HORMONES THAT AFFECT BLOOD SUGAR
The Pancreas
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Contains two types of cells
o digestive enzyme producers
o Hormones producers
Two types of hormone producing cells: alpha cells and beta cells
Both are found in structures called the islets of Langerhans
Beta cells
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Produce insulin
Released when blood sugar levels rise (e.g. after a meal)
Causes muscle and liver cells (and other cells to a lesser degree) to become permeable to
glucose
Cellular absorption of glucose returns blood sugar levels to normal
Individuals with diabetes mellitus do not produce sufficient insulin due to degeneration
of the beta cells
Without insulin injections the body becomes starved for glucose and begins to metabolize
fats and proteins
Excessive fat and protein metabolism can lead to a decrease of blood pH (ketoacidosis)
Alpha cells
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Produce glucagon
Released when blood sugar levels are low (e.g. after fasting)
Causes an increase in blood sugar level by promoting the conversion of glycogen to
glucose
The Adrenal Glands
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Located above each kidney
Each adrenal gland is made up of two glands, one surrounds the other
Outer gland is the adrenal cortex and inner gland is the adrenal medulla
Adrenal cortex
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Regulated by hormones from the pituitary gland
Regulates the long-term stress responses
Produces three types of hormones: glucocorticoids, mineralocorticoids, and androgen
Glucocorticoids: Group of hormones that help control blood glucose levels
 Cortisol: An important glucocorticoid that acts as an antagonist to insulin and helps the
body restore homeostasis after stress
o Causes gluconeogenesis (synthesis of glucose – the reverse of glycolysis) and the
breakdown of lipids and proteins
o Increases blood glucose levels and causes the formation of glycogen by the liver
o Lowers the activity of the immune system
Mineralocorticoids: Hormones used to regulate the salt-water balance
 Aldosterone: A mineralocorticoid that increases sodium retention and water
reabsorption by the kidneys
o Helps to maintain body fluid levels and raise blood pressure
Adrenal medulla
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Regulated by the nervous system
Regulates the short-term stress responses
Produces two hormones: epinephrine (i.e. adrenaline) and norepinephrine
(noradrenaline)
Adrenal medulla is stimulated during times of stress
Effects of the release of epinephrine and norepinephrine into the blood:
o Blood sugar rises
o Glycogen is converted into glucose
o Heart rate, breathing rate, and cell metabolism increase
o Blood vessels dilate (allowing more oxygen to reach the tissues)
o Pupils dilate
Response to Stress
Long-term stress
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Brain identifies stressful situation
Hypothalamus sends a releasing hormone to the anterior lobe of the pituitary
Pituitary secretes adrenocorticotropic hormone (ACTH) into blood
ACTH is carried to target cells in the adrenal cortex
Adrenal cortex secretes mineralocorticoids and glucocorticoids (including cortisol) which
are carried to target cells in the liver, muscles, and kidneys
High cortisol levels signal the cells in the hypothalamus and pituitary to decrease
production of stress hormones
o Negative feedback causes the eventual fall of cortisol levels
Short-term stress
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Hypothalamus sends a nerve signal to adrenal medulla
Adrenal medulla secretes epinephrine and norepinephrine