Applicable for A-Level, IB, DSE, AP-Level Exams

Biological Molecules    Cell Structure    Cell Transport    Immunology    Exchange    Mass Transport    DNA, Genes & Protein Synthesis    Genetic Diversity    Biodiversity    Photosynthesis    Respiration    Energy & Ecosystems    Stimuli and Response    Nervous Coordination & Muscles    Homeostasis    Inheritance    Populations & Evolution    Ecosystems    Gene Expression    Recombinant DNA Technology   

Principles of Homeostasis and Negative Feedback

Homeostasis involves physiological control systems that maintain the internal enviornment within restricted limits. Negative feedback restores systems to their original level.

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Control of Blood Glucose Concentration

Insulin, glucagon and adrenaline all affect the concentration of glucose in the blood through the processes through glycogenolysis, glycogensis, gluconeogensis and the second messenger model of adrenaline and glucagon action.

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Summary of Blood Glucose Control

Summary sheet of insulin and glucagon action.

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Kidneys are where the control of water (osmoregulation) occurs. The pathway of kidney tubules within the nephrone goes from the renal capsule, proximal capsule, loop of Henle, distal convoluted tubule and then back to the collecting duct.

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Osmoregulation is the control of water within the kidney nephrons. As ultrafiltration takes place within the glomerulus through the buildup of hydrostatic pressure, a large part of the filtrate is selective reabsorbed in the proximated convoluted tubule through co-transport with Na+ ions. The Loop of Henle reabsorbs more water through the maintenance of Na+ ions. The counter current principle is established by Na+ ions and more water can then be drawn out within the collecting duct. The distal convoluted tubule reabsorbs the remaining materials and inorganic molecules.

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Summary of Nephron Action

Summary sheet of nephron action in the renal corpuscle, proximal convoluted tubule, loop of Henle, the distal convoluted tubule and the collecting duct.

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