The digestive system breaks down ingested food into nutrients that can be absorbed and used by the body. It consists of the gastrointestinal tract including the mouth, esophagus, stomach, small and large intestines, and accessory organs like the liver, pancreas, and gallbladder. Food is ingested, mechanically and chemically broken down, absorbed in the small intestine, and waste is eliminated. The digestive system works through peristalsis, secretion of enzymes, and absorption of nutrients. Common digestive disorders include gastroenteritis, ulcers, appendicitis, hepatitis, and cirrhosis of the liver. Irritable bowel syndrome and constipation are also linked to mental health issues like depression and anxiety through the gut

1. DIGESTIVE SYSTEM
GROUP 1

2. WHAT IS DIGESTIVE SYSTEM?
• “A system by which ingested food is acted upon by physical
and chemical means to provide the body with absorbable
nutrients and to excrete waste products.”
• The organs and glands in the body that are responsible for
digestion.

3. FUNCTIONS OF DIGESTIVE SYSTEM
• ingestion – the oral cavity allows food to enter the digestive tract and have
mastication (chewing) occurs , and the resulting food bolus is swallowed .
• Digestion:
– Mechanical digestion – muscular movement of the digestive tract (mainly in the oral
cavity and stomach) physically break down food into smaller particles .
– Chemical digestion – hydrolysis reactions aided by enzymes (mainly in the stomach
and small intestine) chemically break down food particles into nutrient molecules ,
small enough to be absorbed . .
• Secretion – enzymes and digestive fluids secreted by the digestive tract and
its accessory organs facilitate chemical digestion.
• Absorption – passage of the end – products (nutrients) of chemical digestion
from the digestive tract into blood or lymph for distribution to tissue cells.
• Elimination – undigested material will be released through the rectum and
anus by defecation.

4. ORGANIZATION OF DIGESTIVE SYSTEM
1. Gastrointestinal tract (GI tract)
• MOUTH
• ESOPHAGUS
• STOMACH
• SMALL INTESTINE
• LARGE INTESTINE
• RECTUM
• ANUS
2. Accessory Structures
• LIVER
• PANCREAS
• GALLBLADDER
• APPENDIX

5. MUSCULAR MOVEMENT OF GI TRACTF
• Peristalsis – wavelike movement that occurs from the
oropharynx to the rectum , allowing GI tract to push food
particles toward the anus .
• Mixing—mixing motion in the oral cavity and stomach that
allows the GI tract to repeatedly break down food into
smaller particles , using mechanical digestion .
• Segmentation – regions of the small intestine contracting
and relaxing independently , allowing the small intestine to
digestive and absorb more efficiently

6. PERISTALSIS AND SEGMENTATION

7. ANATOMY OF GI TRACT BY REGION

8. 1. MOUTH/ORAL CAVITY/BUCCAL CAVITY
• Food enters the GI tract by ingestion.
• Contains teeth, tongue, salivary glands, and ends at
pharynx.
• lined with stratified squamous epithelium walls
(muscular cheeks)
• floor contains tongue
• roof = hard palate
Functions:
• 1. Analyze food (taste buds)
• 2. Mechanically process food (chew)
• 3. Lubricate food (saliva)
• 4. Digest starches (amylase)

9. 2. PHARYNX
• Also called the throat
• oropharynx (back of mouth)
• laryngopharynx (superior to voice box)
• connects oral cavity to esophagus
• shared space with respiratory system
• Involves partly voluntary action
• skeletal muscles surround for swallowing

10. 3. ESOPHAGUS
• Muscular extended tube
• Carries food to the stomach
• Action is totally automatic/ involuntary at this
stage
• Food is pushed through the tube by means of
contractions called peristalsis.
• Just before the opening of the stomach, is an
important ring-shaped muscle called Lower
Esophageal Sphincter (LES)
– Opens to pass food from the tube to stomach
– If doesn’t work properly, one may suffer from
GERD or Reflux which causes Heartburn and
regurgitation (feeling of food coming back up)

11. 4. STOMACH
• Sac-like organ with strong muscular walls
• Holds the food, mixes and grinds the food
• Breaking of food
– Mechanical breakdown of food (churning)
– Chemical breakdown of food (denature and digest
proteins)
• Produce intrinsic factor for Vitamin B12 uptake
(VitB12 necessary for erythropoiesis)
• Secretes acid and powerful enzymes that break
down food and change it to a consistency of
liquid or paste.
• Food then moves to the small intestine
• Between meals, non-liquefiable remnants are
released and ushered through the rest of the
intestines to be eliminated.

12. STOMACH…
• 4 regions: cardia, fundus, body,
pylorus
1. Cardia -where esophagus
connects via gastroesophageal
sphincter -gastric glands
produce mucus to protect
esophagus
2. Fundus -superior region, contact
diaphragm
3. Body -majority of stomach -
holds chyme -gastric glands
secrete enzymes and acids for
digestion
4. Pylorus -inferior region -connects
to duodenum via pyloric sphincter:
regulates chyme entry into
duodenum -gastric glands

13. 5. SMALL INTESTINE
• major digestive organ
• chemical digestion completed
• 90% of nutrients absorbed (remaining absorbed in
large intestine), Also takes secretions from liver and
pancreas
• 20 ft. long, 3, peristalsis is also at work at this stage
• Digests proteins, lipids, carbohydrates, Absorbs
nutrients, water, electrolytes, vitamins and minerals.
• Partitions of intestine
– A. Duodenum: -first 10 inches -retroperitoneal -receives
chyme from stomach through pyloric sphincter -
receives digestive secretions from pancreas and liver –
mixing pot
– Jejunum: -next 8 ft. -majority of chemical digestion and
nutrient absorption occur here
– C. Ileum: -last 12 ft. -mucosa rich in lymphoid tissue -
connects to cecum at ileocecal valve

