"Microbial Marvels: Exploring the Intricate World of Gastrointestinal Flora" (Medical Bacteriology II)
•
Our digestive system is a
network of organs that help us digest and absorb nutrition from your food.
•
It includes your
gastrointestinal (GI) tract and your biliary system.
•
Our GI tract is a series of
hollow organs that are all connected to each other,
leading from your mouth to your anus.
• Your biliary system is a network of three organs that deliver bile and enzymes through to your GI tract your bile ducts.
Function of GIT
•
Ingestion
•
Mechanical Processing
•
Digestion
•
Secretion
•
Absorption
•
Excretion
v Ingestion
o
Occurs when materials enter to
digestive tract via mouth.
v Mechanical Processing
o
Crushing and shearing makes
material easier to propel along digestive tract.
v Digestion
o
A chemical brake down of food
into small fragments for absorption by digestive epithelium.
v Secretion
o
The release of water, acids,
enzymes, Buffers and salt, by epithelium of GIT Tract.
v Absorption
o
Movement of organic substrate
Vitamin, Electrolytes and Water across GIT tract.
v Excretion
o Removal of waste product from body in the form of feces and urine.
Stages of Digestion
- Mechanical Digestion is the
physical brake down of food into small particles by chewing with teeth and
crushing with stomach and intestine.
- Chemical Digestion is series of
hydrolysis rection by acid in stomach and enzymes from saliva. Stomach
pancreas intestine that brake down to macro molecules into monomers such
as:
Polysaccharide’s monosaccharides
Proteins amino acids
Fats Glycerol and fatty acids
What
organs make up the digestive system?
•
The
main organs that make up your digestive system are the organs known
as your gastrointestinal tract. They are: your mouth, esophagus, stomach, small
intestine, large intestine and anus. Assisting your GI organs along the way are
your pancreas, gallbladder and liver.
•
Here’s
how these organs work together in your digestive system.
Mouth
•
The mouth is the beginning of
digestion
•
Saliva glands activate when you
see or smell food
•
Chewing breaks food into
smaller pieces
•
Saliva helps break down food
further
•
Swallowing moves food to the
throat and esophagus
Esophagus
•
The esophagus, located near the
trachea in the throat, receives food from the mouth during swallowing
•
The epiglottis, a flap, folds
over the windpipe during swallowing to prevent choking
•
Peristalsis, muscular
contractions in the esophagus, move food to the stomach
•
The lower esophageal sphincter,
a ring-like muscle, relaxes to allow food into the stomach
•
The sphincter contracts
afterward to prevent stomach contents from flowing back into the esophagus,
preventing acid reflux or heartburn
Stomach
•
The stomach is a hollow organ
that holds food and mixes it with stomach enzymes
•
Enzymes in the stomach break
down food further
•
Lining cells of the stomach
secrete strong acid and enzymes for digestion
•
Once processed, contents are
released into the small intestine
Small
intestine
•
The small intestine consists of
three segments: the duodenum, jejunum, and ileum
•
It is a 22-foot long muscular
tube
•
Enzymes from the pancreas and
bile from the liver break down food
•
Peristalsis moves food through
and mixes it with digestive juices
•
The jejunum and ileum absorb
nutrients into the bloodstream
•
Contents start semi-solid and
end as liquid after passing through
•
Water, bile, enzymes, and mucus
contribute to the change in consistency
•
Once nutrients are absorbed,
leftover residue moves to the large intestine
Pancreas
•
The pancreas secretes digestive
enzymes into the duodenum
•
Enzymes break down protein,
fats, and carbohydrates
•
Pancreas produces insulin,
which is released into the bloodstream
•
Insulin is the main hormone for
metabolizing sugar in the body
Liver
•
The liver processes nutrients
absorbed from the small intestine
•
Bile from the liver aids in
digesting fat and some vitamins in the small intestine
•
Liver acts as the body's
chemical "factory," producing various chemicals needed for function
•
Liver detoxifies harmful
chemicals, breaking down and secreting toxic drugs
Gallbladder
•
The gallbladder stores and
concentrates bile from the liver
•
It releases bile into the
duodenum in the small intestine
•
Bile aids in the absorption and
digestion of fats
Colon
•
The colon processes waste for
easy bowel movements.
•
It connects the small intestine
to the rectum.
•
Components include cecum,
ascending, transverse, descending, sigmoid colon.
•
Stool starts as liquid, ends as
solid.
•
Water is removed as stool
passes through.
•
Stored in sigmoid colon,
emptied into rectum.
•
Takes about 36 hours for stool
transit.
•
Contains food debris and
beneficial bacteria.
Rectum
•
The rectum links colon to anus,
about 8 inches.
•
Receives stool, signals need
for evacuation.
•
Holds stool until evacuation is
possible.
•
Sensors in rectum send message
to brain.
•
Brain decides release of rectal
contents.
•
Sphincters relax, rectum
contracts to dispose contents.
•
If contents can't be disposed,
sphincter contracts.
•
Rectum accommodates until
sensation temporarily fades away.
Anus
•
The
anus is the end of the digestive tract.
•
Consists
of pelvic floor muscles and anal sphincters.
•
Detects
rectal contents, signalling liquid, gas, or solid.
•
Sphincter
muscles control stool release.
•
Pelvic
floor muscle creates angle preventing stool passage.
•
Internal
sphincter stays tight, relaxes when stool enters.
•
External
sphincter holds stool until reaching toilet.
•
Relaxes
at toilet to release stool contents.
Normal flora of GIT
Normal Flora : The microbial population that inhibit at the internal and external
surface of healthy normal human and animal normal flora are also called
COMMENSALS.
i.e. organism that dine together.
