Lecture 16 Flashcards
What does GI stand for
The GI (Gastro-intestinal) Tract
What are the 6 components of the GI tract and the sphincters/valces between them
- Oral cavity
— Upper esophageal sphincter - Esophagus
—- Lower esophageal sphincter - Stomach
— Pyloric sphincter - Small intestine
—- Ileocecal valve - Colon (large intestine)
— Anal sphincter - Rectum
What is the purpose of muscle Sphincters and valves
Muscle Sphincters and valves particularly segregate functions within the tube
What does the GI tract represent
Represents a vast body surface area that is exposed to external environment
The GI tract has unique mechanisms to deal with …
Can sense or expel noxious substances
– Through vomit or diarrhea
Specialized populations of T cells localized to the intestinal mucosa
– Eg. peyer’s patches
How long is the GI tract
About 28 feet long, folded extensively to fit in abdominal cavity
How large is the luminal surface in the human body
Large luminal surface of about 200 to 400 square meters due to lots of villi and microvilli
What is the luminal surface
Lumin = space within tubes, tracts, cavities and cells in body
How long does it take meals to go through the GI tract
Highly variable transit time for ingested meal (total of 30-80 hours)
What does the gut contain
microbiome (bacteria, ext)
–protects against pathogenic microbes that enter/reside in tract
What coordinates the opening and closing of sphincters
Intrinsic (AKA enteric) nervous system
What are the 4 processes of the GI tract
- Mobility
- Secretion
- Digestion
- Absorption
What does the GI tract move
Ability of organisms and fluid to move and get around
What does the GI tract secrete
Saliva
Antibodies
Digestive enzymes
Bile
Bicarbonate
What does the GI tract absorb
Water nutrients
What is the first phase of the GI tract
The Cephalic Phase of Digestion and Absorption