Digestive System Flashcards
the digestive system extends from ____ to ___
mouth to anus
4 layers of the digestive tract
- mucosa (next to lumen)
- submucosa
- muscularis externa
- serosa or adventitia
in the mucosal layer, consists of loose connective tissue and includes blood and lymph vessels and sometimes glands
lamina propria
smooth muscle region called ___ ____ lies below the lamina propria in the mucosa
muscularis mucosae
the movements caused by the ___ ____ act to increase contact of the mucosal epithelium with food in the digestive tract.
muscularis mucosae
_____ is the only section of the intestine that has glands in the submucosa
duodenum
parts of the mucosa
(lumen) epithelial lining lamina propria muscularis mucosae (submucosa)
this layer is often rich in macrophages
- acts as a barrier to bacterial invasion
- act to help prevent the spread of infectious organisms into the body via the digestive tract
lamina propria
layer of dense or loose CT
- has lymph and blood vessels, lies below the muscularis mucosae
- contains a never plexus called Meissner’s plexus
- may also contain glands and lymph nodes
submucosa
the submucosa of the digestive tract has a nerve plexus called
Meissner’s plexus (parasympathetic)
lies outside the submucosa, has two parts in the digestive tract and three in the stomach
- responsible for the gross movements of the digestive tract
muscularis externa
2 layers of the muscularis externs
and 3rd in stomach
- circular smooth muscle (closest to lumen)
- longitudinal smooth muscle ( furthest from lumen
(3rd: stomach: oblique muscle layer, closest to lumen in stomach)
thin layer of loose CT
outermost layer of intestine
- layer is rich in blood and lymph vessels and adipose cells
-covered in simple squamous epithelium which is continuous with the lining of the peritoneal cavity- mesothelium
serosa or adventitia
the transition b/t the Stratified keratinized squamous epithelium of the skin and the stratified nonkeratinized squamous epithelium of much of the oral cavity occurs at the
lips
below the stratified squamous epithelium of the oral cavity is a layer of loose CT called the ____ _____ that contains blood and lymph vessels, small glands, nerves and aggregations of lymphocytes
lamina propria
together the stratified squamous epithelium and the lamina propria form the _____ _____, there is NO ___ ____
oral muscosae
NO muscularis mucosae
the roof of the mouth consists of ____ and ___ plates
hard and soft palates
the ___ ____ of the mouth has an intramembranous bone backing which is covered by a keratinized mucous epithelium
hard palate
the ___- ___ of the mouth has a core of skeletal muscle and is covered by a non keratinized mucous epithelium
soft palate
the ____ consists of a mass of striated muscle covered by a mucous epithelium - NonKSS in most places
tongue
4 types of papillae
- filiform papillae
- fungiform papillae
- foliate papillae
- circumvallate papillae
where are papillae found on the tongue
dorsal surface (top)
this type of papillae has a elongated conical shape, most numerous and found on the entire dorsal surface. Long, pointy
filiform papillae
this type of papillae are mushroom shaped, fewer in number that filiform, found over entire surface
fungiform papillae
this type of papillae are arranged as closet packed folds along the posterior lateral margins of the tongue and are only common in young children
- numerous taste buds in the epithelium covering the papillae
foliate papillae
these are extremely large circular papillae which has a flatted surface that extends above the other papillae. only ~12 on the entire tongue
- MANY rase buds found on these
- a deep groove encircles the body of the papilla
circumvallate papillae
at the base of the groove of a circumvallate papillae, there are ___ ___ glands that act to wash the surface of the papillae and clean material from taste buds.
