Download Villi & Microvilli

The Digestive System
Tiffany Aguilar
Aria Davis
Daidreana Payton
Mary Starks
Anatomy and Physiology
Block C
13 May 2009
Villi & Microvilli
• Vascular projections from the
mucous membrane of the
small intestine
• Shapes:
▫ Short and leaf shaped
(duodenum)
▫ Tongue shaped (jejunum)
• Slow passage of food so the
nutrients in the food is
absorbed
Villi & Microvilli: Structure
• Structure:
▫ Lacteal: rich capillary bed and a modified
lymphatic capillary
▫ Vessels
▫ Epithelium
▫ Basement membrane: surround lacteal, muscular
tissue, and blood vessels
▫ Muscular tissue of mucosa
▫ Held together by retiform lymphoid tissue
The Anatomy of the Stomach
• The stomach is a C-Shaped
organ and holds a principal role
in digestion. The stomach is
about 25 centimeters long.
When the stomach has reached
its maximum capacity it can
hold 4 liters or 1 gallon of food.
When empty the stomach
collapses in to itself. Most of the
digesting occurs in the pylorus
region.
• The stomach is composed of a
couple of major regions
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The Cardiac Region
The fundus
The Body
The Pyloric Antrum
The Pylorus
What does the stomach do?
• The stomach is used to help digest particles of food.
• With the strong muscles contained in the stomach;
the stomach is easily able to physically breakdown
food along with mixing and churning the food. The
stomach is also a place where the chemical
breakdown of proteins begins.
• The stomach secretes gastric juice made up of
hydrochloric acid, pepsin, and rennin to begin the
process.
• The stomach churns and mixes the solutions with
the food particles and it becomes chyme and
proceeds into the small intestine.
The Anatomy of the Small Intestine
• The Small Intestine is the
major digestive organ of the
body. It is also the longest and
most convoluted of all organs.
The Small Intestine can
average a length of 2.5 to 7
meters long or 8 to 18 feet.
• The Small Intestine is
composed of three main parts
▫ The Duodenum
▫ The Jejunum
▫ The Ileum
What goes on in the Small Intestine?
• The Small Intestine’s main purpose is to chemically
digest food.
• The food, or chyme, comes into the first part of the
Small Intestine, the Duodenum, small portions at a
time. Once full, the process begins. Pancreatic
enzymes and bile are added to the food particles and
begin to churn and mix to further breakdown the
food and access nutrients.
• As the broken down food travels down the jejunum
and the ilium, and eventually to the large intestine,
villi and microvilli are able to absorb nutrients.
What is the Large Intestine (Colon)?
• The colon is a tube 6 cm wide and 1.5 m long located
between the small intestine and the rectum.
• Its main purpose is to process remaining undigested
chyme into feces.
• The colon’s exocrine glands secrete a viscous
mucous that aids to mold the solid fecal matter and
protect the colon wall from possible mechanical
damage by the moving and churning solid contents.
• There are four main segments: Ascending,
Transverse, (site of water and sodium absorption)
Descending, and Sigmoid (storage of fecal matter).
How does the Large Intestine
(Colon) work?
• Peristalsis waves force
dehydrated feces along
the colon at regular
intervals (2-3 daily
movements after meals).
• On average it takes 1-3
days for complete
digestion of food.
• 1 Liter of water is
absorbed daily in this
process so drink up!
Rectum
• Continuous with the sigmoid colon and extends
to the anus
• Stores solid waste until it leaves the body
through the anus
• The colon and the rectum form the large
intestine
▫ Colon is the first 6 feet
▫ Rectum is the last 8 to 10 inches
The Liver
• The liver is the largest gland in the body, located under the diaphragm to the right
of the body. It has 4 lobes and is attached to the stomach by a mesentery cord called
the falciform ligament. It has many metabolic and regulatory functions but one of
its main functions is to produce bile, a at-digesting enzyme.
• Without a liver a person would die in 24 hours
• The not only produces bile but:
1. Detoxifies drugs and alcohol in the body
2. Degrade ( dilute) hormones
3. Make substances for the body to use such as albumin and cholesterol
• The hepatic portal circulation drains nutritious blood to liver first. The liver cleans
out amino acids, fatty acids, and glucose to store them for later and the liver’s
phagocytic cells clean out bacteria.
• We have a surplus of liver tissue and the liver is one of the organs in the body that
can regenerate rapidly and easily.
