Digestive Flashcards
wWhat are the 2 main types of organs of the digestive system? Which organs make up each type? (6, 6)
- alimentary canal
- mouth, pharynx, esophagus, stomach, SI, LI - accessory organs
- teeth, tongue, gallbladder, salivary glands, liver, pancreas
What are the 6 function of the digestive system?
Ingestion Propulsion Mechanical breakdown Digestion Absorption Defecation
What does mechanical breakdown involve? and where? (3)
- chewing in mouth
- churning in stomach
- segmentation in SI
What does propulsion involve (2)
swallowing (oropharynx)
peristalsis (esophagus, stomach, SI, LI)
Peristalsis and segmentation movements are a result of ___ contraction and relaxation.
smooth muscle
What are the 4 basic layers of the alimentary canal from inner to outermost layer?
Mucosa
Submucosa
Muscularis externa
Serosa
What is the function of the mucosa? (3) What are its 3 sublayers? What do each layer do?
Secretes mucus, digestive enzymes, and hormones
Absorbs end products of digestion
Protects against infectious disease
Three sublayers:
- epithelium secretes mucous/enzymes/hormones
- lamina propria contains capillaries for nourishment/absorption & lymphoid follicles (MALT)
- muscularis mucosae for movement of mucosa
What does mucous do? (2)
Protects digestive organs from enzymes
Eases food passage
what does the submucosa contain? (3)
blood/lymphatic vessels, nerves
What 2 movements is the muscularis externa responsible for? Which muscle is used for each movement? What kind of motion is it? Which muscle is the sphincters made of?
- segmentation = circular muscle (back and forth motion)
- peristalsis = longitudinal muscle (squeezing motion)
sphincter = circular layer
Serosa (visceral peritoneum) is replaced by ___ in the esophagus
adventitia
the mucosa, submucosa, and serosa are made of ___ tissue.
areolar connective tissue
What is the oral cavity bounded by? (4)
lips, cheeks, palate, and tongue
What are the hard and soft palates made of? What are their functions? What hangs from the soft palate?
hard palate = bone; create friction against tongue to help breakdown food
soft palate = skeletal muscle; closes off nasopharynx during swallowing
uvula hangs
What muscle is the tongue made of? What is its function? (5) What attaches it to the floor of the mouth? What enzymes gets secreted and what do they digest (2)?
-skeletal muscle
Functions
- Repositioning and mixing food during chewing
- Formation of bolus
- Initiation of swallowing, speech, and taste
- Lingual frenulum: attachment to floor of mouth
- lingual lipase = simple fats
- amylase = carbs
What is the function of a papillae? What are the 4 types of papillae of the tongue and which one do not contain taste buds?
- give sensations of touch
- filiform (do not contain taste buds), fungiform, vallate, and foliate
What are the major salivary glands? What is the difference between minor salivary glands?
- parotid, submandibular, sublingual (likes outside oral cavity)
- minor scattered throughout oral cavity
What are the functions of saliva? (4)
Cleanses mouth
Dissolves food chemicals for taste
Moistens food; compacts into bolus
Begins breakdown of starch with enzymes
Mumps is the inflammation of ___ gland.
parotid
What are the 2 types of secretory cells in salivary glands? What makes up each? Which ones are found in the paratid, submandibular, and sublingual glands?
serous cells: watery, enzymes, ions, mucin
-parotid & submandibular
mucous cells: mucus
-sublingual
What is the function of the teeth? why are 20 deciduous teeth replaced by 32 permanent teeth?
- Tear and grind food for digestion
- replaced to accommodate change in jaw size
What are the 4 different kinds of teeth and its functions?
incisors - cutting
canine - tear/pierce
premolar - grind/crush
molar - grind
State the dental formulas for both deciduous and permanent teeth.