serous (von Ebner’s) glands
oval (football) shaped muticellular structures found in the oral cavity, on the side of papillae
taste buds
3 cell types of a rase bud
- gustatory (taste) cells
- sustentacular (support) cells
- basal cells: stem cells for replacement of gustatory cells (only live 7-10 days)
in adults there are ___ permanent teeth
32
in childhood, there are ___ deciduous teeth
20
the tooth lies in a bony socket, the ____, that is covered by an oral mucosa celled the ____ (__) that consists of a Keratinized SSE and a lamina propria of Loose CT
the alveolus (bony socket) oral mucosa: gingiva (gums)
two major parts of the tooth
- crown
2. root
the portion of the tooth that protrudes above the gum line
crown
the portion of a tooth that extends into the alveolus
the root
3 layers of a tooth
inside: pulp
dentin
outside: enamel
these secrete organic matrix that mineralizes and forms the dentin
ondontoblasts
layers of a tooth to the bony socket
inside: pulp dentin cementum periodontal ligament alveolar bone outside: gingiva surround bone
ondontoblasts extend thin processes (____ ____) along which the organic matrix of the dentin is secreted
Tome’s fibers
dentin is covered by a further layer of mineralized organic matrix
- hardest substance in the body
formed by ameloblasts before tooth “erupts” from socket
enamel
between the cementum and the bone of the socket lies the ____ ____- consists of fibroblasts and associated collagen fibers with glycosaminoglycans in between
- forms cushion between tooth and bone
- attaches tooth to bone
periodontal ligaments
gingival sulcus
if your gingival sulcus is too deep, it indicates the breakdown between enamel and junctional epithelium, which is ____ ____
periodontal disease
prior to the ___ week of gestation in human embryos, the developing jaws are solid masses of tissue with little differentiation
5th
tooth development begins during the ___ to ___ weeks of gestation
5-6th week
the first indication of tooth development is the appearance of a thickened plate of epithelium labialgingival lamina (_______ _____) b/t the tongue and the upper and lower jaw
vestibular lamina
C shaped band of tissue in the gums of the upper and lower jaw is called the ___ __ or___ __
dental ledge of dental lamina
in regions where a tooth will form, a further ingrowth of the dental lamina form the ___ __
tooth bud
in 10 distinct regions of each jaw, the cells of the dental ledge proliferate rapidly by mitosis forming a cup shaped structure called the ___ ____ that is surround by jaw mesenchyme
enamel organ
the mesenchyme that fills the enamel organ cup will become the dental papilla which eventually forms the ____ and the ___ of the tooth
dentin and the pulp
the enamel organ and dental papilla are surrounded by a sheath of connective tissue called the __ __
dental sac
this stage of tooth development is first, and then differentiates into the bell stage
cap stage
formed from the cap stage of tooth development
bell stage
the inner enamel organ epithelium will eventually differentiate into cells called ____ that will form the enamel of the tooth
ameloblasts
neural crest cells in the dental papilla will form an epithelial layer directly adjacent to the ameloblasts that will differentiate into cells called ____ which will for the tooth dentin
ondontoblasts
the lips of the cup that forms the enamel organ are called the ____ ____
cervical loop
the cervical loop will partially generate as the root of the tooth develops and will become ___ ___ ___ ___
hertwig’s epithleial root sheath
in species that continuously grow teeth like rabbits and mice, the ___ ___ is retained through adulthood
cervical loop
the central region go the root is called the
radicular pulp cavity
once the tooth is fully formed it is ready to undergo ___, this process occurs after birth and involves active movement of the tooth such that it penetrates the gum tissues and extends above them.
eruption
muscular tube that transports food from mouth to stomach
esophagus
the lining of the esophagus is
nonkeratinized stratified squamous epithelium
layers of the esophagus
- mucosa(epithelium, lamina propria, muscularis mucosae)
- submucosa
- muscularis externa ( inner circular muscle, outer longitudinal muscle)
- serosa or adventitia
three major regions of the stomach
- cardia: cardiac stomach (connects with esophagus)
- body (corpus) and funds (upper hump)
- pyloric region( connects to duodenum)
the inner surface of the stomach is thrown into folds called ____ that include both mucosa and submucosa
rugae
a narrow circular region where esophagus connects to the stomach
- produces mucous
- simple unbranched tubular glands in lamina
cardiac stomach
4 cell types present in cardiac stomach
- mucous secreting cells
- lysozyme secreting cells
- enteroendocrine cells
- a few parietal cells
has branched tubular gastric glands,
each gastric gland is separated into 3 regions (isthmus, neck, base)
main part of stomach
body(corpus) and fundus
3 regions of a gastric gland
isthmus
neck
body
5 cell types present in gastric glands of the body and funds of the stomach
- isthmus mucous cells
- neck mucous cells
- parietal (oxyntic) cells
- chief (zymogenic) cells
- enteroendocrine cells
which type of cell is present in all 3 regions of a gastric gland
parietal cells
cells present in the isthmus of a gastric gland
parietal cells
isthmus mucous cells
cells present in the neck of a gastric gland
neck mucous cells
stem cells
parietal cells
cells present in the base of a gastric gland
peptic cells
parietal cells
neck mucous cells
nueroendocrine cells
present in isthmus
- similar to mucous secreting epithelial cells of gastric pit region
- secrete neutral mucus that protects surface from acid
isthmus mucous cells
may be present in clusters in the neck of gastric glands
- secrete acid glycoprotein mucus
irregular in shape with basal nucleus
neck mucous cells
these produce hydrochloric acid
- present in entire gland but fewer at the base of gastric gland
- rounded of pyramidal cells with spherical nucleus and acidophilic cytoplasm
- secrete intrinsic factor
- NO SECRETORY GRANULES
parietal (oxyntic) cells
what 2 things does a parietal cell secrete
- hydrochloric acid
2. intrinsic factor
essential for adsorption of vitamin B12 further down the digestive tract
- secreted by parietal cells in the stomach (body and fundus)
intrinsic factor
mainly in the base of gastric gland in the body of the stomach
- protein synthesizing and secreting cells structure
- granules in cytoplasm
- when pepsinogen is released, it activates these cells
- forms the proteolytic enzyme pepsin
and also secretes some lipase
chief (zygomatic) cells
chief cells in the body of the stomach become activated when ____ is released into the acidic environment of the stomach.