The Gallbladder
•
•
•
•
•
The gallbladder is a small, thin-walled green
sac that sits in a shallow opening in the
inferior surface of the liver.
When food is not being digested, the bile
produced by the liver is goes back up in the
cystic duct and is stored in the gallbladder
until digestion occurs.
Bile is a greenish-yellow, watery substance
containing bile salts, bile pigments,
cholesterol, phospholipids, and electrolytes.
The phospholipids and bile salts emulsify
fats, breaking them down into smaller
pieces
If bile is stored in the gallbladder for too
long or becomes too concentrated, it forms
gallstones, which are extremely painful. If
the bile backs up into the liver, the liver cells
press bile salt and pigments into the
bloodstream causing jaundice, or yellowing
of the tissues.
The Pancreas
• The pancreas is a soft, pink, triangular gland that
extends across the abdomen form the spleen to the
duodenum.
• It produces enzymes that breakdown all categories of
digestible foods
• It also produces hormones called insulin and glucagon,
this is related to diabetes
• The pancreas’ enzymes flow through the pancreatic ducts
to the hepatopancreatic ampulla or “the liver-pancreatic
enlargement” where bile and pancreatic fluids meet.
After the two fluids pass into the duodenum to
chemically breakdown substances.
• Alkaline pancreatic juices help make the chyme in the
stomach neutralize to make a better place for enzymes to
work
Vitamins C, D, and K
• Water Soluble: Vitamin C
• Vitamin C is involved in the metabolism of cholesterol to bile acids, which may
have implications for blood cholesterol levels and the incidence of gallstones.
• Fat-Soluble: Vitamins D and K
▫ Absorbed in the chylomicrons: lipoproteins that transport dietary lipids.
• The major function of vitamin D is to maintain normal blood levels of calcium
and phosphorus.
• Vitamin D2 is synthesized by plants.
• Vitamin D3 is created when the skin is exposed to UVB rays from the sun.
• Individuals who have inflammatory bowel disease (e.g., Crohn's disease) are at
risk for vitamin D deficiency.
• Potassium is essential for the functioning of several proteins involved in blood
clotting.
• Potassium is secreted in the large intestine causing a depletion during severe
diarrhea.
Metabolism
• Refers to all chemical reactions that are necessary to maintain
life
▫ Catabolism: substances broken down to smaller substances
▫ Anabolism: larger molecules are built from smaller ones
• Carbohydrates are broken down to make ATP
• Fats are used to build cell membranes, make myelin sheaths,
insulate the body, and to produce ATP when no carbohydrates
are in the diet
• Proteins are carefully conserved by body cells because they are
the major structural materials used for building cell structures
Works Cited
• Higdon, Jane . "Vitamin K." Oregon State University. May 2004.
Micronutrient
Information Center. 10 May 2009
<http://lpi.oregonstate.edu/infocenter/vitamins/vitaminK/>.
• Higdon, Jane . "Vitamin C." Oregon State University. January
2006.
Micronutrient Information Center. 10 May 2009
<http://lpi.oregonstate.edu/infocenter/vitamins/vitaminC/>.
• Wagner, CL. "Vitamin D." Mayo Clinic. 2009. Natural Standard. 10
May 2009
<http://www.mayoclinic.com/health/vitamin- d/NS_patient-vitamind>.
• Kapit, Wynn and Lawrence M. Elson. The Anatomy Coloring Book.
Glenview: Pearson
Education, Inc., 2002.
• Myers, Donna. What is the Rectum. July 2008. May 2009
<http://coloncancer.about.com/od/faqs/f/Rectum.htm>.
• Gray, Henry . Gray's Anatomy. 15th ed. New York: Barnes & Noble,
Inc, 1995.
• Marieb, Elaine N. Essentials of Human Anatomy and Physiology.
8th ed. San
Francisco: Pearson Education, Inc, 2006.
• Kapit, Wynn and Robert I. Macey and Esmail Meisami. The Physiology Coloring Book. ed.
2. San Francisco: Addison Wesley Longman, Inc., 2000
Images
• http://graphics8.nytimes.com/images/2007/08/01
/health/adam/19220.jpg
• http://medicalimages.allrefer.com/large/vitamin-dsource.jpg
• http://healthhabits.files.wordpress.com/2008/11/vi
tamin-k.jpg
• http://www.puduvai.in/images/health/vitamin-k1.jpg
• http://www.belmarpharmacy.com/images/clip_ima
ge002.jpg
• http://www.takebackyourhealth.com/images/Diges
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