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Human Digestion:

The Pancreas
by

Andra Roventa

on 20 March 2014

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Transcript of Human Digestion:

Human Digestion:
The Pancreas

2nd Hour
By Andra Roventa, Lexie Alexander, Sarah Herndl, Caitlin Blackmer, and Aly Donselar

The Pancreas: What Is It and What Does It Do?
Pancreas-
an endocrine gland that also has an exocrine function by secreting pancreatic juices into the small intestine for digestion, both functions deem the pancreas a
heterocrine gland

Anatomy of the Pancreas:
Pancreas is 6 inches long
Sits near back of the abdomen
Pancreas connected to the duodenum (the first section of the small intestine) by the pancreatic duct
Pancreatic acinar cells-
glandular cells that give it its loose, clumpy structure
Form around small tubes that secrete the juices and lead to the
pancreatic duct

Pancreatic duct also fuses with the bile duct coming from the liver and gallbladder
1. Head of pancreas
2.Uncinate process
3.Pancreatic notch
4. Body of pancreas
5. Anterior surface
6. Inferior surface
7. Superior margin
8. Anterior margin
9. Inferior margin
10.Omental tuber
11.Tail of pancreas
12. Duodenum

Anatomical Structure of the Pancreas
Enzymes: The Exocrine Function of the Pancreas
Pancreatic juice-
contains enzymes that digest carbohydrates, fats, nucleic acids, and proteins in order to have them absorbed to fuel the body of nutrients

Pancreatic Amylase

• Digests
carbohydrates

• Splits molecules of
starch
or glycogen into disaccharides (MALTOSE)
• Amylase breaks down carbohydrates (starch) into sugars which are more easily absorbed by the body, this enzyme is also found in saliva

Pancreatic Lipase
• Digests
fats
• Breaks triglyceride molecules into fatty acids and glycerol
• Active enzyme that doesn’t need to undergo conversion to digest lipids
• Breaks down triglycerides, critical since these particular lipids cannot be absorbed through the intestinal lining without first undergoing hydrolysis
Also works with bile from the liver to break down fat molecules

Two Pancreatic Proteases (Proteolytic Endopeptidases)

• Breaks down
proteins
Proteases first initiated by the
stomach's pepsin
, continuing its work once it is released
• The two major pancreatic proteases are
trypsin
and
chymotrypsin
Synthesized and packaged into secretory vesicles as the inactive forms proenzymes trypsinogen (activated by enterokinase from intenstinal mucosa) and chymotrypsinogen (activated by chymotrypsin)
Both split bonds of certain pairs of amino acids in proteins

Other Digestive Enzymes
Nucleases

Break down nucleic acid molecules (RNA and DNA) into nucleotides by separating their bonds
• Split the bonds between particular combinations of amino acids in the proteins
• Stored in tiny cellular structures called zymogen granules
• secreted in inactive forms

Carboxypeptidase (A proteoclytic exopeptidase enzyme)
Digest proteins and peptides into SINGLE amino acids
The inactive form is converted to its active form by enzyme enteropeptidase
Sodium Bicarbonate (NaHCO3)
Acts to keep the pancreas from becoming acidic
Secreted into the small intestine to keep the stomach's chyme at a neutral level when digestion continues (released by
epithelial cells
lining small pancreatic ducts)
Hormones: The Endocrine Function
The pancreas is part of the endocrine system, and its job is to produce
hormones
, which are chemical messengers, that will keep the body's metabolism in balance.

Hormones are made by groups of cells clumping together to form
Islets of Langerhans
throughout the organ, secreting hormones directly into the
bloodstream
.

Included PRIMARY cells are: Alpha, Beta, Delta, and Gamma
Glucagon
Released by alpha cells
When blood sugar is low, glucagon is released to stimulate the liver to break down glycogen, which is the body's store of sugar in order to increase glucose levels
Insulin
Released by beta cells
When blood sugar is high, insulin is released to promote the uptake of glucose in the body's cells and use the sugar for energy
Somatostatin