•
In s normal condition in a
healthy human they are harmless and may even be beneficial.
Origin of Normal Flora
A fetus is sterile when born. The new
borning starts the normal flora passes through virginal tract and then to
environment such as air, foods etc.
Involve internal and external organ
Normal Flora depend on age, Diet ,
geographic habitats.
Factor Influencing the Normal Flora
•
Local Environment
•
Age
•
Diet
•
Sex
•
Immune Condition
•
Use of Antibiotics
Types of Normal Flora
•
Resident Flora Members of the Flora that are constantly present in/on the body
that cannot be removed permanently these prevent the permanent colonization of
the body by other organism e.g. E.coli in intestine region.
•
Transient Flora Population which varies from time to time and that can removed
permanently e.g. Pneumococcus or meningococcus may be found in nasopharynx of
Human from time to time.
Importance of Normal Flora
•
Synthesized B-complex and
vitamin-K.
•
They protect our body by
preventing the colonization of pathogenic microorganisms.
•
It elevates the immune system.
•
Produces the anti-biotic like
substance, e.g. :Fatty acids, peroxidases Bacteriocins which inhabits the
growth of pathogenic Microorganisms.
•
Some produce endotoxins which
activates the complement pathway, it augment the defense
mechanism of the body.
Harmful Effect of Normal Flora
•
When host immune system
decreases they become opportunistic pathogens and cause diseases.
•
Some may cause diagnose
confusion.
•
Some penicillinase producing
Microorganisms can aggregate and develop antibiotic resistance
(Drug resistant).
Nature of Normal Flora
•
Commensal microflora: These microorganisms gets benefits from human host and give neither
benefits nor harmful effects to host. Majority of normal flora are commensal
types.
•
Mutualistic microflora: These microorganisms gets benefits from host and at the same time
give benefits to the host.
• Opportunistic microflora: These microorganisms, under normal condition live as commensal on host body but they causes diseases if opportunity is available. For example; Normal flora of Gl tract ie. E.coli causes urinary tract infection (UTI), if the site of habitat is changed.
Normal Flora of Oral Cavity
•
The oral cavity or mouth is
totally free of microorganisms at the time of birth, but it is colonized by
microorganisms from the surrounding environment within hours after a human baby
is born.
•
In the beginning the microbial
flora that establish in the mouth belong to the genera Streptococcus,
Neisseria, Actinomyces, Villanella, Lactobacillus, and some yeasts.
•
These initial microorganisms
are aerobes and obligate anaerobes.
Normal Flora of Digestive Tract
•
The stomach contains fewer
bacteria due to its high acidity nature.
•
However, there are some
bacteria that survive there like the Helicobacter Pylori that is currently
proving to be the cause of most cases of gastritis and peptic ulcers.
•
Likewise, the small intestine
contains small numbers of Streptococci, Lactobacilli, and yeasts, particularly
Candida albicans.
•
Nevertheless, bigger numbers of
these bacteria are found in the lower parts of the ileum. The colon is the main
site for bacteria in the body. Several bacteria like Bacteroides,
Bifidobacterium, Eubacterium, Coliforms (e.g. E. coli), Streptococcus,
Lactobacillus and Clostridium reside in the large intestine.
NORMAL FLORA OF GASTRO INTESTINAL TRACT
STOMACH
•
INTESTINE
•
Small intestine:
•
Duodenum gram + positive cocci and rods are more.
•
Jejunum : gram positive, gram negative bacterium can be seen, Lactobacilli
Diphtheroid, Enterococcus faecalis, yeast-candida, albicans.
•
Ileum pH-alkaline, anaerobic gram negative bacteria are more mainly
enteron bacterial, shigellosis, typhoid.
e.g.
acid tolerant streptococci, staphylococci lactobacilli, candida albicans,
Helicobacter.
NORMAL FLORA OF GASTRO INTESTINAL TRACT
STOMACH
•
Large Intestine: The large intestine or colon contains the largest number of
bacterial community number of bacterial community in human body.
•
In Large intestine or colon act as a fermentation vessel, and the microflora of it
consists primarily of anaerobic, gram-negative, non-sporing bacteria and gram
positive, spore forming, and nonsporting.
https://pathologistforyou.blogspot.com/2024/05/streamlining-genomic-analysis.html
https://pathologistforyou.blogspot.com/2024/03/grand-iftar-party-0n-28-march-2024-17.html
https://pathologistforyou.blogspot.com/2024/03/exploring-biochemical-tests-in.html
https://pathologistforyou.blogspot.com/2024/03/essential-practices-in-specimen.html
https://pathologistforyou.blogspot.com/2024/03/essential-workplace-safety-guidelines.html
https://pathologistforyou.blogspot.com/2024/03/understanding-trypanosoma-life-cycle.html
https://pathologistforyou.blogspot.com/2024/03/understanding-trypanosoma-life-cycle.html
https://pathologistforyou.blogspot.com/2024/03/malaria-caused-by-parasite-that.html
https://pathologistforyou.blogspot.com/2024/03/understanding-trichomoniasismode-of.html
https://pathologistforyou.blogspot.com/2024/03/understanding-giardiasis-definition.html
https://pathologistforyou.blogspot.com/2024/03/first-short-notes-of-clinical.html
https://pathologistfromkust.blogspot.com/2024/03/acute-lymphoblastic-leukemia-all-and.html
https://pathologistfromkust.blogspot.com/2024/03/understanding-acute-myeloid-leukemia.html
https://pathologistfromkust.blogspot.com/2024/03/comprehensive-overview-of-chronic.html
https://pathologistfromkust.blogspot.com/2024/03/understanding-white-blood-cell.html
Comments
Post a Comment