Lecture 5 - Digestive system I Flashcards
the digestive system consists of
the alimentary canal
and associated or accessory digestive organs
AKA gastrointestinal track - consists of the mouth, most of the pharynx, esophagus, stomach, small intestine, and large intestine
the alimentary canal
consists of the tongue, teeth, salivary glands, pancreas, liver, and gallbladder
assocaited/accessory digestive organs
these organs come in direct contact with food and help to physically break it down
tongue, teeth
these organs produce or store secretions that will reach the digestive tract via ducts;never come in contact with food directly, secretions for chemical breakdown of food
salivary glands, pancreas, liver, gallbladder
a continuous hollow tube that varies in diameter from mouth to anus, about 9 meters or 30 feet in cadaver but shorter in living people
alimentary canal
things in stomach and alimentary canal are inside or outside of the body
outside - have to cross epithelial lining to be considered inside of the body
bringing in of food/liquid inside the mouth
ingestion
glands and cells of the GI tract ____ about 7 liters of water, HCL,etc.
secretion
moving food from one place to another, and helping physcially break down of food
mixing and propulsion
the physcial breakdown of food from large pieces to smaller, creates surface area
mechanical digestion
bonds are broken and enzymes are used to break down macromolecules to micromolecules
chemical digestion
moving broken down macromolecules across epithelium lining into the body
absorption
90% of absorption takes place ____
10% takes place
small intestine
large intestine/stomach
waste products and getting rid of undigested food
defecation of feces
GI tract selective against things crossing epithelium lining
barrier
Processes of GI tract- first line of defense
immunologic protection
also referred to as the oral or buccal cavity, is bound by the cheeks, hard and soft palates, tongue, and floor
the mouth
are fleshy folds that surround the opening of the mouth and contain the orbicularis oris muscle
lips or labia
the____ are the location of a mucocutaneous junction
lips
The oral cavity opens into the oropharynx through an opening called the
fauces
part of the oral cavity; between the lips and teeth and between the cheeks and teeth.
vestibule
part of the oral cavity; superior border is the hard and soft palates; inferior border is the tongue and floor of the mouth; the posterior border in the entrance into the oropharynx; all other borders are the teeth
oral cavity proper
99.5% water and 0.5% solutes
average secretion of 1000ml/day to 1500ml/day
saliva
Moisten oral mucosa
Moisten dry foods
Provide medium for food materials to dissolve so they can chemically stimulate taste buds
Buffer contents of oral cavity (bicarbonate and phosphate ions)
Contains amylase that partially breaks down starch (i.e. polysaccharide
saliva’s protective and digestive roles
connects nasal and oral cavities to larynx and esophagus
passageway for food and air
pharynx
has respiratory epithelium and some stratified squamous epithelium
pharynx
the pharynx behind the nasal cavity and oral cavity are divided regionally into the ____(found posterior to the nasal cavity), the ______(posterior to oral cavity), and the _______ (begins at the level of the superior border of the upright epiglottis and opens into the esophagus and larynx).
nasopharynx
oropharynx
laryngopharynx
ciliated pseudostratified columnar epithelium
air passageway only
superior to soft palate; when swallowing the soft palate and the uvula move superiorly to close off the nasopharynx.
nasopharynx
nonkeratinized stratified squamous epithelium
air and food passageway
posterior to oral cavity; between level of soft palate to the epiglottis.
oropharynx
nonkeratinized stratified squamous epithelium
air and food passageway
laryngopharynx is continuous with both the esophagus and the larynx; extends from an upright epiglottis to the larynx.
laryngopharynx
wall structure of the alimentary canal from the lumen outward
1.Mucosa
~Lining epithelium
~Lamina propria
~Muscularis mucosae
2.Submucosa
3.Muscularis externa
4.Serosa or Adventitiawall structure of the alimentary canal, Mucosa - lining epithelium -nonkeratinized stratifirf squamous epithelium?
Simple columnar epithelium
NKSSE - protective role
simple columnar - absorption and secretion
wall structure of the alimentary canal, Mucosa - lamina propria,
loose connective tissues, GALT
wall structure of the alimentary canal, Mucosa- muscularis musosae
smooth muscle tissue - contraction
wall structure of the alimentary canal, Submuscoa
dense irregular connective tissue, meissner’s plexus
part of the innervation of the GI tract, located in the submuscosa, controls secretion cells
meissner’s plexus
wall structure of the alimentary canal - muscularis externa
smooth muscle (inner circular layer and outer longitudinal layer)
myenteric nerve plesus (Auerbach’s PLexus - contraction and relaxtion of SM
can be thickened to form sphincters or valves
smooth muscle inner circular layer of muscularis externa (3 of wall structure)
wall structure of the alimentary canal - serosa or adventitia
serosa - mesothelium and loose connective tissue, visceral peritoneum
adventita- loose connective tissue, outside peritoneum cavity
Mucosa - Nonkeratinized stratified squamous epithelium
Submucosa
Muscularis externa - varies; skeletal muscle tissue and smooth muscle tissue
Serosa or Adventitia
Mucous Glands:
Esophageal glands (proper) - ___
Esophageal cardiac glands - _____
esophagus
Esophageal glands (proper) - submucosa Esophageal cardiac glands - lamina propria
collapsable muscular tube about 10 inches long, and connects laryngopharynx to the stomach, found ___ to trachea
esophagus (T10)
found posterior
esophagus muscularis externa; upper 1/3?lower 1/3? middle 1/3
upper 1/3 - skeletal muscle
lower 1/3 - smooth muscle
middle 1/3 mixed
esophageal cardiac glands help protect against
gastric reflex
J-shaped enlargement of GI tract
stomach
gross anatomical subdivisons of stomach
Cardia
Fundus
Body
Pylorus
first portion of the stomach where food enters
cardia of stomach
collects gases of stomach
fundus
where most of the food hangs out
body of stomach
last portion of the stomach , 2 areas.
pylorus
pyloric antrium and pyloric canal(sphincter)
folds of the stomach for expansion when food enters
rugae
Histological subdivisions of stomach:
Cardia – cardiac glands; primarily mucous
Fundus/Body – fundic glands contain cells that secrete HCl and pepsin
Pylorus – pyloric glands; primarily mucous
Mucosa
- Simple columnar epithelium
- Surface mucous cells
Gastric pits which lead to glands (simple branched tubular glands)
Submucosa
Muscularis Externa Three layers of smooth muscle Outer longitudinal Middle circular Inner oblique
Serosa
stomach wall modifications
Simple columnar epithelium
Surface mucous cells
Gastric pits which lead to glands (simple branched tubular glands)
mucosa of the stomach (wall)
Cardiac glands
Primarily mucous
cardia of stomach
Pyloric glands
Primarily mucous
pylorus of stomach
Contain cells that secrete HCl and pepsinogen (pepsin)
Three Parts: Isthmus, Neck, & Base
fundic glands of stomach
required for the uptake of vitamin B12
intrinsic factor of parietal cell of fundic glands of the stomach
contain zymogen cells that produce proteins
chief cells of fundic glands of stomach (pepsinogen)
what do G cells secrete
hormone gastrin
