Junctional rhythm Junctional rhythm Junctional rhythm describes an abnormal heart rhythm resulting from impulses coming from a locus of tissue in the area of the atrioventricular node, the "junction" between atria and ventricles. Under normal conditions, the heart's sinoatrial node determines the rate by which the organ beats – in other words, it is the heart's "pacemaker". The electrical activity of sinus rhythm originates in the sinoatrial node and depolarizes the atria. Current then passes from the atria through the atrioventricular node and into the bundle of His, from which it travels along Purkinje fibers to reach and depolarize the ventricles. This
Lymph node stromal cell travel from the bone marrow or high endothelial venules of the thymus where they develop as lymphoblasts, to lymph nodes, where they mature. The primary role of lymph node stromal cells is structural. They form a scaffold for hematopoietic cells and assist their movement along it. The molecular signaling systems (chemokines) that distribute lymphocytes to appropriate localities within the lymph node (T and B cell segregation) are also created by lymph node stromal cells. Lymphocytes have receptors for such chemokines. For example, Naive T cells express the CCR7 receptor for the chemokine CCL21. and B cells exhibit CXCR5 receptors for