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Circulation Review

Circulation Review - Circulation Homeostasis maintenance of...

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Circulation Homeostasis : maintenance of relative constancy of internal environment Negative Feedback Regulation of Plasma : beta cells in pancreas sense plasma glucose concentration, combine this information with other information (control center) and make a decision to act—secreting insulin; b cells act as sensors, control centers, and effectors o Eat, increase blood glucose, sensed by B cells, increase secretion of insulin for glycogen synthesis (storage form of glucose), glucose uptake occurs, decreases glucose, process begins again Negative feedback regulation: examples include when lower body temperature causes shivering, which increases heat, salty food triggers salt excretion, exercise stimulates breathing Pathways Heart Arteries Arterioles Capillaries Venules Veins Heart Left Atrium Left Ventricle Aorta Body Superior or Inferior Vena Cava Right Atrium Right Ventricle Pulmonary Artery Lungs Pulmonary Vein Arteries carry blood away from the heart, veins carry it back Need for the Circulatory System Time is proportional to Distance 2 Heart generates pressure, which is highest at the aorta and decreases forward At the downstream end of the veins, pressure is the lowest Blood pressure is measured at the brachial artery (arm) N.B. The higher pressure gradient, the higher the blood flow Avian and Mammalian Heart Pulmonary and systemic circuit: two pumps in series
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Output of left heart always equals that of the right heart because otherwise blood would back up in the lungs or body o If the left heart is weaker, then blood backs up in the pulmonary circuit o If the outputs are not equal, congestive heart failure When one side is weakened by disease (for example a heart attack) blood backs up, the heart is weakened and failure increases, so blood volume and pressure builds up in an area o For example congestive heart failure with lowered left output leads to increase in fluid in lungs, backup in the left lung which enlarges Heart divided by septum to prevent mixing of oxygen rich and poor blood
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Circulation Review - Circulation Homeostasis maintenance of...

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