12.3 Hormones and the regulation of blood glucose.

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The regulation of blood glucose is an example of...
homeostasis.
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What produces hormones?
Glands, which secrete the hormone directly into the blood stream.
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What carries hormones?
Blood plasma.
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What are the cells called which hormones directly affect?
Target cells.
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The second messenger model is used by 2 hormones involved in regulation of blood glucose. What are they?
Adrenaline and glucagon.
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What is the first step of the second messenger model?
The hormone is the first member. It binds to specific receptors on the cell-surface membrane of target cells to form a hormone-receptor complex.
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What is the second step of the second messenger model?
The hormone-receptor complex produced activates an enzyme inside the cell that results in the production of a chemical that acts as a second messenger.
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What is the third step of the second messenger model?
The second messenger causes a series of chemical changes that produce the required response. In adrenaline, this response is the conversion of glycogen to glucose.
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What is the pancreas?
A large, pale gland situated in the upper abdomen, behind the stomach.
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What are the enzymes produced for digestion?
Amylase, lipase and protease.
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What are the hormones for regulating blood glucose?
Glucagon and insulin.
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The pancreas contains hormone producing cells. What are these cells called?
The islets of Langerhans.
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The islets of Langerhans are of two types. What are the two types and what do they produce?
alpha cells - produce glucagon. beta cells - produce insulin.
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What happens if there is too much glucose in an animal's blood?
It lowers the water potential of the blood and creates osmotic problems that cause dehydration.
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What happens if there is too little glucose in an animal's blood?
Their cells will be deprived of energy and die. Brain cells will be the worst affected because they can only respire glucose.
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What is the normal level of blood glucose?
90mg per 100cm3
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How can glucose be obtained directly from the diet?
Through the break down of disaccharides e.g. starch, maltose, lactose, and sucrose.
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How can glucose be obtained from the break down of glycogen?
Glycogenolysis - glucagon is found in the liver and muscle cells and is produced by converting excess glucose from the diet in glycogenolysis.
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How can glucose be obtained from glyoneogenesis?
it is the production of new glucose from sources other than carbohydrates.
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What the the B cells of the islets of langerhan do?
detect a RISE in blood glucose level and respond by producing insulin.
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What is insulin?
A globular protein made up of 51 amino acids.
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What happens when insulin binds with glycoprotein receptors on the body cells of an organism?
change in the tertiary structure of the glucose transport protein channels, causing them to open and allow glucose into cells. There is an increase in number of carrier proteins in the CSF, enzyme that converts glucose to glycogen & fat is activated
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How does insulin decrease levels of blood glucose? example 1.
by increasing the rate of absorption of glucose in to the cells, especially muscle cells.
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How does insulin decrease levels of blood glucose? example 2.
By increasing the respiratory rate of the cells which therefore use more glucose and increase their uptake of glucose from the blood.
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How does insulin decrease levels of blood glucose?example 3.
by increasing the rate of gluconeogenesis in cells of the liver and muscles.
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How does insulin decrease levels of bloody glucose? example 4.
by increasing the rate of conversion of glucose to fat.
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What is the overall effect of insulin? What type of feedback is this
To restore blood glucose levels to normal, which is negative feedback.
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What cells are not affected by insulin?
Red blood cells.
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When is glucagon secreted by glands?
When the alpha cells of the islets of langerhan detect a fall in blood glucose levels.
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What cells have receptors that bind to glucagon?
The liver cells.
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How do the glucagon cells respond?
By activating enzymes that convert glycogen to glucose, and by increasing the conversion of amino acids and glycerol into glucose.
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What is the overall effect of glucagon production?
To increase the amount of glucose in the blood and return it to it's normal level.
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When is adrenaline released?
When the glucose levels need to be raised.
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How does adrenaline work?
It raises the blood glucose level by activating an enzyme that causes the breakdown of glycogen to glucose in the liver, and by inactivating an enzyme that synthesizes glycogen from glucose.
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Card 2

Front

What produces hormones?

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Glands, which secrete the hormone directly into the blood stream.

Card 3

Front

What carries hormones?

Back

Preview of the front of card 3

Card 4

Front

What are the cells called which hormones directly affect?

Back

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Card 5

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The second messenger model is used by 2 hormones involved in regulation of blood glucose. What are they?

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