BTEC APPLIED SCIENCE UNIT 8 LEARNING AIM B(LYMPHATIC SYSTEM) updated document 2022/ 2023

BTEC APPLIED SCIENCE UNIT 8 LEARNING AIM B(LYMPHATIC SYSTEM) updated document 2022/ 2023 Unit 8: Authorised Assignment Brief for Learning Aim B – Physiology of Human body. Lymph Vessels The lymphatic system spreads widely across the entire body and is made up of many different parts, those parts consist of the lymph vessels, lymph nodes, valves, thymus gland, tonsils, lacteals, and the spleen. The lymph vessels are thin-walled and valved, they are with endothelial cells and consists of a smooth, thin muscle wall and the outer wall binds the vessels to tissue that surrounds it. The endothelial is simple squamous epithelium, which has a highly permeable membrane, it also has junctions where the endothelial cells over-lap each other on these vessels in order to allow lymph in but not out. The smooth muscles bellow them are in a circular fashion and allows for the lymph to be pumped slowly around the body, and is involved with vasoconstriction and vasodilation, vasoconstriction increases blood pressure and vasodilation is the dilation of blood vessels, which decreases blood pressure. The outer layer is known as the adventitia and made out of collagen mostly and mainly acts to hold the lymph vessels stable within the body, but not all vessels contain the adventitia. Much like the vessels that transport blood around the body in the circulatory system, the lymph vessels transport lymph around the body, it carries it from the tissue through the lymph nodes and delivers cleaned fluids back to the blood. The lymph travels through the vessels due to smooth muscles, valves, and compression when the adjacent skeletal muscle and arterial pulsation compresses. Lymph Nodes Lymph nodes are small glands that are bean shaped. They are split into nodules and each nodule contains an outer cortex and then a paracortex, with the medulla inside. They are surrounded in connective tissue; this creates the capsule. The nodules are the store for the P-cell and T-cell lymphocytes and white blood cells are stored in its medulla. There are five major nodes known as axillary, supratrochlear, abdominal, inguinal, and popliteal nodes. Nodes can be found in all areas of the body other than the central nervous system. They filter lymph fluid and then return it to the blood, they maintain blood volume and pressure, defend against infection, and prevent fluid build-up in tissues. Axillary Nodes: The axillary nodes are located in the armpit and its main role is to perform filtration and conduct lymph. These nodes can be split into five different groups: the pectoral, lateral, subscapular, central, and subclavicular. Each of these nodes are all important in the transportation of nodes. The pectoral groups are made of four or five nodes in the superior border of the pectoralis. The afferent vessels send lymph too these nodes and efferent vessels carry lymph away from these nodes to the central lymph node. Lateral group boarders the lateral edge of the pectoral group and consist of between four and six different nodes that cluster around the axillary vein. Lymph from the upper arm flows into the lateral group and then into the central lymph nodes via the efferent vessels. Subscapular groups are located in the back of the shoulder blade and consists of six to seven nodes. It filters the lymph from the back of the neck and upper back. Efferent vessels take the lymph from them into the central lymph nodes. Central nodes consist of three or four nodes within the adipose tissue in the bottom of the axilla. They further filter the filtered lymph from the pectoral, lateral, and subclavicular nodes. The lymph from there is then taken to the subclavicular node bellow the collar bone. The subclavicular node is composed of between six and twelve nodes and they are the final filtration process the lymph goes through before going on to the subclavian trunk. These different groups are all regions that make up the axillary node.