. Large kidney stones require medical attention to remove them.
Kidney stones are solid crystals that grow in the kidneys. Sometimes urine forms a saturated solution that cannot dissolve any more minerals or wastes. In this situation, solid wastes can precipitate out of urine and collect to form a kidney stone.
Saturated urine can form in several ways. When the body has low water levels, the kidneys do not release water into urine. Less water solvent in urine creates a more saturated solution. Uric acid is a waste produced when the body breaks down animal proteins. People who eat a lot of dairy and meat products produce a lot of uric acid. Their kidneys filter out more uric acid solute into urine, which increases the saturation of the urine solution.
Kidney stones are sometimes very tiny and pass out of the urinary tract without pain. However, some kidney stones grow large enough to block the ureters leading out of the kidneys. This is a very painful condition as urine backs up in the kidneys. Large kidney stones require medical attention to remove them.
Watch More
How Do Stones Get Into Your Kidneys?
This video explains how to prevent kidney stones.
This video explains how to prevent kidney stones.
Watch this video to see an explanation of how kidney stones form.
Think • Interpret • Decide
Kidneys
This video shows how your kidneys work.
This video shows how your kidneys work.
Questions:
After you have finished watching the video, carefully consider the following questions. Then, type or write your answers. When you have your answers, click the questions for feedback.
After you have finished watching the video, carefully consider the following questions. Then, type or write your answers. When you have your answers, click the questions for feedback.
The kidneys are responsible for filtering the blood.
The kidneys are responsible for filtering the blood. Unwanted substances are eliminated in the urine, and water and desirable substances are reabsorbed back into the blood.
The kidneys are like a security guard because they prevent certain substances from remaining in the bloodstream. The kidneys are like a garbage collector because they take away unwanted substances from the body. The kidneys are like an office
manager because they help to control the levels of various substances (including water) in the body.
Connections
Figure B.3.12.4– Kidney dialysis patients are connected to dialysis machines several times
a week.
Figure B.3.12.5– Dialysis machines filter wastes out of the body when the kidneys don’t work.
Figure B.3.12.6– Dialysis machines involves many steps and chemicals. Image by YassineMrabet.
>> Kidney Dialysis
Many different conditions and diseases can cause a person’s kidneys to stop working. Kidney dialysis is a technology that uses a machine to clean wastes out of a person’s blood when their kidneys fail. Kidney dialysis keeps people with kidney failure alive. There are two main types of kidney dialysis.
Hemodialysis uses a machine with tubes that connect into the patient’s veins. Blood travels from the patient into the hemodialysis machine, where the wastes are filtered out. Another tube returns the clean blood back into the patient’s body. Hemodialysis patients need to undergo this treatment at a clinic three times every week.
A peritoneal dialysis machine has tubes that insert and remove a waste-cleaning fluid from a patient’s belly cavity. Peritoneal dialysis can be done by a patient at home.
Dialysis keeps patients alive, but it is inconvenient and interferes with work, school, and travel. A kidney transplant allows a patient to stop dialysis. People only need one kidney to remove wastes from their bodies. Since people have two kidneys, kidney transplant donations often come from live donors willing to give one of their kidneys to a patient in need.
Watch More
Dialysis: Filtering a Body's Worth of Blood
When a person’s kidneys start failing, they need to make decisions about dialysis treatment. This video explains the different types of available dialysis treatments.
Watch this video to see a kidney transplant story.
Artificial kidneys could solve the limitations of dialysis or kidney transplants. Watch this video to learn more about artificial kidney research.
Figure B.3.12.7– Urine is used to diagnose diseases.
Figure B.3.12.8– Healthy urine is a pale yellow colour.
Figure B.3.12.9– Some foods, such as rhubarb, asparagus, and beets, change the colour or smell of urine.
Urine
Urine is a solution of many different substances in water. Medical professionals test the substances dissolved in urine to diagnose many body conditions.
For example, blood in urine is a symptom of several diseases, such as bladder or kidney infections. Dark-coloured concentrated urine indicates that the body is dehydrated. Coloured urine is not always something to be alarmed about. Some foods can change the colour of urine, such as beets, which make urine turn pink.
Some testable substances in urine are invisible. For example, pregnant women’s bodies produce a special hormone. Some of this hormone leaves the body in urine, which can be tested to confirm pregnancy. Drugs leave the body through urine, which is why urine tests are used to test for illegal drug use in athletes and workers.
It might surprise you to find out that urine can be recycled for useful purposes! People have been using urine for centuries. Urine was used in ancient leather tanning methods to preserve animal skins. Fabric makers in the Middle Ages collected and used urine to seal coloured dyes into fabric. Urine contains many of the same substances as fertilizer, so diluted urine can be used as a fertilizer to grow plants.
Urine is a solution of many different substances in water. Medical professionals test the substances dissolved in urine to diagnose many body conditions.
For example, blood in urine is a symptom of several diseases, such as bladder or kidney infections. Dark-coloured concentrated urine indicates that the body is dehydrated. Coloured urine is not always something to be alarmed about. Some foods can change the colour of urine, such as beets, which make urine turn pink.