Released by delta cells
Works to reduce the rate at which food is absorbed from the contents of the intestine
Is also secreted by the hypothalamus and the small intestine
Polypeptide
Released by gamma cells
Reduces Appetite
DUAL ROLES OF THE PANCREAS
(A summary so far)
*ENZYMES (minus NaHCO3) are SECRETED BY
ACINAR CELLS
*
Pancreatic Juice: The Exocrine Function
Pancreatic Juice: The Exocrine Function
*SECRETED BY ACINAR CELLS*
Hormones Activating the Pancreas
Cholecystokinin (CCK)
Synthesized and secreted by endocrine cells located in the duodenum
Stimulated by the presence of partially digested proteins and fats in the small intestine
As chyme floods into the small intestine, CCK is released into blood and order pancreatic cells to secrete large quantities of digestive enzymes
Secretin
Product of endocrinocytes located in the epithelium of the proximal small intestine
Secreted in response to acid in the duodenum
Effect of secretin on the pancreas is to stimulate duct cells to secrete water and bicarbonate
Gastrin
Secreted in large amounts by the stomach in response to gastric distention and irritation
Gastrin also stimulates pancreatic acinar cells to secrete digestive enzymes
Most Frequent Diseases and Issues Associated With the Pancreas
Pancreatitis
Pancreatitis
is the inflammation of the pancreas that occurs when digestive enzymes start digesting the pancreas itself
Acute Pancreatitis
- occurs suddenly and is often caused by gallstones, usually goes away in a few days if treated

Chronic Pancreatitis
- can't be healed and worsens over time, can lead to permanent damage

Important not to smoke or drink alcohol

Pancreatic Cancer
Neuroendocrine
tumors (abnormal cells) arise the islet cells
Symptoms or signs: jaundice, pain in abdomen and lower back, unexplained weight loss, fatigue, and digestive problems
It is often found late and spreads quickly, making it extremely difficult to treat
According to 'The American Cancer Society', about
23%
of patients with cancer of the exocrine pancreas are still living after
one year
after diagnosis and only
4%
are still living
five years
after diagnosis
Diabetes Mellitus
Diabetes is group of diseases that affect how your body uses
blood glucose
(blood sugar)
Potentially reversible diabetes conditions include
prediabetes
— when your blood sugar levels are higher than normal, but not high enough to be classified as diabetes — and
gestational diabetes
, which occurs during pregnancy but may resolve after the baby is delivered
Symptoms: extreme thirst or hunger, unexplained weight loss, frequent urination, fatigue, high blood pressure, slow-healing sores and frequent infections
Type 1 Diabetes
: Immune system attacks and destroys insulin-producing cells, leaving pancreas with little/no insulin. Without going to the cells, blood sugar builds up in bloodstream. Type 1 Diabetes is caused by genetic and environmental factors.
Type 2 Diabetes
: Prediabetes can lead to Type 2, where cells become resistant to action of insulin and pancreas is unable to overcome the resistance
Risk factors for Type 1
: Dietary factors (low vitamin D intake, early exposure to cow's milk, early exposure to cereals), race (Caucasian), location (Scandinavian countries)
Risk factors for Type 2
: Obesity, inactivity, family history, race, older age, high blood pressure and abnormal cholesterol levels
A Final Thought...
On April 26th, 1986, the Chernobyl Nuclear Power Plant in Ukraine had a catastrophic nuclear accident, and fires and explosions released huge quantities of radioactive particles in the atmosphere, covering much of Eastern Europe
The Chernobyl explosions, along with the Fukushima nuclear explosions in Japan after the 2011 earthquake are considered the worst nuclear catastrophes of its kind
My grandfather Stefan was living in Iasi, Romania, at the time, and later he was diagnosed with pancreatic cancer in 1990, passing away in 1991 only after one year of treatment at the age of 65
My grandpa's last moments alive included excruciating pain that morphine couldn't help, being bedridden, delirium, severe weight loss, and failing to recognize his closest family, including my mom
His pancreatic cancer only showed symptoms of lower back pain a year before he was diagnosed
PANCREATIC CANCER AWARENESS! CHECK IT!
Cancer is relentless and doesn't wait for you to say 'good-bye' to your loved ones. One moment they're fine and the next, everything changes. Know the signs and treat it before it's too late!
<---Shots used to add insulin into
the bloodstream
<---Famous celebrities that have fallen victim to
Pancreatic Cancer
A Recap of the Pancreas
http://education-portal.com/academy/lesson/accessory-digestive-organs-pancreas-gallbladder-liver.html#lesson
<--- An islet at a microscopic level
Full transcript