GI Anatomy Flashcards
Oral cavity
Includes mouth, teeth, gums, tongue, palate, palatine tonsils
Food is ingested and prepared for digestion
2 parts = oral vestibule (slit-like space between teeth and lips), oral cavity proper (space between upper and lower dental arches, fully occupied by tongue when at rest)
Lips
Upper and lower lips are mobile muscular folds surrounding the mouth
Covered externally by skin and internally by mucous membrane
For grasping food, clearing food, sucking liquids, forming speech, and osculation
Labial frenula are free-edged muscosal folds in midline of lips
Cheeks
Form over zygomatic bones and prominences
Essentially same structure as lips
Buccal fat pad more prominent in babies to reinforce cheeks and prevent collapse when sucking
Gingivae (gums)
Fibrous tissue covered with mucous membrane
Gingivae proper is firmly attached to alveolar processes and teeth
Excellent blood supply and nervous innervation
Gingivitis can spread to other structures (teeth, connective tissue, etc)
Teeth
Hard conical structures set within alveoli of upper and lower jaws
Used in mastication and assist in articulation
Identified and described based on whether it is primary or secondary, type of tooth, and location
Adults normally have 32secondary teeth = medial incisor (1), lateral incisor (1), canine (1), premolars (2), molars (3)
Parts of a tooth = crown, neck, root
Composed of dentin and covered by enamel over crown and cementum over root
Pulp cavity contains connective tissue, vessels, nerves (CN V)
Root canal transmits nerves and vessels
Tongue
Mobile muscle that can assume a variety of shapes
Involved in mastication, taste, degulation, articulation, and oral cleansing
Motor innervation by CN Xll
Root of tongue is posterior 1/3(relatively fixed)
Body of tongue is remaining portion which is visible and most mobile
Mucous membrane on anterior portion
Contains lingual papillae (taste buds) = foliate, vallate, fungiform, filliform
Salivary glands
3 glands = parotid (largest), submandibular, sublingual
Functions = moisten mucous membrane of mouth, lubricate food, begin digestion of starches, intrinsic “mouthwash”, prevent tooth decay
Abdominal viscera
Esophagus Stomach Small intestine Large intestine Spleen Pancreas Liver Gallbladder Kidneys Adrenal glands
Esophagus
Extends from pharynx (laryngopharynx) to stomach
Carry food to stomach
Consists of voluntary muscle (upper 1/3)
Smooth muscle (lower 1/3)
And mixture in middle 1/3
Passes through esophageal hiatus of diaphragm at level T10
Terminates by entering stomach via cardial orifice
Stomach
Expandable portion of digestive tract (can hold 2-3L of food)
Acts as a food blender and reservoir (enzymatic digestion)
Gastric juice gradually convert food mass into liquid (chyme) to pass into small intestine
Parts of stomach
Gastroesophageal sphincter
Greater curvature (convex inferior border)
Lesser curvature (concave superior border)
Cardia (surrounds cardial orifice)
Fundus (superior portion related to left dome of diaphragm)
Body (between fundus and pyloric part)
Pyloric part (funnel-shaped, pylorus thickens to form pyloric sphincter)
Gastric mucosa
Smooth inner surface of stomach
When contracted forms gastric folds (rugae) to increase surface area for increased digestion
Small intestine
3 parts
Duodenum
Jejunum
Ileum
Duodenum
First and shortest part
Widest and most fixated
Majority of digestion and absorption of nutrients
C-shaped around head of pancreas
Receives = chyme (from stomach), bile (via bile duct), pancreatic fluid (via pancreatic duct)
Gallbladder
Small pouch inferior to liver
Stores bile created by the liver
Releases bile to duodenum for digestion (emulsification) of fats
Can be removed with minimal changes to digestive tract
Pancreas
Divided into head, body, and tail
Head embraced by C-shape curve of duodenum
Entire structure lies posterior to stomach and superior to L/R renal arteries and veins
Digestive gland
Functions = produce pancreatic juice for duodenum (alkaline fluid to reduce acidity and digest food), produce glucagon to convert glycogen to glucose, produce insulin to facilitate movement of glucose to muscle cells
Pancreatic duct runs the length of the pancreas
Empties into the duodenum
Insufficient secretion by the pancreas leads to starvation
Jejunum
Middle portion of small intestine (2/5 of length)
Most lies in upper left quadrant
Functions to absorb remainder of nutrients, fat, and H2O
Ileum
Remaining 3/5 of small intestine
Together with jejunum is 6-7m long
Most lies in lower right quadrant
Mainly H2O and fat absorption and passage of remnants (chyme) into large intestine
Large intestine
Consists of cecum, appendix, colon, rectum, and anus
Different from small intestine = teniae Coli (3 thickened bands of smooth muscle), haustra (sacs between the teniae Coli), omental appendices (small fatty projections), size (much larger in diameter)
Cecum
Ileum terminates into cecum via ileocecal orifice and valve Large pouch for collection of food (chyme) No mesentery (can be displaced from Iliac fossa)
Appendix
Vermiform appendix (wormlike) Part of the gastrointestinal and lymphatic immune system (GALT) Repopulation of symbiotic bacteria
Large intestine function
Movement of food for elimination
H2O absorption
Lined with Bactria to absorb any remaining nutrients (breaks down indigestible food)
Chyme moved through the large intestine, dehydrated, mixed with bacteria and mucous, and becomes feces
Large intestine after cecum
Ascending colon Right colic flexure (hepatic) Transverse colon Left colic flexure (splenic) Descending colon Sigmoid colon Rectum Anus
Blood supply and circulation for liver and intestines
Arteries = superior mesenteric artery, inferior mesenteric artery, hepatic artery proper
Veins (hepatic portal system) = superior mesenteric vein, inferior mesenteric vein, splenic vein, hepatic portal vein
Liver has a double blood supply (hepatic artery proper, hepatic portal vein)
Liver
Largest gland of the body
One of 2 organs able to repair itself
Immediately inferior to diaphragm
In addition to its main filtering function the liver also = secretes bile (for digestion), stores glycogen, produces lymph
Surfaces of liver
Diaphragmatic surface (anterosuperior) Visceral surface (posteroinferior, gastric and pyloric areas, duodenal areas, colic area, renal and suprarenal areas, gallbladder)
Lobes of liver
Functionally independent left and right lobe (separated by falciform ligament) Quadrate lobe (separated from left lobe via liagmentum teres/round ligament, partially covered by gallbladder) Caudate lobe (separated from left lobe via ligamentum venosum)
Fetal circulation
All embryonic nutritional and respiratory needs are provided by placenta
Blood leaves baby and travels to placenta via umbilical arteries (arising from internal Iliac arteries)
Blood returns to baby via the umbilical vein (F1)
Umbilical vein bypasses the liver via the ductus venosus (F2) and enters IVC
Pulmonary circuit is not needed so blood will bypass via foramen ovale (RA > LA) and ductus arteriosus (RV > aorta)
Fetal circulation when baby is born
Th umbilical cord is clamped and the baby takes its first breathe
Umbilical vein (F1)changes into ligamentum teres/round ligament (A1)
Ductus venosus (F2) changes into ligamentum venosum (A2)
Umbilical arteries change into ligaments
Vasodilation of pulmonary vessels/circuit
Foramen ovale and ductus arteriosus close
Foramen ovale becomes fossa ovale
