The Endocrine SystemThe Endocrine System

Glands and Hormones

Regulation of Metabolism

The Stress Response

Blood Sugar

Glands and HormonesGlands and Hormones

Endocrine Glands

Hormone Action

Regulation of Hormones

Endocrine Glands• A gland is a structure that

secretes products in the body• An exocrine gland secretes

substances (oils and proteins) into ducts that lead directly to the target tissue

• An endocrine gland secretes hormones into the blood stream for delivery to the target tissue

Endocrine Glands• The functions of

endocrine glands can be determined by:

1. Removing the gland and observing the effects

2. PET scans allow close observation of gland and target tissue membranes

Hormone Action• There are two types of hormones

1. Lipid soluble (steroids) including testosterone, cortisol, estrogen and others

2. Water soluble (protein) including growth hormone, insulin, thyroxine and others

Regulation of Hormones

• Hormones are regulated by negative feedback loops

• Tropic hormones from the anterior pituitary gland activate other endocrine glands

• ACTH, TSH, FSH, LH are examples of tropic hormones

Regulation of MetabolismRegulation of Metabolism

The Pituitary Gland

Growth Hormone

Thyroxine

Calcium

The pituitary Gland• The pituitary gland is divided into

two lobes

1. Anterior Lobe: manufactures and secretes hGH, TSH, ACTH, FSH, LH and PRL

2. Posterior Lobe: receives oxytocin and ADH from the hypothalamus and secretes them

Growth Hormone• Human growth hormone (hGH)

regulates growth, development and metabolism

• Hypersecretion of hGH causes acromegaly

• Hyposecretion of hGH causes dwarfism

• hGH is a common performance enhancing substance used by athletes

Thyroxine• Thyroxine increases the rate at which

the body metabolizes fats, proteins and carbohydrates for energy

• Secretion of thyroxine is regulated by a feedback loop

• Hypothyroidism is less than normal secretion of thyroxine

• Hyperthyroidism is greater than normal secretion of thyroxine

Calcium• Calcium is required for

development of bones and teeth

• Calcium is necessary for blood clotting

• Calcitonin and parathyroid hormone act antagonistically to keep calcium levels in the blood constant

The Stress ResponseThe Stress Response

The Adrenal Gland

Epinephrine/Adrenalin

Cortisol

Aldosterone

The Adrenal Gland• The adrenal glands are divided into

two regions

• Medulla: the inner portion of the adrenal gland (epinephrine, norepinephrine)

• Cortex: the outer portion of the adrenal gland (cortisol, aldosterone)

Epinephrine/Adrenalin• Epinepherine and norepinephrine

regulate short term stress responses

• The short term stress response is referred to as the fight or flight response

• Epinephrine is released due to direct stimulation by the hypothalamus

Cortisol• Cortisol deals with the long term

stress response• Cortisol causes protein metabolism

to increase glucose concentration and decreases inflammation

• Cortisol is secreted due to a feedback loop

• Chronically high cortisol levels have been linked to stress related diseases

Aldosterone• Aldosterone causes the kidneys to

increase absorption of sodium into the blood

• More sodium in the blood causes the kidney to retain water

• More water in the blood raises blood pressure

• ADH also increase water retention and blood pressure

Blood SugarBlood Sugar

The Pancreas

Glucose Imbalance

Diabetes Mellitus

Other Hormones

The Pancreas• The pancreas is both an endocrine

and exocrine gland

• Exocrine tissue secretes enzymes for the digestive system

• Endocrine tissue is located in the islets of langerhans

• There are two types of hormone producing cells in the islets of langerhans

The Pancreas

1. Alpha cells: produce glucagon to raise blood sugar concentration

2. Beta cells: produce insulin to lower blood sugar concentration

Glucose Imbalance• Blood glucose concentration

(BGC) must be regulated to avoid hyperglycemia or hypoglycemia

• Hypergylcemia: BGC is too high

• Hypoglycemia: BGC is too low

Diabetes Mellitus• Diabetes mellitus causes the

regulation of BGC to be upset• There are two types of

diabetes mellitus• Type I: beta cells cannot make

insulin (insulin dependent)• Type II: beta cells make insulin but

body cells are unresponsive (non-insulin-dependent)

Diabetes Mellitus• Treatments for type I diabetes

mellitus include:1. Insulin Injections/Pumps/Inhalers

2. Islet Cell Transplant

• Gestational diabetes temporarily affects some pregnancies

Other Hormones• Other hormones (besides

insulin and glucagon) can influence BGC

1. Cortisol

2. Thyroxine

3. Epinenphrine/Norepinephrine

4. TSH

5. ACTH