In a tooth, ___ is the entry for blood vessels, nerves, which run in the ___.
apical foramen is the entry for blood vessels, nerves, which run in the pulp cavity
___ is the hardest substance in body. What is it used for? What cells produce them? What happens to these cells when the tooth erupts? What does this do?
enamel
force of chewing
Enamel-producing cells degenerate when tooth erupts > no healing if decay or crack
True or false
There are some movement in the root of tooth
true
___ anchors tooth in bony socket
Periodontal ligament
what is dentin?
bonelike material under enamel
(if time) What is in saliva? (7)
water, electrolytes, amylase, lipase, mucin, metabolic waste (urea & uric acid), lysozyme/IgA/defensins (etc. for immune function)
What is the passageway of food through the pharynx? It allwos passage of ___ (3). What cells line the epithelium?
mouth → oropharynx → laryngopharynx
Allows passage of food, fluids, and air
stratified squamous
The esophagus transports ___ from ___ of the mouth to ___,
-transport bolus from mouth (laryngopharynx) to stomach
What is heartburn? What are causes?
Stomach acid regurgitates into esophagus
-Likely with excess food/drink, extreme obesity, pregnancy, running
What is the function of the upper (2) and lower (1) esophageal sphincters?
Upper
- prevent air from entering the esophagus when breathing
- prevent reflux of esophageal contents into pharynx and blockage
Lower
-prevent reflux of stomach acid into the esophagus
What are the 3 layers muscle in the esophagus?
skeletal superiorily
mixed middle
smooth inferiorily
What are the 4 digestive processes of the mouth?
ingestion
Mechanical breakdown - Chewing
Propulsion - Deglutition (swallowing)
Digestion (salivary amylase and lingual lipase)
What body parts do deglutition involve? What are the 2 phases of deglutition? Are they voluntary or involuntary? Where are the control centers? Where do the larynx rise?
tongue, soft palate, pharynx, esophagus
- buccal phase - voluntary contraction of tongue
- pharyngeal-esophageal phase - involuntary by vegas nerve (control center in medulla & pons)
- here, uvula and larynx rise to prevent food from entering respiratory passageways
In the stomach, the bolus becomes ___.
chyme
In the stomach, what is the function of the cardiac and pyloric sphincters?
cardiac sphincter - prevent stomach contents from going back up into the esophagus
pyloric sphincter - controls passage of food down to the small intestine
What is the cardia?
where food enters from the stomach
function of fundus, body, and pylorus (3)
fundus = collect digestive gas body = secretes pepsinogen and HCl pylorus = secretes mucus, gastrin, pepsinogen
What are the 2 mesenteries of the stomach? What do they do?
lesser & greater omentum tether stomach
What is the additional muscle on top of circular and longitudinal found in the stomach, and what does it do?
Inner oblique layer allows stomach to churn, mix, move, and physically break down food
What is the function of rugae? (2)
increase SA for digestion and allow for distensibility of stomach
What cells make up the gastric glands of the stomach?
mucous cells, mucous neck cells, parietal cells, enteroendocrine cells
Gastric juice is mostly produced by these 2 areas of the stomach.
fundus & body
What does the parietal cell secrete? What do those secretions do? What is it also called?
HCl - activates pepsin
intrinsic factor - required for absorption B12 in SI
xynic cell
What does the chief cell secrete? (2) What is it also called?
pepsinogen - digest proteins
lipase - digest lipids
zymogenic cells
Pepsinogen activation is an example of ___
positive feedback mechanism (pepsin turns on more pepsinogen)
What de enteroendocrine cells secrete? (2) What is a specific example? What does that hormone do?
hormones (including gastrin) & paracrines
gastrin = turns on stomach
What is the function of mucous cells?
secrete mucous that protects stomach from HCl
The function of the mucosal barrier is to ___. They have ___ between epithelial cells. The damaged epithelial cells are also ___.
-protect from digestive enzymes
-tight junction (Prevent juice seeping underneath tissue)
replaced by rapidly dividing stem cells
What are the digestive processes that occur in the stomach? (6)
Mechanical breakdown
Denaturation of proteins by HCl
Enzymatic digestion of proteins by pepsin
Delivers chyme to small intestine
Lipid-soluble alcohol and aspirin absorbed into blood
Secretes intrinsic factor for vitamin B12 absorption
What is the one stomach function essential to life? What is it needed for? What is the disease called when do not have enough?
