7th Class Science Nutrition in Animals Feeding and Digestion in a Human Body

       Feeding and Digestion in a Human Body

Feeding and digestion in a human body starts from mouth. Food particle from the mouth is transported into stomach through the food pipe and thereafter to small intestine. After the absorption of nutrients, undigested food is transported to large intestine where small amount of salt and water is absorbed.

Look at the following picture of digestive system in the human body:

           Mouth part of the Digestive System

Mouth of the human body is called buccal cavity.

Teeth in the mouth breakdown the injected food into small pieces with the help of saliva, which is secrete by salivary glands. Saliva breaks down the starch into sugars. The functions of different teeth are different. Two pairs of teeth at the front in each jaw are called incisor. Incisors work for biting and cutting of the food. A pair of teeth which is called canine works for piercing and tearing the food. There are four pairs of teeth in each jaw which work for chewing and grinding called premolars and molars respectively.

Look at the following picture of different types of teeth in the mouth of the human body:

Mouth of a human body has a tongue for tasting the injected food. Taste buds on the tongue sense the taste of the injected food and send it to the brain for identification of the kinds of taste. Specific area on the tongue senses the specific taste as shown in the picture below.               

Look at the following picture of structure of tongue in the mouth of the human body:

There are huge amount of taste buds on the tongue of the human body. Salty and sweet taste buds are located at the front of the tongue. Sour taste buds are on both sides of the tongue and bitter taste buds are on the back side of the tongue. Taste buds from the tongue can disappear due to the smoking, not eating enough vitamins, head injury and effect of radiation.

           Digestion of Food in the Stomach of a Human Body

Partially digested food enters into the stomach through oesophagus or food pipe. Wall of the food pipe pushes the injected food downwards into the stomach. When food pipe unable to push the injected food downward, it is vomited out. Stomach secretes, mucous, hydrochloric acid and digestive juice.

Hydrochloric acid kills bacteria present in the injected food entered into the stomach through the food pipe.

          Function of Small and Large Intestine

Now food enters into the small intestine from the stomach, Villi on the wall of the small intestine absorbs nutrients present in the digested food. Undigested food then goes into the large intestine, wherein small amount of salt and water are absorbed. Waste part of food comes out through the anus and is called ejection.

     Consider the following statements:

Statement 1: Digestion of starch begins in buccal cavity.

Statement 2: Digestion of starch begins in stomach.

Which one of the following is correct about the above statements?

(a) Statement 1 is true and 2 is false

(b) Statement 1 is false and 2 is true

(c) Both statements 1 and 2 are false

(d) Both statements 1 and 2 are true

(e) None of these

Answer: (a)

Explanation 

Digestion of starch begins in buccal cavity. Therefore, option (A) is correct and rest of the options is incorrect.

      In which one of the following parts of the digestive tract, digested food is absorbed by the blood vessels?

(a) Large intestine

(b) Buccal cavity

(c) Stomach

(d) Small intestine

(e) None of these

Answer: (d)

Explanation 

Digested food is absorbed by the blood vessels in small intestine.

Therefore, option (D) is correct and rest of the options is incorrect.

Animals have heterotrophic mode of nutrition.

Undigested food is passed out through the anus.

Stomach secretes hydrochloric acid.

Hydrochloric acid kills bacteria.

Liver secretes digestive juice which is called bile.