3.1 Digestive System Flashcards
Mechanical digestion
Involves the physical breakdown of food into very small pieces.
Chemical Digestion
Involves the breakdown of large particles into smaller particles by substances called enzymes.
Food’s path to stomach
The digestive system is actually a long tube, with a few attachments along its length. It starts at your mouth and finishes at the rectum.
What happens before the food reaches your stomach?
It comes in contact with many organs. Digestion begins at the entrance to the tube, the mouth, with the mechanical breakdown of your food.
What do your teeth do?
teeth mechanically digest the food by grinding it and mixing it with saliva
What does saliva do?
Three pairs of salivary glands are located in the tissues. surrounding your mouth to produce saliva.
What does Saliva contain?
Saliva contains water to moisten the food, making the food easier to swallow. It also contains, an enzyme known as salivary amylase.
What does this enzyme do?
This enzyme chemically digests large starch molecules into smaller sugar molecules
What happens as you swallow?
As you swallow, a flap of skin called the epiglottis moves across your windpipe, and food is funneled into the esophagus.
Peristalsis
Is caused by contractions of muscle tissue that lines the esophagus.
Gastric juice
Is composed of mucus, hydrochloric acid, water, and digestive enzymes. The hydrochloric acid, along with the enzymes, chemically digests proteins into smaller particles
What does mucus do?
The mucus helps to prevent the gastric juice from digesting the stomach itself. The stomach slowly releases the food, which is now a liquid, into the small intestine
What does the pancreas do?
The pancreas sends digestive enzymes into the small intestine.
What do these enzymes do?
These enzymes, complete the breakdown of starches and proteins into very small particles.
What does the liver produce?
The liver produces a substance called bile, which is stored in the gall bladder.
What does the gall bladder do?
The gall bladder sends bile into the small intestine where it breaks up large globules of lipids into much smaller droplets.
What happens when the food is broken down?
Once the food has been broken up into small particles, the small intestine absorbs these particles. The inner surface of the small intestine forms into villi
What are villi?
Hair like projections
What do these do?
These increase the surface area of the intestine to aid in absorbing nutrients
What is each villi covered by?
Each villi is covered with a epithelial tissue
What does this tissue do to food?
The food molecules get absorbed by this tissue.
Where do blood vessels lie?
Blood vessels lie just below the epithelial tissue, and the nutrients are transferred to the bloodstream.
How long is your small intestine?
The small intestine is 6 m long
What do cells do?
The cells of the epithelial tissue have modified cell membranes that form more finger-like projections called microvilli
What is a Microvilli?
Finger like projections
How do Microvilli help?
Microvilli increase the surface area of the small intestine to help absorb nutrients.
What happens when food reaches your reaches your stomach
By the time the food reaches the large intestine, mechanical and chemical digestion are complete.
How long is the large intestine?
The large intestine is about 1.5 m long.
What does the huge intestine absorb?
The large intestine absorbs water, along with some vitamins and minerals.
What happens to the food that has not been digested?
Are formed into feces, which is collected in the rectum
