Digestive System Flashcards
What does the GI stand for?
Gastrointestinal tract
What is the the main role of your digestive system?
To metabolize food (storing, breaking down, absorbing food)
True/false
Your digestive system is a long tube that runs through your body from your mouth to your anus
True
How long is your digestive tract?
6-9m long
What is peristalsis?
A contractile motion of muscle where food is moved through the esophagus.
How long does it take for food to pass through the digestive system?
About 1-3 days
What is mechanical digestion?
Physical breakdown of food like chewing, stomach churning. This increases surface area of food.
What is chemical digestion?
Use of enzymes to chemically break down food (lipases, proteases, carbohydrase)
What is absorption?
The movement of nutrients and particles into the blood
What is egestion?
Removing waste (poop)
What is the purpose of chewing?
To create more surface area on food, allows enzymes to act more efficiently
What are incisors?
Sharp teeth used for tearing (meat)
What are molars?
Flat teeth for grinding (veggies)
What is the bolus?
A ball of food formed in your mouth
What macromolecule is broken down in your mouth?
Carbohydrates (by amylase in saliva)
What does saliva do?
Lubricates and dissolves food
What is the pharynx?
A pathway for both food and air, before the epiglottis
What is the epiglottis?
A valve that covers the esophagus until you swallow, then covers the trachea so no food enters your lungs
What is smooth muscle contraction?
Muscle contraction that you don’t consciously control
What happens if the esophageal sphincter didn’t contract?
You would get stomach acids in your esophagus, causing “heartburn”
How does the stomach hold up to 4L of food?
Folds in the stomach unfurl and expand for more room
What are the functions of the stomach?
Storage of food, digestion, (Mainly protein) transporting chyme, (food) and some absorption.
How does the stomach digest food mechanically?
The stomach uses mechanical digestion to churn and mix the food
How does the stomach digest food chemically?
Uses HCL which comes from parietal cells, and kills bacteria. Also needed for enzymes to function because they need a ph of around 2. Enzyme called pepsin is activated by HCL
What is pepsin?
The main protease in the stomach that comes from chief cells. Starts as pepsinogen (inactive) but becomes pepsin in the presence of HCL. Breaks down proteins into polypeptides.
What is mucus?
Lines the stomach to protect against its own digestive juice.
What is absorbed in the stomach?
Small amounts of water, medications (aspirin) amino acids (protein) and ethanol (alchohol)
What ph is the mouth?
Around 6.7
What two ducts enter the small intestine?
The common bile duct and the pancreatic duct
What is the purpose of bile?
Bile contains an emulsifier which divides fat up into fat droplets
What is the purpose of pancreatic juice?
Pancreatic juice contains enzymes that act on starch, lipids, proteins and nucleic acids.
What is the purpose of villi?
The villi contain exocrine which secrete enzymes to finish digestion by breaking disaccharides to monosaccharides and polypeptides to amino acids
What other role do the villi play?
They also absorb the small nutrients that the enzymes they released broke down
Where do small nutrients go after being absorbed by the villi?
The fats go to the lacteals and the others enter the hepatic portal vein. They then go to the liver where glucose is stored as glycogen
Which part of the digestive tract does pancreatic juice enter?
Duodenum (small intestine)
Which part of the tract does bile enter?
The small intestine
Which parts of the digestive tract actually contain food in the process of being digested?
Mouth, small intestine, stomach
What parts of the system are accessory organs?
Gall bladder, liver, pancreas, salivary glands
What part of the digestive tract absorbs the most water ?
The large intestine
Where does the food go after the stomach ?
It passes through the pyloric sphincter into the small intestine
What two ducts enter the small intestine?
The common bile duct from the gall bladder and the pancreatic duct from the pancreas
What are the enzymes in pancreatic juice?
Trypsin, chymotrypsin amylase, and lipase ( also contains bicarbonate which neutralizes stomach acid)
True/false
Does bile let lipase enzymes work more effectively due to higher surface area on the fats?
True
What other functions does the liver have?
Breaks down hemoglobin, and stores the product in the gallbladder. Also stores vitamin a,b12, and d.
What is the role of the duodenum?
The duodenum receives chyme (food) and enzymes from the pancreatic duct and bile from the gall bladder. Also the site of some absorption ex. Iron and the site of chemical digestion
What is the role of the jejunum?
The jejunum is where most absorption occurs. Fats into lacteals then into lymphatic vessels and sugars and amino acids into blood.
What is the role of the ileum?
The ileum is where the last of nutrient absorption occurs, absorbing things like vitamin b12
