Insulin Oscillations with Intermediate Frequency

Insulin also oscillates with a period of about 10-20 minutes Figs. 19.11 and 19.12 . Because these oscillations occur in islets and the isolated pancreas, it appears that unlike the ultradian oscillations, they are caused by a mechanism intrinsic to the pancreatic islets. These oscillations also occur in the experimental perifusion system depicted in Fig. 19.16. A thin layer of insulin-secreting -cells is sandwiched between beads and exposed to the flow of a solution, the perifusate, with flow...

Pulsatile Insulin Secretion

Pulsatile Testosterone Secretion Men

Hormones secreted from cells in the pancreas are responsible for the control of glucose, amino acids, and other molecules that are necessary for metabolism. The pancreas contains a large number of secretory cells, grouped into about one million islets of Langerhans consisting of approximately 2,500 cells each. There are three principal Figure 19.9 Pulsatile secretion of LH, FSH, and testosterone in men. Berne and Levy, 1993, Fig. 48-15, p. 912. Figure 19.9 Pulsatile secretion of LH, FSH, and...

Ultradian Oscillations

Glucose Insulin Delay Equation Liver

Ultradian insulin oscillations have a number of observable features. First, oscillations occur during constant intravenous glucose infusion and are not dependent on periodic nutrient absorption from the gut. However, damped oscillations occur after a single stimulus such as a meal. Second, glucose and insulin concentrations are highly correlated, with the glucose peak occurring about 10-20 minutes earlier than that of insulin. Third, the amplitude of the oscillations is an increasing function...

Multicompartment Circulatory System

Symbolic Diagram Circulatory System

To construct a more detailed linear model of the circulatory system, we assume that the systemic and pulmonary loops each consist of two compliance vessels, the arterial and venous systems, connected by the capillaries, a pure resistance. Further, we assume that the heart has two chambers, the left and right hearts. A schematic diagram of the model is given in Fig. 15.8. We must write equations for the flow through each of these compartments and keep track of the total volume of blood contained...