Tr Resistance Lab Report

i) TPR is adjusted through intrinsic and extrinsic physiological responses that affect arteriolar resistance. The intrinsic controls include chemical and physical influences. The relative input of a various local metabolites is coordinated to control arterial blood flow; vasodilation results from chemical factors such as decreased oxygen, increased carbon dioxide and increased potassium. Another local chemical mediator is histamine, which is released during injury or allergic reactions to cause vasodilation. The physical influences include the application of local heat or cold to cause a respective vasodilation or vasoconstriction, the opposition of passive stretch by arteriolar smooth muscle through vasoconstriction, and the release
The systolic blood pressure is not the same across all types of vessels and organs because of different proximities to the heart and different percentages of the cardiac output allocation. Blood pressure depends on the volume of blood contained within the vessel and the dispensability of the vessel walls, which vary across the circuit. The arteries have high systolic pressure, which drops as blood proceeds through the arterioles against high resistance. The blood pressure continues to drop across the capillaries, venules and veins. A distinct systolic pressure is no longer evident upon entering the capillaries due to the nonpulsatile nature that facilitates effective gas and nutrient
The parasympathetic nervous system acts on the SA node to decrease the heart rate; without this activity, the heart rate is dependent upon the rate of the SA node’s discharge. This lack of innervation means the heart rate is only affected by noradrenaline and adrenaline released from the adrenal medulla and circulating through the blood. This would cause a more gradual increase in heart rate upon the onset of exercise and a corresponding delayed decrease upon the cessation of exertion. The heart rate would also have less capacity to increase, so the diminished cardiac reserve would result in a poorer ability to cope with physiological