Structures and Functions Science and Technology.pptx
1. STRUCTURES AND
FUNCTIONS: FOCUS ON
THE DIGESTIVE SYSTEM
ORGANS OF THE DIGESTIVE SYSTEM AND THEIR INTERACTION WITH ORGANS OF
THE RESPIRATORY, CIRCULATORY, AND EXCRETORY SYSTEMS
3. OBJECTIVES
At the end of the lesson, the students must
have:
1. Described the coordinated functions of the
organs of the digestive system.
2. Valued the important roles of enzymes in
digesting food.
3. Locate the organs which are parts of the
digestive system.
7. DIGESTIVE SYSTEM
Man’s digestive system has functions
which basically involve the following
processes 1) Ingestion or taking in food
into mouth, 2) digestion and 3) absorption
that refer to the processing of food into a
form that will be assimilated into living cells
and lastly 4) excretion or eliminating
indigestible substances and certain wastes
through the anus.
8. DIGESTIVE SYSTEM
What enables man’s digestive system
to perform such multifold functions?
To carry out its numerous functions,
man’s digestive system consists of the
digestive tract or food tube and the
so-called accessory digestive glands.
9. DIGESTIVE SYSTEM
Suppose you are trapped in a place
where there is no food and water. How
long will you live? What will you do to
survive?
Have you gone to school without eating
your breakfast? What do you feel? Can
you understand your lessons well?
Suppose you have a surprise quiz. Can
you think well of the answer?
10. DIGESTIVE SYSTEM
Food and digestion fuel the body to
make it move, just as gasoline fuels
the car to make it run. This also
includes all parts of your body from
the cellular level to enable them to
perform their specific functions.
Without food, you are like a car
without fuel.
11. DIGESTION
Digestion is the process by which the
complex food taken into the body is
transformed into simpler molecules that can
pass through the cell membrane so the
body can use them. The food that you eat –
like fruits, vegetables, fish, meat or rice
cannot be used directly by the body. The
cells cannot absorb them.
12. DIGESTION
Large molecules of carbohydrates and
proteins are first changed to simpler
molecules like amino acids, simple sugars,
fatty acids and glycerol before they can
pass through the cell membranes. This is
made possible by the process of digestion
with the aid of special protein molecules
called enzymes. They act as catalysts that
speed up the chemical reactions.
13. DIGESTION
Digestion can be intracellular and
extracellular.
Intracellular digestion takes place inside a
cell while extracellular digestion takes
place outside the cell but inside the
digestive cavity or digestive system.
Digestion may also be complete or
incomplete. Incomplete digestive system
takes place in animals without anus.
14. DIGESTION
Man’s digestive tract or food
tube is about nine meters long,
extending from the mouth
down to the anus. It is a
continuous tube of varying
diameter and length.
16. MOUTH CAVITY
Mouth cavity or digestive cavity.
The mouth serves as the
entrance of food. Inside the
mouth are teeth, tongue and
salivary glands.
17. MOUTH CAVITY
The teeth cut and chew the food into small
pieces. The tongue manipulates the food for
better chewing action and mixes it with saliva
which contains an enzyme. The back part of the
tongue secretes mucus which lubricates the food
and, thus, makes swallowing easier. Then it pushes
the food particles to the pharynx, the funnel-
shaped end of the mouth of the cavity that leads
to the esophagus.
18. ESOPHAGUS
Esophagus is a moist, muscular tube that
connects the pharynx to the stomach. It
delivers food to the stomach.
From the mouth, the swallowed food is pushed
down the food tube by a series of rhythmic
wavelike contractions of the muscles of the
esophagus. This muscular activity is called
peristalsis. The food stays for a while at the
lower end of the esophagus.
20. STOMACH
Stomach is the saclike, most expanded
portion of the food tube. The inner surface of
the stomach is highly folded, allowing it to
collapse when empty and expand as food
fills it. Thus it can expand to hold as much as
two to four liters of food and liquids when full.
The walls of the stomach contain gastric
glands that secrete substances for a
preliminary digestion of food.
21. STOMACH
As the food enters the
stomach, another circular
valve muscle called the pyrolic
sphincter at the lower end of
the stomach remains closed.
After about two hours, the
pyrolic sphincter relaxes. The
partly digested food gradually
leaves the stomach and enters
the small intestine.
22. SMALL INTESTINE
Small Intestine has three parts namely duodenum, jejunum
and ileum. The upper part of the small intestine has a wider
diameter while its lower potion has narrower diameter is
highly coiled. Duodenum or the upper part receives the
partly digested food mass from the stomach, digestive juice
from the pancreas and bile from the liver and gall bladder.
Meanwhile, absorption of fully digested food mass takes
place at lower portion of the small intestine. The wall of this
organ is covered with very tiny projections called intestinal villi
(singular villus). They increase the absorbing capacity of the
small intestine. Undigested food with other wastes pass on to
large intestine by peristaltic action.
23. LARGE INTESTINE
Large Intestine is also known as colon, this
organ is referred to a large intestine because
of its large diameter. Based on its position, the
parts of the large intestine are ascending
colon, transverse colon and descending
colon. The last part of the large intestine ends
into a short tube called rectum that leads to
the lower opening of the food tube, the anus.
The large intestine has no villi and is not as
highly coiled as the small intestine.
24. LARGE INTESTINE
In the large intestine, the undigested food
passed on by the small intestine undergoes
decomposition by bacterial action. The resulting
refuse materials (called feces), are compacted
and stored temporarily in the large intestine.
Defecation or bowel movement is the process
by which the feces are being propelled out of
the body. A sphincter controlled by the brain
allows conscious effort to delay defecation.
25. ACCESSORY DIGESTIVE GLANDS
Accessory Digestive Glands. There are certain organs that
are associated with the food tube because they produce
secretions that aid digestion. Known as accessory digestive
glands, they include salivary glands, liver and pancreas.
These digestive glands secrete saliva which contains a
starch-digesting enzyme called salivary amylase or ptyalin.
This enzyme changes starch into a double sugar called
maltose.
The liver is the largest accessory digestive gland in the
body. It produces a yellow-green liquid called bile which is
stored in the gall bladder. Meanwhile, the pancreas
secretes pancreatic juice that contains digestive enzyme.
