Digestive anatomy review Flashcards
What is the general function of the digestive system
1) Ingestion/eating -food intake
2) Digestion - mechanical (crush/mix) or chemical (enzymatic breakdown)
3) Absorption - Nutrient absorbed by epithelial cells into blood/lymph
4) Egestion - defecation - excretion of undigested food
Layers of the alimentary canal/GI tract from inside to out
1) Lumen
2) Epithelium (mucosa)
3) Lamina propria (mucosa)
4) Muscularis mucosa (mucosa)
5) Submucosa CT
6) Circular layer ( Muscularis externa)
7) Longitudinal layer (muscularis externa)
What does the longitudinal muscle do to propel food
Shortens the canal (wider)
what does the circular muscle do to propel food
(lenghtens & narrows)
It the propulsion of food through the canal neural or hormonal control?
both
& it’s 2 separate movements
What does peristalsis do
propels food toward the anus
what does the peristaltic reflex do
stretching go the smooth muscle by food triggers the contraction proximal to the bolus & to relax distally
what is segmentation
a back & forth moving
what are mesenteries & their function
double layer of visceral peritoneum extending from organ to body wall
hold intraperitoneal organs in place & provide a network for Blood vessels & nerves
what does retroperitoneal mean
outside the peritoneal cavities
what organs are retroperitoneal
Rectum
Duodenum
Pancreas
Ascending/descending colon
What are the 2 ventral(anterior) mesenteries
1) Falciform ligament
2) Lesser momentum
explain falciform ligament
attaches liver to the diaphragm & ventral wall
explain the lesser omentum
attaches lesser curvature of stomach to liver
what are the 3 dorsal/posterior mesenteries
1) Greater omentum
2) mesentery proper
3) Mesocolon
what does the greater omentum do
Drapes over coils of small intestine, attaches greater curvature of stomach to dorsal wall
what does the mesentery proper do
links coils of jejunum & ileum & binds to dorsal wall
what does the mesocolon do
large sheet that attaches transverse & sigmoid colon to the dorsal wall
What does the tongue do
glossal muscles manipulate food to form a bolus
anchored to the floor by frenulum
what do the papillae/bumps on the tongue do
Grip food, associated with glands that secrete lingual lipase ( fat digesting)
where are tastebuds/sensory chemoreceptors
in the pits between papillae
how many teeth
32 adult, 20 deciduous
what do incisors do
Bite & grip. 4 pairs
what do canine/cupid do
tearing (2 pairs)
what do premolars/bicuspid do & molars
chew/grind (8) 12 molars
what is the function of the salivary glands
- exocrine
- moisten & dissolve food
- Antimicrobial b/c lysozyme & IgA antibodoes
- buffers acids
- lubricated bolus
where are parotid salivary glands
cheek
where are sublingual salivary glands
under tongue
where are submandibular salivary glands
floor of mouth (secret 70%)
What is the epithelium of the esophagus made of
Non-keratinized stratified squamous
what do the submucosal mucus glands do in the esophagus
lubricate bolus
what does the cardiac/esophageal sphincter do
regulates food into stomach
Explain how swallowing/deglutition occurs
initiated voluntarily but proceeds automatically
Explain the swallow reflex
1) initiated when bolus contacts uvula
2) Pharyngal muscles contract to push food into esophagus
3) Peristalsis moves food toward stomach
what is the fundus of the stomach
the top part
what is the pylorus of the stomach
bottom b4 sphincter
what does the pyloric sphincter do
between stomach & duodenum
function of the stomach & special feature
Storage organ w/ ruggae folds that expand
Had an additional oblique muscle in the muscularis
What do the gastric pits of the stomach do
house the gastric bands
what do the mucous neck cells of the stomach do
secrete mucous
what do the parietal cells of the stomach do
secrete HCL and intrinsic factor (required for B12 reabsorption)
What do the Chief cells of the stomach do
secrete pepsinogen (which is activated by HCL to become pepsin which is an enzyme that digests proteins)
what do the g cells in the stomach do
secret gastrin (stimulates secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility)
what ph is gastric juice
2
What is acid chyme
acidic food paste via stomach churning. Moves through pyloric sphincter into duodenum
What are the 3 subdivisions of the small intestine
1) Duodenum
2) Jejunum
3) Illium
describe the duodenum
- proximal
- main-site or enzymatic digestion/chemical
- recieves pancreatic juice
- receives bile from gallbladder (produced in liver)
Describe the Jejunum & Illium
huge SA specialized for absorption of water & nutrients. Also secrete digestive enzymes
What are the plicae chambers of the sm. intestine
large fold in the mucosal membrane
what are the villi in the sm. intestine
finger like projections on the mucosal surface
what are the microvilli in the sm. intestine
folds in apical surface of epithelial cells -> form brush boarder membrane
What do the goblet cells secrete in sm. intestine
mucus
what do the crypt cells secrete in sm. intestine
digestiv eenzymes
what do the brunners gland secrete in small intestine.
