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8.2 Hormones that affect blood sugar. Recap. Hormones Endocrine Glands Steroid vs. Protein Hormones The different types of signaling Pituitary Gland Pituitary Hormones (Table 1. page 377). Pancreas. The pancreases contain two types of cells: Cells that produce digestive enzymes
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Recap • Hormones • Endocrine Glands • Steroid vs. Protein Hormones • The different types of signaling • Pituitary Gland • Pituitary Hormones (Table 1. page 377)
Pancreas • The pancreases contain two types of cells: • Cells that produce digestive enzymes • Cells that produce hormones • The hormones located in islets of Lagerhans • Islets contain cells that produce: insulin and glucagon
islets of Lagerhans (Insulin) • There are more than 2000 tiny islets, each containing thousands of cells (either alpha or beta) • Beta produce insulin, and alpha produce glucagon • For example, after a meal, glucose levels rise, and the appropriate amount of insulin is released by beta cells of the pancreas • The effect is that the membrane of muscle and liver cells becomes more permeable to glucose, drawing it out of the blood • In the liver, glucose is converted to glycogen – the storage form of glucose
islets of Lagerhans (Glucagon) • Glucagon and insulin have antagonistic effects • When blood glucose levels are low, glucagon is released by the alpha cells of the islets of Langerhans • During periods of fasting, glucagon is released and promotes the conversion of glycogen to glucose, which is released in the blood – raising the blood sugar level
Figure 1. page 378 Insulin causes a decrease in blood sugar level
Figure 1. page 378 Glucagon causes an increase in blood sugar level
Diabetes • Based on what you know about diabetes, what hormone, insulin or glucagon is being inefficiently produced? • Insulin • Diabetes is a chronic illness • If left untreated, it can cause blindness, nerve damage and kidney failure
People living with Diabetes • Also known as hyperglycemia • Kidneys unable to reabsorb all the blood glucose glucose appears in urine • Insulin is required to make cells permeable to glucose, so little glucose makes it into the cells of the body • The body can turn to use fats and proteins to metabolize energy
There are three main types of diabetes Type I • Referred to as juvenile-onset diabetes • Early degradation of beta cells in the islets of Lagerhans • Pancreas unable to produce insulin • Diagnosed early • People must take insulin to live • Approximately 10% of diabetics have Type I
There are three main types of diabetes Type II • Can be referred to as adult-onset diabetes • Either the body decreases its insulin production or uses it ineffectively • Diagnosed in adulthood • Can be controlled with a proper diet, exercise and oral medication (sulfonamides) • Approximately 90% of diabetics have type II
There are three main types of diabetes Type III • Type of gestational diabetes • Temporary condition (~ 2-4% of pregnancies) • This condition does increase the risk of type II diabetes in the mom, and type I in the unborn child
Adrenal Glands • Each adrenal gland is made of two glands incased in one shell • Adrenal cortex regulated by hormones • Adrenal medulla regulated by nervous system
Inner Gland: Adrenal Medulla • Produces two hormones – epinephrine (adrenalin) and norepinephrine that respond to short-term stress (see Figure 5, p. 382) • Similar to the nervous system, the adrenal medulla produces epinephrine • The sympathetic nerves stimulate the adrenal medulla to produce these hormones and release them into the blood
The effect of these hormones: • When they exist in the blood, they cause the blood sugar level to rise as glycogen is quickly converted to glucose – a quick energy source • Heart rate increases, breathing rate increases and cell metabolism increases • Blood vessels dilate • Iris of the eye dilate
Adrenal Cortex (outer gland) • Produces three different types of hormones that deal with long term stress: • Glucocorticoids • Mineralocorticoids • Sex hormones
Long-term stress response works as follows: • The hypothalamus sends a releasing hormone to the anterior lobe of the pituitary, which stimulates the release of a hormone called corticotrophin, also known as adrenocorticotropic hormone (ACTH) • The blood carries the ACTH to the adrenal cortex • The ACTH influences the adrenal cortex to release mineralocorticoids, as well as glucocorticoids, which are carried to target cells in the liver and muscles
Glucocorticoids • Cortisol is one of the most important glucocorticoids unique association with blood sugar levels • Cortisol increases the amount of amino acids in the blood in an attempt to help the body recover from stress • The amino acids are converted to glucose by the liver raising the level of blood sugar increases the amount of energy reserves in the blood • Fats are converted to fatty acids, producing yet another energy source for the body
Mineralocorticoids • Aldosterone is an example of a mineralocorticoids • Increases sodium retention and water reabsorption to the kidneys • Helps maintain body fluid level
Table 1. page 382 Hormones that affect blood sugar