14. SMALL INTESTINE…
• Nutrients are absorbed by the walls and go into the bloodstream.
• Structural modification
– Finger like structures formed by mucosa
• Circular folds (plicae circulares)
• Villi
• microvilli
– Give the small intestine more surface area
– Responsible for better absorption

15. 6. LARGE INTESTINE
• Leftovers from small intestine are moved to large
intestine
• All the activities above this stage lie in the upper
part of GI tract
• Consists of Cecum and colon (7-5ft long)
that connects to rectum
• 4 main functions
– Reabsorption of water and minerals ions
– Formation of storage of feces
– Maintaining a resident population of over 500
species of bacteria
– Bacterial fermentation of indigestible material
• Transmits the useless waste material from the
body
• Moving forward the waste in sigmoid happens
once or twice a day

16. 7. RECTUM
• 8 inch chamber that connects the colon to
anus
• Stores Stool
– Mainly food debris and bacteria
• Functions
– Receives stool from the colon
– Let’s the person know there is stool to be
evaluated
– Holds the stool until evacuation happens
• Sensors send message to brain which then
decides whether to release stool right away
or not
• If release doesn’t happen, the rectum
contracts and the feeling goes away

17. 8. ANUS
• Last part
• Consists of…
Pelvic floor muscles create an angle to stop stool to
coming out when its not supposed to
Internal and external sphincters provide fine
control of stool.
Internal sphincter is always tight that stops stool
coming out while sleeping.
External Sphincter lets us to release the stool.

18. ACCESSORY ORGANS
1. PANCREAS
• Pancreas is the chief of factory Digestive Enzymes
• These enzymes are secreted in Duodenum (first
part of small intestine)
• To breakdown protein, fats and carbohydrates
• Feature
– 6-8 inches long
– On the right side of stomach
– Duct is connected to it with small glandular tissue (responsible of
transfer of bile to duodenum

19. 2. LIVER
• It has a right and a left lobe, separated by a Ligament
• Makes and secretes an important substance called “Bile”
• Processes the blood coming from small intestine
• Purifies the blood of several impurities

20. 3. GALLBLADDER
• Storage sac of excess bile.
• Bile first travels to the small intestine, if not needed it is transferred to gallbladder
• Bile: two purposes
– Helps absorbs fats in diet
– Carries waste from liver that cannot go through the
kidneys

21. 4. APPENDIX
• Present at the beginning end of the large intestine
• Has no known function
• It is thought to be a remnant from a
previous time in human evolution

22. DIGESTIVE SYSTEM DISORDERS

23. • GASTROENTERITIS: inflammation of the stomach and intestines,
typically resulting from bacterial toxins or viral infection.
– Common cause = Virus
– Symptoms – diarrhea and vomiting for 24-36 hours
– Complication = dehydration
– Psychological symptoms: Hypersensitivity and stress
• ULCER: Sore or lesion that forms in the mucosal lining of the stomach
– Cause – H. pylori (bacteria) is primary cause, cigarette smoking, alcohol, stress,
certain drugs
– Symp – burning pain in abdomen, between meals and early morning,
– Contributes highly in higher levels of stress
• APPENDICITIS: When appendix becomes inflamed
– If it ruptures, bacteria from appendix can spread to peritoneal cavity.
– Symptoms- fever, nausea, and vomiting
– Goal frustration, depression

24. • Hepatitis A: Infectious, affects liver
– Cause – virus
– Spread through contaminated food or H2O
– Social Health gets affected, slow psychomotor speed
• Hepatitis B: Serum Hepatitis
– Caused by virus found in blood
– Transmitted by blood transfusion or being stuck with contaminated
needles (drug addicts)
– Anxiety and stress
• Cirrhosis: Cirrhosis is a late stage of scarring (fibrosis) of the liver
– caused by many forms of liver diseases and conditions, such as hepatitis
and chronic alcoholism.
– 75% caused by excessive alcohol consumption
– Problematic cognitive, social and emotional life, stress anxiety and
depression
• Cholelithiasis: gallstones
– When bilirubin and cholesterol particles cluster together
– Pain in the gallbladder, especially after fatty meals.
– Aggressiveness, propensity towards depression

25. COMMON DIGESTIVE ISSUES
The connection between the gut and brain is strong, but not all digestive problems can be
associated with depression.
• Irritable Bowel Syndrome (IBS) commonly co-occurs with depression or anxiety.
Approximately 60% of people with IBS also have a mental issue.
• Constipation is related to imbalance of right bacteria in your gut. Eating foods that body
struggles to digest can exacerbate the situation.
– can be resolved with probiotics, eliminating constipation can help depression symptoms
• Nausea is also a gut problem, usually accompanies anxiety.
– can be a result of chemical imbalance and muscle tension.
– Both the situation can be caused by depression – affecting brain’s communication with digestive
system
• Stomach pain (without any physical cause) is associated with depression.
• Autonomic Arousal Disorder (ANS) is characterized by increased heart rate an
palpitations, respiratory issues, Stomach issues(Nausea, Vomiting), the need to urinate and
flushed skin.
– Basically, it’s associated with Anxiety and Panic Disorders

26. THANK YOU