Secretes intrinsic factor for vitamin B12 absorption
B12 needed to mature red blood cells
Lack of intrinsic factor causes pernicious anemia
What produces gastrin? (2) What stimulates its secretion? What is its function? (2)
- pyloric antrun & duodenum
- vagus nerve stimulation (decreased secretion with sympathetic stimulation)
- turns on stomach (↑Enzyme and HCl secretion)
What produces gastrin? What stimulates its secretion? What is its function? (2)
- G cells of pyloric antrum & duodenum
- vagus nerve stimulation (decreased secretion with sympathetic stimulation)
- turns on stomach (↑Enzyme and HCl secretion)
What are the 3 stages of gastric secretion (regulation) in the stomach?
- cephalic (reflex) phase
- gastric phase
- Intestinal phase
In the gastric phase, what 3 chemicals stimulate the parietal cell through second-messenger systems? What does this ensure?
ACh, histamine, gastrin ensure max HCl secreted
When does the cephalic (reflex) phase occur? What is it triggered by? (4)
- begins before food enters mouth
- triggered by aroma, taste, sight, thought
How does HCl form?
What happens in the stimulatory component of the intestinal phase of gastric secretion?
Partially digested food enters small intestine to encourage more secretion of gastrin
What regulates the inhibitory effect on the intestinal phase of gastrin secretion? (2) What is the effect of the 2?
- enterogastric reflex
- triggered by Chyme with H+, fats, peptides, irritating substances
- inhibit vagus nerve
- inhibit local reflex
- Activate sympathetic fibers → tightening of pyloric sphincter → no more food entry to small intestine - enterogastrones
- secretin and CCK released which inhibits gastric secretion
Decreased gastric activity → protects small intestine from excessive acidity & prevents duodenum from being overwhelmed with food
Gastric juice secretion regulation chart
The ___ supply the alimentary canal and control GI tract wall motility. What stimulates and inhibits digestive activities?
enteric neurons
Sympathetic impulses inhibit digestive activities
Parasympathetic impulses stimulate digestive activities
What are the3 subdivisions of the small intestine?
duodenum, jejunum, ileum
In the duodenum, the ___ duct and ___ duct join at the ___, enters at the ___, whose entry is controlled by ___.
Bile duct (from liver) and main pancreatic duct (from pancreas) Join at hepatopancreatic ampulla Enter duodenum at major duodenal papilla Entry controlled by hepatopancreatic sphincter
What is the length of each part of the SI from shortest to longest?
duodenum < jejunum < ileum
What are the 3 structural modifications that increase nutrient absorption in the SI?
Circular folds (plicae circulares)
Villi
Microvilli
What does microvilli have?
brush border enzymes to digest carbs, protein, nucleic acids not digested up until this point
The ___ in the SI contains lacteals
vili
What is the function of the jejunum and ileum (3)? What is the difference between the 2?
- jejunum = absorption of nutrients
- ileum = absorption of anything not absorbed until this point & B12 & bile salts
-ileum has a lot of lymphoid tissue (peyers patches)
What do intestinal crypts contain? (3)
enteroendocrine cells (that make enterogastrones), IELs/paneth cells (that kill pathogens), stem cells
What is the function of the liver? (2) What is it?
produce bile (fat emulsifier) & detoxify
What is the function of the gallbladder?
bile storage
___ is the largest gland in the body.
liver
Identify the 4 lobes of the liver
The ___ anchors liver to stomach.
lesser omentum
The ___ peritoneum is on the external surface of digestive organs and ___ peritoneum lines body wall.
