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hollow tube that wind through the body
alimentary canal or gi tract
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The GI tract includes (7):
mouth, pharynx, esophagus, stomach, SI, LI and anus
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The accessory digestive organs include:
teeth, tongue, gallbladder, salivary glands, liver and pancreas
-
__________ organs assist in the digestion of food material, but are not necessarily required.
accessory
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The purpose of the digestive system is to acquire _______ and __________.
nutrients and water
-
T/F Food never enters the body.
True! it remains outside the body but passes through it
-
Alcohol is absorbed through the __________
stomach
-
nutrients are absorbed through the ____________-
small intestines
-
water, electrolytes and vitamins are absorbed by the ______________
large intestines
-
Absorbed nutrients are passed into _______ of the digestive system and then go into the _________.
veins, liver
-
Fats are absorbed through the small intestine and passed into the lymphatic system through a
lacteal duct
-
fats will eventuall enter into the ______________ system
circulatory
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The ___________ colon is a storage site for feces.
sigmoid
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There are 6 essential food-processing activities of the Digestive system:
ingestion, propulsion, mechanical disgestion, chemical digestions, absoption, defecation
-
Propultion = __________(party voluntary) and ______________ (involuntary movement of food)
swallowing and peristalsis
-
mechanical digestion = cheming, churning food in stomach and ___________. It occurs in the mouth, __________ and ___________.
segmentation, stomach, SI
-
CHemical disgestion = breakdown of food into molecules occurs in the _______, ____________, and _____________.
mouth, stomach, SI
-
Absorption= transporting nutrients/electrolyts/ water into __________; and fats into the ____________
veins, lymphatics
-
Defecation
elimination of indigestible substances
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Peristalsis vs. Segmentation
Peristalsis utilizes coordination of these muscles to propel food through lumen.
Segmentation utilizes these muscles to mix rather than propel.
-
The organization for the entire length of the GI tract it: (4)
mucosa, submucosa, muscularis externa, serosa or adventitia
-
true epithelium+lamina propria+muscularis mucosae
*epithelium is either stratified squamous or simple columnar
mucosa
-
contains arteries, veins, nerves, lymphatics and sometimes mucus glands
submucosa
-
a layer of smooth muscle (muscularis)
muscularis externa
-
a layer of mesothelium
serosa or adventitia
-
Enteric Nervous plexes
- independent control of digestion
- made up of submucosal and myenteric layers
-
Signals submucosal glands to secrete and muscularis mucosae to contract
submucosal
-
located between the ciruclar and longitudinal layers of muscularis externa; controls peristalsis and segmentation
myenteric
-
Ther are 4 mucosal types in the GI tract:
protective, secretory, absorptive and absorptive/protective
-
stratifies squamous epithelium found in the oral cavity, pharynx, esophagus and anal canal
protective mucosa
-
simple columnar eithelium; specialized for secreting mucous; contains mucus-secreting cells and mucus-neck cells (stomach)
secretory
-
simple columnar cells; modified for absorbing nutrients (SI)
absorptive
-
simple columnar cells; for absorbing water/electrolytes switching to stratified squamous; absorptive cells in LI, stratifies squamous in anal canal
absorptive/protective mucosa
-
the line between the tooth and gum
alveolar ridge
-
the space between the lip and the alveolar ridge
vestibule
-
a fold
frenulum
- labial frenulum =lip to the gum
- lingual frenulum = tongue to floor of oral cavity
-
Salivary glands open into the oral cavity ___________ and ____________.
under the tongue and through the cheek
-
the ________ dangles down from the soft palate
uvula
-
the lips are formed from _______ _____, and the cheeks are formed by the _____________ muscle
orbicularis oris, buccinator
-
Lateral arches of the soft palate:
- palatoglossal arch (palate to tongue)
- palatopharyngeal arch (palate to pharynx)
- *palatine tonsils are between the two arches
-
The congue is covered with ___________.
