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The heart is the driver of the circulatory system, pumping blood through rhythmic contraction and relaxation. The rate of blood flow out of the heart (often expressed in L/min) is known as the cardiac output (CO). Blood being pumped out of the heart first enters the aorta, the largest artery of the body.
Venous return (VR) is the flow of blood back to the heart. Under steady-state conditions, venous return must equal cardiac output (Q), when averaged over time because the cardiovascular system is essentially a closed loop. Otherwise, blood would accumulate in either the systemic or pulmonary circulations.
In this way, the same flow through the coronary circulation is maintained over a range of pressures. This part of coronary circulatory regulation is known as auto regulation and it occurs over a plateau, reflecting the constant blood flow at varying CPP & resistance. The slope of a CBF (coronary blood flow) vs. CPP graph gives 1/Resistance.
As the heart fills with more blood than usual, there is an increase in the load experienced by each myocyte. This stretches the muscle fibers, increasing the affinity of troponin C to Ca 2+ ions, causing a greater number of cross-bridges to form within the muscle fibers.
Experiments have shown that a strong muscle contraction can occur without a corresponding increase in skeletal muscle blood flow. [6] Given the proposed manner of action of the muscle pump to increase arterial blood flow, it would seem impossible for a muscle contraction and skeletal muscle hyperemia to be uncoupled.
This response occurs because vasodilatory substances, like adenosine, are released in response to the blood flow interruption, meaning that when blood flow resumes it occurs in a wider blood vessel and thus at an increased flow rate. This is classically seen in weight lifting, as skeletal muscle can become occluded momentarily during this ...
where is the stability of the protein in water and [D] is the denaturant concentration. Thus the analysis of denaturation data with this model requires 7 parameters: Δ G w {\displaystyle \Delta G_{w}} , Δ n {\displaystyle \Delta n} , k , and the slopes and intercepts of the folded and unfolded state baselines.
Gap junctions are particularly important in cardiac muscle: the signal to contract is passed efficiently through gap junctions, allowing the heart muscle cells to contract in unison. The importance is emphasized by a secondary ephaptic pathway for the signal to contract also being associated with the gap junction plaques.