Transport System

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CLASS: SS2

SUBJECT: BIOLOGY                                                   PERIOD(S): 3

TOPIC:       TRANSPORT SYSTEM

SUBTOPIC 1: MATERIALS FOR TRANSPORTATION

SUBTOPIC 2: MEDIA OF TRANSPORTATION

SUBTOPIC 3: COMPOSITION AND FUNCTIONS OF BLOOD AND LYMPH

PREVIOUS KNOWELDGE: Students are familiar with the topic 

OBJECTIVES: At the end of the period(s) students should be able to

Period 1:

1. Explain the necessity of a transport system in complex organisms
2. Explain the in adequacy of diffusion alone as a transport system for complex organisms

 Period 2:

1. Identify the source of materials for transportation
2. Identify where there materials are transported to:

Period 3: Discuss the different types of transportation media such as cytoplasm, cell sap, lymph and blood.

References : 

Modern Biology for Senior Secondary Schools 1-3 page 301 – 312.

Essential Biology for Senior Secondary Schools 1-3 by MC Michaels pg 275 – 280

CONTENT

Transport system in a living organism is the movement of metabolic materials from various parts of the organisms to the plants where they are produced or obtained to the parts where they are neither needed, stored or removed from the body.

Transport system is necessary because

1. it helps to move necessary materials e.g. oxygen, nutrients, water, mineral saltsetc to where they are needed.
2. It removes and disposes metabolic wastes e.g. carbon dioxide, water, urea etc.

In unicellular organisms such as Amoeba, Euglena, and paramecium, the surface area to volume ratio of the body is large, therefore, essential nutrients and excretoary products move in and out of the body by diffusion. However, as the organisms become larger, the body surface area ot volume ratio decrease and diffusion is not effective for the  exchange of metabolic materials within their bodies in between theme and their external environment.

MATERIALS FOR TRANSPORTATION

Other materials transported in plants are oxygen, auxins, or hormones, amino acids, lipids, nitrogenous waste products, latex, excretory products etc.

MEDIA OF TRANSPORTATION

There are 4 major media of transportation  and they are cytoplasm, cell sap (latex), blood and lymph.

1. Cytoplasm – This is found in unicellular organisms. Materials are transported from one part of the cell to another through the cytoplasm.
2. Cell sap. This is found in plants. Cell sap is a concentrated solution found in cell vacuoles which serve as a stronger solution. Cell sap transport water and dissolved mineral salts from the soil through the root hairs to other plant parts.
3. Blood – This is found in most animals especially vertebrates. Blood is a liquid tissue and its is capable of moving large materials over the entire body through blood vessels from the site of production to where they are required.
4. Lymph – This can also be found in higher animals and it is similar in composition to tissue fluid, although it contains extra lymphocytes, there is no red cell present. It returns fluid to the main veins through opening in the subclavian (left jugular vein below the neck e.g. of lymph vessel is the lateal which transports fatty acids and glycerol.

COMPOSITION AND FUNCTIONS OF THE BLOOD AND LYMPH

An average adult has about 5.5litres of blood (5-6litres)

The blood consists of liquid plasma in which a mixture of blood cells float.

1. PLASMA: This is a pale yellow liquid made up of 90% of water substances dissolved in it include hormones and antibodies, plasma, proteins, gasses, salts, enzymes, digested food materials, and waste materials. The major functions of plasma is to transport the substances dissolved in it as well as the blood cells and participate in the clotting of blood.

There are 3 types of blood cells or corpuscles

2. Red blood cells /Erythrocytes: There are about 5 million red blood cells in one cubic millimeters of blood. Erythrocytes are small, round and biconcave or disc like in shape. A mature cell has no nucleus and it has an elastic cell membrane with allows it to pass through narrow capillaries. Haemoglobin, the oxygen carrying pigtment is responsible for erythrocyte characteristic red colour. Red blood cells have a short life span of 3 months (120 days) before they become worn out and become destroyed in the spleen (worn out cells are ingested by phagocytes in the speleen and the heamoglobin is broken down to bilinruin and ferritin and released into the blood, the liver stores ferritin and excretes the birubin via the bile) Red blood cells are produced in the bone marrow and it transport oxygen (oxyhaemoglobin) small quantities of carbon dioxide and take part in blood clothing.
3. White blood cells (leucocytes) There are above 7,000 leucocytes in one cubic millimeter of blood. They are large, colourless, irregular and amoeboid in shape. They are produced in the bone marrow, lymph nodes and spleen. The lifespan of leucocytes is about 13 – 20 days after which they are destroyed by the lymphatic system. There are 2 types of white blood cells
4. Phagocytes – found in the lymphatic system where they ingest bacteria, viruses and dead cells and help in preventing diseases. they inject materials through a process called phagocytosis, hence these groups of white blood cells are called phagocytes.
5. Lymphocytes – are produced in the lymph glands. They produce antibodies which stick to the surface of germs and kill them.