papillae ARE NOT TASTE BUDS
-
A type of papillae that resembles pointed cones; most numerous; no tastebuds
Filiform papilla
-
A type of papillae that resemble mushrooms; possesses taste-buds
fungiform papillae
-
a papilla resembling a circular wall; possesses taste-buds
circumvallate papillae
-
separates the circumvallate papilla and lingual tonsil
sulcus terminalis
-
the opening between the oral cavity and the oropharynx
palatoglossal arch - uvula - sulcus terminalis
fauces
-
ring of protective tonsils in the oropharnyx = palatine + lingual tonsils
tonsilar ring
-
produce and deposit saliva into oral cavity
salivary glands
-
salivary gland made of serous cells; secrete amylase and lysozymes; parotid duct passes through buccinator muscle
parotid gland
-
enzyme to digest carbohydrates
amylase
-
enzyme to lyse bacteria
lysozyme
-
glands composed of mucous cells; secrete mucus for lubrication; utilizes many ducts
sublingual
-
gland made of serous and mucous cells; usues the submandibular duct
submandibular gland
-
Types/numbers of teeth per side
- 2 incisors
- 1 canine
- 2 premolars
- 3 molars
-
carries food material (bolus) from oral cavity to stomach
esophagus
-
muscularis externa:
the upper 1/3 is _________ muscle
the middle 1/3 is ___________
the inferior 1/3 is __________ muscle
- skeletal (voluntary)
- mixed
- smooth (involuntary)
-
esophagus: The the lumen is collapsed except when
food passes through it
-
esophagus: the mucosa has a protective ____________ __________ epithelium
stratified squamous
-
esophagus: there are __________ glands in the submucosa
*as the bolus passes the glands, they secrete mucus for lubrication
mucous
-
esophagus: the external layer is ________ not ___________.
adventitia not serosa
-
The esophagus passes through the diaphragm at the level of
T10
-
The muscularis externa ______ function as the sphincter of the esophagus
MAY
-
muscle fibers of the diaphragm serve as a functional sphincter muscle in the esophagus
cardiac sphincter
-
A site for chemical and mechanical digestion
stomach
-
Regions of the stomach (4)
cardiac, fundus, body, pyloris
-
a sphincter to prevent food from leaving the stomach
pyloric sphincter
-
Greater curvature
greater omentum
-
lesser curvature
lesser omentum
-
folds formed when stomach decreases in sizes
rugae
-
stomach: lined by modified simple columnar cells called "mucus-secreting cells"
gastric pits
-
T/F there are goblet cells in the stomach
FALSE, some texts are in error
-
secrete mucus and line the neck of the gastric pit
mucus neck cells
-
The mucus mucus protects the stomach from
digesting itself
-
The _______ and __________ of the stomach are called Gastric Pits
fundus and body
-
the gastric pits have ___________ glands
gastric
-
Types of cells in the gastric glands:
parietal cells, chief cells, enteroendocrine cells
-
What is the function of parietal cells?
- secrete HCl and intrinsic factor (for absorption of Vitamin B12)
- HCl makes pH=2 (hydrolyze food and kill microorganisms)
-
Function of cheif cells?
secrete Pepsin (protease) to breakdown proteins
-
Function of Enteroendocrine cells
secrete gastrin
-
When food enteres the stomach, _________ is produced
gastrin
-
Gastrin stimulates Parietal cells to secrete
HCl
-
Has 3 layers of smooth muscle: innermost oblique, middle circular and outer longitudinal
The muscularis externa
-
The pyloric sphincter muscle is formed from a thinkened ______ ________ layer.
middle circular layer
-
A site for absorphtion of nutrients (carbs, proteins and fats)
SI
-
Three parts of the SI
duodenum + jejunum + ileum
-
the duodenum begins after the _______ ___________.
pyloric sphincter
-
the ileum ends at the ____________ _______.
ileo-cecal valve
-
Modified simple columnar cells for absorbing nutrients
absorptive cells
-
specialized ducts of the lymphatic system to carry fats; absorptive cells transfer the emulsified fats into lacteal ducts
Lacteal vessels (or capillaries)
-
Mucus secreting cells in the SI
goblet cells
-
aggregated lymphoid nodules
(lymphoid tissue that appears as macroscopic white patches - only in the SI)
Peyer's patches
-
The muscularis externa has 2 layers of smooth muscle
- -inner circular
- -outer longitudinal
-
The surface of the lumen has modifications to increase surface area for absorption such as:
plica circularis, villi, microvili,crypts, and paneth cells
-
Thinkened areas of submucosa
plica circularis
-
macroscopic finger-like projections of the mucosa
villi
-
microscopic folds on apical surface of cells
microvilli
-
located in SI between adjacent villi
crypts (of lieberkeuhn)
-
Located at he base of crypts; secrete lysozymes to lyse bacteria
Paneth cells
-
Mucus secreting cells in the submucosa of the duodenum specifically
Brunner's glands
-
Food material entering duodenum stimulates the secretion of cholecystokinin and secretin
enteroendocrine cells
-
Signals the gallbladder to contract and release bile into the duodenum
Cholecystokinin (CCK)
-
Stimulates the pancrease to secrete digestive juices and bicarbonate into duodenum
Secretin
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