Accessory organs of digestive system

1. Food provides us with fuel to live, energy to work and Food provides us with fuel to live, energy to work and
play, and the raw materials to build new cells. All the play, and the raw materials to build new cells. All the
different varieties of food we eat are broken down by our different varieties of food we eat are broken down by our
digestive system and transported to every part of our digestive system and transported to every part of our
body by our circulatory systembody by our circulatory system..

6. The liver is the largest glandular organ of the body. It
weighs about 3 lb (1.36 kg). It is reddish brown in color
and is divided into four lobes of unequal size and shape.
The liver lies on the right side of the abdominal cavity
beneath the diaphragm. Blood is carried to the liver via
two large vessels called the hepatic artery and the portal
vein. The heptic artery carries oxygen-rich blood from the
aorta (a major vessel in the heart). The portal vein carries
blood containing digested food from the small intestine.
These blood vessels subdivide in the liver repeatedly,
terminating in very small capillaries. Each capillary leads
to a lobule. Liver tissue is composed of thousands of
lobules, and each lobule is made up of hepatic cells, the
basic metabolic cells of the liver.

7. Your Liver Lets You Live

Your liver, located under your right rib cage, normally
weighs about three pounds and is the body's second
largest organ. (Your skin is the largest.) It is a complex
chemical factory which produces many important
substances such as bile, digestive enzymes, clotting
factors, cholesterol, and proteins. It is essential in the
metabolism of fats, carbohydrates, proteins, and the
various vitamins and minerals. It helps control the level
of blood sugar and fats. It cleanses the blood and
detoxifies drugs and potentially harmful chemicals
such as alcohol. The liver is a storehouse for blood,
vitamins and minerals, and glycogen - the stored form
of sugar - the body's major fuel. The liver is an amazing
machine and largely unappreciated - until something
goes wrong.

8. What is its major function?
The liver has many functions. Some of the
functions are: to produce substances that break
down fats, convert glucose to glycogen, produce
urea (the main substance of urine), make certain
amino acids (the building blocks of proteins), filter
harmful substances from the blood (such as
alcohol), storage of vitamins and minerals
(vitamins A, D, K and B12) and maintain a proper
level or glucose in the blood. The liver is also
responsible fore producing cholesterol. It produces
about 80% of the cholesterol in your body.

9. •Excretion of IgA (defense against bacteria in the gut)
•Special macrophages (Kupffer cells) gobble up bacteria
which have crossed from the gut into the blood.
Macrophage means "big eater" and so they are!
Defense
•poisons from the gut
•nutrients such as amino acids, sugar and fat
•bilirubin, bile acids
•IgA
•drugs
Filter
•cholesterol, bile acids, phospholipids
•bilirubin
•drugs
•poisons (e.g. pesticides, insecticides, heavy metals)
Excretion
•vitamins
•cholesterol
Storage
•proteins including the clotting factors
•bile acids (products of cholesterol, important in fat
digestion)
•cholesterol
Synthesis
•Glucose (sugar)
•proteins
•fat and cholesterol
•hormones
•vitamins, in particular the fat soluble ones (A, D, E and K)
Homeostasis

13. The pancreas does not actually digest any of the foods that
you eat, but makes most of the enzymes that do. The pancreas
sends the enzymes to the small intestine through a tube called
the pancreatic duct.

14. The pancreas, is a gland in the abdomen that
produces enzymes and hormones.
The pancreas produces digestive juices
(enzymes) that continue the process of
breaking down foods, which begins in the
stomach. The pancreas also produces
hormones, most famously insulin, which control
the balance of glucose between the blood and
the rest of the body. Thanks to the pancreas,
the body can use the sugars and store the fats,
which are essential for health.

15. What the pancreas looks like?
The pancreas looks like a flat, elongated tadpole 6-10 inches (18-25 cms.)
long. It lies behind the stomach in the upper abdomen. Its broadest part,
called the head, is attached to the duodenum, which is the loop at the top of
the small intestine. The stomach empties already partially digested food and
liquid into the duodenum and it is here that it mixes with the secretions
from the pancreas.
The main part of the pancreas, the body, extends leftwards and slightly
upwards, narrowing towards a tail. The pancreas can be compared with a
stalk with clusters of grapes attached to it. It has a duct running through its
length which is joined by many small branches from the glandular tissue.
This duct joins another duct bringing bile from the liver, and a single duct
then opens into the duodenum.
The pancreas is composed of two main types of tissue. Most of this is known
as exocrine tissue which produces pancreatic enzymes - a litre (2.2 pints) or
more every day - which aid digestion. If insufficient enzymes are produced
serious malnutrition can result even though enough high quality food is
being eaten.
Embedded throughout the mass of exocrine tissue are the grape-like
clusters of hundreds of thousands of endocrine cells, known as islets of
Langerhans. These produce two main hormones which regulate pancreatic
secretions and control blood glucose, the body's fuel.

