Download DIGESTIVE SYSTEM

DIGESTIVE SYSTEM
THE ALIMENTARY CANAL
• The alimentary canal- is the path that food
will take from the moment it enters your
body until it exits.
• AKA- The Gastrointestinal Tract, GI,
or Gut!
• Includes the mouth, esophagus,
stomach, and small and large
intestines, and anus.
• An adults DT is about 30 feet long.
THE ACCESSORY ORGANS
• The Accessory Organs- include the teeth,
tongue, gallbladder, liver, pancreas,
salivary glands.
• The accessory digestive glands
produce a variety of secretions that
contribute to the breakdown of
foodstuffs.
The Digestive Process
•
•
The digestive tract can be viewed as a “disassembly
line” in which food becomes less complex at each step
of processing and nutrients then become available to
the body.
The six essential activities are:
1. Ingestion
2. Propulsion
3. Mechanical digestion
4. Chemical digestion
5. Absorption
6. Defecation
THE ALIMENTARY CANAL
Mucous Membrane
 Mucous
membrane,(aka
mucosa), lines
most of the
alimentary canal
from mouth to
anus.
 Formed of surface
epithelium and a
small amount of
smooth muscle
 Functions include:
 Protection against
infectious disease.
 Secretion of mucus,
digestive enzymes,
and hormones
 Absorption of end
products of
digestion into the
blood.
Digestion
 Digestion is the mechanical and
chemical breakdown of foods into
forms that cell membranes can
absorb.
 Mechanical digestion breaks large
pieces into smaller ones without
altering their chemical composition
 Chemical digestion breaks food into
simpler chemicals
Mouth
 Mouth- a mucosa-lined cavity, is also called the
oral cavity, or buccal cavity.
 The mouth receives food and begins digestion by
mechanically breaking up the solid particles into
smaller pieces. This is called mastication.
 The mouth is also part of the speech and sensory
perception.
 The mouth is in all responsible for the following
 To ingest
 Begins mechanical digestion by chewing
 Initiates propulsion by swallowing.
Tongue
Tongue
 Tongue- mixes saliva with food and moves it
toward pharynx.
 The surface of the tongue has rough projections
called papillae. These can provide friction which
handles food most other papillae contain most of
the taste buds.
 The tongue is connected in the midline to the floor
of the mouth by a membranous fold called the
frenulum.
 The root of the tongue is anchored to the hyoid
bone.
3 Types of Tonsils
 All Tonsils are lymphatic tissue and are
there for associated with fighting infection.
 Alingual Tonsils, Palatine Tonsils, and
Pharyngeal Tonsils- (aka Adenoids).
 We will discuss these in more detail during
the Lymphatic System.
Palate
 The palate forms the roof of the oral
cavity and consists of a hard anterior
part and a soft posterior part.
 The soft palate forms a muscular
arch, which extends posteriorly and
downward as a cone-shaped
projection called the uvula.
Saliva
o Saliva- Functions:
o Cleanses the mouth
o Dissolves food chemicals so that they can be
tasted
o Moistens food and aids in compacting it into a
bolus (which is a lump of chewed food)
o Contains enzymes that begin the chemical
breakdown of starchy foods.
Salivary Glands
o There are three pairs
of major salivary
glands:
o Parotid (1) is the
largest
o Submandibular (2)
o Sublingual (3) (is the
smallest)
Salivary Glands
Salivary Glands
o
o
o
o
Salivary Glands-
produce two types of
secretory cells: mucous
and serous.
The parotid glands
contains only serous cells.
The sublingual gland
contains mostly mucous
cells
The submandibular
contains both cells
 Serous Cells – they
produce a digestive
enzyme called amylase.
It begins the chemical
digestion of complex
carbohydrates, such as
sweet potatoes even
before it leaves the
mouth.
 Mucous Cells- produce
mucus which binds food
particles and acts as a
lubricant.
Salivary Glands
 Mumps, a common
children’s disease,
is an inflammation
of the parotid
glands caused by
the mumps virus.
 Saliva is mostly 97
to 99.5% water.
THE ALIMENTARY CANAL
 Teeth- 20 primary,
32 secondary,
hardest structures in
the body that are
not part of the
skeletal system
 By age 2..most
children have ALL of
the primary teeth.
PHARYNX
 Swallowing (deglutition), moves food into
the throat or pharynx.
 A passage way for both food and air.
 It connects the nasal and oral cavities with
the larynx (where your vocal cords are) and
esophagus.
 Over 22 muscles groups must work
together during the process of swallowing
in order to close of the air passageway and
lead food down the esophagus.
 A flexible flap of tissue called epiglottis
reflexively closes over the trachea when we
swallow to prevent choking.
Esophagus
 ESOPHAGUS is a straight collapsible tube
about 25 centimeters long.
 Provides passageway for food from the
pharynx to the stomach
 Waves of muscle contractions called
Peristalsis forces food down the
esophagus.
Esophagus
 At the end of the esophagus, a
muscular ring called the lower
esophageal sphincter (aka cardiac
sphincter) allows food to enter the
stomach and then squeezes shut to
keep food or fluid from flowing back
up into the esophagus.
Heartburn
 Heartburn is the burning, radiating
substernal pain that occurs when the acidic
gastric juice regurgitates into the
esophagus.
 Common in one who has eaten or drunk to
excess, extreme obesity, pregnancy, and
running which cause stomach contents to
splash upward with each step.
Movement of food from the
esophagus to the stomach.
STOMACH
 Stomach- is a temporary
storage tank.
 It lies in the upper left
quadrant of the
peritoneal cavity, nearly
hidden by the liver and
the diaphragm.
 Though relatively fixed
at both ends the
stomach is quite
movable. Running
horizontal in short
people and vertical in
tall people.
STOMACH
 The stomach is a j-shaped, pouchlike about 25-30 cm.
STOMACH
 Stomach- The stomach
is a saclike organ.
 It has walls made of
layers of muscle,
each arranged on a
different angle.
 As the food enters
the stomach, muscle
contractions begin to
twist, turn, and churn
the food.
 The twisting, turning,
and churning of food
in the stomach is part
of mechanical
digestion.
STOMACH
 The stomach produces
gastric juice and mixes
it with the food. This
gastric juice contains
Pepsin which is an
important enzymes
that begin the
digestion of proteins.
 Proteins are the only
substances digested in
the stomach. Proteins
are even then only
partially digested in
the stomach.
 The food is churned
and mixed with
stomach fluids until a
thick paste called
chyme is produced.
 The chyme passes
through the stomach
into the small intestine
STOMACH
 Glands in the stomach produces about
2.8 liters of gastric juices daily.
 Pepsin is by far the most important
digestive juice, it begins the digestion
of nearly all types of dietary protein.
STOMACH
 When empty has the
volume of 1/5 of a
cup, but it can expand
to hold 8 cups of food
after a large meal.
 A ring of muscle the
pyloric sphincter
located between the
stomach and the
duodenum of the
small intestines
controls food entry.
 It leaves the stomach
and enters the small
intestines through
peristaltic waves.
Why does your stomach growl?


