Control Of Water And Ion Content Of The Body
Overview
Breathe onto a cold window and a patch of mist appears. That water was inside you a moment earlier, and nothing you decided put it there. Spend an afternoon working in the sun and your shirt dries into a faint pale crust, which is what stays behind when the water in sweat evaporates and the dissolved salts do not. Neither loss asked your permission and neither of them ever stops.
This lesson follows water, dissolved ions and a little waste out of the body by the three routes that carry them: the lungs, the skin and the kidneys. You will learn exactly which substance leaves by which door, why two of those doors cannot be closed however short of water you are, what the small word excess is doing in the phrase excess water is removed via the kidneys, and how to set a day of intake against a day of losses accurately enough to work out a volume nobody measured.
Objectives
- Water leaves the body via the lungs when we breathe out and the skin when we sweat. Excess water is removed via the kidneys in the urine.
- Urea and ions are lost via the skin when we sweat. Excess ions are removed via the kidneys in the urine.
Mind map
This topic is mapped out so you can see how the ideas connect.
Open the mind map in the app
Lesson Note
Complete Note Available on the Green Bridge App
Get the Green Bridge CBT app on your phone or computer for the complete IGCSE library: past papers, mark schemes, mind maps, flashcards and audio lessons.
Lesson Evaluation
Congratulations on completing the lesson on Control Of Water And Ion Content Of The Body. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- By which route is water lost from the body but ions are not? A. The lungs B. The skin C. The kidneys D. The liver Answer: A
- Which substances are lost from the body in sweat? A. Water only B. Water and glucose only C. Water, ions and a small amount of urea D. Ions and urea only Answer: C
- What is removed from the body by the kidneys in the urine? A. All of the water and all of the ions in the body B. Excess water and excess ions C. Excess water only D. Excess ions only Answer: B
- What decides how much water is lost from the skin? A. How much water the body has to spare B. How many ions there are in the food eaten that day C. How hot the body is D. How fast the person is breathing Answer: C
- In one day a woman takes in 2600 cm3 of water in total and loses 1100 cm3 by routes other than urine. The water content of her body does not change. What volume of urine does she produce? A. 1100 cm3 B. 1500 cm3 C. 2600 cm3 D. 3700 cm3 Answer: B
Work through these questions in the app
Work through these questions in the app
Recommended Books
Practice Mock Questions
Want to practice mock questions on Control Of Water And Ion Content Of The Body? Download the Green Bridge CBT app to access mock questions and full practice assessments for this topic.
Download The App On Google Playstore
Everything you need to excel in your exams
