Digestive System overview Flashcards
What is the workhouse of the digestive system? & why?
The small intestine.
Because it is responsible for most digestion of nutrients and absorption into blood and lymph.
what is the function of the mucus membrane?
produces mucus form get epithelium.
what type of epithelium is in the mucosa of mouth, pharynx, esophagus, and anal canal? / and in the small intestine?
Simple squamous non- keratinized epithelium./ simple columnar epithelium.
compare between the functions and location of goblet cells and endocrine cells.
they are located in the mucosa of the alimentary canal. - - function of goblet cells: secrete mucus into lumen.
- function of endocrine cells: secrete hormones into interstitial fluid.
what are the main tissue layers of the AC?
1- Mucosa 2-Submucosa 3- Muscularis
4- Serosa.
What are the subdivisions of the Mucosa?
1- Epithelium 2- Lamina propria (loose connective tissue) 3- muscularis mucosa (internal)
why does the epithelium of the mucosa has a short life span of a couple of days - week?
because that way, it preserves the health of the AC.
why does the lamina propria contain blood & lymphatic vessels?
to transport nutrients from AC to the body.
Why does the lamina propria serve as an immune function?
Because it contains clusters of lymphocytes (MALT) = mucosa associated lymphoid tissue.
what is the location and function of Peyer’s patch?
Located in the distal ileum, it protects against pathogens and exposure to bacteria from food.
compare between muscularis internal and external.
- internal: subdivision of the Mucosa layer.
- external: one of the 4 main tissue layers of AC.
why is the muscularis mucosa (internal) in a constant state of tension?
because its pulling the mucosa of stomach and intestine into folds, to increase surface area for digestion and absorption.
The submucosa is a thick layer of connective tissue. what are its functions?
1- connects mucosa (above) to muscularis (under).
2- submucosa glands secrete digestive enzymes.
3- serves as a channel for the ( submucosa plexus) = dense branching of nerves.
what are the types of muscularis externa muscles?
1- inner circular 2- outer longitudinal
what is the function of muscularis externa in the small intestine?
1- move food along AC. 2- promote mechanical digestion. 3-exposes food to digestive enzymes.
what type of muscle is in the most proximal and distal regions of the mouth, pharynx, esophagus, and external anal sphincter?
Skeletal (voluntary) muscle.
what is the oblique muscle? and what is its function?
its the 3rd muscle layer in the stomach that is responsible for churning.
What is the (Tenia coli)?
Its the longitudinal muscle of the colon, and it is segregated into narrow parallel bands.
What is the only region of the AC that is within the abdominal cavity?
The Serosa layer.
What is the function of Serosa?
holds the AC in place near the ventral surface ( the front) of the vertebral column.
what does the Serosa consist of?
a layer of visceral peritoneum overlying a layer of loose connective tissue (areolar).
What does the serosa in the mouth, pharynx, and esophagus consist of?
A dense sheath of collagen fibers (adventitia)
where does ingestion occur?
ONLY in the mouth.
Amylase and Lipase are secreted during ingestion in the saliva. what are their functions?
1- amyalse: breaks down carbs. 2-lipase: breaks down lipids.
compare between voluntary and involuntary propulsion.
1- voluntary: mastication= chewing= increases surface area of food and produces bolus.
2- involuntary: peristalsis= alternating waves of contraction and relaxation of smooth muscle= propels & mixes food with digestive juices.
Give an example of how powerful the movement of peristalsis is.
It moves food to stomach even if the person is upside-down.
What are the types of mechanical digestion?
1- mastication 2-tongue movement 3-churning of stomach 4- segmentation.
Why does the stomach churn?
exposes food to digestive juices which creates chyme.
compare between segmentation and peristalsis.
1- segmentation: localized contractions of CIRCULAR muscle = moves food back and forth to subdivide and mix it up.
2- peristalsis: waves of contraction and relaxation of BOTH longitudinal and circular muscles = moves food through digestive tract.
what does chemical digestion secrete and where?
secretions vary in composition; but usually contains water, salt, enzymes, and acids.
- secreted in the small intestine.
where and how are nutrients absorbed?
nutrients are absorbed from the Lumen to the blood stream via epithelial cells in the mucosa.
how are lipids absorbed?
lipids are absorbed through lacteals and are transported to the blood stream via the lymphatic vessels. (subclavian vessels near the heart)
where does defecation occur?
ONLY in the anus.
where are alcohols and aspirin absorbed?
in the stomach.
