Digestive system
Digestive system
Dr. Malak Qattan
2
•
The GI tract
(gastrointestinal
tract)
–
Mouth
–
Pharynx
–
Esophagus
–
Stomach
–
Small intestine
–
Large intestine
–
Anus
•
The accessory digestive
organs
Supply secretions contributing to
the breakdown of food
–
Teeth & tongue
–
Salivary glands
–
Gallbladder
–
Liver
–
Pancreas
•
Acquires nutrients from environment
•
Anabolism
•
Uses raw materials to synthesize essential compounds
•
Catabolism
•
Decomposes substances to provide energy cells need to
function
Digestive system function
Actions of Digestive (GI) Tract
Ingestion
Occurs when material enters via
the mouth
Mechanical Processing
Crushing – makes material easier
to move through the tract
Digestion
Chemical breakdown of food into
small organic compounds for
absorption
Secretion
Release of water acids, buffers,
enzymes & salts by epithelium of
GI tract and glands
Absorption
Movement of substrates,
electrolytes, vitamins & water
across digestive epithelium
Excretion
Removal of waste products from
body fluids
5
•
Mouth = oral cavity
•
Lips
•
Cheeks
The Mouth
6
Tongue
•
Mostly muscles
–
Grip food
–
Help in swallowing
•
Taste buds
•
Tonsil – back of tongue
7
Pharynx
•
Oropharynx and laryngopharynx
Sequentially squeeze food into esophagus
___oropharynx
___laryngopharynx
8
Esophagus
•
Continuation of pharynx in
mid neck
•
Muscular tube collapsed
when lumen empty
•
Descends through thorax
Esophagus___________
9
Stomach
•
J-shaped; widest part of alimentary canal
•
Temporary storage and mixing – 4 hours
•
Starts food breakdown
–
Pepsin
–
HCl (hydrochloric acid) helps kill bacteria
–
Stomach tolerates high acid content but esophagus doesn’t
– why it hurts so much when stomach contents refluxes
into esophagus (heartburn)
•
Most nutrients wait until get to small intestine to be
absorbed; exceptions are:
–
Water, electrolytes, some drugs like aspirin and alcohol
(absorbed through stomach)
–
Capacity: 1.5 L food; max capacity 4L (1 gallon)
10
Small intestine
•
Longest part of alimentary canal (2.7-5 m)
•
Most enzymatic digestion occurs here
–
Most enzymes secreted by
pancreas
, not small
intestine
•
Almost all absorption of nutrients
•
3-6 hour process
Small intestine___________
11
Large intestine
Subdivisions
•
Cecum
•
Appendix
•
Colon
•
Rectum
•
Anal canal
•
Main function: to absorb water and electrolytes
12
The Liver
Largest gland in the body
Over 500 functions
R and L lobes
13
Gallbladder
Bile is produced in the
liver
Bile is stored in the
gallbladder
Bile is excreted into the
duodenum when
needed (fatty meal)
Bile helps dissolve fat
and cholesterol
If bile salts crystallize,
gall stones are formed
*
14
Pancreas
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Lowers blood glucose (sugar)
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Raises blood glucose (sugar)
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The most common problems
experienced are: bloating, heartburn and acidity, colitis,
constipation, diarrhea, nausea and vomiting, trouble digesting...
1.
Tooth Decay (dental caries) Bacterial Diseases of the Upper
Digestive Tract (Mouth)
Most common infectious disease of humans
Young are more susceptible than old
2. Gastritis
Inflammation of the stomach associated with the production
of gastric ulcers
Caused by
Helicobacter pylori
Infection can persist for years or life
Can develop either peptic or duodenal ulcers or both
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3. Mumps
Mumps is an acute viral infection of the parotid glands
(Parotitis)
Humans are the only source of the virus
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4.
Hepatitis – inflammation of the liver (A, B, C, D,
E, & G)
•
Hepatitis A (HAV) – formerly called infectious
hepatitis
•
Spreads via fecal-oral route
•
Most infections are asymptomatic or show only
mild symptoms
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References
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The digestive system, comprising the GI tract and accessory organs, processes food for nutrient absorption through actions like secretion, absorption, excretion, ingestion, and digestion. Explore the functions of organs like the mouth, tongue, pharynx, esophagus, stomach, and more.
