Lesson Notes By Weeks and Term - Senior Secondary 2
Excretory system
Excretory system
TERM – 1ST TERM
WEEK SEVEN
Class: Senior Secondary School 2
Age: 16 years
Duration: 40 minutes of 5 periods each
Date:
Subject: Biology
Topic: EXCRETORY SYSTEM
SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to
INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source
INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures
INSTRUCTIONAL PROCEDURES
PERIOD 1-2
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PRESENTATION |
TEACHER’S ACTIVITY |
STUDENT’S ACTIVITY |
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STEP 1 INTRODUCTION |
The teacher refresh the students memories about excretion. |
Students pay attention |
|
STEP 2 EXPLANATION |
Teacher Identify special organs responsible for excretion in organisms. |
Students pay attention and participate |
|
STEP 3 DEMONSTRATIO N |
Teacher discusses the organs of excretion mentioned earlier |
Students pay attention and participate |
|
STEP 4 NOTE TAKING |
The teacher writes a summarized note on the board
|
The students copy the note in their books |
NOTE
EXCRETORY SYSTEM
The excretory system is responsible for removing waste and excess substances from the body, maintaining a balance of fluids and electrolytes. Key components include the kidneys, which filter blood to produce urine, and other organs like the bladder, ureters, and urethra, involved in storing and eliminating urine. This system helps regulate the body's internal environment and maintain homeostasis.
Contractile vacuole
A contractile vacuole is a cellular structure found in certain protists, including some single-celled organisms like amoebas and paramecia. Its primary function is to regulate water content within the cell. The contractile vacuole collects excess water that enters the cell through processes like osmosis and then contracts, expelling the water from the cell to prevent it from bursting due to overhydration. This mechanism helps these organisms adapt to varying environmental conditions, particularly changes in water availability.
Flame cells
Flame cells are specialized cells found in the excretory system of some invertebrates, particularly in flatworms (Platyhelminthes). These cells are involved in osmoregulation and the removal of metabolic wastes. Flame cells have a distinctive flickering, flame-like appearance due to the movement of cilia (hair-like structures) on their surfaces.
The cilia create currents that propel fluids through tubules, ultimately leading to the expulsion of waste from the organism. Flame cells play a role in maintaining the internal balance of fluids and electrolytes in these simpler organisms, helping them excrete excess water and waste products.
Malpighian tubules
Malpighian tubules are excretory organs found in insects and some other arthropods. These tubules are an essential part of the insect's excretory system, serving to remove metabolic wastes and maintain the insect's internal balance.
Unlike vertebrates, insects do not have kidneys. Instead, they rely on Malpighian tubules, which are typically attached to the digestive system. These tubules extract waste products, including nitrogenous compounds, from the hemolymph (the insect's equivalent of blood). The collected waste is then released into the insect's hindgut, from which it is expelled as solid feces.
Malpighian tubules play a crucial role in osmoregulation and the elimination of nitrogenous waste, contributing to the overall homeostasis of the insect's internal environment.
Kidney
The kidney is a vital organ within the excretory system, responsible for filtering blood and eliminating waste products from the body. As part of this system, kidneys play a central role in maintaining homeostasis by regulating the balance of fluids, electrolytes, and other essential substances. The excretory function of the kidneys involves the formation of urine, which contains the waste products that are removed from the bloodstream. Additionally, the kidneys contribute to the regulation of blood pressure and the production of certain hormones, making them a crucial component of the overall excretory and regulatory functions within the body.
Stomata and Lenticels
Stomata are microscopic pores found on the surface of plant leaves and stems. They play a crucial role in gas exchange, allowing plants to take in carbon dioxide for photosynthesis and release oxygen.
Lenticels, on the other hand, are openings in the bark of woody plants. They facilitate gas exchange and are essential for the respiration of underlying tissues. Unlike stomata, lenticels are more prominent in woody stems and provide a pathway for gases like oxygen to enter and exit the plant.
NOTE: Neither stomata nor lenticels are directly involved in excretion in plants. Excretion in plants typically occurs through processes like the secretion of waste substances into vacuoles or through the shedding of older leaves.
EVALUATION: 1. Define excretory system
CLASSWORK: As in evaluation
CONCLUSION: The teacher commends the students positively