Digestive system Flashcards by Mia Hebert

Basic functions of the digestive system (6)

Ingestion
Secretion
Mixing and propulsion
Digestion
Absorption
Defecation

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Layers of the GI tract

Mucosa, submucosa, muscularis, serosa

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3 layers of the mucosa

Lining of epithelium
Lamina propria
Muscularis mucosa

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Eptihelium in mouth, pharynx, esophagus and anal canal serves a ____ function

protective

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Epithelium in the stomach and intestines functions in ___ and ____

secretion and absorption

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Every __ to __; epithelial cells are replaced by new ones

5 to 7 days

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2 types of cells within the absorptive epithelial cells

Exocrine cells = secrete mucous and fluid into the lumen

Endocrine cells = secrete hormones into the bloodstream

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Roles of the lamina propria layer (2)

supports the epithelium and binds it to the muscularis mucosa- also contains MALT

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what is MALT

mucosa-associated lymph tissue

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Roles of the muscularis mucosa (2)

increases the surface area for digestion and absorption

- movement of muscle ensures that all absorptive cells are fully exposed to contents of the GI tract

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Content of submucosa (1)

Meissner’s plexus

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What is meissner’s plexus

portion of the Enteric nerve plexus - ENS (“brain of the gut”)

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why is meissner’s plexus important

important in controlling secretions in the GI tract

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Muscularis layer - involuntary contractions help in 3 ways

help break down food physically
mix it with digestive secretions
propel it along the GI tract

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muscularis layer contains what

second plexus of the ENS

- myenteric (auerbach) nerve plexus

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role of myenteric nerve plexus

controls primarily the frequency and strength of contraction of the muscularis

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serosa layer + other name

superficial layer

also called visceral peritoneum on structures inferior to the diaphragm

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Layers of the peritoneum

Parietal peritoneum
Visceral peritoneum
Peritoneal cavity

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peritoneum - lines the wall of the abdominopelvic cavity

parietal peritoneum

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peritoneum - covers some organs in the cavity and forms their serosa

visceral peritoneum

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peritoneum - thin space between the parietal and visceral peritoneum (contains serous fluid)

peritoneal cavity

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what is the largest peritoneal fold?

greater omentum

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hangs loosely over the transverse colon and coils of SIdouble sheet that folds back on itself

greater omentum

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name the other peritoneal folds (4)

falciform ligament
lesser omentum
mesentery
mesocolon

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attaches the liver to the anterior abdominal wall and diaphragm

falciform ligament

arises as 2 folds in the serosa of the stomach and duodenum + suspends stomach and duodenum from liver

lesser omentum

binds the SI to the posterior abdominal wall (pied de choufleur)

mesentery

fold of peritoneum which binds the LI to the posterior abdominal wall

mesocolon

cheeks, hard and soft palate, tongue

the mouth

what is the labial frenulum

fold of mucous membrane that attaches the lips to their corresponding gums

what forms the hard palate (2)

maxilla and palatine bones

what is the uvula

muscular process hanging from the free border of the soft palate

what is the soft palate

muscular separation between oropharynx and nasopharynx

the mouth - palatine tonsils location

situated between the arches

the mouth - lingual tonsils location

situated at the base of the tongue

the mouth - fauces

opening between the oral cavity and the pharynx (throat)

when food enters the mouth, secretion from the salivary glands ___ and chemical breakdown of food begins

increase

roles of salivary glands when secreting saliva (2)

keep mucous membrane of mouth and pharynx moist | cleanse the mouth and teeth

3 major salivary glands

parotid glands submandibular glands sublingual glands

salivary glands - located inferior and anterior to the ears, btw the skin and masseter muscle

parotid glands

how does the parotid gland secrete saliva into the oral cavity?

via the parotid (Stensen's) duct

salivary glands - found beneath the base of the tongue in the posterior part of the floor of the mouth

submandibular glands

where do the submandibular (Wharton's) ducts enter the oral cavity?

lateral to the lingual frenulum

salivary glands - superior to submandibular glands

sublingual glands

which ducts open into the floor of the mouth?

lesser sublingual (Rivinus) ducts

salivary glands - sympathetic innervation

initiates vasoconstriction = decrease production of saliva

salivary glands - parasympathetic innervation

initiates vasodilation = increase production of saliva

what are the two important components of the saliva (made of mostly water)

salivary amylase | lingual lipase

what can also stimulate secretion in saliva

smell, sight, sound or thought of food

the tongue attaches to which 3 bones

hyoid bone, styloid process of temporal b., and mandible

extrinsic muscles of the tongue(3)

hyoglossus, genioglossus, styloglossus

role of extrinsic muscles of the tongue

move the tongue from side to side and in & out to maneuver food

role of intrinsic muscles of the tongue

alter shape and size of tongue for speech and swallowing

dorsal and lateral surfaces of the tongue are covered with papillae (4)

fungiform papillae filliform circumvallate foliate papillae

which papillae of the tongue don't have taste buds?

