Page 18 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

v Liver is the largest gland which secrete digestive juice called bile, that helps in converting

the acidic medium of partially digested food to alkaline medium.
v Bile juice is stored in a sac-like structure called gall bladder. It helps in digestion of fats by

breaking them down into simpler form.
v Pancreas secrete pancreatic juice and a hormone called insulin. The pancreatic juice helps in
the digestion of proteins into amino acids, fats into fatty acids and glycerol and carbohydrates

into simple sugars, such as glucose.
v The intestinal juice along with bile juice and pancreatic juice breaks down all components

of food into simpler substances. This completes the digestion of food.
v The inner walls of small intestine containsmall finger-like projections called villi, that increase

the surface area of small intestine and help in the absorption of food, which further diffuses
into the blood stream.

v The villi have a network of blood vessels that carry the absorbed food to different cells of
the body where they are used to obtain energy for growth and repair. The utilisation of food
by the body is called assimilation.

v Large intestine is a tube-like structure about 1.5 m long. It is wider but shorter than the
small intestine. The undigested food from the small intestine moves to the larger intestine.

v Water and salts are absorbed by large intestine and the remaining waste passes into the
rectum as semi-solid faeces. These are removed through the anus timely. This process is

called egestion.
v A disorder of the digestive system where a person passes watery stools frequently is called

diarrhoea. It may be caused by contaminated food or due to indigestion. Patients suffering
from diarrhoea are given plenty of Oral Rehydration Solution (ORS).
v Herbivores eat grass which is rich is a complex carbohydrate called cellulose and can be

digested by certain bacteria.
v Grass-eating animals have stomach of four chambers—rumen, reticulum, omasum and

abomasum.
v Rumen is the first and the biggest chamber. Food is stored and cellulose is digested here.
Partial digestion takes place in reticulum and the partially digested food is called cud. While

resting, grass-eating animals bring the cud back into their mouth and chew it. This is called
regurgitation. After chewing, the food from the mouth goes into omasum which is the

smallest chamber and then to the fourth chamber called abomasum which is known as true
stomach. After digestion in abomasum, food enters the small intestine where absorption of

nutrients takes place.
v In animals such as rabbits and horses, a small organ called caecum is present between the

large and small intestine which helps in the digestion of cellulose.

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