Transcript Digestive System

1 of 27
“Well, yeah, of course I’m impressed Frank,
but strollers can’t be good for your
digestion.”
2 of 27
What is Digestion ?
The body carries out
digestion of food to
convert large insoluble
food molecules into
smaller soluble ones.
Carbohydrate
Protein
Lipid
Small food molecules can pass through the
walls of the small intestine and then
dissolve into the blood stream. Large food
molecules cannot do this.
3 of 27
Digestive System
a) Teeth
4 of 27
b) Tongue
c) Salivary
Glands
d) Oesophagus
e) Liver
f) Gall Bladder
g) Stomach
h) Pancreas
i) Small Intestine
j) Large Intestine
k) Rectum
In the Mouth
 Digestion
begins in the mouth where
food is broken down by the teeth.
This is called mechanical breakdown.
The
small parts of
food are mixed with
saliva and swallowed.
5 of 27
In the Mouth
 Saliva
contains enzymes that start to
chemically breakdown some of the
starch and fats in the food.
Enzymes are
biological catalysts
that speed up
chemical reactions.
6 of 27
Enzymes in Action
7 of 27
Amylase and Starch
 Amylase
breaks the long
starch chains into glucose
molecules.
 How
long can you keep a
piece of bread in your
mouth?
8 of 27
Down to the Stomach
 Food
then passes the
epiglottis, a flap of
skin and cartilage
that prevents food
from entering the
trachea (air tube).
9 of 27
10 of 27
11 of 27
Down to the Stomach
 The
food is moved down
the oesophagus with the
help of wave like
contractions, a process
called peristalsis.
12 of 27
In the Stomach
 The
stomach is a
hollow muscular sac
with a variety of
functions.
a)
b)
c)
13 of 27
It stores masticated food.
Produces acid and enzymes for
chemical breakdown.
Churns food before it moves on to the
rest of the digestive system.
The Journey So Far...
14 of 27
After the Stomach
 The
contents of the stomach are then
moved to the small intestine.
 Here,
the content is
mixed with bile and
enzymes from the
pancreas and
intestinal walls.
15 of 27
Mmmmmm… Bile!
 Bile
– a greeny-yellow substance
excreted from the gall bladder which
emulsifies fats to allow absorption,
neutralizes the chyme.
16 of 27
Small Intestine
 The
digestive enzymes
chemically break down
food particles.
 These
nutrients are then
absorbed into the blood
stream though the wall of
the small intestine.
17 of 27
Villi
The walls of the
small intestine are
not smooth.
They are covered in
villi which increases
the surface area
18 of 27
Large Intestine
 After
the long trip
through the small
intestine, the remains
enter the large intestine.
 Here
remains are fermented by the
action of gut bacteria, excess water
is absorbed and faeces is stored
until released.
19 of 27
Label the Diagram
20 of 27
Digestion Summary
21 of 27
22 of 27
23 of 27
Anagrams
24 of 27
Digestion Quiz
25 of 27