As the peristalis muscles
contraction move your meal
along its digestive path, these
contractions also help churn
food, liquid and different
digestive juices together,
rendering them into a gooey
mix known as chyme.
Stomach growling is the result
of this process. Moving with
those solid and liquid chyme
ingredients are gasses and
air. As all these ingredients
get pushed around and broken
down into easy-to-absorb bits,
pockets of air and gas also get
squeezed and create the
noises we hear.
Small Intestines
 Small intestinereceives secretions
from the pancreas and
liver completes
digestion of nutrients,
absorbs the products
of digestion, and
transports the residues
to the large intestines.
 Tubular organ with
many loops and coils
that fills much of
abdominal cavity
 5.5-6.0 meters long
and 5 cm in diameter
Small Intestines
 Small Intestines is made up of 3 key
parts
 The duodenum- The C-shaped first part
 The jejunum- the coiled midsection
 The ileum- the final section that leads to
the large intestines.
Small Intestines
 The jejunum and ileum are
suspended from the posterior
abdominal wall by a double-layered
fold of peritoneum called the
Mesentery. The mesentery
supports the blood vessels, nerves,
and lymphatic vessels that supply the
intestinal wall.
Small Intestines
 A filmy, double fold
of peritoneal
membrane called
the Greater
Omentum drapes
like an apron from
the stomach over
the transverse
colon and the folds
of the small
intestine.
CATS!
Small Intestines
 The inner wall of the small intestines
is covered with millions of
microscopic, fingerlike projections
called villi. Nutrients can be absorbed
into the body through this villi.
ABSORPTION OF THE SMALL
INTESTINE
 Most absorbing
organ in the
alimentary canal
 Its so effective that
only very little
amounts water and
electrolytes reach
the large intestine
 Enzymes from the
intestinal mucous
membrane and the
pancreas break down
and absorb
carbohydrates,
proteins, and fat
molecules
 Intestinal villi,
projections of mucosa,
absorb water and
electrolytes
Small Intestines
 The Ileocecal sphincter joins the
small intestine’s ileum to the large
intestine’s cecum.
 Normally remains closed, however
eating a meal elicits a gastroileal
reflex that increases peristalsis in the
ileum and relaxes the sphincter,
forcing the contents of the small
intestine into the cecum.
Large Intestines

