Neural oscillation sinoatrial node normally initiates it, simply because it generates impulses slightly faster than the other areas. Hence, these cells generate the normal sinus rhythm and are called pacemaker cells as they directly control the heart rate. In the absence of extrinsic neural and hormonal control, cells in the SA node will rhythmically discharge. The sinoatrial node is richly innervated by the autonomic nervous system, which up or down regulates the spontaneous firing frequency of the pacemaker cells. Synchronized firing of neurons also forms the basis of periodic motor commands for rhythmic movements. These rhythmic outputs are produced by a group
Lymph node biopsy enlargement (swollen glands or lymphadenitis). It may also determine whether tumors in the lymph node are cancerous or noncancerous. Enlarged lymph nodes may be caused by a number of conditions, ranging from very mild infections to serious malignancies. Benign conditions can often be distinguished from cancerous and infectious processes by microscopic examination. The pathologist may also perform additional tests on the lymph node tissue to assist in making a diagnosis. Some of the conditions where abnormal values are obtained are: Lymph node biopsies may be performed to evaluate the spread of cancer. See Lymphadenectomy#With_sentinel_node_biopsy. However, Sentinel lymph node biopsy for