blood glucose regulation — HSC biology, live

Blood glucose regulation

Blood glucose is held near a set point by negative feedback between two pancreatic hormones. When glucose rises, beta cells release insulin and the liver and muscles take glucose up and store it as glycogen; when it falls, alpha cells release glucagon and the liver releases glucose. Diabetes, hypoglycaemia and stress show what happens when one side of that loop fails or is overridden. This is the real knowscape from knowhere, not a picture of one. Drag it. Watch what actually changes.

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why this one carries the topic.

Your body keeps about forty things almost perfectly steady while the world does whatever it likes. Same trick every time: notice the drift, push back, repeat forever.

A model body over five hours: pick healthy, type 1, type 1 with insulin or type 2, add a meal, exercise or stress, and watch insulin, glucagon, the liver and the glucose curve, with the feedback loop spelled out at every moment.

what examiners catch — A common slip is naming insulin and glucagon without their actions. Earn the mark with cell, hormone, target and effect: beta cells release insulin, so liver and muscle take up glucose and the liver stores glycogen; alpha cells release glucagon, so the liver breaks glycogen down. For diabetes, say which step of the loop fails.

five things, not forty.

Beta cells in the pancreas release insulin when blood glucose rises: liver and muscle cells take glucose up and the liver stores it as glycogen, so glucose falls.

Alpha cells release glucagon when blood glucose falls: the liver breaks glycogen down and releases glucose, so the level rises back toward its set point.

This is negative feedback: stimulus, receptor, hormone, effector and a response that cancels the change, holding blood glucose at about 4 to 7.8 mmol/L.

Stress hormones raise blood glucose: adrenaline from the adrenal medulla speeds glycogen breakdown, and cortisol from the adrenal cortex drives gluconeogenesis.

Type 1 diabetes: beta cells are destroyed, no insulin, glucose stays high. Type 2: cells resist insulin. Hypoglycaemia is below 4 mmol/L, often from injected insulin.

Hyperthyroidism is another broken loop: the thyroid makes too much thyroxine, raising metabolic rate, and feedback through TSH fails to switch it off.

nothing here is a standalone fact.

knowhere maps every concept to what it rests on and what rests on it — 1 underneath this one, 4 built on top. Each one says why, in a sentence, not as an arrow on a diagram.

this conceptblood glucose regulationA model body over five hours: pick healthy, type 1, type 1 with insulin or type 2, add a meal, exercise or stress, and watch insulin, glucagon, the liver and the glucose curve, with the feedback loop spelled out at every moment.

sits under itnegative feedback mechanismsbecause glucose control is feedback with insulin

built on itautoimmune diseasebecause Loss of beta cells removes insulin and glucose control in type 1 diabetes.

built on itnon-infectious disease: causes and patternsbecause The modelled condition is type 2 diabetes-like; knowing insulin control helps.

built on ithormonal and neural coordinationbecause glucose control is the worked example of hormones doing coordination

built on itblood composition around the bodybecause The liver storing or releasing glucose is the same control that keeps blood glucose steady.

they don't read it. they run it.

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why this one carries the topic.

five things, not forty.

nothing here is a standalone fact.

3 more, same treatment.

they don't read it. they run it.