 1.5 meters long vs/
the small intestines
which is 6 meters
long.
 It is located in the
lower abdominal
region, posterior to
the stomach…
 It begins on the lower
right side of the
abdominal
cavity…crosses
obliquely to the left
and then descends
into the pelvis

Large Intestines

 By the time the food
reaches the large
intestines most of the
work of absorbing
nutrients is nearly
finished.
 The large intestine’s
main function is to
remove water from the
undigested matter
and form solid waste
that can be excreted
 Bacteria in the colon
help to digest the
remaining food
particles.
Large Intestines
 Large intestineconsist of the
cecum, the colon,
the rectum, and
the anal canal.
 Cecum- a pouch at
the beginning of
the large intestine
that joins that
small intestine to
the large
intestines.
 The colon is
divided into four
portions…the
ascending,
transverse,
descending and
sigmoid.
Large Intestines
 The colon extends from the cecum
up the right side of the abdomen
(ascending), across the upper
abdomen (transverse), and then
down the left side of the abdomen
(descending), then it makes an Sshaped curve called the (sigmoid)
finally connecting to the rectum.
Large Intestines
 The rectum is where
feces are stored until
they leave the
digestive system.
 The anal canal
connects the rectum to
the anus.
 The anal canal opens
to the outside as the
anus.
 Guarded by two
sphincters. Internal
anal sphincter
(involuntary
controlled) External
anal sphincter
(voluntarily controlled)
ABSORPTION OF THE LARGE
INTESTINE
 The large intestine
has very little
digestive function
 It absorbs the left
over water and
electrolytes
 90% of the water
that enters the
large intestine is
absorbed so that
very little sodium
and water is loss
Large Intestines
Appendix
 The appendix- a small
hollow, fingerlike
pouch.
 Hangs at the end of
the cecum.
 Scientist think it is left
over from a previous
time in human
evolution…it is no
longer necessary to
the DT
ESSENTIAL ORGANS THAT ARE NOT
PART OF THE DT
 The Liver (located under the rib cage
in the right upper part of the
abdomen).
 The Gallbladder (hidden just below
the liver)
 The pancreas (beneath the
stomach).
 These are NOT part of the alimentary
canal, but these are essential to
digestion.
Liver
 Liver- largest internal
organ
 Shaped like a wedge
 Lies almost entirely
within the rib cage.
 Has 4 lobes
 Is a very vital organ
with many important
roles. Its digestive
function is to
produce bile for
export to the
duodenum.
Liver
 Bile- is a fat
emulsifier, it
breaks up fats into
tiny particles so
that they are more
accessible to
digestive
enzymes.
Gallbladder
 The gallbladder is a thin-walled green
muscular sac about 10 cm (4 inches) long.
 It stores bile that is not immediately
needed.
 Bile is often 10 times more concentrated
when it leaves the gallbladder than when it
entered.
 These enzymes and bile travel through
special channels called the bile ducts which
lead directly into the duodenum of the
small intestine.
Pancreas
 Pancreas is a soft
tad-pole shaped
gland.
 It is an endocrine
gland but also
plays a role in
digestion.
 It secretes a
digestive juice
called pancreatic
juice
 Produces enzymes
that help digest
proteins, fats, and
carbs.
 Also makes a
substance that
neutralizes
stomach acid.
Pancreas
 The cells that produce
pancreatic juices
release them into the
pancreatic duct that
extends the length of
the pancreas and joins
with the bile ducts
from the liver and
gallbladder and empty
into the duodenum of
small intestines.
MAJOR MINERALS
 Calcium- helps in the
structure of bones,
essential for nerve
impulse conduction,
muscle fiber
contraction, and blood
coagulation, increases
permeability of cell
membranes and
activates certain
enzymes.
 Calcium is found in
milk, cheese, leafy
green products.
 An excess can
cause kidney
stones.
 Not enough
calcium can cause
stunted growth,
misshapen bones,
and fragile bones.
MAJOR MINERALS
 Phosphorus- helps in
structures of bones
and teeth, component
in nearly all metabolic
reactions, constituent
of nucleic acids, many
proteins, some
enzymes and some
vitamins, it also occurs
in the cell membrane,
ATP, and phosphates
of body fluids.
 Phosphorus is
found in meats,
cheese, nuts,
whole grain
cereals, milk,
legumes
 Not enough
phosphorus can
cause stunted
growth
MAJOR MINERALS
 Potassium- helps
maintain
intracellular
osmotic pressure
and regulate pH;
promotes
metabolism;
needed for nerve
impulse conduction
and muscle fiber
contraction.
 Potassium is found
in avocados, dried
apricots, meats,
nuts, potatoes, and
bananas.
 A lack of potassium
can cause
muscular
weakness, cardiac
abnormalities, and
edema.
MAJOR MINERALS


