Topic 15.2Hormones that Affect Blood Sugar

Into to Blood Sugar Levels

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 200 000 islets with thousands of cells in each

The islet contains beta and alpha cells that make insulin and glucagon

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

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

Glucagon and insulin work together to maintain homeostasis

Insulin causes a decrease in blood sugar

Glucagon causes an increase in blood sugar levels

Diabetes

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?

Types of 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

Islet Cell Transplants

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

cell transplants

Adrenal Glands

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

Adrenal Medulla

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

Adrenal Cortex

Produces 3 types of steroid hormones:1) Glucocorticoids - more info following2) Mineralocorticoids - help regulate

electrolyte and water balance3) Sex hormones – save for next unit

Glucocorticoids

-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

Glucocorticoids continued

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

Stress Response – Long term

1) Brain identifies stressful situation2) 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

Stress Response – Short Term

1) Brain identifies stressful situation2) Cells in hypothalamus send signals

to nerve cells in spinal cord3) Spinal cord cells stimulate adrenal

medulla to secrete hormones

4) Adrenal medulla secretes epinephrine and norepinephrine5) Target organs physically respond to stress (ex. Breathing rate and blood flow)

To Do:

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