Endothelial Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Endothelial and links to relevant pages within the course.
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| Which of the following statements about Rickettsia is false: | View Page |
| Primary Hemostasis – The Vascular System & Platelet Involvement As discussed earlier, a break in the vessel endothelium leads to exposure of collagen and the vessel's subendothelial surface. Ruptured endothelial cells leak ADP and Serotonin, which are the chemical triggers that induce platelet adhesion, the next step in the sequence of hemostatic events. Circulating platelets are drawn to the area by those liberated chemical signals, and begin to physically attach themselves to the rough, damaged surfaces of the breach. As platelets continue to arrive and bind to the exposed collagen and basement membrane, a rudimentary barrier begins to form, as the platelets themselves serve to fill in the breached vessel wall. Platelets possess an inherent “sticky” property which enables them to adhere to one another, and not just to the damaged vessel endothelium. The process by which platelets bind to one another is referred to as platelet aggregation, and is vital because it allows for a platelet plug to be formed. The platelet plug is the structure responsible for plugging the hole in the vessel wall. | View Page |
| Supporting Cells Reticular cells (adventitial cells) provide structural support for the endothelial cells that line the venous sinus and the developing blood cells within the hematopoietic cord. The cytoplasm of the reticular cells is capable of extending itself in fiberlike strands deep into the hematopoietic cords. These strands provide a meshwork for the blood cells. Other types of cells which furnish support in the cord include macrophages and fat cells. | View Page |
| The cells that provide support for the developing cells in the hematopoietic cords are: | View Page |
| Location of Cells within Cord continued Another representation of the cells in a hematopoiectic cord which focuses in the appearance of various cells as well as their location within the cord is shown here.
HC: hematopoiectic cordVS: venous sinusAdv: adventitial cellEnd: endothelial cellGP: granulopoiesisF: fat cellsEi: erythroipoietic islandHist: histiocyte (macrophage)Meg: megakaryocyteA: arteriole | View Page |
| Sinuses/Blood Vessels Circulating blood enters the bone through the central artery which branches out into small arterioles. These arterioles are interspersed in the cords of hematopoietic tissue. The arterioles drain into venous sinuses (space or cavity). Sinuses have a basement membrane which is lined by endothelial cells within the sinus and surrounded by reticular (e.g. adventitial) cells on other side. Blood from several venous sinuses may combine in a collecting sinus which leads to a central vein. The venous sinuses alternate with hematopoietic cords in a spokelike pattern with the central vein as the core. | View Page |
| Epitopes It is also important to note that in addition to red cells, ABO antigenic determinants (epitopes) are found in many tissues, body fluids, and other cells including endothelial cells and platelets. Because ABO antigens are so widely expressed, ABO antigens are also a major consideration in solid organ and bone marrow transplants. | View Page |