Ch 8 - Digestive System Flashcards
What is the gastrointestinal (GI) tract?
The tube where organs of the digestive system are located
What does hydrolyze mean?
To break down macromolecules into their subunits using water
What do carbohydrates break down to?
Glucose
What does protein break down to?
Amino Acids
What does fat break down to?
Monoglycerides and free fatty acids (which are broken down from triglycerides)
Which enzymes break down carbs?
Salivary & pancreatic amylase + intestinal enzymes
Which enzymes break down proteins?
Trypsin (protease) released by the pancreas (acts in small intestine) + intestinal enzymes
Which enzymes break down fats?
Lipase
What emulsifies fats?
Bile
What organ produces bile and what organ stores it?
The liver produces bile and the gallbladder stores bile
What is the name of the first 25 cm of the small intestine where most enzymes and bile are secreted?
The duodenum
What is peristalsis?
Wavelike contractions of smooth muscles, starting in the esophagus and continuing through the colon
What is the role of the pancreas?
Produces pancreatic juice
Releases digestive enzymes in the small intestine
Produces insulin & secretes it into the blood after eating
What is the passageway where food is swallowed?
The pharynx
Which organs of the digestive system do not play a role in chemical digestion?
The esophagus and the large intestine
What is the role of the large intestine?
Absorbs water and salt to form feces
What is the lumen?
The hollow area of the digestive tract where food travels.
What are the four layers of the GI tract?
- Starts from the inside w/ the lumen
1. Mucosa
2. Submucosa
3. Muscularis
4. Serosa
What role does the mucosa play?
This layer contains cells that produce and secrete mucus to protect all the layers of the tract from the digestive enzymes inside the lumen.
What is a common disease in the mucosa layer?
Diverticulosis = when the mucosa (primarily in the large intestine) have pushed through the other three layers and create a pouch where food can collect. When these pouches become infected or inflamed, it’s called diverticulitis.
What role does the submucosa layer play?
A band of loose connective tissue that contains blood vessels, lymphatic vessels and nerves. These vessels carry the nutrients that are absorbed by the mucosa. Lymph nodules also located here.
What is a common disease in the submucosa layer?
Because it contains blood vessels, it can be a site for inflammatory responses that lead to IBD, inflammatory bowel disease.
What role does the muscularis layer play?
Two layers of smooth muscle that contract to create peristalsis
What is a common disease in the muscularis?
IBS (Irritable bowel syndrome). Where contractions of the wall cause abdominal pain, constipation or diarrhea.
What role does the serosa layer play?
It’s the membrane, which secretes a lubricating fluid. Part of the peritoneum, the internal lining of the abdominal cavity.
Why are our lips so red?
Because they’re poorly keratinized, allowing blood to show through.
What does the soft palate in our mouth connect to?
The uvula, which hangs down in the back of our mouth.
What is the tube called where air travels from your nose to the pharynx?
The nasopharynx
What are the adenoids and where are they located?
Right above the soft palate where the nasal cavity opens. They, along with the tonsils, are part of the lymphatic system. The adenoids are a single pharyngeal tonsil.
How many pairs of salivary glands are there that secrete into the mouth?
Three.
What happens when a person has the mumps?
The salivary glands above the molars swell. The mumps are a viral disease.
What is saliva?
A solution of mucus and water. It also contains salivary amylase, which breaks down starch.
What is enamel?
An extremely hard outer covering of calcium compounds
What is the inner pulp of a tooth?
It contains the nerves and the blood vessels.
What are dental caries?
Cavities, which occur when bacteria within the mouth metabolize sugar.
What is gingivitis?
Inflammation of the gums
What is periodontitis?
A loss of bone and loosening of the teeth.
What is the pharynx?
Where the mouth and nasal passages lead. A hollow space at the back of the throat where food gets swallowed and air passes through
Which tubes branch off of the pharynx?
The esophagus and the trachea (windpipe)
What happens when we swallow food (a bolus)?
The soft palate moved backwards to cover the nasopharynx/nasal passages, and the epiglottis covers the glottis so food can’t get into the trachea
What is the glottis?
The opening to the larynx (voice box) and, therefore, the air passage
What is the lower gastroesophageal sphincter?
The entrance of the esophagus to the stomach. Sphincters act as valves
What prevents stomach acid from going up into the esophagus?
The gastroesophageal sphincter contracting
What takes place during vomiting?
When strong contractions of the abdominal muscles and the diaphragm force the contents of the stomach into the esophagus and the oral cavity.
What is the role of the stomach?
Stores food
Initiates the digestion of protein
Controls movement of food into small intestine
Nutrients aren’t absorbed by the stomach
Which layers of the stomach is modified?
It has all four layers of the GI tract, but the muscularis has three layers of muscle instead of 2
What is the oblique layer?
The extra third layer of the muscularis in the stomach that allows it to stretch and mechanically break down food into smaller fragments that are mixed with gastric juice.
What is emulsion?
Breaking down fat into smaller molecules and spreading them out. Dispersing them. When fat is emulsified, it breaks up into droplets, which provide a larger surface area for digestive enzymes to act upon them.
What does the mucosa layer of the stomach contain?
Rugae, which are deep folds with gastric pits and gastric glands where cells secrete gastric juice.
What enzymes do gastric glands secrete (part of gastric juice)?
Pepsin, which is an enzyme that breaks down protein. It also secretes hydrochloric acid (HCl)
What is the role of hydrochloric acid?
Causes the stomach to be very acidic so as to kill bad bacteria and help break down connective tissue of meat for digestion AND activates pepsin. Has an acidity of about 2.
How long does it take the stomach to empty?
2-6 hrs
What is chyme?
The thick, soupy liquid of the stomach’s partially digested food that enters into the small intestine.
What is the sphincter called that connects the stomach to the small intestine where chyme passes through?
The pyloric sphincter.