anatomy chapter 26

gastrointestinal tract

continuous tube connecting oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, anal canal

digestive functions

ingestion, motility, digestion, absorption, elimination

types of digestion

mechanical (chewing/movement) and chemical (saliva/chemoreceptors)

four tunics (deep to superficial)

1. mucosa
2. submucosa
3. muscularis (smooth muscle)
4. serosa (anchors)

oral vestibule

just inside opening of mouth

palate

upper roof of mouth, hard palate and soft palate

hard palate

anterior 2/3, bones

soft palate

posterior 1/3, muscular

uvula

extends from soft palate closes of nasopharynx when swallowing

tongue

primary skeletal muscle, lingual frenulum, papillae

lingual frenulum

thin flap of tongue anchoring tongue to mouth

papillae

surface of tongue, bumpy projections

salivary glands

secrete saliva

saliva funtion

moistens ingested materials creating slick bolus (chewed ball of food), cleanses and lubricates oral cavity, dissolves food so taste receptors on tongue can be stimulated

three pairs of salivary glands

1. parotid
2. submandibular
3. sublingual

parotid salivary glands

largest, anterior and inferior to ear, one parotid duct from each gland runs parallel to zygomatic arch opening near 2nd molar

submandibular salivary glands

inferior to mandible, one submandibular duct from each gland runs to lingual frenulum

sublingual salivary glands

inferior to tongue, multiple sublingual ducts open onto inferior surface of oral cavity

dentition

teeth

crown

superior surface of tooth above gums

enamel

hardest substance in body, protection of tooth

neck of tooth

middle portion of tooth, slimmer

root(s) of tooth

inferior part of tooth, below gums

gingiva

gums

dentin

solid, surrounds pulp cavity

pulp cavity

middle space with tiny arteries, veins, and nerves

root canal

opening in root for vessels to leave tooth

mesial surface

away from back molar

distal surface

toward the back molar

buccal surface

side touching cheeks (only on lateral teeth)

labial surface

side touching lips (only medial teeth)

lingual surface

inside surface of teeth

occlusal surface

chewing surface of back teeth

incisal surface

chewing surface of front teeth

deciduous teeth

20, baby teeth

permanent teeth

32, adult teeth

insisors

most anterior, for slicing

canines

posterolateral to incisors, for puncturing and tearing

premolars

posterolateral to canines, for crushing and grinding

molars

most posterior teeth, for crushing and grinding

esophagus

transitions from skeletal to smooth muscle, connects to stomach

esophageal hiatus

hole in diaphragm where esophagus passes through

superior esophageal sphincter

superior part of esophagus, closes during inhalation preventing air entry

inferior esophageal sphincter

inferior part of esophagus, prevents materials from regurgitating from stomach

peristalsis

rhythmic contraction of muscles to propel substances forward, voluntary top 1/3 and turns completely involuntary

mechanical digestion in stomach

3 layers of muscularis tunic, outer- longitudinal layer, middle- circular layer, inner- oblique layer

chemical digestion in stomach

gastric acid, turns bolus into chyme

cardia

part just under junction with esophagus

fundus

superior dome shape

body of stomach

middle part, sides are greater and lesser curvature

pyloris

just inside junction with pyloric sphincter

pyloric sphincter

connects stomach to intestines

greater curvature

lateral curve, larger

lesser curvature

medial curve, smaller

rugae

folds in the internal surface of stomach

greater omentum

apron of fatty tissue hanging from greater curvature to protect abdominal organs

lesser omentum

connects lesser curvature to small intestine, anchoring

heartburn

from reflux (gastric acid comes into esophagus) c

3 causes of heartburn

weakened esophageal sphincter, hiatal hernia (stomach moves up through esophageal hiatus), increased pressure

small intestines

chemical digestion and nutrient absorption

small intestine segments

duodenum, jejunum, ileum

duodenum

c-shaped, emulsify fat and receives pancreatic secretions

jejunum

chemical digestion and nutrient absorption

ileum

final segment of small intestine

ileocecal valve

sphincter that controls entry of materials into large intestine

circular folds

plicae circularis

villi

microscopic fingerlike projections on surface of circular folds

microvilli

fingerlike projections on the surface of the villi

large intestine

stores feces until defecation

teniae coli

longitudinal muscle that forms bundles

haustra

bunches/sacs from contraction in teniae coli

large intestine parts

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

cecum

sac located in lower right underneath ileocecal valve

ascending colon

right lateral border

hepatic flexure (right colic)

90 degree turn to left

transverse colon

across the body

splenic flexure (left colic)

90 degree turn inferiorly

descending colon

left lateral border

sigmoid colon

s-shaped

rectum

muscular tube that expands prior to defecation

anal canal

last few centimeters, external/internal anal sphincters (relaxed during defecation)

digestive pathway

lips -> vestibule -> oral cavity -> oropharynx -> laryngopharynx -> superior esophageal sphincter -> esophagus -> inferior esophageal sphincter -> stomach -> pyloric sphincter -> duodenum -> jejunum -> ileum -> ileocecal valve -> cecum -> ascending colon -> hepatic flexure -> transverse colon -> splenic flexure -> descending colon -> sigmoid colon -> rectum -> anal canal -> anus (internal/external anal sphincters)

appendicitis

inflammation of appendix

diarrhea

too much water left in intestine, flushing system or stress

constipation

not enough water left in intestine

diverticula

sac-like appendages along the colon

diverticulosis

development of diverticula

diverticulitis

inflammation of diverticula

liver

right and left lobe separated by falciform ligament

right lobe

caudate (posterior) and quadrate (anterior) subdivisions

hepatic portal vein

carries nutrient-rich blood from GI tract and accessories

hepatic artery

oxygen-rich blood to liver

hepatic veins

empty into IVC

gallbladder

store and concentrate bile

biliary apparatus

network of thin ducts that transport bile from liver/gallbladder to duodenum

cystic duct

duct from gallbladder

common hepatic duct

duct from liver

common bile duct

junction of cystic and common hepatic

pancreas

endocrine: production/secretion of insulin and glucagon
exocrine: production of pancreatic enzymes

jaundice

yellowing of skin and membranes from deposits of bilirubin (breakdown of RBC's)