Excretion In Humans
Overview
Your cells are constantly making waste. Respiration makes carbon dioxide, and breaking down spare protein makes a poisonous substance called urea. If these waste products built up they would harm you, so the body has organs whose job is to remove them: this is excretion.
In this lesson you will learn what the lungs and kidneys excrete, name the parts of the urinary system, and (for the extended curriculum) follow how a kidney nephron filters the blood and reabsorbs what the body needs. You will also see how the liver makes urea from spare amino acids and why removing it matters.
Objectives
- State that carbon dioxide is excreted through the lungs
- State that the kidneys excrete urea and excess water and ions
- Identify in diagrams and images the kidneys, ureters, bladder and urethra
- [Supplement] Identify in diagrams and images the structure of the kidney, limited to the cortex and medulla
- [Supplement] Outline the structure and function of a nephron and its associated blood vessels, limited to: (a) the role of the glomerulus in the filtration from the blood of water, glucose, urea and ions (b) t he role of the nephron in the reabsorption of all of the glucose, some of the ions and most of the water back into the blood (c) the formation of urine containing urea, excess water and excess ions (details of these processes are not required)
- [Supplement] Describe the role of the liver in the assimilation of amino acids by converting them to proteins
- [Supplement] State that urea is formed in the liver from excess amino acids
- [Supplement] Describe deamination as the removal of the nitrogen-containing part of amino acids to form urea
- [Supplement] Explain the importance of excretion, limited to toxicity of urea
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Lesson Evaluation
Congratulations on completing the lesson on Excretion In Humans. 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.
- Which substance is excreted by the lungs? A. urea B. carbon dioxide C. excess ions D. glucose Answer: B
- Which tube carries urine from a kidney to the bladder? A. urethra B. ureter C. renal vein D. renal artery Answer: B
- Urea is made in the: A. kidney B. bladder C. liver D. lungs Answer: C
- In a healthy person, which substance is completely reabsorbed in the nephron? A. urea B. excess ions C. glucose D. water (all of it) Answer: C
- Deamination is the removal of the nitrogen-containing part of: A. glucose B. amino acids C. fatty acids D. glycogen Answer: B
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