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Science Chapter 11: Human Digestive System - Coggle Diagram
Science Chapter 11: Human Digestive System
Why do we need to eat?
Our body needs the
nutrients
in food for survival.
Three important nutrients are:
Proteins
Why do we need them?
They are used for
growth
and
repair
of
damaged tissues in our body
.
They
provide energy
when there are
insufficient carbohydrates and fats
.
Sources
Animal Proteins sources include
fish
,
Meat
,
Egg white
and
chees
e
Plant Proteins sources includes
soya beans
and
nuts
Carbohydrates
Why do we need them?
They provide our body with
energy
.
Sources
Starch
and
sugars
Starch can be found in
rice bread
and
cereals
Fats
Why do we need them?
They provide our body with energy
(Twice as much as carbohydrates)
They keep our body warm
Soucres
Butter,
Margarine
,
cooking oil
,
oily fish
,
meat
,
peanut
and
cocunt oil
.
Why does food needs to be digested?
Molecules of nutrients,such as starch,proteins and fats,are too
large
to pass through the cell membranes.
They must first be broken down into small molecules.
This is done in digestive system through a process called
digestion.
Digestion is breaking down of large food molecules into smaller molecules in the body
Which organs are responsible for digestion?
Organs of alimentary canal
Mouth
Oesophagus/gullet
Stomach
Small intestine
Large intestine
Liver
Gall bladder
Pancreas
How is food digested?
The digestion of food begins in the
mouth
Digestion continues in the stomach and
ends
in the small intestine
Enzymes and physical actions bring out digestion in these three organs
Mouth
Stomach
Small intestine
What is the role of enzymes?
The body produces substances called
enzymes
or digestive enzymes
to digest food.
These enzymes act like chemical
'scissors'
to cut up the large molecules into small molecules.
They also
speed up
the process of digestion
What are the roles of the organs in the digestive system?
In the mouth
(
CARBO
)
The teeth
cut
food into smaller pieces.This
increase
the surface area of the food which makes digestion faster.
(PHYSICAL / MECHANICAL DIGESTION)
Starch
is broken down into
maltose
by enzymes
(carbohydrates)[salivary enzymes]
in
saliva(chemical digestion)
.
Food then moves down the
oesophagus(gullet)
to the stomach,
In the oesophagus
(gullet)
No
enzymes are produced here
Food take about 10 seconds to make down to the stomach
Peristalsis
(pushing down food in the oesophagus)
In the stomach
(PROTEINS)
A liquid called
gastric juice
mixes with the food when in the stomach churns.
complex
proteins are broken down into simpler proteins by enzymes
(protease)
in gastric juice
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In the small intestine
(lipase[fats],Carbo,protines)
The process of digestion is
completed
by the action of enzymes in the small intestine
These enzymes digest fats and complete the digestion of maltose and simpler proteins
the digested food
(small molecules)
diffuse
through the walls of the walls of the small intestine and into the blood vessels that surround it.
In the large intestine
Only food that
cannot
be digested reaches the large intestine
As the food passes through the large intestine, a lot of
water
is removed and taken back into the body.
The undigestiable material passes out of the body through the
anus as the feases
How do food pass through the digestive system?
The walls of the alimentary canal are made of
muscles.
As the food passes through,the front of the food
relax
while muscles behind the food
contract
. This action squeezes food along the canal.
What happen to the digested food?
How does the food enter the blood stream.
Digested
molecules such as glucose and amino acids are small enough to diffuse through the walls of the small intestine and enter the blood stream.
The movement of the food molecules through the walls of the small intestine into the bloodstream is called the
absorption of food.
The blood then carries the
small
food molecules to all the cells in the body where they are used.
The small intestine is only about 7m long.This length
increases
the surface area of the small intestine which helps absorption take place
faster
.
The wall of the small intestine is only one cell thick. This shortens the distance travelled between the blood vessels and the interior of the small intestine. This make absorption faster.
What are the end products of digestion used for?
To provide
energy
To promote
growth
of cells and tissues.
To
repair
damaged tissues
To keep us healthy
how do our body systems work together?
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Food-borne diseases
Food-borne diseases
(also called food posing)
are caused by consuming
contaminated
food or drinks
Bacteria
are the most common causes of food-borne diseases
Some bacteria causes infection when they enter the intestine. Others produce a toxin(poison) that is absorbed into the bloodstream and carried to various parts of the body where infection occurs.
Ways in which bacteria could get into our food.
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What are the symptoms of food-borne diseases?
Diarrhoea
Fever
Vomiting
Stomach cramps
Dehydration
Death
(in the case of serious infections)
How can we prevent food-borne diseases.
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