Digestive System Flashcards
Structures of the gastrointestinal (GI) tract
Mouth Pharynx Esophagus Stomach Small intestine Large Intestine Anus
mucosa
description/function
Innermost layer of GI tract which lubricates the lumen, protects cells of the GI tract, and assists in digestion and assilimation.
submucosa
description/function
The second innermost layer of the GI tract which consists of connective tissue, blood vessels, lymph vessels and nerves. It provides the blood supply which maintains the cells of the digestive system, transports products of digestion, and provides the nerves which coordinate the contractions of the muscularis.
serosa
description/function
The outermost layer of the GI tract consisting of a thin layer of epithelial and connective tissue which secretes a fluid that lubricates the outside of the GI tract to reduce friction between it and other abdominal organs.
saliva
The secretions of the salivary glands which make food easier to pass through the digestive system by moistening and binding food particles together. It also contains an enzyme which helps to break down starches.
salivary amylase
The enzyme contained in saliva which assists in the breakdown of starches.
pharynx
The common passageway for air, food, and drink–commonly called the throat.
esophagus
The tube that connects the pharynx to the stomach.
peristalsis
The process which occurs in the muscularis which propels food along the GI tract.
stomach
A J-shaped muscular sac which stores and liquifies food and begins the digestion of proteins.
chyme
The liquid mixture resulting from the churning of food and gastric juices in the stomach.
gastric glands
Pits in the stomach which release hydrochloric acid and pepsinogen, which mix to become gastric juices. They also secrete mucus, which protects the walls of the stomach, and intrinsic factor, a protein necessary for the absorption of vitamin B-12.
pepsin
A protein-digesting enzyme released by the gastric glands in the stomach as pepsinogen and activated by hydrochloric acid.
small intestine
A long tube between the stomach and large intestine which has many circular folds and small projections called villi to increase the surface area used for absorption of nutrients
duodenum
The first region of the small intestine which regulates the amount of chyme entering the small intestine by squirting small amounts at one time.
bile
A mixture of water, ions, cholesterol, bile pigments and bile salts which plays an important role in the mechanical digestion of fats.
villi
Small projections out of the inner surface of the small intestine which increase absorption through increased surface area.
lacteal
A lymphatic vessel found in the core of the villi in the small intestine
pancreas
An accessory organ of the digestive system which sits behind the stomach. It releases pancreatic juices which combine with bile in the duodenum. Pancreatic juices play an important role in neutralizing acidic chyme.
liver
An accessory organ of the digestive system which sits above and to the left of the stomach
gallbladder
Accessory organ of the digestive system which squirts bile into the duodenum.
large intestine
Tube of the digestive tract between the small intestine and the rectum which is responsible for absorbing water and forming/expelling feces.
colon
The largest region of the large intestine.
rectum
Where feces are deposited from the large intestine which stimulates the defecation reflex.
List the types of nutrients.
lipids
carbohydrates
proteins
lipid
fats, oils, and cholesterols
95% of lipids found in foods are triglycerides
cholesterol
A type of lipid. Gives structure to cell membranes and steroid hormones.
low-density lipoproteins
A form of cholesterol which brings cholesterol to cells and deposits cholesterol in vessel walls. Considered the bad form of cholesterol.
high-density lipoproteins
A form of cholesterol which carries cholesterol from the body to the liver for elimination. Considered the good form of cholesterol.