Hormones that Affect Blood Sugar

 2 parts of the endocrine system affect blood sugar levels – cells in the pancreas and the adrenal glands  The pancreas contains 2 types of cells 1) Cells that produce digestive enzymes 2) Cells that produce hormones

 The cells that produce hormones are located in structures called the islets of Langerhans – there are more than islets with thousands of cells in each  The islet contains beta and alpha cells that make insulin and glucagon

 In the liver, glucose is converted into glycogen which is the storage molecule of glucose – this allows blood sugar levels to return to normal  It is made by the alpha cells in the islet of Langerhans and is released when blood sugar levels are low

 Glucagon promotes the conversion of glycogen to glucose which is released into the blood

 Insulin is made in the beta cells and is released when blood sugar levels rise (when you eat)  The presence of insulin causes cells of the muscles, live and other organs to become more permeable to glucose

 Glucagon and insulin work together to maintain homeostasis  Insulin causes a decrease in blood sugar  Glucagon causes an increase in blood sugar levels

 Diabetes is a disease where the body cannot produce insulin or not enough insulin or cannot use it properly  The blood sugar levels of these individuals rises and doesn’t decrease because of the lack of insulin – they need to take insulin injections to help their cells take in the glucose  What symptoms would you expect from an individual discovering they have diabetes?

Type 1 – Diabetes Mellitus – when the pancreas cannot produce insulin because of degeneration of the beta cells – about 10% Type 2 – adult on-set diabetes – when decreased insulin production or ineffective use of insulin produced – about 90%

 Type 3 – gestational diabetes –temporary condition of some mothers during pregnancies – occurs in about 2% of pregnancies

 Let’s read page 480 together  Write down a few notes about islet cell transplants

 The adrenal glands are located above the kidneys  They are made of 2 glands in one shell 1) adrenal medulla – the inside gland – regulated by the nervous system 2) adrenal cortex – outer casing – regulated by hormones

 Produces epinephrine (aka adrenaline) and norepinephrine (aka noradrenaline)  NOTE: epinephrine is produced by the nervous system and the adrenal medulla  Do you remember what the release of epinephrine is for?  It gets the body ready for stress

 During a release of epinephrine glycogen is converted into glucose for a ready source of energy

 Produces 3 types of steroid hormones: 1) Glucocorticoids - more info following 2) Mineralocorticoids - help regulate electrolyte and water balance 3) Sex hormones – save for next unit

-The glucocorticoids are associated with blood glucose levels and cortisol (a part of glucocorticoids) increases the level of amino acids in the blood to help recover from stress

 The amino acids can be used as an energy source or used for protein synthesis including helping repair damaged cells

 Fat is also broken down into fatty acids which provides a second source of energy and conserves glucose  Cortisol causes glucose to not to be taken in by many cells (ex. Muscle cells) but not the brain – this helps during times of fasting

1) Brain identifies stressful situation 2) The hypothalamus sends a releasing hormone to the anterior lobe of the pituitary stimulating creation of adrenocorticotropic hormone (ACTH) (ACTH is a tropic hormone which targets another endocrine gland)

3) ACTH is carried in the blood to the target cells in the adrenal cortex 4) The adrenal cortex secretes mineralocorticoids and glucocorticoids (including cortisol) which are carried to target cells in the liver and muscles

5) Cortisol levels rise within the hypothalamus and the pituitary decreases the production of regulatory hormones Note: aldosterone is a mineralocorticoid – causes increased sodium retention and water reabsorption by the kidneys

1) Brain identifies stressful situation 2) Cells in hypothalamus send signals to nerve cells in spinal cord 3) Spinal cord cells stimulate adrenal medulla to secrete hormones

4) Adrenal medulla secretes epinephrine and norepinephrine 5) Target organs physically respond to stress (ex. Breathing rate and blood flow)

 Lab exercise 15.A on page 483  #1-4 on page 484