pepsinogen
what do the chief cells of the body of the stomach secrete/produce
- pepsin
2. some lipase
cells in the body of the stomach found at the base of gastric glands
- hormone function
- can release serotonin
enteroendorcrine glands
hormone % hydroxytryptamine (5-HT) is also called
- secreted from enteroendorcrine glads
- stimulates smooth muscle activity of the stomach
serotonin
the area of the stomach has deep gastric pits
- these glands secrete lysozyme and gastrin
- area closest to duodenum
pyloric stomach region
pylorus
hormone that stimulates the secretion of HCL by parietal cells that are mostly bin body and funds of stomach
gastrin
gastrin stimulates the secretion of ____ by parietal cells in the stomach body
hydrochloric acid (HCL)
the muscular layer of the stomach has 3 layers instead of 2
external muscle sublayer is longitudinal
middle muscle sublayer is circular
inner muscle sublayer is oblique
this organ will continue the process of digestion and will also act to absorb nutrients, essentially completing the digestive process that was started higher in the tract (mouth and saliva, stomach and acid/pepsin)
small intestine
long narrow tube about 21 ft in length
small intestine
how long is the small intestine
21 ft (4-7 meters)
3 segments of the small intestine
- duodenum (closest to stomach)
- jejunum
- ileum
shortest part of the small intestine
10 inches long (25-30 centimeters)
duodenum - 10 inches long
part of the small intestine that is 8ft long (250 cm)
jejunum
part of the small intestine that is 11 ft (350cm) long
ileum
what is the length of the entire small intestine
630 cm
6.3 meters
what is the circumference of the small intestine
0.1 m
surface area of the small intestine
6.78 sq ft
the folds of the wall of the small intestine that include both the mucosa and the submucosa are called
plicae circularis ( or valves of Kerckring) singular: plica circularis
the mucosa of the small intestine is divided up into 3 characteristic sublayers
- epithelial lining of lumen
- lamina propria (loose CT)
- muscularis mucosae (smooth muscle)
the epithelial lining of the small intestine is completely renewed every
2-5 days
there are around ____ microvilli convering every square millimeter of the surface of the small intestine
200 million
actual inner surface area of the small intestine
about 200 sq meters
2153 sq feet
cells present in to crypts of Lieberkuhn
- interspersed b/t columnar enterocytes
- less abundant in the duodenum and increase in number toward the ileum
- they produce mucus- lubrication for the intestinal tract
goblet cells
these cells are found in the basal regions of the crypts of Lieberhuhn
- synthesize a zymogen that is a precursor of lysozyme
Paneths cells
a neurohormone that will stimulate the contraction of smooth muscle causing an increase in motility of the intestine
serotonin
serotonin is secreted by
argentaffin cells
these cells take up amine precursors and decarboxylate them to amines for use in the synthesis of polypeptide hormones
- have endocrine function
- secrete gastrin, secretin, and somatostatin
APUD cells
Amine Precursor Uptake and Decarboxylation
APUD cells
Amine Precursor Uptake and Decarboxylation cells secrete _____,_____,_____ that affect activities of the stomach and small intestine
gastrin
secretin
somatostatin
stomach-G cell
gastrin
small intestine-S cell
secretin
duodenum and pyloric stomach-D Cell
somatostatin
A-stomach cells
glucagon
I - small intestine
cholecystokinin
at the beginning of the duodenum, coiled tubular glands located in the submucosa open into the base of the intestinal crypts that lie between adjacent villi
Brunner’s glands
Brunner’s glands secrete ____ ___ that protects the duodenal epithelium from stomach acids
alkaline mucus
these structures are the intestinal glands
- these extend into the lamina propria b/t adjacent villi
- the epithelium lining these glands is continuous with the epithelium of the villi
crypts of liberkuhn
section of the small intestine
- lacks brunner’s glands
- lacks lymph nodes in the lamina propria
- lacteals (lymph vessel in the lamina propria) are well developed to maximize fat absorption
jejunum
section of the small intestine
- presence of dense aggregations of diffuse lymphatic tissue and lymphoid nodules in the lamina propria and submucosa that are called peyer’s patches
