5. THE DIGESTIVE SYSTEM Flashcards
Mastication (chewing)
salivary glands secrete enzymes (start of chemical digestion)
chemical digestion
enzymatic
secretion
largely reabsorbed
glands
accessory digestion glands
muscularis
smooth muscle
externa, mucosa
enteric nervous system
organization, controls movement + mixing of food
hormone release
control + regulation
absorption
nutrients- energy, growth
elimination
feces, undigestible material
esophagus
transit (mouth - stomach)
stomach
acid peptic digestion
large intestine
reabsorption of fluid
microbiome (bacteria)
problem– diarrhea- dehydration
small intestine
digestion continued
majority of absorption
gastrointestinal tract
digestive organs
muscularis mucosae
smooth muscle layer
mucosal motility
boundary between mucosa and submucosa
submucosa
connective tissue
submucosal nerve plexus
regulates secretion by glands and motility smooth muscle (contraction)
muscularis
controls motility of 2 large smooth muscle layes
what are the two muscularis smooth muscle layers?
inner circular layer and outer longitudinal layer
what are both of the muscularis layers important for?
parstalis (wave moving food down) and segmentation moving food back and forth (mixing)
serosa
loose CT
blood vessels etc
covered by mesothelium
present in body cavity
ESAPHAGUS skeletal muscle (smooth muscle)
voluntary swallow
involuntary processes (THROWING UP)
esophageal mucous glands
submucosal
mucous does not stain
lubrication for transit
stomach
secrete mucous (forms barrier for stomach to protect itself)
what do fundus and the body do
secrete acid and pepsin
what are the main 4 parts of the stomach
- cardia
- fundus
- body
- pylorus
rugae
folds in stomach wall
gastric glands
simple branched tubular glands
in fundus and body region
parietal cells
eosinophilic (abundant mitochondria)
secrete HCL acid
proton pump - use ATP to pump acid against conc gradient in stomach
chief cells
basophilic (abundant rough ER for secretion)
making pepsinogen
H+ pump in inactive state (parietal cell)
present in in tuboloviscular system
in vesicle only secretes acid into vesicle
enclosed state
H+ pump in active state
acid secreted into apical lumen space
rapid secretion of acid
tuboloviscular system merges w apical membrane
enteroendocrine
not sensing anything in the lumen
dense core of vesicles containing peptide hormone
small intestine has a large _____
surface area
characteristics of the small intestine
circular folds
intestinal villi
microvilli
very long intestinal length
what does the small intestine do when it is ready for digestion/absorption
increases sa and volume/capacity
eosinophic granules
release contents into crypts
base of intestinal crypt
local vs distant effect
local (paracrine)- released affecting close cells
distant (endocrine)- released into blood stream
can chylomicrons (lipids) enter the blood stream via fenestrated capillaries?
no too large
why are duodenal glands important?
secretion is alkaline
recieving acid chyme of stomach
help neutralize acidic chyme
what is the lateral intercellular space indicitave of? (colon mucosa)
water reabsorption
accessory organs/glands
secretion faciliate transport and digestion
salivary glands
mastication (chewing) mechanical and chemical breakdown
pancreas
contributes enzymes for intestinal digestion
( proteases, lipases, amylases, DNAase, RNAase)
liver
bile for imulsification of fat
important for processing absorbed nutrients
what is the total secretion in L that the large intestine reabsorbes?
8 L
what are the three major sets of paired glands
- parotid salivary gland
- sublingual salivary gland
- submandibular salivary gland
sublingual salivary gland
just beneath the tongue
largely mucous-type secretion
submandibular salivary gland
sermucous secretion (mix of serous + mucous)
parotid salivary gland
produces watery/serous saliva (protein as enzymes)
amylase + antimicrobial peptides
myoepithelial cells
contractile- squeeze to help w/ secretion
striated ducts
carry secretions
modify secretions
basolateral infolding
involved in ion transport
what two cells stain nice with H + E
serous and acinis
demilune
serous cells associated w mucous cells
duodenum
input from pancreus + bile duct
intercalated duct
produce alkaline fluid
neutralize acidity of chyme
zymogen granules
inductive proenzymes
activated in the lumen of the intestins
acinus
any cluster of cells that resembles a many-lobed berry
endocine pancreas
well vascularized (blood vessels)
transport hormones
alpha cells (endocrine pancreas)
produce glucogen for glucose mobilization
deep brown/purple
beta cells (endocrine pancreas)
brownish/orange w fuchsin stain
for glucose storage
what type of relationship do insulin and glucogen have?
antagonistic relationship
islets
islands of tissue
liver
metabolically very active
highly diverse function
hepatocytes
arranged in plate-like organization
blood flows between
hepatic sinusoids
capillaries with large holes
branch of hepatic portal vein
contains blood from instestine (nutrient rich)
branch of hepatic artery
delivers oxygenated blood to liver
hepatocytes (hepatic lobule)
irregular branching of plates
hepatocyte functions
glucose stored as glycogen in cell
lipids form droplets in cell–> not adipose cells
hepatocyte functions
glucose stored as glycogen in cell
lipids form droplets in cell–> not adipose cells
bile caniculus
on apical membrane
bile secretion
perisinusoidal space
gap between endothelial and cell