Some testable substances in urine are invisible. For example, pregnant women’s bodies produce a special hormone. Some of this hormone leaves the body in urine, which can be tested to confirm pregnancy. Drugs leave the body through urine, which is why urine tests are used to test for illegal drug use in athletes and workers.
It might surprise you to find out that urine can be recycled for useful purposes! People have been using urine for centuries. Urine was used in ancient leather tanning methods to preserve animal skins. Fabric makers in the Middle Ages collected and used urine to seal coloured dyes into fabric. Urine contains many of the same substances as fertilizer, so diluted urine can be used as a fertilizer to grow plants.
Watch More
Recycle Your Pee, Or Urine Trouble!
The colour of urine provides a lot of information about your body. Watch this video to learn more.
The colour of urine provides a lot of information about your body. Watch this video to learn more.
Watch this video to learn about some interesting uses for urine.
Making fertilizer from urine can help solve problems related to poverty and sanitation in developing countries. Watch this video to learn more about urine fertilizer research.
Figure B.3.12.10– Coffee contains caffeine, a diuretic.
Figure B.3.12.11– Diuretics in cola soda make you urinate more.
Figure B.3.12.12– Energy drinks contain caffeine.
Staying Hydrated
Some substances make the body urinate more. These substances are called diuretics. Two commonly consumed diuretics are caffeine and alcohol. Drinks such as coffee, tea, cola pop, and energy drinks contain caffeine. These liquids increase the amount of urine produced by the kidneys. It is a good idea to drink some water after consuming a diuretic, to replenish the water in your body.
Drinking water regularly maintains healthy water levels in the body. The adult human body needs two to three litres of water every day, to make its cells function properly. Whenever you are thirsty, choose a glass of water rather than a sugary or caffeinated drink. On hot days, or when you exercise, it’s important to drink more water than you normally do, because your body loses a lot of water to sweat.
Some substances make the body urinate more. These substances are called diuretics. Two commonly consumed diuretics are caffeine and alcohol. Drinks such as coffee, tea, cola pop, and energy drinks contain caffeine. These liquids increase the amount of urine produced by the kidneys. It is a good idea to drink some water after consuming a diuretic, to replenish the water in your body.
Drinking water regularly maintains healthy water levels in the body. The adult human body needs two to three litres of water every day, to make its cells function properly. Whenever you are thirsty, choose a glass of water rather than a sugary or caffeinated drink. On hot days, or when you exercise, it’s important to drink more water than you normally do, because your body loses a lot of water to sweat.
Watch More
Hydration
What problems are caused by drinking too little or too much water? Watch this video to learn more.
What problems are caused by drinking too little or too much water? Watch this video to learn more.
Watch this video to find out how to keep your body hydrated.
Make sure you have understood everything in this lesson. Use the Self-Check below, and the Self-Check & Lesson Review Tips to guide your learning.
Unit B Lesson 12 Self-Check
Instructions
Complete the following 6 steps.
Don't skip steps – if you do them in order, you will confirm your
understanding of this lesson and create a study bank for the future.
- DOWNLOAD the self-check quiz by clicking here.
- ANSWER all the questions on the downloaded quiz in the spaces provided. Think carefully before typing your answers. Review this lesson if you need to. Save your quiz when you are done.
- COMPARE your answers with the suggested "Self-Check Quiz Answers" below. WAIT! You didn't skip step 2, did you? It's very important to carefully write out your own answers before checking the suggested answers.
-
REVISE your quiz answers if you need to. If you answered all the questions correctly, you can skip this step. Revise means to change, fix, and add extra notes if you need to. This quiz is NOT FOR MARKS, so it is perfectly OK to correct
any mistakes you made. This will make your self-check quiz an excellent study tool you can use later.
- SAVE your quiz to a folder on your computer, or to your Private Files. That way you will know where it is for later studying.
- CHECK with your teacher if you need to. If after completing all these steps you are still not sure about the questions or your answers, you should ask for more feedback from your teacher. To do this, post in the Course Questions Forum, or send your teacher an email. In either case, attach your completed quiz and ask; "Can you look at this quiz and give me some feedback please?" They will be happy to help you!
Be a Self-Check
Superhero!
Self-Check Quiz Answers
Click each of the suggested answers below, and carefully compare your answers to the suggested answers.
If you have not done the quiz yet – STOP – and go back to step 1 above. Do not look at the answers without first trying the questions.
On a hot day, lots of water is lost from your body through sweat. You should carry a water bottle so that you can replenish that water and avoid the risk of dehydration.
A kidney stone blocks the path of urine from the kidneys to the bladder. When urine does not have a path to leave the body, it can back up and cause pain.
The urinary bladder stores urine before it leaves the body. The urinary bladder is important because the kidneys are constantly working to produce urine. Without a bladder, urine would constantly run out of a person’s body.
A dehydrated person does not have enough water in their body. As a result, the dehydrated person’s body tries to conserve water. The kidneys produce less urine that is more concentrated, so the dehydrated person urinates less.
Kidneys remove harmful wastes from the body through urine. If the kidneys are not able to remove wastes from the body, toxins build up in the body, leading to death.