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Lesson Note
Subject: Biology
Topic: Tissue and Supporting System.
Lesson Objectives: By the end of the lesson, the learners should be able to:
1. Define the term Transport system;
2. State the Need for transport system;
3. Relate transport in lower organism to that of higher organism;
4. State the Transport material in animals and plant;
5. Discuss Diverse mechanism of transportation in some organisms;
6. Explain Transport system in mammals (man);
7. State the Functions of blood.
TRANSPORT SYSTEM
Transport system is the movement of metabolic materials from various parts of an organism where they are produced and transported to other parts where such are used, stored or removed from the body.
NEED FOR TRANSPORT SYSTEM
All living organisms (plants and animals) need transport system for the following reasons
- To obtain essential materials such as oxygen, water and nutrients.
- To remove metabolic waste such as carbon dioxide, urea, water, etc.
- For moving water and mineral salts from the soil through the roots to the various parts of plant.
- For transfer of hormones from production site to site of action.
- For transfer of glucose to various parts of plants.
Other materials transported in plants are:
TRANSPORT MEDIA
Liquid or fluid is usually the medium of transportation of minerals. Generally speaking, the four major media of transportation in organisms are:
Cytoplasm: Used in lower unicellular organisms such as amoeba, chlamydomonas, euglena, etc.
Cell sap/ Latex: A concentrated solution in the cell vacuole of plants.
Blood: Used in most animals, especially vertebrates for conveyance of essential materials like oxygen, digested food, etc.
Lymph: Found in higher animals. Lymph is a fluid with extra lymphocytes (W.B.C with no red blood cells present). It returns its fluid to the main vein through opening in the subclavian (left jugular) vein below the neck. Lacteal is a lymphatic vessel transporting fatty acids and glycerol. The lymph movement is enhanced by muscular action. It moves through lymph vessel. Some swellings exist in the gut along the lymphatic vessel, especially in the neck, groin and armpit called lymph nodes. These are where lymph passes through to be purified before entering into the blood stream. Unlike the circulatory system, the lymphatic system ends blindly.
DIVERSE MECHANISMS OF TRANSPORTATION IN SOME ORGANISMS
Unicellular Organisms
Materials are transported through the continuous streaming movements. The streaming could be along the direction of movement of the organism, back to front (e.g. Amoeba) or in circular motion (e.g. Paramecium)
Multicellular Organism
Hydra
The movement of the gut wall draws water into the gut and causes digested food and oxygen within it to circulate. Thus the cell lining the gut absorbs the materials. The whopping movement of the flagella of flagellated cells also helps in material circulation in the gut.
Flatworms
The large body surface area to volume ratio and extensive branching gut throughout the body makes the food and oxygen to diffuse into all the body cells. Movement of the body wall assists to transport waste products out of the body.
Insects and mollusks
Both have open circulatory system i.e. the heart pumps blood out into a blood vessel with branches open into spaces in the body cavity known as Haemocoels. Blood from these spaces eventually flows into the vessels leading into the heart. Blood flows in unidirectional and blood distribution is poorly controlled.
TRANSPORT SYSTEM IN MAMMALS (MAN)
The media of transportation in man include the blood and lymph.
COMPOSITION AND STRUCTURE OF BLOOD
The blood is a tissue in a fluid form. It is about 5-6 liters in the body. Blood is made of two major components. The blood cells (corpuscles); which are solid. The plasma which; is liquid.
BLOOD CELLS
There are three types
- Red blood cells (erythrocyte)
- White blood cells (leucocytes)
- Blood platelets (thrombocytes)
BLOOD CELLS DESCRIPTION AND FUNCTION
White blood cells areof two types;
a. Phagocytes– found in lymphatic system which ingest bacteria, viruses and dead cells to prevent diseases in a process called phagocytosis.
b. Lymphocytes- made in lymph glands and they produce antibodies i.e. chemicals which stick to the surface of germs to kill them.
FUNCTIONS OF BLOOD
1. Oxygen is transported through hemoglobin.
2. Temperature regulation by evenly distributing heat produced in the liver and the muscles throughout the body.
3. Transportation of digested food (glucose, amino acid, fatty acids and glycerol) from the villi to all body cells and tissues for use or storage.
4. Transportation of excretory products (C02, water, urea) from site of production to excretory organs like skin, lungs, liver and kidney for removal.
5. Transfer of hormones from production site to target organs.
6. Transportation of water (90% of the blood content) to various cells for metabolic activities. 7. Defense against infection through the action of WBC.
8. Blood clotting initiated by the platelets when injury is sustained.
9. Production of anti bodies by the WBC for destroying pathogens and their harmful product.
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Evaluation
Define the term Transport system.
2. State the Need for transport system.
3. Relate transport in lower organism to that of higher organism.
4. State the Transport material in animals and plant.
5. Discuss Diverse mechanism of transportation in some organisms.
6. Explain Transport system in mammals (man).
7. State the Functions of blood.
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