Digestive System Flashcards
Ingestion
Intake of food via the mouth
Name the five steps of the digestive process.
Ingestion Digestion Movement Absorption Elimination
Digestion
Mechanically or chemically breaking down foods into their subunits.
Movement
Food must be moved along the GI tract in order to fulfill all functions.
Absorption
Movement of nutrients across the GI tract wall to be delivered to cells via the blood.
Elimination
Removal of indigestible molecules.
What are the 4 major layers that make up the wall of the GI tract?
Mucosa
Submucosa
Muscularis
Serosa
Mucosa
Innermost layer of the GI tract that produces mucus to protect the lining and also produces digestive enzymes.
Submucosa
2nd layer of the GI tract, made of loose connective tissue that contains blood vessels, lymphatic vessels, and nerves.
Muscularis
3rd layer of the GI tract made of 2 layers of smooth muslce that moves food along the tract.
Serosa
Outer lining of the GI tract that is part of the peritoneum
Lumen
Central space in the GI tract containing the food being digested.
What does the mouth do?
The mouth contains teeth that begin the mechanical breakdown of food (chewing).
What begins carbohydrate digestion, and where does this reside?
3 pairs of salivary glands in the mouth secrete salivary amylase which begins carbohydrate digestion.
What are the tonsils made of, and what do they do?
Tonsils are made of lymphatic tissues, which are important in fighting disease.
What does the tongue have, and what does it do?
The tongue is covered in taste buds, and it assists in the mechanical breakdown and movement of food, forming a bolus and moving it towards the phalynx.
Bolus
A mass of chewed food
Pharynx
A cavity between the mouth and esophagus that serves as a passageway for food and air.
Esophagus
A long, muscular tube that carries food to the stomach.
Name the two phases of swallowing food.
Voluntary Phase
Involuntary Phase
What occurs during the voluntary phase of swallowing food?
Food being swallowed from the mouth into the pharynx is a voluntary act.
Describe the involuntary phase of swallowing food.
Once the food is in the pharynx, swallowing becomes a reflex. The epiglottis covers the voice box to make sure food is routed into the esophagus, and food moves down the esophagus through peristalsis.
Peristalsis
Peristalsis is the rhythmic contraction that ensures food moves down the esophagus.
When does heartburn occur?
Heartburn occurs when acids from the stomach pass into the esophagus.
What does heartburn feel like?
Heartburn feels like a burning sensation in the esophagus.
What is chronic heartburn called?
Chronic heartburn is called gastroesophageal reflux disease.
Give four tips for decreasing heartburn.
Avoid high fat meals
Do not overeat
Eat several small meals rather than the standard 3 larger meals each day
Exercise lightly
What are the functions of the stomach?
The stomach functions to store food, start digestion of proteins, and control movement of chyme into the small intestine.
Chyme
Partially digested food
How many layers of muscle does the stomach have, and what do they do?
The stomach has 3 layers of muscle, and they help in mechanical digestion and allow the stomach to stretch.
What is the pH of the stomach? What does this help do?
The stomach has a pH of 2 to help kill bacteria found in food and activate the protein pepsin.
What does the protein pepsin do?
Pepsin digests dietary protein.
When does the stomach empty chyme, and where does it empty it to?
The stomach empties chyme into the small intestine after 2-6 hours.
How long is the small intestine?
The small intestine is, on average, 6 m (18 feet) in length.
What do the enzymes secreted by the pancreas do?
Enzymes secreted by the pancreas into the small intestine digest carbohydrates, proteins, and fats.
What does bile do, and what is it secreted by?
Bile is secreted by the gallbladder into the small intestine, and it emulsifies fats.
What does the absorption of digested food depend on?
The absorption of digested food depends on the large surface area created by numerous villi, finger-like projections, and microvilli.
What enters the capillaries?
Amino acids and sugars enter the capillaries.
What enter the lacteals (small lymph vessels)?
Fatty acids and glycerol enter the lacteals.
What is the pancreas?
The pancreas is the fish-shaped spongy organ behind the stomach.
Name the three functions of the pancreas.
- Secretes enzymes into the small intestine
- Secretes bicarbonate into the small intestine to neutralize stomach acids
- Secretes insulin into the blood to keep blood sugar levels under control
What does the enzyme trypsin, secreted by the pancreas, do?
The enzyme trypsin digests proteins.
What does the enzyme lipase, secreted by the pancreas, do?
The enzyme lipase digests fats.
What does the enzyme pancreatic amylase, secreted by the pancreas, do?
The enzyme pancreatic amylase digests carbohydrates.
What is the liver, where is it, and what is is made of?
The liver is a large metabolic organ that lies under the diaphragm and is made of 100,000 lobules.
Give three things that the liver does.
The liver filters blood from the GI tract, removing poisons and detoxifying the blood.
The liver stores glucose as glycogen and breaks it down to help retain blood glucose levels.
The liver makes bile, which is then stored in the gallbladder to be secreted into the small intestine to emulsify fats.
What is stored in the gallbladder?
Bile from the liver is stored in the gallbladder to be secreted into the small intestine to emulsify fats.
What is Hepatitis?
Hepatitis is an inflammation of the liver that can lead to liver damage, cancer, and/or death.
What can hepatitis be caused by?
Hepatitis can be caused by Hepatitis A, B, and C.
What is cirrhosis of the liver?
Cirrhosis is when the liver becomes fatty and eventually the liver tissue is replaced by fibrous scar tissue. It can lead to liver failure in which the liver cannot regenerate as fast as it is being damaged.
Where is cirrhosis seen? What groups are at risk for it?
Cirrhosis is seen in alcoholics and obese people.
Name the four parts of the large intestine.
Cecum
Colon
Rectum
Anal Canal
How does the large intestine compare in size to the small intestine?
The large intestine is larger in diameter but shorter than the small intestine.
What is the projection on the cecum called, and what might it do?
The projection on the cecum is called the appendix, and it may play a role in fighting infections.
Give three functions of the large intestine.
The large intestine absorbs water to prevent dehydration.
The large intestine absorbs vitamins produced by intestinal flora.
The large intestine forms and rids the body of feces through the anus.
What vitamins are produced by the intestinal flora?
B complex and K are vitamins produced by the intestinal flora.
Diarrhea
Increased peristalsis and failure to reabsorb water, due to either an infection or nervous stimulation.
Constipation
Feces are dry and hard; condition may be controlled with water and fiber.
Hemorrhoids
Enlarged and inflamed blood vessels of the anus due to chronic constipation, pregnancy, aging, or anal intercourse.
Diverticulosis
Occurrence of pouches of mucosa from weak spots in the muscularis layer that can become infected; often occur in the descending colon.
Irritable Bowel Syndrome (IBS)
Muscularis layer contracts with power, but without its normal coordination; characterized by chronic diarrhea and abdominal pain.
Inflammatory Bowel Disease/Colitis (IBD)
A group of inflammatory disorders such as ulcerative colitis or Crohn’s disease.
Polyps and Cancer
Small growths found in the epithelial lining that can be benign or cancerous.
