Studied by 0 peopleKey information required for this part of the Hormonal Control topic for OCR A Level Biology
Define gluconeogenesis, glycogenosis and glycogenolysis
Production of glucose from non-carbohydrate sources (eg: glycerol, amino acids); production of glycogen from glucose; breakdown of glycogen to glucose
Explain how respiration affects blood glucose concentration, and how eating carbohydrate-rich foods affect blood glucose concentration
Glucose is used in respiration to produce energy, decreasing blood glucose concentration; carbohydrates are broken down in the digestive system to glucose, increasing blood glucose concentration
When is insulin production stimulated, which cells secrete it, and state the processes this initiates
When blood glucose concentration is too high; beta cells in the pancreas; increased rate of absorption of glucose into cells, increase respiratory rate of cells, increase glycogenesis, increase glucose to fat conversion, inhibit release of glucagon
When is glucagon production stimulated, which cells secrete it, and state the processes this initiates
When blood glucose concentration is too low; alpha cells in the pancreas; increased glycogenolysis, increased gluconeogenesis, reduced glucose absorption by liver cells
Describe the mechanism of insulin secretion beginning with state of beta cells at normal blood glucose concentration
At normal blood glucose levels, potassium ion channels of plasma membrane are open to allow diffusion of potassium ions and potential difference is -70mV. As blood glucose concentration rises, glucose enters the cell via a glucose transporter and is metabolised in the cell to produce ATP. ATP binds to ATP-sensitive potassium ion channels, causing them to close. This causes potential difference to reduce to -30mV, causing the membrane to depolarise, causing voltage-gated calcium ion channels to open. Calcium ions diffuse into the cell, stimulating secretory vesicles to release insulin by exocytosis
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