Question

The lymphatic system includes our bodies' defenses against infections. AIDS, Leukemia, many autoimmune disorders, and allergies are all manifestations of a breakdown in the normal functioning of the lymphatic system. Find an online source that helps to explain how these diseases interact with the lymphatic system mechanisms. Provide the link and a brief summary of fewer than 250 words. Then, read at least two classmates' posts. What questions are you still wondering about after reading the summary they posted?

Answer 1

Active lymph transport by collecting lymphatic vessels depends critically on a combination of factors that combine to produce propulsive and centripetal movement of lymph. Lymph propulsion requires not only robust, spontaneous it also contractions of LMCs, but contraction waves that are coordinated over the length of a lymphangion, which is the segment of a collecting lymphatic vessel and it containing two intraluminal valves comprising the elementary pumping unit. In conjunction, unidirectional valves in the vessel lumen must operate normally to minimize backflow. For the purpose of this discussion, lymphatic pumping is the net outflow of a collecting lymphatic segment due to active contraction of the LMC layers. So the total outflow is equal to forward (centripetal) flow due to a propulsive contraction minus any reflux through the valves during the contraction cycle.

Pumping behaviour can be visualized in the lymphangions held at constant pressure. The linked movies (Movies S1 and S2 in the online Supporting information) show contractions of a popliteal afferent lymphatic from a mouse expressing green fluorescent protein (GFP) in lymphatic endothelial cells (LECs) under the control of the LEC‐specific transcription factor, Prox1. Robust and nearly synchronous contractions of a single layer of LMCs are evident.

Lymphangion from a Prox1GFP mouse after dissection, cannulation and partial cleaning
Lymphatic muscle is non‐striated and usually classified as vascular smooth muscle, but it shares biochemical and functional characteristics with both vascular and cardiac muscles Like vascular smooth muscle, lymphatic muscle contraction is regulated primarily by the balance of myosin light chain kinase (MLCK)/myosin light chain phosphatase (MLCP) activity controlling myosin light chain phosphorylation Lymphatic vessels resemble arterioles in that they develop basal tone and exhibit myogenic constriction to pressure elevation. Although the physiological role of the myogenic response in lymphatic vessels is not known, myogenic tone/constriction may serve primarily to preserve valve function , as discussed below. Like blood vessels, lymphatic behaviour is regulated by nitric oxide (NO) and other endothelium‐derived factors such as prostaglandins and histamine Both lymphatic tone and spontaneous contractions are inhibited by NO produced as a result of shear stress on the endothelium (in response to either forward or reverse lymph flow) Like cardiac muscle, LMCs express troponin C and I as well as cardiac isoforms of tropomyosin however, the functional roles of these contractile proteins remain unclear, as are the ways in which they might complement or interact with MLCK/MLCP to control the contraction cycle.

Lymphatic muscle shares several electrophysiological properties with both vascular smooth muscle (VSM) and cardiac muscle. LMC contractions depend predominantly on Ca2+ influx through L‐type, voltage‐gated Ca2+ channels while the resting membrane potential is influenced substantially by Cl− and voltage‐gated K+ channels. Further, the activation of ATP‐sensitive potassium (KATP) channels and Ca2+‐activated K+ channels in lymphatic muscle can dramatically modulate spontaneous contractile activity. Like cardiac muscle, the spontaneous contractions of LMCs are initiated by action potentials (APs) that probably originate in LMCs, but also might be generated by a network of interstitial cells. LMCs also express several types of ion channels that are similar to those that control pacemaking in the sino‐atrial node, e.g. fast Na+ channels. T‐type Ca2+ channels hyperpolarization‐activated cyclic nucleotide‐gated (HCN) channels related gene. The roles of these channels in lymphatic pacemaking are not yet fully understood.

DISEASE OF LYMPHATIC- Cancers such as Hodgkin's and non-Hodgkin's lymphomas, blockages such as lymphedema, inflammation such as lymphangitis, and even infection such as lymphadenitis can damage your lymphatic system, making it difficult for it to function normally.

Interaction - The lymphatic system clears away infection and keeps your body fluids in balance. If it's not working properly, fluid builds in your tissues and causes swelling, called lymphedema. Other lymphatic system problems can include infections, blockage, and cancer.

Link ? :- https://medlineplus.gov/lymphaticdiseases.html

Link ? :- https://www.ncbi.nlm.nih.gov/pmc/articles

/PMC5063934/

Mechanism ..