THE DIGESTIVE SYSTEM

_____________ Canal - (Gastrointestinal tract, 29 feet long) Uses mechanical and chemical methods of digestion.

Organs include:

Mouth, pharynx, esophagus, stomach, small intestine, Large intestine, Rectum, Anus

Accessory organs: teeth, tongue, gallbladder, pancreas, liver, salivary glands, appendix

_____________ = study of the stomach and intestine and their diseases.

(Gastero = _____________) (enteron = _____________)

_____________ - inflamation of stomach

_____________ - inflamation of intestine

WALL OF THE DIGESTIVE TRACT

Four Layers from inside out:

1. _____________ - mucous lining

2. _____________ - contains many blood vessels

3. _____________ - uses muscles to move and mix food

4. _____________ or Serosa - outermost covering of tube (Parietal peritoneum)

_____________ - a fold of tissue that anchors the tube to the abdominal cavity.

_____________ - the empty space inside the tube

MOUTH

Oral cavity is lined with mucous membranes keeping is soft and pliable as well a moistening food.

_____________ - bony structure at the top anterior portion of mouth

_____________ - softer part of roof of mouth posterior to the hard palate.

_____________ - soft muscle that hangs down from the soft palate. Prevents food and liquid from going up the nasal cavity.

_____________ - made of muscle, covered in mucous membrane and taste buds

_____________ - a thin membrane that attaches the tongue to the floor of the mouth

Tongue-tied: frenulum is too _____________, causing an inability to pronounce properly

_____________ - small elevations on tongue surface

Taste buds are located on the sides of papillae

TEETH:

First tooth approx. 6 mos. (varies)

20 Baby teeth (_____________ teeth) by age two.

32 permanent teeth when mature.

Structure of teeth:

_____________ - above the gum

_____________ - in the gum

_____________ - in the bone socket

Enamel - hardest tissue in body

_____________ - softer material containing pulp cavity with nerve and blood vessels

_____________ - covers dentin in neck and root

Type of Teeth:

_____________ - for biting

_____________ (cuspids) - pierce or tear food

_____________ (bicuspids) - grinding

_____________ (tricuspids) - grinding

_____________ - (Dental Caries)

Decay occurs where food debri, bacteria, and plaque accumulate. Acid from the bacteria disolves enamel leading to infection, loss of teeth and gum disease

SALIVARY GLANDS (3 pairs)

1. _____________ glands - largest, near ear at angle of jaw,

(mumps causes infection of these glands)

_____________ ducts - opening inside cheek beside upper molars

2. _____________ glands - along the lower jawbone

_____________ ducts - openings on either side of the frenulum

3. Sublingual glands - under tongue

Saliva contains both mucus and enzymes.

Salivary amylase - breaks down _____________ (amylose) into _____________.

Mucous acini - produces mucus

Serous acini - produces _____________

_____________

Tube-like structure of muscle and mucous membranes, located behind mouth and nasal cavities, functions in both digestive and respiratory systems

_____________ - food pipe

10 inches long, connects pharynx to stomach,

uses waves of muscle contractions called _____________.

_____________ - serves as a pouch to collect food, and begin both mechanical and chemical digestion.

_____________ sphincter - valve at the bottom of the esophagus.

_____________ sphincter - valve at the end of the stomach.

3 layers of muscle, _____________, _____________, and _____________ layers break up food and cause peristalsis.

_____________ - semisolid mixture of food and digestive juices

3 main parts of stomach:

_____________ - upper portion

_____________ - main portion

_____________ - lower section

_____________ - folds in the lining of stomach

Lesser curvature - the inside curve of the stomach

Greater curvature - the outside curve in stomach

Gastric glands - secrete gastric juice and hydrochloric acid.

_____________ - burning sensation caused when stomach acid flows up into the esophagus.

_____________ - total emptying of stomach through the mouth (vomiting)

Food stays in the stomach for about 3 hrs.

Ulcers - an open wound or sore in the digestive system that is acted on by acid gastric juice, usually in the stomach or duodenum.

SMALL INTESTINE

Approximately 20 feet long.

3 sections:

_____________, _____________, _____________

Mucous lining contains intestinal glands that secrete the digestive juices.

_____________ - folds in the intestinal lining

_____________ - finger-like projections in the plica that contain blood capillaries to absorb sugars and amino acids

_____________ - a lymphatic vessel in the villus that absorbs fats from the chyme

_____________ - brushlike border of the epithelial cells of the villi

Duodenal papilla (major & minor) - openings from the pancreatic duct and bile duct.

LIVER AND GALLBLADDER:

Liver is the largest _____________ in the body; producing _____________ of bile a day.

Hepatic ducts drain bile to the duodenum through the Gallbladder and Common Bile Duct (combined ducts)

Bile _____________ fats.

Presence of fat in chyme triggers _____________, a hormone produced by the duodenum. CCK then triggers contraction of the gallbladder.

Gallstones may block the bile duct. The accumulating bile causes _____________, a yellowish skin discoloration.