Visceral peritoneum on external surface of most digestive organs
Parietal peritoneum lines body wall
What is a mesentery? What is its functions? (3)
- double peritoneum layer
- routes for vessels, lymph, nerves to reach digestive organs
- store fat
- hold organ in place
___ chyme moves quickly through duodenum and ___ chyme remains duodenum 6 hours or more
Carbohydrate-rich chyme moves quickly through duodenum
Fatty chyme remains in duodenum 6 hours or more
The ___ cells secrete pancreatic juice in pancreas.
acinar
What does the pancreatic juice contain? (3)
Watery alkaline solution (pH 8) neutralizes chyme
Electrolytes (primarily HCO3–)
Enzymes - Amylase, lipases, nucleases, protease
What is bile secretion stimulated by?
Bile salts, CCK
What is gallbladder contraction stimulated by?
CCK exposed to acidic, fatty chyme, vegas nerve (VN)
Hepatopancreatic sphincter closed unless digestion active. ___ causes the sphincter to relax.
CCK
Pancreatic secretion is induced by (3)
CCK, secretin, vagal stimulation
Mechanism of secreting and releasing bile and pancreatic juice. Image.
Small intestine, like stomach, no role ___ or ___.
Small intestine, like stomach, no role in ingestion or defecation
Most of the water is absorbed in the ___.
small intestine
Segmentation or peristasis is most common motion of SI?
segmentation
____ moves Meal remnants, bacteria, and debris moved to large intestine
peristalsis
What initiates segmentation and peristalsis?
segmentation = pacemaker cells peristalsis = hormone motilin
What movement Mixes/moves contents toward ileocecal valve?
segmentation
What is the migrating motor complex? Where does it occur? What movement is responsible for it?
each peristalsis wave move food closer and closer to the ileum
What does the Gastroileal reflex do?
enhances force of segmentation in ileum
When does the Ileocecal sphincter relaxes and admits chyme into large intestine? (2)
Gastroileal reflex enhances force of segmentation in ileum
Gastrin increases motility of ileum
What are the 5 regions of the LI?
Cecum Appendix Colon Rectum Anal canal
What is the function of the ileocecal valve?
Prevents regurgitation into ileum
What is the function of the cecum?
digest cellulose
What is the appendix made of? What is its function? Does it count as a part of the alimentary canal?
- masses of lymphoid tissue (Part of MALT of immune system)
- storehouse for good bacteria
The internal anal sphincter is ___ muscle. The external is ___ muscle. How does defecation happen?
Internal anal sphincter—smooth muscle
External anal sphincter—skeletal muscle
internal sphincter to relax while the external one contracts; shortly thereafter the external sphincter also relaxes and allows fecal discharge.
What is the function of the colon? ascending? descending? sigmoid? Rectum? Anus?
removes water and some nutrients and electrolytes from partially digested food
- ascending colon is to absorb the remaining water and other key nutrients f
- descending colon stores feces
- sigmoid colon contracts to increase the pressure inside the colon, causing the stool to move into the rectum
- rectum holds the feces awaiting elimination by defecation.
- anus where stool leaves body
What digestive processes occur in the LI? (4)
No food breakdown
propulsion of feces to anus
defecation
Vitamins (made by bacterial flora), water, and electrolytes (especially Na+ and Cl–) reclaimed
What are contractions of the colon called? What is it?
Haustral contractions
Slow segmenting movements
What is the Gastrocolic reflex? What is it initiated by?
Initiated by presence of food in stomach
Activates three to four slow powerful peristaltic waves per day in colon (mass movements)
What makes cholecystokinin (CCK)? What is the stimulus for production? What does it do? (3)
duodenal mucosa
stimulus = fatty chyme
- slows down stomach function by encouraging chyme to move down duodenum
- help production of bile
- encourages motility in SI
Where is secretin made? What is the stimulus for production? What does it do?
duodenal mucosa
stimulus = acidic chyme
turns on liver & gallbladder
Where is glucose-dependent insulinotropic peptide produced (GIP)? What is the stimulus for production? What does it do? (2)
duodenal mucosa
stimulus = fatty chyme
- inhibits HCl production in stomach
- stimulates insulin release in pancreas
Where is histamine produced? What is the stimulus for production? What does it do?