Sulfur- essential part of various
amino acids, thiamine, insulin,
biotin, and mucopolysaccharides.
Water soluble sulfur is an oil in
it's pure water soluble form, it is
the flexible bond that holds your
cells together making your skin
look good without wrinkles.



Sulfur is found in meats, milk,
eggs, legumes
A deficiency of water soluble
sulfur can lead to a variety of
conditions ranging from skin
irritations and rashes to total
breakdown of cellular
regeneration.
For instance have you ever
wondered why your pets like to
go out and chew on the grass, or
scratch consistently yet don't
have fleas, these are signs that
your pets are deficient in water
soluble sulfur. The consistent
scratching is an attempt to
relieve the pain caused by a loss
of nutritional sulfur which
provided the flexible bond in the
skin tissue and has now resulted
in dry, brittle skin.
MAJOR MINERALS
 Sodium- helps
maintain osmotic
pressure of
extracellular fluids and
regulate water
movement; needed for
conduction of nerve
impulses and
contraction of muscle
fibers; aids in
regulation of pH and in
transport of
substances across cell
membrane
 Sodium is found in
table salt, cured ham,
sauerkraut, cheese,
graham crackers.
 An excess of sodium
can cause
hypertension and
edema.
 A lack of sodium can
cause nausea, muscle
cramps, and
convulsions.
MAJOR MINERALS
 Chlorine – maintain
osmotic pressure of
extracellular fluids,
regulate pH, and
maintain
electrolyte balance
 Chlorine can be
obtained in table
salt, cured ham,
sauerkraut,
cheese, graham
crackers
 Too much chlorine
causes vomiting
 A deficiency of it
causes muscles
cramps
MAJOR MINERALS
 Magnesium – is
needed in
metabolic
processes (ATP
production in
mitochondria)
 Found in dairy
products, legumes,
nuts, leafy green
vegetables
 If you consume too
much magnesium
it will cause
diarrhea
 A lack of it will
cause
neuromuscular
disturbances
VITAMINS
 Thiamine (B1) needed
for oxidation of carbs
 It is found in lean
meats, liver ,eggs,
whole-grain cereals,
green vegetables
 A deficiency of vitamin
B1 enlarges the heart,
causes muscular
weakness, and
beriberi.
 Beriberi is a nervous
system ailment.
Symptoms include
severe lethargy and
fatigue, together with
complications affecting
the cardiovascular,
nervous, muscular,
and gastrointestinal
systems.
VITAMINS
Riboflavin (B2) needed in the
oxidation of
glucose and and
fatty acids
Found in meats, dairy
products, whole
grain cereal, and
leafy green veggies
 If you do not get
enough B2 you get
blurred vision and
dermatitis
VITAMINS
Pantothenic acid–
o Also a B vitamin
o Needed for oxidation
of carbs and fats
o
Found in meats, milk,
fruits, vegetables,
legumes, whole-grain
cereal
 A shortage of this
vitamin is rare, but it
causes mental
depression, loss of
appetite, and muscle
spasms
VITAMINS
 Cyanocobalamin
(B12) – needed for
synthesis of nucleic
acids and for
metabolism
 In liver, meat, and
cheese, eggs
 A loss of B12
causes pernicious
anemia
VITAMINS
 Folacin- (Folic Acid) Folic
acid is a B vitamin. It
helps the body make
healthy new cells.
Everyone needs folic
acid.
 For women who may get
pregnant, it is really
important. When a
woman has enough folic
acid in her body before
and during pregnancy, it
can prevent major birth
defects of her baby's
brain or spine.
 Metabolism of certain
amino acids and for
synthesis of DNA
 Found in leafy green
vegetables, legumes,
whole grain cereals
VITAMINS
 Ascorbic acid (C) –
needed for
production of
collagen and
metabolism of
some amino acids
 Found in citrus
fruits, tomatoes,
potatoes, leafy
green vegetables
 An excess of
vitamin C
exacerbates gout
and kidney stone
formation
 A shortage of it
causes scurvy,
lowered resistance
to infection, and
wounds heal slower