Transcript Digestion Organs - Hicksville Public Schools

Aim: How does digestion take place
in humans?
A – Mouth
B – Esophagus
C – Stomach
D – (Pancreas)
E – Small Intestine
F – Large Intestine
G – (Gall Bladder)
H – (Liver)
I - Appendix
I
Alimentary Canal – the “tube”
digestion takes place in.
Gastrointestinal Tract – another name for
the digestive system. Gastro = stomach;
intestinal = intestines
Four Stages of Food Processing:
Ingestion – the act of eating or
drinking
Digestion – the process of breaking
food down into molecules small
enough for the body to absorb.
Absorption – cells take up (absorb)
the small molecules (Diffusion).
Elimination – (Egestion)
undigested material passes out of the body.
Digestion
 The
process by which food products are
broken down.
 Types:
CHEMICAL:
MECHANICAL:
The physical
breakdown of food
into smaller pieces
(Ex: chewing)
Enzymes
breakdown food
into smaller pieces
(Ex: amino acids)
Chemical Digestion:
Enzymes play a critical role in the
digestion (hydrolysis) of nutrients.
Mouth:
 Intake
of food through the mouth!
 Digestion is both mechanical (teeth
and tongue) and chemical (salivary
amylase – an enzyme that breaks
down starch) digestion occurs.
 Food
mixed
with
saliva
moves
to
pharynx,
What keeps the food from going into the
and travels down through the esophagus.
trachea (wind pipe)? Epiglottis
Esophagus
Long muscular tube connecting the stomach
to the pharynx (upper portion of throat)
No Digestion takes place
here!
Peristalsis
 Process
by which muscular
contractions move food
through the esophagus stomach,
small and large intestine
Stomach
 Both
mechanically (churning) and
chemically (pepsin) digestion occur.
Stomach Glands
Gastric Juice
HCl (Hydrochloric
Acid)
Acidic pH
Kill Bacteria
Enzyme
specificity
Enzymes
Pepsin
Digestion of
proteins
What is the optimum pH and
temperature for pepsin?
Optimum
pH = 2
Optimum
Temp = 40
Small Intestine
 Responsible
for digestion and
absorption of nutrients.
 Most
of the Chemical digestion &
Absorption of nutrients takes place
here.
Small Intestine
 The
enzymes are added to the small
intestine are produced by pancreas.
 Enzymes:
Amylase
Trypsin
Lipase
Digests Lipids
Digests Starch
Digests Proteins
These enzymes + a acid neutralizing agent
make up the “pancreatic juice”
Absorption
The S.I. is ideal for absorption because:
-Its very long (about
21 feet)
-Many folds/ridges
-Has villi (finger like
projections)
Villi
Blood Vessels
Carry Nutrients
away from the
digestive system
to the parts of
the body that
require them.
Nutrients
diffuse
Into the
bloodstream!
Large Intestine
 Undigested
material passes
into the L.I
 No digestion occurs here
 The major function is to
reabsorb water & vitamins.
 Stores waste (feces) in the
rectum.
 Elimination through the anus.
 Appendix – vestigial organ.
Accessory Organs
Make (or store) enzymes, food
does not pass through them
Liver
Gallbladder
Pancreas
Accessory Organs
1. Liver – makes bile
2. Gallbladder – stores and
releases bile into S.I.
3. Pancreas – makes and
releases (pancreatic
juice) amylase, trypsin,
and lipase into S.I. along
with acid neutralizer.
Bile
-Emulsifies fats
-Breaks FAT into
smaller droplets
(mechanical digestion)
-Increases surface area of
fats
What is the major role of the Digestive
System (How doe it help us maintain
homeostasis?
The digestive system is responsible for breaking
down nutrients into smaller components so they can
enter our bloodstream & be delivered to our cells &
can diffuse across the cell membrane.
Polysaccharides
Proteins
Lipids
Monosaccharides
Amino Acids
Fatty Acids &
Glycerlol
Diffusion
Cell
It's a Gas
Scientists estimate that the average adult releases
between 12 and 122 cubic inches of intestinal gas each
day. Most of that gas is made up of hydrogen and
methane produced by the bacteria as they ferment the
fiber that was not digested in the stomach or small
intestine.
Many fruits and vegetables, especially beans, contain
these polysaccharides, which cannot be broken down
by the enzymes in the stomach or small intestine. As
the bacteria decompose these complex sugars, gas is
released. Most of the gas is passed without notice.
Common wisdom tells us that beans give us a lot of gas—
more than could pass without notice. Ever questing for
eternal answers, scientists in one study measured the
intestinal gas produced by people who ate a control
diet and compared them to those who ate a meal that
was half pork and beans. The folks in the control group
released .9 cubic inches per hour of flatus (intestinal
gas) while the pork and beans group released a
whopping 10.7 cubic inches.
Weird Science Fact
Alexis St. Martin, a French Canadian, was
accidentally wounded by a short gun blast in
1822. Fortunately, Dr. William Beaumont, an
army surgeon, was nearby and began treatment
of the wound immediately. St. Martin’s
recuperation lasted nearly three years, and the
enormous wound healed except for a small
opening leading into his stomach. A fold of
flesh covered this opening; when this was
pushed aside the interior of the stomach was
exposed to view. Dr. Beaumont began a series
of experiments and observations that formed
the basis of our modern knowledge of
digestion.