Digestive I Flashcards
The digestive system is a basically a tube from the ____ ____ to the rectal area.
oral cavity
rectal area
What are some accessory structures of the GI system?
teeth tongue salivary glands liver gallbladder pancreas
Voluntary sphincters are made from ______ muscle, involuntary from _______ muscle.
skeletal
smooth
The tube is open to the environment at both ends, so anything in it is considered _______ to the body until it is absorbed by epithelial cells lining the gastrointestinal tract
external
What 4 general things happen in the digestive system?
Ingestion
Digestion
Absorbtion
Defacation
What are the three processes used by the digestive system?
Motility
Secretion
Membrane transport
What is motility? What 2 mechanisms allow for it?
Muscular contraction with smooth muscle
Peristalsis and Segemnetation
How do peristalsis and segmentation provide motility in the digestive system?
Peristalsis- propels chyme (a semi-fluid material produced by gastric digestion)
Segmentation- mix chyme
What is chyme?
A semi-fluid material produced by gastric digestion
What is secreted in the digestive system?
Secretion of enzymes
Sends hormones- they control the process of secretion
How do cells absorb nutrients?
By membrane transport
Once inside the GI cells, carbohydrates and proteins go into blood capillaries, and lipids are absorbed by the _______.
blood
lacteal (lymph capillaries)
What are the two types of digestion? How doe they work?
Mechanical digestion- Teeth which masticate food
Smooth muscle- churns chyme in stomach and small intestine
Chemical digestion- Enzymes
They split carbohydrates, lipids, and protein molecules so they can be absorbed into the simple columnar mucosal cells
What are the three types of glands in the GI system?
Unicellular
Multicellular under epithelium
Multicellular glands outside digestive tract
Which unicellular gland is in the GI tract?
Goblet cells
Which multicellular glands are in the GI tract?
Have ducts leading into lumen of tract- Eg salivary gland in mouth, pancreas, liver
Which 4 tunics are in the GI tract?
Submucosa
Mucosa
Muscularis
Serosa OR adventitia
Why is the innermost layer a “mucosa”?
Because it’s a membrane that lines a body cavity open to the outside
Which three sublayers are in the mucosa tunic?
Epithelium
Lamina propria
Muscularis mucosa
What kinds of cells are in the epithelium of the mucosa tunic? Why?
Stratified squamous at both ends, simple columnar in the middle
In direct contact with the contents of the GI tube
What is the lamina propria of the mucosa tunic?
Loose connective tissue layer- room for lymphocytes, blood, macrophages etc
What is the muscularis musosa?
There is a thin layer of smooth muscle that throws the mucosa into folds, to increase surface area
What kind of lymph tissue is present in the mucosa tunic?
MALT- mucosa-associated lymphatic tissue
What tissues are present in the submucosa?
Loose CT, highly vascular
What kind of nerve ending is present in the submucosa? What nervous system is it part of?
Submucosal plexus of ANS- plexus of Meissner- controls secretions of nearby glands
This is part of the general enteric nervous system (PNS) that regulates digestive tract motility, secretion, and blood flow
What is the muscularis tunic made from? What does it do?
Made from 2 sheets of smooth muscle throughout the tube that are responsible for peristalsis and segmentation of the chyme
In general, the 2 layers of the muscularis are : 1- _____ _____, and 2- _____ ________
inner circular
outer longitudinal
What nerve is in the muscularis? Where is it and what does it do?
Plexus of Auerbach- myenteric plexus of the ANS
Located between the 2 muscle layer
Controls mostly GI tract motility
What composes the tunic serosa?
1- Simple squamous epithelium next to space of abdominal cavity
2- A thin, underlying, supporting layer of CT between the muscle and epithelium
What does a “serosa” do?
Lines a cavity not open to the outside
What is the diffrence between a serosa and an adventita?
Is an adventitia, and not serosa when it is CT that blends into surrounding tissue instead of a smooth lining. Eg when other organs are nearby such as with pharynx, trachea, or rectal area.
What does retroperitoneal mean?
External to the peritoneal lining of the abdominal cavity
What are some retroperitoneal organs?
kidneys, adrenals, duodenum, pancreas, ascending and descending colon, rectum, and bladder.
What is two serous membranes with connective tissue in between that generally extend from the body wall to the digestive organs?
Mesentery
What binds and holds the abdominal organs to each other and the back wall?
Mesentery
What is contained within the mesentery?
blood vessels, lymph vessels, and nerves
What provides a route by which the vessels and nerves can pass from the back of the abdominal wall to the organs?
Mesentery
What organs have mesentery?
Small intestine, transverse colon
What is the mesocolon?
Folds of mesentery that covers the large intestine (colon), but only the part that isn’t retroperitoneal, the transverse colon.
What is the falciform ligament?
A sheet of mesentery that suspends the liver from the abdominal wall.
What is the lesser omentum?
A smaller mesentery that connects the liver to the lesser curvature of the stomach.
What is the greater omentum?
This forms a long double fold of mesentery that extends from the greater curvature of the stomach inferiorly over the surface of the small intestines and back up to the transverse colon.
Which mesentery folds back upon itslef?
Greater omentum
What is the greater omentum also known as?
The “fatty apron”