Filliform

what is deglutition

mechanism that moves food from the mouth to the stomach

condition where a person's lingual frenulum is abnormally short or rigid impairing eating and speech

ankyloglossia

condition where sometimes a portion of the stomach pierces through the esophageal hiatus

hiatal hernia

layers of the esophagus

adventitia muscularis submucosa mucosa

3 parts of muscularis layer of esophagus

superior 1/3 = skeletal muscle middle 1/3 = skeletal and smooth muscle inferior 1/3 = smooth muscle

content of submucosa layer of esophagus (3)

areolar connective tissue, blood vessels and mucous glands

role of mucosa layer of esophagus

offers protection against abrasion and wear & tear from food particles that are chewed, mixed with secretions and swallowed

Functions of the esophagus (2)

secretes mucous and transports food in the stomach

what controls the passage of food from laryngopharyngeal

upper esophageal sphincter

food is pushed through esophagus by ____ (mechanism)

peristalsis

what is peristalsis

progression of involuntary contraction and relaxation of the circular and longitudinal layers of the muscularis

structure that relaxes during swallowing allowing the bolus to pass into the stomachlocated at the narrowing of the esophagus just superior to the diaphragm

lower esophageal sphincter

the stomach connects which 2 structures

connects esophagus to the duodenum

serves as a mixing and holding reservoir since meals are eaten more quickly than intestines can digest and absorb them

stomach

what happens to the macros in the stomach

digestion of starch continues | digestion of protein and triglycerides begins

regions of the stomach (6)

``` cardia fundus body pylorus lesser curvature greater curvature ```

stomach - surrounds the superior opening of the stomach

cardia

stomach - rounded portion superior and to the L. of the cardia

fundus

stomach - large central portion, inferior to the fundus

body

stomach - regions that connects to the duodenum

pylorus

3 parts of the pylorus

pyloric antrum pyloric canal pyloric sphincter

pyloric antrum

connects to body of stomach

pyloric canal

leads to the duodenum

pyloric sphincter

passageway from pylorus to duodenum

stomach - concave medial border

lesser curvature

stomach - convex lateral border

greater curvature

when the stomach is empty, the mucosa lies in large folds called ?

Rugae

arterial supply of the stomach (3)

R/L gastric arteries R/L gastroepiploic Short gastric

stomach - parasympathetic innervation =

vagus nerve (CN X)

stomach - sympathetic innervation =

celiac ganglia

layers of the stomach

mucosa submucosa muscularis serosa

3 parts of the mucosa of stomach

lamina propria muscularis mucosa gastric glands

What are gastric glands (part of mucosa)

exocrine glands cells, that secrete their products into the stomach lumen

3 parts of gastric glands

mucous neck cells chief cells parietal cells

role of mucous neck cells (stomach)

secrete mucous

role of chief cells (stomach)/

secrete pepsinogen and gastric lipase

role of parietal cells (stomach)

produce HCl and intrinsic factor

mucosa of stomach - includes a type of enteroendocrine cell

G cell

location of G cell + role

``` pyloric antrum secretes gastrin (hormone) into the blood stream ```

submucosa layer of the stomach

areolar connective tissue

3 parts of muscularis layer of stomach

outer longitudinal layer middle circular layer inner oblique layer

functions of the stomach (2)

mixing waves mix the food with the gastric juice reducing it to ta liquid called chyme

t/f as digestion proceeds, more vigorous waves begins at the body and intensify as they reach the pylorus

true

digestion of proteins being in ___

the stomach

protein chains of many amino-acids are broken down into smaller fragments called ____

peptides

pepsin also aids in digestion of what

milk proteins

role of gastric lipase (2)

splits the short chain of triglycerides found in milk | limited role in the adult stomach (more pancreatic lipase)

within _ to _ after eating a meal, the stomach usually has emptied its contents into the duodenum

2-4 hours

chemical digestion in the small intestines depends on the activity of which 3 organs?

pancreas, liver and gallbladder

pancreatic duct other name

duct of Wirsung

pancreatic duct joins what and empties where

joins with common bile duct | empties in greater duodenal papillae

accessory pancreatic duct other name

duct of Santorini

accessory pancreatic duct empties where

in lesser duodenal papilla

4 parts of the pancreas

retroperitoneal gland head body tail

arterial supply of the pancreas (4)

sup and inf. pancreaticoduodenal aa. splenic a. superior mesenteric aa.

innervation of the pancreas

celiac and superior mesenteric plexuses

pancreas is made up of small clusters of glandular epithelial cells:- 99% are arranged in clusters called ___- 1% are organized into clusters called ____

``` Acini Pancreatic islets (islets of langerhans) ```

pancreas - exocrine portion of the organ + cells secrete a mixture of fluid and digestive enzymes called pancreatic juice

Acini

pancreas - endocrine portion of the organ + secrete the following hormones : glucagon, insulin, somatostatin & pancreatic polypeptide

Pancreatic islets

the pancreas produces ___ to ___ of pancreatic juice/day

1200 to 1500 mL

stops the action of pepsin in the stomach and creates the proper pH level for action of digestive enzymes in the S.I

pancreatic juice