Lymphatic System

Transportation system that allows waste products from cells to be transported back to the blood stream interstitial fluid Our cells are surrounded by a liquid known as “interstitial fluid”.

Interstitial Fluid

Lymphatic System Interstitial fluid contains: 1.Water 2.Various substances found in blood plasma (wastes, nutrients…) 3.White blood cells (used to protect body against “antigens” such as viruses and bacteria that may invade it)

Main Functions of Lymphatic System 1.To collect and return interstitial fluid to the blood and help maintain fluid balance 2.To defend body against disease by producing white blood cells (lymphocytes)

Lymph Organs Bone Marrow Bone Marrow Spleen Spleen Tonsils Tonsils Thymus Thymus

Parts of Lymphatic System 1. Lymphatic vessels 2. Lymph 3. Lymphatic organs 4. White blood cells

Lymphatic Vessels These vessels are intertwined with the circulatory vessels

Parts of Lymphatic System Lymphatic vessels The lymphatic system is made up of vessels like the circulatory system lymphatic vesselslymph. These vessels known as “lymphatic vessels” carry a fluid called lymph. Their job is to carry lymph to the blood

Lymphatic Vessel Tissue fluid moving into lymphatic vessel opening. Notice how it enters and the direction it takes (unidirectional)

Parts of Lymphatic System As with the circulatory system, the lymph vessels form a network throughout the body one-way Lymph vessels are a one-way highway!Lymph Lymph → composed mainly of water and cell waste

Parts of Lymphatic System Lymphatic Organs white blood cells These organs are the primary location where white blood cells are found and created They filter lymph to remove harmful elements such as bacteria and viruses from our body

Lymph Organs and nodes Area in which substances are filtered out of lymph

Parts of Lymphatic System White blood cells PHAGOCYTOSIS Eliminate antigens directly through PHAGOCYTOSIS or by producing antibodies Antibodies → neutralize specific antigens Diapedesis: Diapedesis: is the action in which white blood cells can exit the capillaries and move freely throughout the lymphatic and circulatory system

Diapedesis White blood cells undergoing diapedesis

Differences between lymphatic and circulatory system Circulatory system Blood Blood → collecting and distributing O₂, nutrients and hormones to tissues of body Blood flows continuous loop Blood flows → in a continuous loop throughout the body by arteries, capillaries and veins Lymphatic system Lymph Lymph → collecting and removing of waste products left behind by tissues of body Lymph flowsopen circuit Lymph flows → in a open circuit from tissues to lymphatic vessels. Is unidirectional, has valves to stop from flowing backwards

Differences between lymphatic and circulatory system Circulatory system Blood is pumped Blood is pumped → heart pumps blood to arteries. Veins return blood to heart. Blood consists of Blood consists of liquid plasma that transports red and white blood cells and platelets Lymphatic system Lymph is not pumped Lymph is not pumped → passively flows from tissues to lymph vessels. It is moved along by muscle contractions Lymph consists Lymph consists mainly of water

Differences between lymphatic and circulatory system Circulatory system Blood is visible Blood is visible → red color Blood is filtered by kidneys Blood is filtered by kidneys Waste products and excess fluid are removed Lymphatic system Lymph is invisible Lymph is invisible → transparent color Lymph is filtered by “Lymph nodes” Lymph is filtered by “Lymph nodes” Nodes remove some fluid and debris. Kill antigens (bacteria and viruses)