Advertisements
Advertisements
प्रश्न
Answer in detail.
What changes occur in food in the mouth?
उत्तर
The mouth is the first part of the digestive system. It receives food and starts mechanical digestion. The ingested food is first broken down in the mouth when it is chewed. Simultaneously it gets mixed with the saliva. This process is called mastication or mechanical digestion. It prepares the food for chemical digestion, that is, the digestion by action of enzyme. The teeth help in chewing down the food. There are 4 kinds of teeth. These are incisors, canines, premolars and molars, incisors are the cutting teeth. These help in biting and cutting the food. Canines are the tearing teeth that helps to tear and hold the food. Premolars and molars are the crushing and grinding teeth which help in grinding the food. When we chew the food it is mixed with saliva, secreted by salivary glands softens the food. Saliva contains an enzyme called salivary amylase also called ptyalin, acts on starch to convert it into maltose.
starch \[\ce{->[salivary][amylase]}\] maltose.
APPEARS IN
संबंधित प्रश्न
Which of the organs perform the following functions in humans Absorption of water?
Define holozoic nutrition. Give one example
Which of the following is the correct sequence of parts as they occur in the human alimentary canal?
(a) Mouth → Stomach → Small intestine → Oesophagus → Large intestine
(b) Mouth → Oesophagus → Stomach → Large intestine → Small intestine
(c) Mouth → Stomach → Oesophagus → Small intestine → Large intestine
(d) Mouth → Oesophagus → Stomach → Small intestine → Large intestine
When a person puts food in his mouth, then teeth cut it into small pieces, chew and grind it. The glands A in the mouth secrete a substance B which is mixed with the food by tongue. The substance B contains an enzyme C which starts the digestion of food in the mouth. The slightly digested food from the mouth goes down a tube D. The special type of movements E in the walls of tube D push the food into stomach for further digestion. The stomach wall secretes gastric juice containing three substance F, G and H. One of the functions of F is to kill bacteria which may enter the stomach with food. The substance G protects the inside layer of stomach from the damaging effect of substance F whereas substance H is and enzyme for digestion. The partially digested food then enters into small intestine for further digestion.
(a) What is (i) gland A (ii) substance B, and (iii) enzyme C?
(b) Name the tube D.
(c) What is the movement E known as?
(d) What are (i) F (ii) G, and (iii) H?
Observe the diagram given alongside and answer the following:
- Name the parts numbered 1-8.
- Which parts shown in the diagram are non-living?
- Is the tooth suited for cutting, tearing or grinding?
- What is the function of parts 8 and 7?
- What is the total number of teeth present in adult human beings?
- Write the dental formula of human beings.
Which systems work together to provide the body with energy?
Eating fast-food ad junk food affects our health. Justify.
Identify which three of the following terminologies is true for human dentition.
What are the compounds present in the food?
Label the following parts in Figure 2.2 and name them.
- The largest gland in our body.
- The organ where protein digestion starts.
- The organ that releases digestive juice into the small intestine.
- The organ where bile juice gets stored.
