For example, when an individual is exercising, more blood will be directed to skeletal muscles, the heart, and the lungs. Following a meal, more blood is directed to the digestive system. Only the brain receives a more or less constant supply of blood whether you are active, resting, thinking, or engaged in any other activity. Table 20.3 provides the distribution of systemic blood at rest and during exercise. Although most of the data appears logical, the values for the distribution of blood to the integument may seem surprising. Systemic Blood Flow During Rest, Mild Exercise, and Maximal Exercise in a Healthy Young Individual (Table 20.3) During exercise, the body distributes more blood to the body surface where it can dissipate the excess heat generated by increased activity into the environment. Three homeostatic mechanisms ensure adequate blood flow, blood pressure, distribution, and ultimately perfusion: neural, endocrine, and autoregulatory mechanisms. Figure 20.4.1 – Summary of Factors Maintaining Vascular Homeostasis: Adequate blood flow, blood pressure, distribution, and perfusion involve autoregulatory, neural, and endocrine mechanisms. The nervous system plays a critical role in the regulation of vascular homeostasis. The primary regulatory sites include the cardiovascular centers in the brain that control both cardiac and vascular functions. In addition, more generalized neural responses from the limbic system and the autonomic nervous system are factors. Neurological regulation of blood pressure and flow depends on the cardiovascular centers located in the medulla oblongata. The vasomotor centers control vessel tone or contraction of the smooth muscle in the tunica media.The cardioinhibitor centers slow cardiac function by decreasing heart rate and stroke volume via parasympathetic stimulation from the vagus nerve.The cardioaccelerator centers stimulate cardiac function by regulating heart rate and stroke volume via sympathetic stimulation from the cardiac accelerator nerve.The cardiovascular center contains three distinct paired components: This cluster of neurons responds to changes in blood pressure as well as blood concentrations of oxygen, carbon dioxide, and hydrogen ions. Changes in diameter affect peripheral resistance, pressure, and flow, which affect cardiac output. Increased radius, increases flow How does the plot differ from the plots for tube radius, viscosity, and tube length? diameter changes pressure changes requires the heart to respond to force Explain why pressure changes are not the best way to control blood flow.The majority of these neurons act via the release of the neurotransmitter norepinephrine from sympathetic neurons.Īlthough each center functions independently, they are not anatomically distinct. Increased viscosity, decreases blood flow increases pressure, increases blood flow Explain the effect that pressure changes had on flow rate. blood vessels lengthen when we gain weight Describe why blood flow has an effect on obesity. decreases blood flow Describe the effect that obesity would have on blood flow. radius is multiplied to the 4th power, length is not Explain why you think blood vessel radius can have a larger effect on the body than changes in blood vessel length. Blood vessel radius length stays constant when we reach adulthood Which is more likely to occur, a change in blood vessel radius or a change in blood vessel length? increases BV length, decreases flow rate Explain the effect that the change in blood vessel had on flow rate.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |