digestive system Flashcards
As heterotrophs we cant create carbon so what do we need to do?
we need to ingest carbon in our food
What are the function of the digestive system?
- Break down of food into nutrients.
- Nutrients absorbed in the body.
- Transported throughout the
circulatory system.
Nutrients in the cell can be used as a source of energy
What are the stages of the digestive system?
Ingestion: eating/drinking nutrients
Digestion: breaking down molecules into smaller ones.
- Absorption: absorbing digested molecules
- Egestion: removal of waste.
what is the
Gastrointestinal tract (GI tract):
the tube that extends from the mouth to the anus and where digestion takes place.
What is mechanical digestion?
• pieces of food become smaller , increasing the surface area
• Chewing food in the mouth
• mixing of food that occurs in stomach.
What is chemical digestion?
• digestive tract makes digestive enzymes
• enzymes break down macromolecules into small organic molecules that can be absorbed.
Where does digestion start ?
The mouth
What does the saliva contain?
Water, mucus, and enzymes
what is Amylase?
Enzyme in saliva that breaks starch down into simple sugars.
what is a bolus?
food that has been chewed and mixed with saliva
What happens after the bolus is pushed into the pharynx?
The soft palate raises to stop food from entering nasal passage
What does the epiglottis do when the bolus is swallowed?
the epiglottis covers the entrance to the trachea so food doesn’t enter lungs
what is the esophagus?
a muscular tube that passes food from pharynx to stomach
what pushes the food toward the stomach?
muscle contractions called peristalsis move food towards stomach
Where does mechanical and chemical digestion occur?
In the stomach
What shape is the stomach and how much can it store?
-J shaped & stores food
- capacity of 2 L
what does the food enter and exit the stomach through?
sphincters
What are sphincters?
muscles surrounding a tube-like structure
What happens when the esophageal sphincter relaxes?
The bolous enters the stomach
what happens when the esophageal sphincter contracts?
It stops food from going back into esophagus
what does the stomach release?
Gastrin
what does gastrin do?
It stimulates gastric juice Secreted by the cells in the stomach lining
What does gastric juice contain a mixture of?
hydrochloric acid(HCL)
Enzymes (pepsin)
Mucus
what does the hydrochloric acid do in gastric juice?
breaks down fibres and bacteria