produce alkaline secretion
What is the function of the large intestine
1) water reabsorption
2) Compaction/ storage of feces
3) absorption of some vitamins
4) many non-pathogenic bacteria called coliform
- Protect, digest, stimulate immune system, produce vit.K & vit. B’s
What is the inside of the large intestine like
Simple columnar, no villi, lots of goblet cells
what is mass peristalsis & where does it take place
Strong contractions of the large intestine
what is the ileocecal valve
connect the ilium to the cecum (appendix is part of cecum)
what is the taenia coli
3 longitudinal bands of smooth muscle. slow strong contraction -creates pouches
what is haustra
pouches in large intestine
what is the internal anal sphincter made of
smooth muscle.
what is the external anal sphincter made of
skeletal muscle
what is the largest visceral organ
liver
what is the function of the liver
1) Metabolic factory
- Recieves nutrients through digestive system -> metabolizes & stores
2) produces bile from cholesterol which emulsifies fats
3) inactivation of drugs, toxins & hormones
4) breaks down RBC, hemoglobin & antibodies
5) synthesis of plasma proteins (clotting factors, albumin, complement)
The liver recieves ___ of cardiac output
25%
what does the hepatic artery do
Delivers O2 rich blood from the heart
what does the hepatic portal vein do
delivers nutrient rich blood from the digestive blood from the digestive system
what does the hepatic vein do
drains deoxygenated blood into inferior vena cava
what are the cells of the liver called
hepatocytes
what is the functional unit of the liver called
a lobule (hexagon shape) forms portal triads connected by a central vein
what is a portal triad
central vein in middle of lobule
on each corner there is a bile duct, portal venue & hepatic arteriole called a triad
what are sinusoids
nutrient rich blood percolates through these liver capillaries as it passes through, hepatocytes absorb & secrete materials in the blood stream
what does the gall bladder do
stores & concentrates bile
How is bile released (flow)
1) gallbladder contracts
2) Cystic duct
3) common bile duct
4) hepatopancreatic sphincter
5) duodenum
How is bile stored (flow)
1) L&R hepatic ducts
2) Common hepatic ducts
3) Hepatopancreatic sphincter is closed so it goes up the mystic duct to the dilated gallbladder
What are the pancreatic acidic
house exocrine, secrete pancreatic juice
what is in pancreatic juice
1) Alkaline soln
2) lipase - digests lipids
3) Nucleases - digests RNA/DNA
4) Amylase - Digests starch
5) proteases -digests proteins
What is the alkaline soln. in pancreatic juice
NaHCO3 that neutralizes HCL
what are proteases actually secreted as from the pancreatic acini
Inactive Zymogens
what are the 4 inactive zymogens
1) Chymotrypsinogen
2) Trypsinogen
3) procarboxypeptidase
4) elastase
what does the pancreatic duct do
delivers pancreatic juice to hepatopancreatic sphincter & duodenum