16. The pancreas is an amazingly efficient, self-regulating organ, far
cleverer than any machine ever invented. Day in, day out throughout a lifetime,
a healthy pancreas produces exactly the right chemicals at the right times in the
right quantities for digesting the food we eat.
As soon as food enters the duodenum, the pancreas begins its biggest
job, which is to secrete from its exocrine tissue the clear, watery, alkaline juice
containing enzymes that help break down food into molecules small enough to
be absorbed by the intestine.
Two of these enzymes, trypsin and chymotrypsin digest proteins.
The enzyme amylase breaks down carbohydrate foods.
Another enzyme, lipase, breaks down fats, into smaller molecules
called fatty acids and cholesterol.
The two main hormones produced by the endocrine tissue are insulin and
glucagon.
1. Insulin is secreted when the blood sugar is raised and causes the muscles and
other bodily tissues to take up glucose from the blood to fuel their activity.
Insulin also promotes the absorption of glucose into the liver, where it is stored
as glycogen for use in response to stress or exercise.
2. Glucagon is released from the pancreas when the blood sugar is low. It's
main effect is on the liver to cause the breakdown of glycogen (the stored form
of glucose) into glucose which is released into the blood thus restoring the level
to normal.

17. What can go wrong with the pancreas
For most of us, the pancreas is a wonderfully self-sustaining organ. But of course, like any organ, it
can malfunction. If it fails to produce sufficient digestive enzymes and food is poorly absorbed, weight loss
and/or diarrhoea can result. Much more important, however, is the risk of diabetes if the islets of Langerhans
produce too little insulin. This raises the level of glucose in the blood, and increases the risk of a number of
problems throughout the body. (for more information about diabetes,see our factsheet.)
The most important disease of the pancreas itself is pancreatitis (inflammation) which can be acute or
chronic. It may occur as a complication of mumps. However, the most common cause of acute pancreatitis is
blockage by a gallstone of the main duct from the pancreas. This causes pancreatic juice to accumulate in the
organ which can damage the pancreas or even result in the pancreas digesting itself.
Fortunately, this serious condition is rare. However when it does occur it requires immediate medical attention.
The symptoms include severe stomach pain and tenderness, nausea and vomiting, swelling of the abdomen and
wind, fever and muscle aches. Treatment involves painkillers, stopping all solid food and providing fluid and
nourishment with intravenous fluids (through a drip into a vein). Most people with acute pancreatitis recover
completely but about 10% of people develop complications which are fatal.
Chronic pancreatitis occurs either when repeated episodes of acute pancreatitis result in permanent
damage to the organ or as the result of chronic damage resulting from alcohol abuse. It affects mainly middle
aged men. Symptoms include persistent pain in the upper abdomen and back, weight loss, diarrhoea, and
sometimes diabetes and mild jaundice (yellow eyes and skin).
Occasionally, chronic pancreatitis can lead to cancer of the pancreas. In most cases, however, the cause of
pancreatic cancer, (which unfortunately, is on the increase in the UK) is unknown. Smoking or heavy drinking
may increase the risk, and cancer of the pancreas is also about twice as common in people with diabetes. It is
also more common in men than women.
Symptoms may not appear for some time and, even then, are usually vague, no more than
discomfort or pain in the stomach and back or, if the cancer blocks a duct, jaundice. The skin may itch and there
may be constipation and loss of appetite and weight. Such symptoms can be caused by many conditions other
than cancer, but tell your doctor about any which persist as early diagnosis is important. Treatment of pancreatic
cancer is difficult and the outlook is usually poor. Quite often, by the time the cancer is diagnosed it has
advanced too far to be treated with anything except pain relief.

18. The pancreatic juices are composed basically of water,
bicarbonate and three enzymes.
Water
Water helps the nutrients and enzymes to come into contact with
one another, by allowing them to move around within the small
intestine.
Bicarbonate
The acid of the stomach is neutralized by bicarbonate made by
the pancreas.
Trypsin
Trypsin acts on the proteins and completes the process of
breaking proteins into amino acids begun in the stomach by pepsin..
Pancreatic Amylase
Pancreatic Amylase continues the action on the carbohydrates
that the saliva began.
Pancreatic lipase
Pancreatic lipase contributes to the transformation of fats begun
by the bile from the liver. Without the bile from the liver, the fats
would be too large for pancreatic lipase to work.