Tuesday, May 13, 2014

Abby Mcguire

Unity of Form and Function:

Breakdown of function of each part of the digestive system:

The mouth is the beginning of the digestive tract; and, in fact, digestion starts here when taking the first bite of food. Chewing breaks the food into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down into a form your body can absorb and use.
Located in your throat near your trachea (windpipe), the esophagus receives food from your mouth when you swallow. By means of a series of muscular contractions called peristalsis, the esophagus delivers food to your stomach.
The stomach is a hollow organ, or "container," that holds food while it is being mixed with enzymes that continue the process of breaking down food into a usable form. Cells in the lining of the stomach secrete a strong acid and powerful enzymes that are responsible for the breakdown process. When the contents of the stomach are sufficiently processed, they are released into the small intestine.
Small intestine
Made up of three segments — the duodenum, jejunum, and ileum — the small intestine is a 22-foot long muscular tube that breaks down food using enzymes released by the pancreas and bile from the liver. Peristalsis also is at work in this organ, moving food through and mixing it with digestive secretions from the pancreas and liver. The duodenum is largely responsible for the continuous breaking-down process, with the jejunum and ileum mainly responsible for absorption of nutrients into the bloodstream.
Contents of the small intestine start out semi-solid, and end in a liquid form after passing through the organ. Water, bile, enzymes, and mucous contribute to the change in consistency. Once the nutrients have been absorbed and the leftover-food residue liquid has passed through the small intestine, it then moves on to the large intestine, or colon.
The pancreas secretes digestive enzymes into the duodenum, the first segment of the small intestine. These enzymes break down protein, fats, and carbohydrates. The pancreas also makes insulin, secreting it directly into the bloodstream. Insulin is the chief hormone for metabolizing sugar.
The liver has multiple functions, but its main function within the digestive system is to process the nutrients absorbed from the small intestine. Bile from the liver secreted into the small intestine also plays an important role in digesting fat. In addition, the liver is the body’s chemical "factory." It takes the raw materials absorbed by the intestine and makes all the various chemicals the body needs to function. The liver also detoxifies potentially harmful chemicals. It breaks down and secretes many drugs.
The gallbladder stores and concentrates bile, and then releases it into the duodenum to help absorb and digest fats.
Colon (large intestine)
The colon is a 6-foot long muscular tube that connects the small intestine to the rectum. The large intestine is made up of the cecum, the ascending (right) colon, the transverse (across) colon, the descending (left) colon, and the sigmoid colon, which connects to the rectum. The appendix is a small tube attached to the cecum. The large intestine is a highly specialized organ that is responsible for processing waste so that emptying the bowels is easy and convenient.
Stool, or waste left over from the digestive process, is passed through the colon by means of peristalsis, first in a liquid state and ultimately in a solid form. As stool passes through the colon, water is removed. Stool is stored in the sigmoid (S-shaped) colon until a "mass movement" empties it into the rectum once or twice a day. It normally takes about 36 hours for stool to get through the colon. The stool itself is mostly food debris and bacteria. These bacteria perform several useful functions, such as synthesizing various vitamins, processing waste products and food particles, and protecting against harmful bacteria. When the descending colon becomes full of stool, or feces, it empties its contents into the rectum to begin the process of elimination.
The rectum (Latin for "straight") is an 8-inch chamber that connects the colon to the anus. It is the rectum's job to receive stool from the colon, to let the person know that there is stool to be evacuated, and to hold the stool until evacuation happens. When anything (gas or stool) comes into the rectum, sensors send a message to the brain. The brain then decides if the rectal contents can be released or not. If they can, the sphincters relax and the rectum contracts, disposing its contents. If the contents cannot be disposed, the sphincter contracts and the rectum accommodates so that the sensation temporarily goes away.
The anus is the last part of the digestive tract. It is a 2-inch long canal consisting of the pelvic floor muscles and the two anal sphincters (internal and external). The lining of the upper anus is specialized to detect rectal contents. It lets you know whether the contents are liquid, gas, or solid. The anus is surrounded by sphincter muscles that are important in allowing control of stool. The pelvic floor muscle creates an angle between the rectum and the anus that stops stool from coming out when it is not supposed to. The internal sphincter is always tight, except when stool enters the rectum. It keeps us continent when we are asleep or otherwise unaware of the presence of stool. When we get an urge to go to the bathroom, we rely on our external sphincter to hold the stool until reaching a toilet, where it then relaxes to release the contents.
How stomach ulcers causes the digestive system to not facilitate function properly in the stomach and small intestine:

Stomach ulcers are found in two main parts of the digestive system, the lining of the stomach and the first part of the small intestine called the duodenum. The lining of the stomach is a very unique anatomical feature that plays a key role in protecting the stomach and intestines during times of high acidity during the breakdown of food. The lining of your stomach and small intestine is responsible for secreting substances used in digestion, and for protecting the rest of the body from highly acidic acid reaching the rest of the body’s digestive track. The anatomical features of this structure is why stomach ulcers have such a negative effect on the body’s digestive system. The stomach lining has a number of types of epithelial cells, divided by type. Mucous cells generate the mucus which stands between the stomach lining and the acids of the stomach, creating a protective layer. Parietal sells secrete acid, while chief cells make enzymes used in digestion, and G cells make gastrin, a hormone. Causing damage to these specific cells causes inflammation and hole like sores in the stomach and duodenum, a burning and aching pain, bloating, nausea, vomiting, bleeding, potential weight loss and more. With the pain of stomach ulcers, and the potential of eroding through the entire wall of the stomach or intestine the entire GI track and the function of the digestive system can be affected. The primary purpose of the gastrointestinal tract is to break food down into nutrients, which can be absorbed into the body to provide energy. Stomach ulcers causes the suffering patient to loose appetite and choose not to eat because of the pain the inflammation in the stomach or GI tract is causing to the body. Loss of appetite, or vomiting after eating, throws off the entire functionality of the digestive system and can cause severe problems of higher risk of infection of the stomach, and a weakened immune system from lack of nutrient intake. Peptic ulcer disease can have a serious impact on the digestive system and can effect how it functions properly to ensure a healthy GI tract, and homeostasis within the body. 

Monday, May 12, 2014

Part 1: Hierarchy of Structure

Digestive system at organ level
Stomach ulcers take place in the digestive system and involves the stomach, small intestine, and the inside lining of your esophagus.

Digestive system at tissue level
- The mucous membrane of the stomach contains simple columnar epithelium tissue with many exocrine cells.
   -Connective tissues support the tissues of the mucosa and connect it to the muscularis layer.
   -The muscularis is made of 3 layers of smooth muscle tissue arranged with its fibers running in 3 different directions. The layers of smooth muscle allow the stomach to contract to mix and propel food through the digestive tract.
   -The outermost layer of the stomach surrounding the muscularis layer is the serosa and is made of simple squamous epithelial tissue and areolar connective tissue. 
    -Stomach is lined with columnar epithelium (simple) that is studded with gastric pits
Small Intestine:
    -simple columnar epithelium with microvilli to aid absorption
    -Pits are lined with mucus secreting simple columnar epithelium
    -consists of 4 layers
    -The mucus membrane is lined with stratified squamous non-keratinized epithelium
    -muscularis externa is composed of skeletal muscle, while the remaining 2/3 is composed of smooth muscle

Digestive system at a cellular level
    -Zymogenic and Chief cells are located in the stomach and secrete digestive enzymes
    -Middle neck and isthmus contain neck mucus and parietal cells, which secrete HCl, also located in the stomach
Small Intestine:
    -Goblet cells (located between columnar cells) in the small intestine are used to produce mucus
    -Paneth cells and oligomucus cells work as absorptive cells in the small intestine
    -contains goblet cells

 esophagus tissues

stomach diagram

esophagus diagram

stomach tissues

small intestine diagram

small intestine tissues

small intestine cells

esophagus cells

stomach cells

Stomach Ulcer Circle of Life

Bacteria (Helicobacter Pylori)
Frequent use of anti-inflamitory painkillers (asprin, midol)

Lining of the digestive system
Small Intestines

Hole in the digestive lining

Gnawing/burning pain
     Weight loss
     Vomiting blood

     Vitamin E


Part III:
The digestive system’s most basic functioning is well known. Food in one form or another is consumed. It passes into the stomach where it undergoes a chemical process that converts it into the energy the body requires. Excess energy is stored as fatty tissue. Waste products that the body cannot utilize are expelled.

Digestion process turns food into a form that is usable for the body. It occurs in the mouth, stomach and in the small intestines. It maintains homeostasis by maintaining the pH balance, for instance the pH of the small intestines is high and therefore it balances with low PH of the food due to the acids from the stomach lining. There are intestinal microflora that aid in digestion, and protect against harmful bacteria.

Muscles/Glands who help the stomach with digestion and homeostasis:
Salivary glands – secrete saliva into the mouth to moisten food
Amylase – enzyme that breaks down starch
Peristalsis – series of involuntary smooth muscle contractions to help move food
Pepsin – gastric juice secreted into the stomach to digest proteins
Villi – fingerlike lining of the small intestine that helps absorb food and nutrients

Friday, May 9, 2014

How does the digestive system maintain homeostasis?

Digestion: the process of turning food into usable energy source

- acids break down complex carbs
- small particles absorbed into the blood stream
Small Intestine
-where they are broken down and absorbed by intestinal wall to be used as energy or energy reserves (fat)
Large Intestine
-final stages of absorption and digestion 
  • Maintaining Homeostasis: pH Levels
  • Different levels of pH are required at various points in digestion to maintain balance during the process. Saliva in the mouth, the starting point of digestion, is only slightly acidic in order to break down the food without damaging the teeth or the tissue in the throat. The stomach, on the other hand, is highly acidic to jump-start the breakdown process as well as act as a defense for the body against any harmful bacteria. To balance things out, it is important that the small intestine has a high pH (basic), because most of the enzymes used in digestion can't function properly in an acidic environment.

Maintaining Homeostasis: Helpful Bacteria

  • Helpful bacteria are also important to maintaining homeostasis in the digestive system. It is estimated that the average human has around 500 species of helpful bacteria (called microflora). They are located in the digestive tract and are mostly concentrated in the large intestine. These bacteria aid in digestion, help produce vitamins and help guard against harmful bacteria.