Post on 28-Dec-2015
The Endocrine SystemThe Endocrine System
Glands and Hormones
Regulation of Metabolism
The Stress Response
Blood Sugar
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 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
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