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 butnot out. The smooth muscles bellow them are in a circular fashion and allows for the lymph tobe 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 outof collagen mostly and mainly acts to hold the lymph vessels stable within the body, butnot all vessels contain the adventitia. Much like the vessels that transport blood around the bodyin the circulatory system, the lymph vessels transport lymph around the body, it carries it from the tissue through the lymph nodesand 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 isto 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 nodesin the superior border of the pectoralis. The afferent vessels send lymph too these nodes and efferent vessels carry lymph away from these nodesto 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 nodeis composed of between six and twelve nodesand 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. lOMoAR cPSD|3013804 Supratrochlear Node: The supratrochlear nodeis located within the elbow and consists of two nodes. There afferent vessels work to drain the forearm, hand, ring finger, little finger, and middle finger. There efferent vessels join the deeper vessels and are alongside the basilic vein. The lymph drained is then filtered in the supratrochlear node and is then sent to the lateral group of the axillary node where it is further filtered. Cross drainage in these vessels is possible as they are in free communication from other vessels in the forearm. Abdominal Nodes: The Abdominal nodes are sorted into two different groups: The superficial group and the deep group. The superficial group is the first drainage point of the abdominal wall and the deep groups work to send the lymph from the superficial group into the abdominal viscera, of which they are usually associated with, and the superficial group is associated with the subcutaneous blood vessel, the lymph from the superficial abdominal nodeis drained into the superficial inguinal nodes. The abdominal region can be split into the upper and lower abdominal wall, the deep abdominal nodes drain from the lower abdominal wall into the circumflex iliac. The drainage point of the adnominal viscera would mainly be through the thoracic duct. Inguinal Nodes: Inguinal nodes have two layers that are below the inguinal ligament, this runs from the largest bone at the front of the ilium to a bottom centre of the pelvis in the public region. The two layers are the superficial inguinal nodes and the deep inguinal nodes. The superficial inguinal nodes are located in the upper, inner thigh and consists of ten nodesand drains into the deep inguinal nodes. The deep inguinal nodes are located below the connective tissue of the upper, inner thigh along with being on the medial side of the femoral vein and consists of three to five nodes. There is also another type of inguinal node known as the Cloquet’s nodeanditis the top-most deep inguinal nodeandis below the inguinal ligament. These nodes work to drain the lymph into the external iliac node, then the pelvic nodeand finally, the paraaortic nodes. These nodes still do the same basic function that all nodesdo which isto filter waste, maintain fluid balance in the bloodstream, and help play a role in immune defence but inguinal nodes main purpose isto drain the reproductive organs and the bladder as well as the pelvic region. Popliteal Nodes: Popliteal nodes are located behind the knees and consists of six or seven nodes, and they work on the lower legs, feet, and toes. Most people have between two and nine popliteal nodes that form as a big cluster. There are two sets of popliteal nodes known as: the deep popliteal node and the superficial popliteal node, the deep popliteal nodeis located close to the popliteal vessels and the superficial popliteal nodeis located with the small saphenous vein. The superficial anddeep popliteal nodes drain lymph from the toes, feet, and legs and then the popliteal nodes drain the lymph from those, sometimes on rare occasions even draining the overlying skin. These nodes also do the same filtration and balancing as all of the other nodes. Valves: The valves are oneof the lymphatic vessel’s main features, they are semilunar valves that are attached to sides of the endothelium. They are only located in the larger lymph vessels along with the collecting vessels but would not be found in the lymphatic capillaries. The role of the valves is to prevent backflow of fluid so that the lymph will be flowing forwards instead of falling backwards.