Biology *1080 Lecture 16 Flashcards
What is the GI tract?
Aids to digest and absorb ingested nutrients, and to excrete waste products of digestion.
What does the GI tract consist of?
Oral cavity, esophagus, stomach, small intestine, colon and rectum
What does the GI system do?
It “sees” not only our food, but toxic substances and infectious agents
How does the GI tract deal with toxic substances?
Vomit and Diarrhea
T-cells localized in the intestinal mucosa
How long is the GI tract?
28 ft and folded extensively in the abdominal cavity
Why is the SA large in the GI tract?
Due to lots of villi/microvilli (finger-like projections)
What is the variable transit time for ingested meal?
30-80 hours
What stays longer in the GI tract?
Fibre, where as carbs go quicker through GI tract
What does the GI tract house?
Gut microbiome (bacteria) to protect against pathogenic microbes that enter/reside in the tract (breakdown of indigestible food)
What is the GI tract controlled by?
Intrinsic nervous system - opening and closing of sphincters
Motility in GI tract
Peristalsis (involuntary) - constriction and relaxation of the muscles in the GI tract
Secretion in GI tract
Saliva, mucous
Antibodies (protect against antigens)
Digestive enzymes
Bile (breaks down fatty acid)
Bicarbonate (glycerine and three fatty acids)
Digestion in GI tract
Break down of food
Absorption in GI tract
Water (large intestine)
Nutrients (small intestine)
What is the cephalic phase of digestion and absorption?
Secretions initiated by the sight, smell, thought or taste of food (related to the head)