Hormones that Affect Blood Sugar

Insulin, glucagon,epinephrine, norepinephrine

and cortisol

Pancreatic enzymes

• The pancreas contains two types of cells: – one type produces digestive enzymes – the other type produces hormones

• The hormone-producing cells are located in structures called theislets of Langerhans

Pancreas

• More than 2000 tiny islets, each containing thousands of cells, are scattered throughout the pancreas.

http://www.leedsth.nhs.uk/sites/diabetes/teenage/IsletsofLangerhans.php

Pancreas

• The islets contain beta and alpha cells that are responsible for the production of two hormones: – insulin – Glucagon

http://pathology2.jhu.edu/pancreas/anatphys/pancpart.htm

Effect of Insulin

• Insulin is produced in the beta cells of the islets of Langerhans and is released when blood sugar levels increase.

Effect of Insulin

• Insulin causes cells of the muscles, the liver, and other organs to become permeable to the glucose

• The glucose leaves the blood and enters the cells

Effect of Insulin• In the liver, the

glucose is converted into glycogen, the primary storage form for glucose.

• Insulin enables the blood sugar level to return to normal and to maintain homeostasis

Glucagon

• Glucagon is produced by the alpha cells of the islets of Langerhans,

• Glucagon is released when blood sugar levels are low, such as after periods of fasting.

Glucagon• Glucagon promotes the conversion of

glycogen to glucose, which is released into the blood.

• As glycogen is converted to glucose in the liver, the blood sugar level returns to normal.

http://www.biology.arizona.edu/biochemistry/problem_sets/carbomet/05t.html

Adrenal Glands

• The adrenal glands are located above each kidney.

• Each adrenal gland is made up of two glands encased in one shell.

http://genericlook.com/anatomy/Adrenal-Gland/

Adrenal Glands

• The inner gland, the adrenal medulla, is surrounded by an outer casing, called the adrenal cortex.

• The adrenal medulla is regulated by the nervous system

• The adrenal cortex is regulated by hormones

http://iahealth.net/adrenal-gland/

Adrenal medulla

• The adrenal medulla produces two hormones: – epinephrine (also known as adrenaline)– norepinephrine (noradrenaline)

• The nervous system and the adrenal medulla are linked by the fact that both produce epinephrine.

Reaction to Stress

• The hormone-producing cells within the adrenal medulla are stimulated by sympathetic nerves in times of stress.

• Epinephrine and norepinephrine are released from the adrenal medulla into the blood.

Effects of Epinephrine and Norepinephrine

• Blood sugar level rise• Glycogen is converted into glucose• The increased blood sugar level ensures that a

greater energy reserve will be available for the tissues of the body.

Effects of Epinephrine and Norepinephrine

• Epinephrine and norepinephrine cause an increase in:– heart rate increase– breathing rate – cell metabolism

Effects of Epinephrine and Norepinephrine

• Blood vessels dilate, allowing more oxygen and nutrients to reach the tissues.

• The iris of the eye dilates, allowing more light to reach the retina

The Adrenal Cortex • The Adrenal cortex produces three different

types of hormones: – the glucocorticoids– the mineralocorticoids – small amounts of sex hormones

Glucocorticoids

• The glucocorticoids are associated with blood glucose levels.

• Cortisol increases the level of amino acids in the blood in an attempt to help the body recover from stress.

• The amino acids are converted into glucose by the liver, thereby raising the level of blood sugar.

• Any of the amino acids not converted into glucose are available for protein synthesis.

• The proteins can be used to repair damaged cells.

Effects of Cortisol

• Fats in adipose tissue are broken down into fatty acids.

• A second source of energy is provided, helping conserve glucose in times of fasting.

• Under the influence of cortisol, blood glucose uptake is inhibited in many tissues, especially in the muscles

Long-term stress responses

• The brain identifies stressful situations. • The hypothalamus sends a releasing hormone

to the anterior lobe of the pituitary• The pituitary secretes corticotropin, also

called adrenocorticotropic hormone (ACTH). • The blood carries the ACTH to the target cells

in the adrenal cortex.

Long-term stress response

• The cells of the adrenal cortex secrete mineralocorticoids and glucocorticoids which are carried to target cells in the liver and muscles.

• As cortisol levels rise, cells within the hypothalamus and pituitary decrease the production of regulatory hormones, and, eventually, the levels of cortisol begin to fall.

• This process is called a long-term stress response.

Short-term stress response

• The brain identifies stressful situation• The hypothalamus sends a nerve signal to the

adrenal medula• The adrenal medulla secretes epinephrine and

norepinephrine.

Mineralocorticoids

• Aldosterone is a mineralocorticoids prdoced by the adrenal cortex

• Secretion of aldosterone increases sodium retention and water reabsorption by the kidneys, thereby helping to maintain body fluid levels.

Homework

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