ileum
dense aggregations of diffuse lymphatic tissue and lymphoid nodules in the lamina propria and submucosa called
- in ileum of SI
Peyer’s patches
specialized for
- water adsorption, electrolyte absorption, some vitamin absorption
- condensation and formation of the fecal mass
- mucus production for lubrication and gives body to feces
Large intestine
how long is the large intestine
1.5 meters
the epithelium lining the large intestine is a ____ ____ ____ of enterocyte absorptive cells with microvilli at apical ends and goblet cells
simple columnar epithelium
the entire walls of which compose the large intestine are made of
crypts of lieberkuhn
3 outer longitudinal bands of smooth muscle called the ____ ___-, in the muscularis externs of the colon
taenia coli
the serial layer of the colon is characterized by protuberances of adipose tissue called ___ ____
appendices epiploicae
there are a number of organ associated with the digestive tract that assist in the digestion of food in several ways (4)
- salivary glands
- pancreas
- liver
- gall bladder
secrete fluid and mucus to wet and lubricate ingested food
secrete various proteineceous enzymes (amylase, lipase, maltase) that initiate the process of digestion
salivary glands
what do salivary glands secret
fluid mucus amylase lipase maltase
7 types of salivary glands
- labial
- palatine
- parotid
- buccal
- submaxillary
- sublingual
- anterior lingual
a mixed endocrine and exocrine organ involved in digestion
pancreas
precursors of enzymes like lipase and the proteolytic digestive enzymes trypsin, and chymotrypsin are synthesized and secreted by ___ ___ of the pancreas
(exocrine function)
acinar cells
what is the exocrine function of the pancreas
zymogen secretion
enzymes (trypsin)
what is the endocrine function of the pancreas
hormone secretion
insulin, glucagon, and somatostatin are secreted by cells of the ___ ___ _____ in the pancreas
islets of langerhans
exocrine portion of pancreas is a ____, compound, acinar gland
racemose
small sacs that attach to a central (intercalated) duct of a racemose gland - compound
acinus cell
having the form of a raceme
racemos
a type of inflorescence composed of a group of structures connected to a central axis. usually related to flowers
raceme
T/F: the pancreas has a connective tissue capsule
true
ducts that the pancreatic acini connect to are called ______ ___ (ducts to which acini of a gland directly connect)
intercalated ducts
the intercalated ducts connect to ___ ___ located within the pancreatic lobes
intralobular ducts (not much CT)
the intralobular connect to larger ____ ____ in the septa between lobes
interlobular ducts (lots of CT)
interlobular ducts connect to the main pancreatic ducts, the major duct of ____ and the accessory duct of ______
major duct of Wirsung
accessory duct of Santorini
all secretions eventually reach the main pancreatic ducts that empty into the ___ ___ duct via the duct of Wirsung in humans
common bile duct
pancreatic exocrine secretion is controlled by the hormones ____ and _____
secretin and cholecystokinin
endocrine portion of pancreas
- amongst the acini of the pancreas are globular cellular aggregations containing a number of different types of secretory cells and fenestrated capillaries, these aggregations are called
islet of langerhans
these contain the cells that secrete
glucagon
insulin
and somatostatin
islets of langerhans
alpha cells of the islets of langerhans in the pancreas secrete
glucagon
20% of the cells
what % of the islet of langerhans in the pancreas are alpha cells that secrete glucagon
20%
beta cells of the islets of langerhans in the pancreas secrete
insulin
70% of cells
what % of the islet of langerhans in the pancreas are beta cells that secrete insulin
70%
delta cells of the islets of langerhans in the pancreas secrete
somatostatin
5%
what % of the islet of langerhans in the pancreas are delta cells that secrete somatostatin
5%
increases blood glucose
glucagon
lowers blood glucose
insulin
inhibits release of growth hormone
somatostatin
glucagon has what effect
increases blood glucose
insulin has what effect
lowers blood glucose
somatostatin has what effect
inhibits release of growth hormone
if enzymes are activated inside pancreatic ducts, it will cause ______, will start to digest pancreas
pancreatitis : inflammation of the pancreas