BIOLOGY LESSON NOTE ON HUMAN KIDNEY

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Lesson Note on the Human Kidney

Topic:

The Human Kidney

Duration:

40 minutes

Specific Objectives:

By the end of the lesson, students should be able to:

1. Define the kidney and state its location in the human body.
2. Identify and describe the structure and functions of the kidney.
3. Explain the processes involved in urine formation (filtration, reabsorption, and secretion).
4. Describe how the kidney contributes to homeostasis.
5. Identify common kidney-related diseases and how to prevent them.
6. Evaluate the importance of maintaining kidney health.

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Lesson Content:

1. Introduction to the Human Kidney

The kidneys are vital organs in the human body responsible for filtering waste from the blood and regulating water and electrolyte balance. They are part of the excretory system and play a crucial role in homeostasis.

Location:

• The kidneys are located in the abdominal cavity, on either side of the spine, just below the rib cage. Each kidney is bean-shaped and about the size of a fist.

2. Structure of the Kidney

The kidney has the following major parts:

• Renal Cortex: The outermost layer where the glomeruli are located.
• Renal Medulla: The inner layer containing the renal pyramids.
• Renal Pelvis: A funnel-shaped structure that collects urine and channels it into the ureter.

3. Functional Unit of the Kidney – The Nephron

The nephron is the basic structural and functional unit of the kidney. Each kidney contains about one million nephrons.

Parts of the Nephron:

• Glomerulus: A network of capillaries where blood is filtered.
• Bowman’s Capsule: Surrounds the glomerulus and collects the filtrate.
• Proximal Convoluted Tubule (PCT): Responsible for reabsorbing useful substances like glucose and amino acids.
• Loop of Henle: Helps in concentrating the urine by reabsorbing water.
• Distal Convoluted Tubule (DCT): Regulates pH, potassium, and sodium levels.
• Collecting Duct: Transports urine to the renal pelvis.

4. Functions of the Kidney

The kidney performs the following key functions:

1. Excretion: Removes waste products like urea, ammonia, and uric acid from the blood.
2. Osmoregulation: Regulates water and salt balance in the body.
3. Blood Pressure Regulation: Produces the enzyme renin, which helps regulate blood pressure.
4. Hormone Production: Produces erythropoietin, which stimulates red blood cell production.
5. pH Balance: Helps maintain the acid-base balance of the blood.

5. Processes of Urine Formation

Urine formation involves three main processes:

1. Filtration: Occurs in the glomerulus, where blood is filtered, and waste products are removed.
2. Reabsorption: Useful substances like glucose, amino acids, and water are reabsorbed back into the blood.
3. Secretion: Additional waste products are secreted into the nephron for elimination.

6. Kidney and Homeostasis

The kidney helps maintain homeostasis by:

• Regulating water and electrolyte levels.
• Removing metabolic waste products.
• Controlling blood pH.

7. Kidney Diseases and Prevention

Common kidney-related diseases include:

1. Kidney Stones: Hard mineral deposits that form in the kidney.
2. Chronic Kidney Disease (CKD): A gradual loss of kidney function over time.
3. Urinary Tract Infection (UTI): Infection affecting the kidneys, bladder, or urethra.

Prevention Tips:

• Drink plenty of water.
• Maintain a balanced diet low in salt and sugar.
• Avoid smoking and excessive alcohol consumption.
• Exercise regularly.

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Evaluation:

Answer the following multiple-choice questions:

1. Where are the kidneys located in the human body?
   A. In the chest cavity
   B. In the abdominal cavity, on either side of the spine
   C. Below the liver and pancreas
   D. In the cranial cavity

2. What is the functional unit of the kidney?
   A. Ureter
   B. Neuron
   C. Nephron
   D. Glomerulus

3. Which part of the kidney contains the glomeruli?
   A. Renal pelvis
   B. Cortex
   C. Medulla
   D. Ureter

4. What is the main function of the renal artery?
   A. To carry urine from the kidney to the bladder
   B. To filter nitrogenous waste from the blood
   C. To supply oxygenated blood to the kidney
   D. To regulate water absorption in the kidney

5. Which hormone regulates water reabsorption in the kidney?
   A. Insulin
   B. Erythropoietin
   C. Thyroxine
   D. Antidiuretic Hormone (ADH)

6. What is the primary nitrogenous waste excreted by the kidney?
   A. Glucose
   B. Amino acids
   C. Urea
   D. Hemoglobin

7. What is osmoregulation?
   A. The breakdown of food in the kidney
   B. The regulation of water and salt balance in the body
   C. The process of urine storage in the bladder
   D. The filtration of red blood cells in the kidney

8. What is the role of the renal pelvis?
   A. To filter blood and form urine
   B. To reabsorb glucose and water
   C. To collect and funnel urine into the ureter
   D. To secrete hormones that regulate blood pressure

9. How does the kidney contribute to homeostasis?
   A. By storing red blood cells
   B. By regulating pH, water balance, and waste excretion
   C. By producing digestive enzymes
   D. By storing excess proteins in the nephrons

10. Which condition is characterized by the formation of hard deposits in the kidney?
    A. Kidney failure
    B. Urinary Tract Infection (UTI)
    C. Kidney stones
    D. Nephritis

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Conclusion:

The kidney plays a vital role in the human body by filtering blood, excreting waste, and maintaining homeostasis. It is essential to take good care of the kidneys to prevent diseases and ensure the proper functioning of the body.

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