Chapter 24 Digestive System Flashcards
Gut
alimentary canal/gastrointestinal (GI) tract
Endocrine
no duct
Exocrine
exit
Foregut
mouth -> duodenum
Midgut
jejunum and ileum
Hindgut
colon -> rectum
bolus formation
swallow-able mass
Vestibule
space btw lips/cheeks & teeth
Gingiva
mucosa covering alveolar bone/hard palate
4 tonsils; how many paired salivary glands?
3
3 salivary glands:
parotid, submandibular, sublingual
Function of saliva
- cleanses teeth, moistens food
- contains enzyme amylase: break down starch
Tongue
- muscular hydrostat=constant volume
- anchored to hyoid and jaw
Tongue too tightly bound to floor of mouth?
ankyloglossia
Uvula acts as?
sealant
Hairy Tongue (Lingua Villosa)
- hypertrophy of filiform papillae
- Causes: smoking, dry-mouth, oral hygiene
Enamel (crown)
hardest substance in body (calcium phosphate)
Dentin (body of tooth)
forms roots & encloses the pulp cavity
Endodontic disease
- Root-canal procedure
- Goal: tooth ankylosis
Pulp cavity
contains blood vessels & nerves
Periodontal disease
- probe gingival pack
- damage to tooth/alveolus
Incisors
1 root, blade-shaped cusp
8
Cuspids
1 root, conical pointed cusp
4
Bicuspids
1-2 roots, blade-like cusps
8
Molars
3-4 roots, large flattened crowns
8-12
Edentulous
no teeth
deciduous teeth
- milk/baby teeth (20)
- no bicuspids
- erupt @ 6 months to 2yrs
adult teeth
- 28-32
- erupt @ 6-21 years
impacted molars
they rotated
How many layers of gut?
4
Mucosa
- innermost tunic
- secretes mucus which protects the lining of gut
- “pleated” appearance (plicae circularis or rugae)
- lamina propria (CT) supports overlying epithelium
Submucosa
- exocrine glands: enzyme secretion = digest food
- highly vascular = absorption of nutrients from food
- Meissner’s plexus of ANS fibers= controls the secretions of the submucosal glands
Muscularis
- 2 layers (peristalsis)
- inner layer: circular muscles = decreases diameter > increase in length
- outer layer: longitudinal muscles = decreases tube length > increases diameter
- myenteric plexus of ANS fibers = controls peristalsis (directional) and segmentation (mixing) of chyme
Serosa
- outermost layer (serous membrane)
- aka visceral peritoneum
Esophagus
- collapsible muscular tube (2 muscle layers)
- extends from pharynx to stomach through diaphragm
How many layers of muscles in stomach?
3
Gastric juices
HCL, pepsinogen/pepsin, rennin
Mucous
protects walls from gastric juices
GERD
Gastro-Esophageal reflux disease
Small intestine mucosa
- more elaborate than gastric
- pleated (plicae circularis) w/ villi: increase SA
- columnar epithelium
Duodenum
- mixing bowl (chyme)
- submucosal glands produce mucus + buffers
- hepatopancreatic sphincter & duodenal papilla
Jejunum
majority of digestion & absorption
Ileum
final digestion, absorption, GALT
Ileocecal valve
controls flow of chyme into cecum
Large Intestine (colon)
- devoted to dehydration/compaction of chyme > feces
- smaller than small intestine
How many sections of large intestine?
- 5
- cecum, ascending, transverse, descending, sigmoid
Cecum
chyme enters cecum @ ileocecal valve
Hepatic flexure
- right colic
- under liver
Splenic flexure
- left colic
- under spleen
Sigmoid
s-shaped bend to pass down into pelvis
Haustra
pouches formed by colon musculature
Taenia coli
3 longitudinal ‘ribbons’ of muscle
Clostridium difficile
- fecal transplant
- restores microbiome
What innervates ascending and transverse colon?
vagus nerve
What innervates descending and sigmoid colon?
pudendal nerve
Appendix
blind pocket, minor lymphoid function
Diverticula
out-pocketing of colon wall (BV’s)
Diverticulosis
presence
Diverticulitis
problem
epiploic appendages
fat associated w. colon
Rectum
- feces enter = urge to defecate
- epithelium keratinized - abrasion-resistant
Internal anal sphincter
ANS
External anal sphincter
voluntary control
Ileostomy/colostomy
- resection of a portion of the gut
- proximal end attached to a surgical stoma (mouth) in the body wall
Liver
- largest organ in body
- large blood reservoir
Liver functions
- metabolize carbohydrates, lipids, amino acids
- stores vitamins & minerals
- detoxify/remove waste products
- inactivate/removes various drugs & hormones
- produce bile
How does bile break down lipids?
emulsifies (chops up)
Hepatic Triad
Bile duct, hepatic portal vein, hepatic artery
Lesser omentum
- Portal v. and Hepatic a.
- common bile duct
Vasculature of liver
- hepatic artery (celiac trunk)
- hepatic vein (returning to IVC)
- hepatic portal vein
Gall Bladder
stores bile
Bile pathway
Liver > ducts > H-P sphincter > duodenum
H-P sphincter close?
- bile backs-up into common bile duct > cystic duct
- gall bladder stores the bile for later use
Cholecystitis
inflammation of gallbladder
Cholelithiasis
- presence of gallstones in gallbladder
- layers added when bile enters
Cirrhosis (hepatitis)
-destruction of hepatocytes due to:
exposure to drugs, viral infection, blockage of hepatic ducts
Hepatic Portal Hypertension
- if blood cannot drain, it finds alternate routes
- backflow via portocaval anastomoses
- metabolites damage brain & other organs
Pancreas
- btw stomach & duodenum
- drains to HPV
- mostly exocrine ducts
Endocrine secretions of pancreas
glucagon and insulin
glucagon
raises glucose levels in the blood
insulin
lowers blood glucose levels
Exocrine secretions of pancreas
Enzymes: proteinases, lipases, nucleases
degrades materials
Endocrine Secretions >
Hepatic Portal System
Exocrine secretions >
pancreatic duct > duodenum
Mesentery
- durable, double layer
- suspends GI tract from walls of the cavity
- supports/protects NAVL
- abrasion resistant
Mesentery Proper
encloses the jejunum and ileum
Duodenum position?
secondarily retroperitoneal
Mesocolon
suspends transverse and sigmoid colon
Asc/desc colon position?
secondarily retroperitoneal
Lesser omentum location
between stomach and liver
Greter omentum (policeman)
- extends from greater curvature of stomach
- fat storage & localization of infection
- 4 serous membranes
Coronary ligament
suspends liver from diaphragm
falciform ligament
btw liver & abdominal wall
*contains ligamentum venosum
Mesogaster (greater omentum) provided blood by?
celiac trunk
Mesentery provided blood by?
superior mesenteric artery
Mesocolon provided blood by?
Inferior Mesenteric artery