Chapter 9.1 : Nutrition ( carbohydrates and proteins ) Flashcards
What is the human digestive system made up of ?
A long and muscular alimentary canal that starts from
Mouth ——> Anus
What does the alimentary canal consists of ?
Mouth , Oesophagus , Stomach , Small Intestine , Large Intestine , Anus
Organs that are involved in the digestive system includes :
Liver , Gall bladder , Pancreas
What digestive glands does the digestive system consists of ?
(glands) , (body part)
- Salivary glands in the mouth
2.Gastric glands in the stomach
3.Intestinal glands in the ileum of the small intestine
Definition of digestion :
Breakdown of large pieces of food into smaller pieces for easy absorption .
Definition of physical digestion :
Breaking down of large food pieces by chewing into smaller pieces
Uses of physical digestion :
What does it also involve ?
To increase the surface area of the food particles for an enzyme reaction.
Involve Peristalsis which moves the food particles down the alimentary canal.
Definition of chemical digestion :
What does it also involve?
The decomposition process of complex molecules into simple molecules .
It also involves enzyme reactions .
Where does the digestion of carbohydrate begins ?
What does it involve ?
Begins in the mouth .
Involves the salivary glands which secrete saliva 唾液 .
What does saliva contain and its function :
Optimum pH for the enzyme to digest carbohydrate :
Saliva contains salivary amylase which hydrolyses starch to maltose .
pH 7
Saliva helps food to form ____
Bolus .
What happens to the epiglottis when swallowing? Why?f
The epiglottis will close the trachea opening to prevent food from entering the trachea .
In the oesophagus , the bolus is moved by ______ .
Peristalsis .
What is peristalsis ?
Peristalsis is the rhythmic contraction and relaxation of muscles along the alimentary canal .
Where does the digestion of protein starts at ?
Starts at stomach
The surface of the stomach wall is lined with _____
Epithelial cells to form gastric glands .
(Epithelial cells are a type of cell that covers the inside and outside of the surfaces of your body. They are found on your skin, blood vessels, and organs)
What does gastric gland consists of ?
Chief cells , parietal cells . mucous cells
What does chief cells secrete ?
Pepsinogen (inactive enzyme) .
Turns into pepsin by the acid in stomach .
What does parietal cell secrete ?
Hydrochloric acid .
What is mucous cell ?
Goblet cell .
What does mucous cell secrete ?
Mucus .
pepsin
Protein + water ————–> ?
Polypeptides .
Salivary Amylase
Starch + water —————————-> ?
Maltose .
What is pepsinogen ?
Pepsinogen is an inactive enzyme that is activated by hydrochloric acid to form pepsin .
Function of pepsin :
Hydrolyses protein into polypeptides .
Optimum pH for digestion of protein :
pH 2
What does gastric juice contain ?
Hydrochloric acid , mucus and enzymes
Function of hydrochloric acid :
activate ___
Activate inactive enzymes into active enzymes .
pepsinogen —-> pepsin
Function of hydrochloric acid :
Provides ____
Provides an acidic medium for pepsin and rennin.
Function of hydrochloric acid :
Kills ___
Kills bacteria .
Function of hydrochloric acid :
Stops ___
Stops the action of salivary amylase . The digestion of starch stops as the pH is too low .
Function of mucus :
Protects the walls of the stomach from being corroded by acid in the stomach .
Function of pepsin :
Hydrolyses protein into peptones and polypeptides .
Function of rennin :
Coagulates milk (solid—->liquid)
Converts caseinogen in mlik to casein . (soluble protein—->insoluble protein)
Process of food in the digestion process of stomach :
(gastric juice , churned , peristalsis , chyme , sphincter muscle)
The food in the stomach is mixed with the gastric juice containing pepsin and hydrochloric acid . Food is churned by the peristalsis action of the stomach wall muscles for a few hours . The content in the stomach finally changes to a semifluid called chyme . Chyme enters the duodenum when the pyloric sphincter muscle relaxs .
