Provide a 4 pages analysis while answering the following question: How do the nervous system and local controls work together to regulate blood pressure and blood flow in different tissues. Prepare th
Provide a 4 pages analysis while answering the following question: How do the nervous system and local controls work together to regulate blood pressure and blood flow in different tissues. Prepare this assignment according to the guidelines found in the APA Style Guide. An abstract is required. The humoral mechanisms are dependent on vasoactive hormones epinephrine and angiotensin II. Blood flow to tissues is dependent on mechanisms that function at a local level. Blood flow in the body is autoregulated, because of which the blood flow is constant, irrespective of changes occurring in arterial perfusion pressure (Johnson 1986). The blood pressure, which is the force responsible for flow of blood through arteries and capillaries, is closely regulated by the three physiological mechanisms described above. The blood pressure depends on the cardiac output, which is the rate of blood flow produced by the heart, and the resistance to blood flow exhibited by the blood vessels (Sharma 1992). The resistance is mainly seen in the arterioles and is called peripheral vascular resistance (PVR) or systemic vascular resistance (SVR). The blood pressure is equal to the product of cardiac output and SVR. Neural Regulation The heart rate is modulated by neural influences that affect the myocardial rhythm. The neural influences involve sympathetic and parasympathetic components of the ANS. These two operate distinctly through different structural pathways, yet in parallel (McArdle, Katch, and Katch 2010). Pressure sensitive receptors called baroreceptors are present on the carotid sinus and aortic arch. These receptors stimulate the sympathetic and parasympathetic autonomic nervous system. The information (upon increase or decrease of blood pressure) is relayed to the vasomotor center for stimulation of sympathetic and parasympathetic systems (Sharma 1992). In the sympathetic influence, chronotropic effect and tachycardia occur. When epinephrine and norepinephrine is released by sympathetic cardioaccelerator nerves, they accelerate SA node depolarization. This, through the chronotropic effect, induces the heart to beat faster (tachycardia). The heart beat rates increase to more than 100 beats per minute at rest (McArdle, Katch, and Katch 2010). Epinephrine and norepinephrine also cause the inotropic effect by increasing the myocardial contractility. When the sympathetic nervous system is stimulated to the maximum, the ventricular contraction almost doubles. When epinephrine is released by the adrenal glands during sympathetic activation, a slow but similar tachycardial effect occurs. Vasoconstriction also occurs due to the effect of sympathetic stimulation on blood flow. In case of parasympathetic influence, acetylcholine is released by parasympathetic neurons upon stimulation. It slows down heart rate by retarding the rate of sinus discharge. The heart rate is thus reduced (called bradycardia) because of the stimulation of the vagus nerves in the medulla. Local Regulation The local mechanisms for control of blood flow are tissue intrinsic and act independently of the humoral or neural influences. These mechanisms offer each tissue to possess some degree of autonomy, so that it can satisfy its specific requirements of blood flow.