Digestive system

organs of the alimentary canal

(MPESSL) mouth, pharynx, esophagus, stomach, small intestine, large intestine

accessory organs of digestion

(TTLGPS) teeth, tounge, liver, gallbladder, pancreas, salivary glands

alimentary canal

tube that food travels through

digestion

process/unit that breaks down the food

mechanical digestion

food is physically broken down

chemical digestion

enzymes/acids break down food molecules

layers of the wall of the alimentary canal (superficial to deep)

(SMSM) serosa, muscularis externa, submucosa, mucosa

peristalsis

rhythmic contractions of the smooth muscle of an organ that results in food being pushed along

where does peristalsis happen

esophagus, stomach, small intestine, large intestine (ESSL)

bolus

soft, round piece of chewed up food with saliva

structures involved in making bolus

teeth, touth, salivary gland, mouth

bolus formation process: teeth _________ break down food, ______ mixes food with saliva and makes the bolus shape, _________ ______ secrete saliva to moisten food

mechanically, tounge, salivary gland

what two strucutres are responsible for making sure that food goes in proper direction when swallowed

epiglottis and upper esophageal sphincter

hiatal hernia

encourages stomach acid to enter the esophagus, gastro esophageal reflux disease (GERD aka heartburn )

how long is the alimentary canal

9 meters

what 3 cells make up gastric glands

Mucous cells,Chief cells, Parietal cells

Mucous cells

Secrete mucus → protects stomach lining from acid and enzymes

Chief cells

Secrete pepsinogen → inactive enzyme that becomes pepsin (digests protein)

Parietal cells

Secrete hydrochloric acid (HCl) and intrinsic factor → HCl activates pepsin & kills bacteria; intrinsic factor helps vitamin B₁₂ absorption

secretion of gastric gland cells make up ______ _____

gastric juice

what is gastrin

digestive hormone

what does gastrin do

stimulate gastrin glands to increase their secretion of gastric juices

what is the semifluid paste that is food mixed up in your stomach

chyme

components of pancreatic juice

pancreatic amylase, pancreatic lipase, nucleases, proteases, and bicarbonate ions

Pancreatic amylase

Breaks down starch → sugars

Pancreatic lipase

Breaks down fats → fatty acids + monoglycerides

Proteases

Break down proteins → peptides/amino acids

Bicarbonate (HCO₃⁻)

Neutralizes stomach acid → protects small intestine & helps enzymes work

_______ activates protein digesting

enteropeptidase, from the pancreas (inactive) intestine (activates it)

chyme stiumlates _______ of ______

release, secretin

secretin

hormone from small intestine, stimulates pancreas to release pancreatic juice into duodenum

what does cholecystokinin (CCK) do

hormone from the small intestine, stimulates release of bile from gallbladder

mouth

beginning of alimentary canal, receives food, breaks down, and moistens it

teeth

break off food, mastification

tongue

mixes food w saliva, contain papillae to grip food and increase friction, move bolus toward pharynx

hard palate

rood of mouth, mostly maxillary bone and small amount of palatine

soft palate

posterior to hard palate, has uvula

what moves up and back during swallowing to partially block opening into nasal cavity

soft palate and uvula

sets of tonsils

palatine, pharyngeal (adenoids), lingunal (posterior region of tongue)

tonsils

all contain lymphatic tissue, wbc to fight infections

salivary glands

release saliva thru tiny ducts to bind and moisten food

saliva contents

water, mucous, salivary amylase, lysozyme

salivary amylase

enzyme that begins chemical digestion of carbohydrates

lysozyme

antibacterial enzyme protects teeth

salivary glands and positions

parotid (around ear), submandibular (below lower jaw), sublingual (below tounue)

pharynx

throat, no digestion/absorption, transport food to esophagus, 3 regions

esophagus

muscular tube, no digestion/absorption

esophagus transports food to

stomach

food from esophagus passes through an opening in the ________ to reach stomach

diaphgram

sphincters

ciruclar rings of muscle (smooth or skeletal)

sphincters are normally ________ and relax to allow _______

relaxed, passage

6 spinchters

Upper Esophageal, Lower Esophageal, Pyloric , Oddi, Ileocecal , and the Anal (internal & external) - (UELEPOIA)

lower esophageal sphincter

at junction of esophagus and stomach, near heart, aka caridiac sphincter

stomach has _ regions

4

rugae

folds on inner stomach wall to help w expanding

stomach is ____-like nad holes ___L

pouch, 1.5

stomach has _ layers of ______ muscle fibers

3, smooth

gastric pits

indentations on inner stomach wall

gastric glands

located deep inside gastric pits

parietal cells are needed for ____________

hematopoiesis

very ____ absorption from stomach into __________ (___ and ________ are exceptions)

little, bloodstream, H2O, medications

____ enters the ______ through ____ sphincter

chyme, duodenum, pyloric

_____ of chyme must be _______

acidity, neutralized

____ and _______ ____ both must pass through the ____________ sphincter (aka oddi) to enter ______ intestine

bile, pancreatic juice, hepatopancreatic, small

liver: _______ visceral organ

largest

liver: stores

glucose and vitamins

liver metabolizes what

proteins, fats, cholestrol

liver: forms ___ and secretes in into ___________

bile, gallbladder

gallbladder is a _____, ____, sack used for sorting and concentration bile, aka a _____

small, thin, cyst

gallbladder: _______ based solution

cholestrol

emulsification of

fats

emulsification

breaks large fat molecules into small, increase surface area, allow enzymes to work more efficiently

gallbladder absorbs _____ from ____ increasing concentration of fluid

fluid, bile

if too much water is absorbed, _______ can percipitate into a solid forming _________

cholestrol, gallstone

small intestine lenght

6m 20ft

small intestine extends from _____ sphincter to _______ sphincter

pyloric, ileocecal

3 segments on small intestine

duodenum, jejunum, ileum

small intestine secrete ______ to finish breakdown of food

enzymes

intestinal lipase

digestion of fatty acids

amino peptidase

splits amino acids

what acts upon disacharides

sucrase, maltase, lactase

nucleases

act upon nucleic acids

small intestine

most enzyme release and absorption of nutrients is accomplished in duodenum

inner lining of small intestine (what food actually touches)

mucoasal surface, very irregular

large circular folds in the lining of the small intestine

plicae circular

plicae circular has finger like structure

villi

villi contain capillaries for absorption of

glucose and amino acids

villi contain lacteals for absorption of

fatty acids

infection/irritation in small intestine increases _______ and moves _____ quickly through small and large intestine

peristalsis, material

peristaltic rush aka

diarrhea

in the small intestine, ileocecal valve regulates movement of material into _____ intestine

large

large intestine aka

colon

large intestine

reabsorbs water, forms solid waste

parts of the large intestine in order superfical to deep

cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal

internal anal sphincter

smooth muscle, involuntary, contracted until pressure stimulates it to relax

external anal sphincter

skeletal muscle, voluntary, can be contracted to keep solid waste in until appropriate to allow to relax before deification