Download Pancreatic Hormones

Pancreatic Hormones
Pancreas
The pancreas is both an endocrine and exocrine gland. It is located in the
curve of the duodenum.
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Pancreas - Exocrine
• Secretes enzymes involved in digestion
Exocrine is NOT endocrine, remember?
Moving on…
Pancreatic Importance!!
Endocrine roles of the pancreas are to:
• Maintain a constant blood glucose level
• Facilitate cellular storage of foodstuffs following a meal
• Provide for mobilization of metabolic substrates during periods of fasting
Over and under production of insulin and glucagon can affect storage and
use of CHO, fats, and proteins within the liver, adipose tissue, and muscle.
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Pancreatic Islets
Endocrine Pancreas
• There are ~ 1 to 2 million islets in the normal human
pancreas which is only 1-2% of the pancreatic tissue
• Two cell types can be visualized histologically:
• a cells → glucagon (15-20%)
• b cells → insulin (60-85%)
• Other cells exist in smaller numbers
• D cells → SST (3-10%)
• F cells → pancreatic polypeptide (3-5%)
• Epsilon cells → ghrelin (<1%)
Insulin
• Insulin is one of a number of hormones that is needed
for normal growth and development
• Insulin directly lowers blood glucose levels
• most others tend to elevate blood glucose
• Absolute insulin deficiency results in unrestrained
glucose production, lipolysis, ketogenesis, proteolysis,
and death
• Insulin excess can result in hypoglycemia, brain failure
and death
Glucagon
• During fasting, prevention of hypoglycemia is not solely due to
decreased insulin secretion but also to an increase in glucagon.
• Adrenal catecholamines become important when glucagon is
deficient.
Pancreatic Islets
Secretion of insulin and
glucagon are controlled by
negative feedback.
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Diabetes
• In patients with T1DM, there is a decrease in the
number of insulin-containing beta cells.
• This may result from development of cell surface AB.
• It may be caused by a virus.
• Type II diabetics have above normal levels of insulin but
their tissues do not respond to the hormone
• A.k.a. insulin resistance
Gonads
Ovaries and Testes
• Gonads produce gametes
• Men  Testes produce sperm
• Women  Ovaries produce oocytes
• Ovaries produce:
•
•
•
•
2 estrogens (estradiol and estrone)
Progesterone
Relaxin  Pregnancy/Partruiton
Inhibin  FSH
• Testes produce testosterone.
• Also Inhibin
Odds & Ends
Pineal Gland
• Pineal gland
• Attached to the roof of the third ventricle
• Secretes melatonin - helps to regulate the body’s biological clock.
Thymus
• Located behind the sternum, between the lungs.
• Produces:
• Thymosin
• Thymic humoral factor (THF)
• Thymic factor (TF)
• Thymopoietin
All of which promote maturation of the immune system’s T cells.
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Pineal Gland and Thymus
Other Hormone Producers
Several tissues and organs which are not part of the
endocrine system are able to produce hormones.
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Other Endocrine
Tissues and Organs
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Eicosanoids and Growth Factors
• Eicosanoids
• Locally-acting hormones
• Derived from arachadonic acid (F.A.)
• Growth Factors
• Stimulate cell growth and division.
• Involved in tissue development, growth and repair.
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Growth Factors
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
The Stress Response
• Eustress - helpful, everyday stress that prepares us to meet
challenges.
• Distress - harmful stress that may be damaging.
• Fight-or-flight response
• 1st stage of the stress response
• Stimulates the body’s resources to prepare for immediate activity.
• Resistance reaction
• 2nd stage in the stress response
• Lasts longer than the fight-or-flight response.
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
The Stress
Response
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Focus on Homeostasis
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Endocrine Disorders
• There are many endocrine disorders. Some are more
common than others.
• Pituitary gigantism and acromegaly are caused by
excess secretion of growth hormone.
• Goiter is caused by a reduction in the production of
thyroid hormone.
• Graves disease (with associated exophthalmos)
develops due to excess thyroid hormone.
• Cushing’s syndrome is caused by excess secretion of
glucocorticoids.
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Endocrine Disorders