stomach mucosa
stimulus = food in stomach
activates parietal cells to secrete HCl
Where is somatostatin produced? What is the stimulus for production? What does it do? (4)
stomach & duodenal mucosa
stimulus = food in stomach & sympathetic nerve fibers
inhibits release gastric, pancreatic, bile juice
inhibits GI blood flow/absorption
Where is motilin produced? What is the stimulus for production? What does it do?
duodenal mucosa
stimulus = fasting, neural stimuli
stimulates migrating motor complex
Explain the effect of the cephalic phase of regulation on the mucous glands. What is it essential for? What cells secrete the watery and mucous?
- SNS activation causes the release of mucin-rich saliva (mucous)
- PNS activation causes release of serous saliva
- essential in swallowing
- done by mucous and goblet cells
What digestive enzymes break down carbs and where?
Salivary amylase (mouth), pancreatic amylase (SI), and brush border enzymes (SI)
Which enzymes break down protein and where? (3)
pepsin (stomach), pancreatic protease (SI), Brush border enzymes (SI)
Which enzymes break down lipids and where?
lingual lipase (mouth), gastric lipase (stomach), emulsification by bile (SI), pancreatic lipase (SI)
Which enzymes break down nucleic acids and where?
pancreatic nuclease (SI), brush border enzymes (SI)
All food; 80% electrolytes; most water is absorbed in the ___. Most are absorbed by ___, except lipids.
SI, active transport
For absorption, lipids enter ___.
lacteals
Water is absorbed via ___.
osmosis
Describe how the digestive organs to all work together to digest food.
Mouth
- salivary glands secrete salivary amylase and lipase to start the breakdown of starch/carbs and simple fat
- tongue facilitates swallowing of the food and into the esophagus (where buccal and pharyngeal/esophageal phases occur)
- cephalic phase turns on secretion of mucous
Esophagus
-peristalsis propels food from laryngopharynx to stomach
Stomach
- cephalic phase turns on gastric glands of stomach
- gastric phase turns on secretion of gastrin which turns on secretion of digestive enymes and HCl
- this is where pareital cells secrete HCl which denatures proteins
- chief cells secrete pepsinogen which is turned on by HCl which then breaks down protein
digestive activity is controlled by ___
mechanical and chemical receptors in the walls of tract organs
digestion is dehydration synthesis/hydrolysis
hydrolysis
what is digestion
food breakdown
contains lobules with sinusoids
liver
true or false
bile is a salt and do not have enzymes
true
what is the function of goblet cells
secrete mucous that protects from digestive enzymes
what is constipation and diarrhea? what are some causes?
constipation = food move too slow thru LI
-too little fiber, dehydration, lack of exercise
diarrhea = chyme moves too fast thru LI
-viral infections, medication
Region where mechanical digestion important
Region that are food conduits
Region that begins protein digestion
Region fat digestion begins
Region where mechanical digestion important - mouth, SI
Region that are food conduits - esophagus, anal canal
Region that begins protein digestion - stomach
Region fat digestion begins - mouth
last place in elementary canal where food can be digested
duodenum (with gallbladder & pancreatic enzymes)
laces where start to absorb the nutrients
jejunum
this layer has the glands that secrete juice
submucosa
the esophagus and anus have ___ epi
stratified squamous
what is bolus, which is made in the?
Amylase, lipase, water
-mouth
what do gastric pits contain
parietal, chief, mucous cells, enteroendocrine cells
Difference in mucosa layer of alimentary canal from esophagus to anus
esophagus/anus - stratified squamous
stomach - gastric pits (chief, parietal, mucous, enteroendocrine cells), rugae
small intestine - intestinal crypt (lacteals), circular folds, microvilli (brush border enzymes). ileum = peyers patches
large intestine - more goblet cells
what kind of enzymes do the pancreas secrete?
pancreatic lipase, protease, nuclease, amylase all of it