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Presentation Transcript
Digestive system Dr. Malak Qattan
The GI tract(gastrointestinal tract) Mouth Pharynx Esophagus Stomach Small intestine Large intestine Anus The accessory digestive organs Supply secretions contributing to the breakdown of food Teeth & tongue Salivary glands Gallbladder Liver Pancreas 2
Digestive system function Acquires nutrients from environment Anabolism Uses raw materials to synthesize essential compounds Catabolism Decomposes substances to provide energy cells need to function
Actions of Digestive (GI) Tract Secretion Release of water acids, buffers, enzymes & salts by epithelium of GI tract and glands Absorption Movement of substrates, electrolytes, vitamins & water across digestive epithelium Excretion Removal of waste products from body fluids Ingestion Occurs when material enters via the mouth Mechanical Processing Crushing makes material easier to move through the tract Digestion Chemical breakdown of food into small organic compounds for absorption
The Mouth Mouth = oral cavity Lips Cheeks 5
Tongue Mostly muscles Grip food Help in swallowing Taste buds Tonsil back of tongue https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTU52nOXa_W5MMcBiM9JwccDinPigInfnZeLRXP4Fqv032Fk6Yo 6
Pharynx Oropharynx and laryngopharynx Sequentially squeeze food into esophagus ___oropharynx ___laryngopharynx 7
Esophagus Continuation of pharynx in mid neck Muscular tube collapsed when lumen empty Descends through thorax Esophagus___________ 8
Stomach J-shaped; widest part of alimentary canal Temporary storage and mixing 4 hours Starts food breakdown Pepsin HCl (hydrochloric acid) helps kill bacteria Stomach tolerates high acid content but esophagus doesn t why it hurts so much when stomach contents refluxes into esophagus (heartburn) Most nutrients wait until get to small intestine to be absorbed; exceptions are: Water, electrolytes, some drugs like aspirin and alcohol (absorbed through stomach) Capacity: 1.5 L food; max capacity 4L (1 gallon) 9
Small intestine Longest part of alimentary canal (2.7-5 m) Most enzymatic digestion occurs here Most enzymes secreted by pancreas, not small intestine Almost all absorption of nutrients 3-6 hour process Small intestine___________ 10
Large intestine Main function: to absorb water and electrolytes Subdivisions Cecum Appendix Colon Rectum Anal canal 11
The Liver Largest gland in the body Over 500 functions R and L lobes 12
Gallbladder Bile is produced in the liver Bile is stored in the gallbladder Bile is excreted into the duodenum when needed (fatty meal) Bile helps dissolve fat and cholesterol If bile salts crystallize, gall stones are formed * 13
Pancreas Pancreatic function (hormones released into blood) Islets of Langerhans are the hormone secreting cells 1. Insulin Lowers blood glucose (sugar) 2. Glucagon Raises blood glucose (sugar) 14
Diseases of the Digestive System The most common problems experienced are: bloating, heartburn and acidity, colitis, constipation, diarrhea, nausea and vomiting, trouble digesting... 1. Tooth Decay (dental caries) Bacterial Diseases of the Upper Digestive Tract (Mouth) Most common infectious disease of humans Young are more susceptible than old
Diseases of the Digestive System 2. Gastritis Inflammation of the stomach associated with the production of gastric ulcers Caused by Helicobacter pylori Infection can persist for years or life Can develop either peptic or duodenal ulcers or both
Diseases of the Digestive System 3. Mumps Mumps is an acute viral infection of the parotid glands (Parotitis) Humans are the only source of the virus
Diseases of the Digestive System 4. Hepatitis inflammation of the liver (A, B, C, D, E, & G) Hepatitis A (HAV) formerly called infectious hepatitis Spreads via fecal-oral route Most infections are asymptomatic or show only mild symptoms 18
References 1. Maton, Anthea.(1993). Human Biology and Health. 2. Thompson WG, Longstreth GL, Drossman DA et al. (2000). Functional Bowel Disorders 19