Liver cells also:

1. maintain normal _____________ concentrations

2. carry on _____________ and _____________ metabolism

3. make _____________, _____________, _____________

4. _____________ blood

5. stores _____________, vitamins ________, ________, and ________

PANCREAS

The pancreas is both an endocrine gland and an exocrine gland involved in digestion.

Pancreatic juice contains enzymes to digest carbohydrates, proteins, and lipids, as well as _____________ to neutralize hydrochloric acid

LARGE INTESTINE - _____________

5 feet in length.

Contains undigested, unabsorbed food.

_____________ valve - sphincter valve between the small intestine and large intestine

Chyme changes to _____________ matter, water and salts are resorbed, bacteria continue breakdown of food, synthesis of vitamins.

Food usually takes _____________ days to pass through large intestine. Quicker passage causes _____________, slower passage causes _____________.

Subdivisions of Large Intestine:

1. _____________ - pouch-like area at the beginning of the large intestine.

2. _____________ colon - goes up right side

3. _____________ colon - begins at hepatic flexure

4. _____________ colon - begins at splenic flexure

5. _____________colon - S-shaped part

6. _____________

7. Anal canal - last section in the rectum containing 2 sphincter muscles, an inner _____________ one and an outer _____________ one.

APPENDIX

_____________ appendix (worm-shape)

No known digestive function in humans.

Composed of _____________ tissue.

_____________ - inflammation of mucous lining of the appendix

_____________ - large, moist, slippery sheet of serous membrane lining abdominal cavity and covering organs

_____________ layer - lines cavity

_____________ layer - covers organs

_____________ - a fan-shaped extension of the peritoneum that anchors the small intestine to abdominal wall

Greater _____________ - extension of peritoneum from stomach that hangs over the intestine like a large apron

DIGESTION

Mechanical digestion includes:

___________ (chewing), ___________ (swallowing), ___________, ___________

Chemical digestion includes:

breakdown of large non-absorbable food by enzymes in saliva, gastric juice, pancreatic juice, and intestinal juice.

CARBOHYDRATE DIGESTION

(No carbohydrate digestion occurs in stomach)

AMYLOSE (starch) is broken down by _____________ in saliva (salivary amylase or ptyalin) and pancreatic juice (pancreatic amylase) in the intestine to form _____________.

_____________ is broken down by _____________ in intestinal juice.

_____________ is broken down into _____________ and _____________ by SUCRASE in intestinal juice.

_____________ is broken down into GLUCOSE and GALACTOSE by _____________ in intestinal juice.

The simple sugars, glucose, fructose, and galactose are absorbed into the blood vessels in the villi.

PROTEIN DIGESTION

_____________ ACID, _____________ and _____________ in gastric juice break down proteins into smaller chains of amino acids called _____________.

_____________ (from the pancreas) and _____________ (from the intestinal juice) break down peptides into _____________.

FAT DIGESTION

Fats are digested partially by GASTRIC _____________ but most go undigested until _____________ emulsifies them.

_____________ from the Pancreas breaks down fats into glycerol and fatty acids.

ABSORPTION:

Digested food moves through mucous membranes in the villi of the small intestines.

For further background information on carbohydrates, lipids, and fats, check out this page from my biology notes:
Carbohydrates, Fats, and Lipids

Digestion begins as saliva mixes with starch in the mouth. The saliva contains an enzyme called amylase which breaks down starch (amylose) into the disaccharide maltose. When the food reaches the stomach starch digestion by amylase ceases because of the low pH of the stomach acid. In the stomach protein digestion is the main action. The gastric glands secrete rennin and pepsin which break proteins (polypeptides) down into dipeptides, often just called peptides. A small amount of fat digestion occurs because of the action of gastric lipase. However, since bile has not mixed with the food yet, fat digestion is not complete. Further fat digestion occurs in the small intestine after the fat has been emulsified by bile from the liver and gall bladder, and acted upon by lipase from the pancreas. This breaks the fats down into glycerol and fatty acids that can be absorbed into the lacteal vessels in the villi. Further digestion of proteins and carbohydrates occurs in the small intestine as well. The peptides that enter the small intestine from the stomach are acted upon by chymotrypsin from the pancreas and peptidase from the glands of the small intestine. This breaks the peptides down into amino acids which can be absorbed into the capillaries of the villi. Carbohydrate digestion continues in the small intestines as maltase, sucrase, and lactase break down maltose, sucrose, and lactose. Maltose breaks down into glucose molecules. Sucrose breaks down into glucose and fructose. Lactose breaks down into glucose and galactose. These monosaccharides, glucose, fructose, and galactose, can then be absorbed by the capillaries in the villi. Note: Some individuals stop producing the enzyme, lactase, as adults. This is common among mammals because most animals do not drink milk after they are weaned. However, in humans this condition is known as "lactose intolerance".

METABOLISM - the use of foods for energy or building complex molecules

_____________ - break down metabolism

_____________ - building metabolism

CARBOHYDRATE CATABOLISM

Involves 3 stages:

1. _____________ - takes place in cytoplasm of cell; uses no oxygen; breaks down glucose to pyruvic acid.

