Lymphatic System and Evolution of Transport System | SSC BIOLOGY | Class 10

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Lecture Name: Lymphatic System and Evolution of Transport System

lecture notes:
Lymphatic system
• Lymphatic system is the parallel system to the venous system that collects tissue fluid from the tissue and transports into to the venous system
• Blood contains solid and liquid particles,
• Lymph: a fluid like substance that contains blood without out solid particles
• Serum: the liquid portion which is formed after the blood clot
• Tissue fluid: the lymph that is present in tissues
• During blood circulation the liquid portion of blood comes out through blood capillaries into tissue (tissue fluid)
• Some amount of Tissue fluid enters into venules, and in turn forms into venous system

• Remaining tissue fluid known as lymph (Latin lymph- water) which is a carried through a separate system called as lymphatic system
• Lymph is vital link between blood and tissues by which essential substances pass from the blood to cells and excretory products from cells to blood
• Contraction of skeletal muscles helps in pushing of lymph into lymphatic vessels and in to veins towards heart
• Valves present in a lymphatic vessels and veins stop the reverse flow of blood

• Why do our legs swell?
• Overnight journey sitting in one position without moving causes swelling of legs, swelling is called edema

• What about the remaining tissue fluid?
• Remaining tissue fluid is carried by lymphatic system

Evolution of transport (circulatory) system
• Evolution of transport system is seen from unicellular organisms to multicellular organisms, a simple diffusion to specialised organs are involved in the transportation of nutrients and gases, example: Brownian movement, protoplasmic currents, water currents, gastrovascular cavity, branched digestive system, pseudocoelom, pulsatile vessels and pulsatile organ
• Brownian movements: a natural moment that occurs in the water that helps in the exchange of nutrients and gases from the cell and distributed throughout the protoplasm, example: amoeba
• Protoplasmic currents: simplest intracellular transport system in multicellular animals, the protoplasm of any cell in the body is mobile that even exist in a nerve cells, example: humans and other animals
• Water currents: multicellular organisms create their own water currents for the transportation of nutrients and gases by beating flagella which are present on their body, example: parazoans, sponges, etc.
• Gastrovascular cavity: a blind sac like a gastro vascular cavity, which has taken up the function of digestion and a transportation of a nutrients to each and every cell of the body, example: hydra, jellyfish, etc.
• Branched digestive system: highly branched digestive system supplies nutrients to all cells and collect the waste from individual cells, most of the body is occupied by digestive and excretory system, example: fasciola hepatica
• Pseudocoelom: a fluid filled body cavity which is taken up the function of a collecting and distribution of materials, example: Nemathehelminthes
• Pulsatile vessels: a fluid with the transporting medium (blood) is transported in vessels for transportation of nutrients, example: eucoelomates
• Pulsatile organs: a pulsatile organ (heart) is developed to pump blood through blood vessels to the tissue, example: arthropods
• Open circulatory system: the supply of oxygen and nutrients directly to the tissues without any blood vessels respiratory system, example: arthropods
• Closed circulatory system: the flow of blood in a blood vessels for the transportation of nutrients and gases, example: annelids, echinoderms, higher chordates, etc.
• Human circulatory system can move 1 ml of blood from heart to foot and back which is approximately to metres in about 60 seconds
This process would take more than 60 years for the substance to move across this distance by diffusion

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