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:1.Cells that produce digestive enzymes

1.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

Insulin causes a decrease in blood sugar

level

Figure 1. page 378

Glucagon causes an increase in blood sugar

level

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 diabetesType 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

Type I Diabetes

There are three main types of diabetesType 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 diabetesType 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:

1.Glucocorticoids

2.Mineralocorticoids

3.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

Figure 5. page 382

Hormones that affect blood sugar

Table 1. page 382