Chapter 2 Flashcards
What are the main structures of the digestive tract
(start) oral cavity- upper digestive system
esophagus -upper digestive system
stomach -upper digestive system
(End) Small and Large intestines- Lower Digestive system
What are the accessory organs of the digestive tract
Pancreas
liver
gallblader
what does the digestive tract do
process mechanically and chemically break down the food that we consume. (degradation)
What are some of the layers of the lumen
Mucosa- inner most layer
submucosa
muscularis externa
serosa-Outer most layer
What is the mucosa made up of
mucosal membrane, lamina propria, and muscularis mucosa (made up of smooth muscle)
What is another name for the muscularis mucosa, what does it do
muscularis externa- made up of smooth muscle
moves the food through the digestive system via peristalsis movement
What are the names for peristalsis movement
myenteric plexus or plexus of auerbadn
What is myenteric plexus
network of nerves involved in regulating perisaltic movement
what type of cells is the mucosa made up of?
epithelial cells
What are epithelial cells broken down to
endocrine cells and exocrine cells
What do exocrine cells secret
digestive juices
what are Endocrine cells involved in?
the making of hormones that aid in the digestive system
What is the submucosa made up of
connective tissue, blood and lymphatic vessels, lymphoid tissue and submucosal plexus
what is the submucosal plexus aka
plexus of Meissner
what does the plexus of Meissner do
blood flow to the digestive system.
what type of cells make up the serosa
flat mesothelial cells
what does the serosa do
creates mucus attached to perineal membrane
the perineal membrane surrounds
all organs around abdominal cavity and is highly vasculized and semi permeable
what does the oral cavity consist of
mouth and pharynx
salivary glands
Enzymes and saliva
what are the salivary glands on both sides of the mouth
parotid
submandibular
sublingual
what type of enzyme is in the saliva
alpha amylase
what does alpha amylase do
starts the digestion of carbohydrates
can alpha amylase survive in the stomach?
for a very short period of time before it is destroyed by the HCL acid in the stomach
What is the name of the enzyme of the top of the tongue
lingual lipase
Who has a high amount of lingual lipase
newborns- it begins to decrease as we age
what doe ligual lipase do
helps in the digestion of triglycerides
What does the esophagus do
moves bolus from oral cavity to stomach
swallowing
peristalsis
gastroesophageal sphincter (at the bottom of the esophagus
Selected disorders of the esophagus
GERD
What do the salivary glands contain
water, electrolytes, mucos, enzymes, antibacterial and antiviral proteins, r-protein, and solutes
Swallowing
voluntary, pharyngeal, esohageal
Four main regions of the stomach
Cardia Region
Fundus
body
Antrum or distal pyloric region
Stomach serves as
resivour on the left side of the abdomen
what occurs in the antrum or distal pyloric region of the stomach
food is ground up by a mechanical process and then the emptying of the stomach occurs
what is rogae and its function
it is folds in the stomach that allow for stretching. you can not see them when your stomach is full
Stomach muscles mix food with gastric juices to form
Chyme
What do gastric juices facilitate
digestion
What are the gastric glands in the stomach
cardiac glands
oxyntic glands
pyloric glands
What are the cells in the gastric oxyntic gland
neck Cells (mucus) parietal cells (oxyntic) chief cells (peptic or zymogenic) enteroendocrine cells
what are the cells in the cardiac glands
neck cells
chief cells
enteroendocrine cells
what are the cells in the pyloric glands
neck cells
parietal cells
enteroendocrine cells
what do parietal cells do
secrete HCL- intrinsic factor (absorbtion of vitamin B 12
What do the chief cells do
secrete pepsinogin and gastric lipase- helps with digestion
Pepsinogin is made in the chief cells in what state
inactive state
what is the active form of pepsinogin
pepsin
Enteroendocrine cells do what
create hormones that aid in the digestive process
how much of the stomach is the antrum or distal pyloric region
1/3 of the stomach
What gastric juices are produced in the stomach
HCL
enzymes
mucus
intrinsic factor
what does HCL do in the digestive process
converts pepsinogin to pesin
denature protein
releases nutrients from organic complexes
acts as bacteriocide
what enzymes are used in gastric juices
pepsin, amylase, lipase
mucus is a gastric juice produced by what cell what is it role
neck cell
lines the stomach and protects it from HCL
What is intrinsic factor
helps in the absorbtion of vitamin B 12
what percent of protein is digested in stomach and what enzyme is used
20%
pepsin
Gastric Lipase starts digesting
lipid only the 3rd carbon fatty acid in a triglyceride.
What are the 3 phases of regulation gastric secretions
Cephalic phase
gastric phase
intestinals phase
What occurs in the cephalic phase
before the food reaches the stomach - this phase causes the activation of the vegus nerve which stimulate nerve fiber in the submucosa (plexus of meisner) causes the release of neurotransmitter acetylcholine which stimulate the G cells in stomach to release hormone gastrin which will stimulate mast cells and enterochromatin -li cells to release histamines
What happens in the gastric phase
once food is in the stomach-
stomach distension enhances gastric secretions
food such as protein, alcohol
Intestinal phase
after food has left the stomach
reduction in chime volume and pH trigger release of somatostatin (released into small intestine)
pyloric sphincter
allows for chime to pass through stomach to the small intestines volume reduces and pH increase
D cells make
somatostatin and slows down gastric secretion slows down HCL from parietal Cells
Regulation of Gastric Motility and Gastric Emptying
peristaltic waves propel digestive contents
- basic electrical rhythm initiated by pacemaker cells
Gastric emptying affected by factors in stomach and duodenum
Dietary fat intake has an inhibitory effect on gastric emptying
Selcted Disorders of stomach
Peptic ulcer disease
what is the cause of peptic ulcer disease
ulcerations or erosions in mucosa and submucosa layers of the stomach, duodenum, or lower esophagus
What is a common cause of peptic ulcer
Helicobbacter pylori (bacteria that survives in high acidity
Other causes of peptic ulcer
chronic alcohol
use of NSAIDs
What is used to treat Peptic Ulcers
H2 receptor blockers
What produces larges amounts of gastrin to cause ulcer
Zollinger Ellison syndrome produces gastrin which stimulates HCL which then attacks mucosa and causes ulcer on the walls of the stomach
Neck Cells secrete small amounts of
sodium bicarbonate
Parietal cells produce hydrogen and chloride but they
do not create HCL until they leave the cells and move to the lumen (formed outside of the cell)
Carbon dioxide and water produce
carbolic acid it disassociates into bicarbonate and hydrogen and moves outside the cell
Chloride comes from the
plasma
Because of the binding parietal cells is
stimulated and secretes HCL before food ever hits the stomach
Acetylcholine Stimulates
Chief cells
Emptying of stomach is delayed by certain types of
protein or carbohydrates
osmotic pressure of chime is
slowed down if it is hypertonic, this can delay gastric emptying
Chyme triggers two cells
s- cells
I-cells
what hormone is secreted by the s cell
secretion
what hormone is secreted by the I cell
CCK
what do the s and I cell do
produce hormones that inhibit gastric juices and gastric emptying
