GI 1 Flashcards
Healthy balanced diet portions are:
1/2 carbs
1/4 protein
1/4 grains
Function of the digestive system:
-Break down foods to release their nutrients
-Absorb into body
The Gastrointestinal Tract includes:
1- Organs of the alimentary canal
2- Accessory glandular tissues
Alimentary Canal
A muscular tube made of DIFFERENT ORGANS with coordinated activity to move food UNIDIRECTIONALLY from mouth to anus
What are the 7 parts (organs) of the alimentary canal?
1- Mouth
2- Pharynx
3- Esophagus
4- Stomach
5- Small Intestine
6- Large Intestine
7-Anus
Exocrine Organs (aka accessory glandular tissues?)
Lie outside the digestive tract and empty their secretions through ducts into the digestive tract lumen
What are the 5 exocrine organs?
1- Salivary Glands
2- Exocrine pancreas
3- Billary system
4- Liver
5- Gallbladder
The 4 tissues lining alimentary canal
1-Mucosa
2-Submucosa
3-Muscularis
4-Serosa
Mucosa:
An epithelial cell layer directly in contact with food/chyme .:. separating the food from the inner environment of the body
**
In the esophagus: squamous cell layer to move food quickly
In the stomach: columnar cell layer to make pits to secrete acid
In the small intestine: also columnar with villi to helo increase SA for absorption
Submucosa
A connective tissue layer anchor epithelia to the rest of the alimentary canal
Muscularis mucosae
Smooth muscle that contracts the mucosa epithelial layer
Serosa
Another layer of connective tissue anchoring GI tract to other organs of the body
ًwhat from the external environment is the alimentary canal a barrier against?
-Acidic pH of the stomach
-The digestive enzymes (could destroy body’s tissues)
-Gut flora
GI tract barrier formed through: (2 things)
-Tight junctions (between epithelial cells in the mucosa layer)
-Mucus* (and other secretions produced by mucosa)
*alkaline to neutralize acid and prevent physical damage
4 main GI functions:
Secretion
Motility
Digestions
Absorption
What does GI secrete? (2 things)
Digestive juices
Gastrointestinal Hormones
Digestive juices
Secreted by exocrine glands into the digestive tract lumen
Gastrointestinal Horomones
Control exocrine gland secretion and GI motility
How does the GI tract perform motility? (2 things)
Propulsive movements
Mixing movements
done by muscular contractions that mix and move forward the contents of the digestive tract
Propulsive Movements
Push food forward through the GI tract
Mixing Movements
Facilitate absorption by exposing intestinal contents to the absorbing surfaces of the digestive tract
How does the GI tract digest
Mechanically and biochemically breaks down food into smaller absorbable units and propels them forward
What is GI absorption?
Transfer of the small absorbable units from the digestive tract to the blood of lymph (along with water and vitamins and electrolytes)
What are the three types of sensory receptors that respond to local changes in the digestive tract
chemoreceptors
mechanoreceptors
osmoreceptors
Chemoreceptors
sensitive to chemical components within the lumen - sense what kind of food we ate
Mechanoreceptors
sensitive to stretch or tension within the wall -
sense how full we are
Osmoreceptors
sensitive to the osmolarity of the luminal contents -
sense thirst and amount of liquid in our diet
Sensory receptor activation triggers —– or ——- to influence digestive effector cells
neural reflexes - hormone secretion
Three types of digestive tract effector cells:
Smooth muscle cells
Exocrine gland cells
Endocrine gland cells
Smooth muscle cells
modify gut motility
Exocrine gland cells
secrete digestive juices
Endocrine gland cells
secrete gastrointestinal hormones