2. _____________cycle - takes place in the mitochondria; uses oxygen; breaks down pyruvic acid to carbon dioxide and water

3. _____________ Phosphorylation - takes place in the mitochondria; uses oxygen; transfers energy from hydrogen protons to ATP.

CARBOHYDRATE ANABOLISM

_____________ - takes place in liver; joins glucose into chains to form glycogen, animal starch. Excess sugar may also be converted to fats and stored in adipose tissue.

FAT METABOLISM

In the absence of _____________, fatty acids can be converted to Acetic acid and enter the _____________ Cycle. Glycerol can be converted to glyceraldehyde-3-phosphate (PGAL) and enter the glycolytic pathway.

PROTEIN METABOLISM

In the absence of _____________ or _____________, amino acids can be converted to many of the acids of the Citric Acid Cycle and used for energy.

Usually amino acids are used to build proteins.

METABOLIC RATES

BMR (_________ Metabolic Rate) - rate at which food is catabolized under minimum conditions.

TMR (_________ Metabolic Rate) - the total amount of energy (calories) used by the body per day.

NUTRITION

A proper diet requires a balance of carbohydrates, fats, and proteins. In addition the body requires vitamins, minerals, and water.

VITAMINS: "_____________" = Latin word for life.

Vitamins are organic substances that act as _____________, chemicals that assist the enzymes in the bodies reactions. They do not provide _____________.

Vitamins may be either _____________ Soluble or _____________ Soluble.

Fat soluble vitamins are stored in the body's fatty tissues. Fat soluble vitamins include the vitamins _____________, _____________, _____________, and _____________.

Vitamin A - Found in fish, liver, eggs, butter, yellow & green vegetables, fruits
Needed for healthy skin, eyes, bones, teeth.
Deficiency causes _____________ blindness, skin disorders, kidney stones

Vitamin D - Found in liver, fish, eggs, milk, sunlight
Needed for growth, healthy bones, metabolism of calcium & phosphorus
Deficiency causes _____________, poor teeth and bones.

Vitamin E - Found in whole grains, leafy vegetables, milk, butter, vegetable oils
Needed for healthy cell membranes, red blood cells
Deficiency causes _____________ rupture, muscle disorders

Vitamin K - Found in leafy vegetables, soybeans, made by intestinal bacteria
Needed for normal blood clotting
Deficiency causes _____________, hemorrhaging.

Water soluble vitamins can be dissolved in water but cannot be stored in the tissues. They must be obtained each day from food. Water soluble vitamins include B1 (Thiamine), B2 (Riboflavin), Niacin, B6 (Pyridoxine), Pantothenic Acid, Biotin, B12, Folic Acid, C (Ascorbic acid)

Vitamin B1 - Found in organ meats, whole grains, vegetables
Needed for proper functioning of heart, nervous system, digestion
Deficiency causes _____________, cardiovascular disorders.

Vitamin B2 - Found in liver, poultry, milk, eggs, cheese, fish, green vegetables, whole grain
Needed for metabolism of protein, carbohydrates, and fats, healthy skin
Deficiency causes dim vision, premature aging, sore _____________

Vitamin B6 - Found in meats, liver, whole grains, vegetables
Needed for sodium and phosphorus balance
Deficiency causes anemia, nausea, loss of appetite, nervousness

Vitamin B12 - Liver , meats, eggs, cheese, dairy products
Needed for red cell production, healthy nervous system.
Deficiency causes _____________.

Vitamin C - Found in citrus and other fruits, leafy vegetables, tomatoes, potatoes
Needed for healthy blood vessels, resistance to infection, healing
Deficiency causes _____________, _____________, bleeding gums

Niacin - Found in red meats, organ meats, fish, green vegetables
Needed for metabolism, digestion, nerves, skin
Deficiency causes _____________ (sore mouth), diarrhea, depression

Folic Acid - Found in green vegetables, liver, whole grains, legumes
Needed for proteins and red blood cells, helps prevent _____________
Deficiency causes inflamed tongue, diarrhea, B12 deficiency.

MINERALS: inorganic substances that are used in the chemical reactions of the body.

Major minerals needed include:
Calcium, Iodine, Iron, Magnesium, Phosphorus, Potassium, and Sodium.

Calcium - Found in milk, cheese, vegetables
Needed for strong _____________ and teeth, blood clotting

Iodine - Found in seafood, iodized salt
Needed for normal thyroid metabolism, prevents _____________

Iron - Found in liver, meat, eggs,
Needed for red cell production, prevents _____________

Magnesium - Found in milk, meat, whole grains, legumes
Needed for proper _____________ and _____________ functioning

Phosphorus - Found in milk, whole grains, meats, nuts, legumes
Needed for ________ and ________ development, ________, nucleic acids

Potassium - Found in whole grains, fruits, legumes, meat
Needed for proper nerve and muscle function

Sodium - Found in seafood, table salt
Needed for _____________ balance, proper nerve and muscle function

FOOD GROUPS:

1. Vegetable / Fruit,
2. Bread / Cereal ,
3. Milk / Cheese,
4. Meat / Poultry / Fish