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.
carbohydrates
Nutrient coming from sugars, starches and dietary fiber. Basic unit is a monosaccharide
dietary fiber
A type of carbohydrate which the human body cannot digest and is passed into the large intestine, giving bulk to feces.
glycemic response
How quickly a serving of food is converted into blood sugar and how much the blood sugar level is affected.
protein
A nutrient consisting of amino acids delivered to the cells to make more proteins.
essential amino acids
Those amino acids which the body cannot synthesize and must be supplied by the diet.
complete protein
A source of protein which contains all 20 amino acids. Usually from a meat source.
incomplete protein
A source of protein which does not contain all 20 amino acids. Usually
complementary proteins
Combinations of food sources containing incomplete proteins which together provide all 20 amino acids.
vitamin
An organic compound essential for health which is needed in small quantities (milligrams or micrograms)
mineral
An inorganic substance which is essential for many life processes.
basal metabolic rate (BMR)
The minimum amount of energy needed to keep an awake, resting body alive.
obese
The state of being overweight as a result of excess fat.
overweight
The state of weighing more than the ideal weight specified on a height/weight chart.
Follow a bite of food through the GI tract from the mouth.
Mouth > Pharynx > Esophagus > Stomach > Small Intestine > Large Intestine > Colon > Rectum
What are the functions of the teeth and tongue in processing food?
The teeth are responsible for mechanically tearing and grinding food into smaller pieces. The tongue is responsible for taste and for moving food to the teeth for processing, as well as to the back of the mouth for swallowing.
What causes tooth decay? What structures of the tooth are affected?
Food particles caught in teeth containing sugar attract acid-producing bacteria which wears away the enamel of the tooth. If untreated, the bacteria can reach the dentin underneath the enamel.
List three primary functions of the stomach.
1) storing food and regulating its release into the small intestine
2) liquefying food
3) carrying out the initial chemical digestion of proteins
how does bile assist in the digestion and absorption of fats?
Bile salts emulsify oils creating a larger surface area for lipase to absorb from.
Where are carbohydrates digested?
The mouth begins the process of digestion, and it is finished in the small intestine.
Where are fats digested?
the stomach begins the process of digestion, and it is finished in the small intestine.
What structure in the small intestine helps to increase absorption? How?
villi are small projections off the inner surface of the small intestine which each have many projections of their own. this dramatically increases the surface area available for absorption.
What are the functions of the large intestine?
- Absorption of remaining water from food residue which adjusts the consistency of the feces
- Storage of feces
- Elimination of feces
Where does the digestion of oil begin?
In the stomach, where bile salts emulsify oils to increase the surface area available for absorption.
What is the most major concern for someone with diarrhea?
Dehydration.
Eating _____ helps to lower blood levels of LDL cholesterol.
Fiber
Which of the following is NOT a function of saliva?
a) begins the chemical breakdown of starches
b) helps clean the mouth
c) contains fluoride to harden tooth enamel
d) moistens food and helps stick it together to make it easier to swallow
c) contains fluoride to harden tooth enamel
_____ is a liquid mixture of food and gastric juices found in the stomach.
Chyme
The ______ is the organ that produces bile.
gallbladder
Saliva contains an enzyme that begins the chemical digestion of _____.
starches
_____ is a hormone produced by the small intestine that causes the gallbladder to contract and release bile.
Cholecystokinin
List the four layers of the GI tract from the inside out.
mucosa, submucosa, muscularis, serosa
muscularis
description/function
The second outermost layer of the GI tract consisting of two layers of smooth muscle which is responsible for peristalsis and mixing ingested materials with digestive fluids.
Which layer of the GI tract is responsible for preventing friction with other abdominal organs?
serosa
Which layer of the GI tract is responsible for peristalsis?
muscularis
Which layer of the GI tract is responsible for supplying blood to the digestive system?
submucosa
Which layer of the GI tract is responsible for protecting the cells of the GI tract?
mucosa
Which layer of the GI tract transports the products of digestion in some parts of the digestive system?
submucosa
Which layer of the GI tract increases the surface area for absorption in some parts of the digestive system?
mucosa
Where are proteins digested?
Small intestine
When is food no longer external in the body?
When it reaches the liver.
Which of these is not an accessory organ in the digestive system?
a) salivary glands
b) oral cavity
c) pancreas
d) liver
b) oral cavity
How does the digestive system play a role in protecting against pathogens?
By releasing hydrochloric acid into the stomach which kills bacteria.
What are some benefits that beneficial bacteria in the large intestine provide?
Production of vitamins, digestion of fiber
What role does the esophageal sphincter play?
What happens when the esophageal sphincter is dysfunctional?
Prevents backflow of stomach contents into the esophagus.
Heartburn
What role does the pyloric sphincter play?
Regulates flow of chyme into the small intestine.