White blood cells defend the body against diseases and also produce antibodies, immunities

4. Platelets (Thrombocytes) are tiny, irregular cell fragments which are non-nucleated. There are about 250,000 platelets percular millimeter of blood. They are produced in large bone marrow cells. Platelets aid in blood clothing by producing the factor which initiates the clothing of blood.

Lymph is a colourless liquid associated with the lymphatic system. Lymph flows in fine lymphatic vessels which join to form large vessels. These eventually join to form two large lymphatic vessels which empty their contents into the subclavran (left jugular) vein below the neck. Lymph is made to flow along the lymphatic vessels by movement of the body muscles and backflow of lymph is prevented by values present in the vessels. At certain points along the lymphatic vessels are bean shaped structures called lymph nodes which produce white blood cells. Diseases causing microorganism foreign particles and cell fragments found in the lymph are filtered out at the lymph nodes and engulfed by phagocytes. Lymph nodes can be found in the neck, groin and armpits. The lymph functions in body defense and in the absorption of fatty acids and clycerol eg lateal.

FUNCTIONS OF THE BLOOD

1. Transport of oxygen – oxygenated blood is bright red while deoxygenated blood is dark red.

Hb                        +                 4O₂                               HbO₈

Haemoglobin                                    low O₂

(dark red)                                         Concentration               Oxyhaemoglobin

                                                          (alveoli)                          (bright red)

 Oxygen combines with the pigment haemoglobin

2. Transport of carbon dioxide
3. Transport of excretory products – CO₂ Water and urea are transported to their excretory organs for excretion
4. Transport of digested food – digested food substances are transported from the villi of the small intestine to cells and tissues within the body for use or storage
5. Transport of hormones
6. Transport of antibodies
7. Heat distribution/temperature control – blood helps to distribute heat uniformly to all parts of the body and also help to regulate the body temperature by getting rid of excess heat or reducing heat loss.
8. Blood clothing – platelets initiate blood clothing when an injury is sustained to prevent further blood loss and entry of pathogenic organisms at the point of the injury. This process is as follows
9. Platelets plugs from to exposure of damaged blood vessels to air and release a chemical which causes involuntary muscles in the damaged blood vessels walls to constrict thus reducing blood flow.

iii.      In a case whereby the injury is very serious to be sealed by a plug, platelets release an enzyme called thrombokinase or thrombopolastin which converts inactive prothrombin into active thrombin

1. Thrombin in the presence of calcium salts (Ca²⁺ ions) converts fibrinogen to fibrin which forms a mesh of fine threads which tarps blood cells by forming a clot that covers the wound and prevents further bleeding and entry of pathogenic germs.

The cloth forms a scab which drops off after a new skin tissue is formed in the injured area.

FUNCTIONS OF LYMPH

1. Body defense – The lymph node produces white blood cells. Disease causing microorganisms, foreign particles etc found in the lymph are filtered out in the lymph nodes and engulfed by phagocytes.
2. Absorption of fatty acids and glycerol: The lymphatic system e.g. lateal is associated with the absorption of fatty acid and glycerol.

INSTRUCTIONAL MATERIALS

PICTURES AND VIDEOS

TEACHING METHODS PROCEDURES

Step 1: Teacher revises the last topic and introduced the new topic:

Step II: Teachers defines transport system and state the materials for transportation

Step III: Teacher explains the functions of the blood and the lymph.

Step IV: Teacher explains the functions of the blood and the lymph.

Step V: Teacher allows students to ask questions and written note under content on the board.

CLASSROOM (ACTIVITIES)

PERIOD 1: The students discuss what they understand about transport system and mention the materials and media of transportation

PERIOD 2: The students list the functions of the blood and lymph

EVALUATION:

PERIOD 1:

1. What is transport System?

State the need for transport system in living organisms

Period 2: Explain transport in lower organisms

Summary/Conclusion; Teacher summaries the topic,  marks the students notes and makes corrections  where necessary.

ASSIGNMENT (S)

PERIOD 1: Explain the mechanism of transportation or

1. Amoeba
2. Hydra

iii.      Insects

PERIOD 2:

1. Explain the composition of the human blood
2. Describe the functioning of the mammalian blood.