Digestive System Quiz

alimentary canal (GI tract)

continuous muscular tube, from mouth → anus

accessory digestive organs

• tongue

• teeth

• liver

• gallbladder

• salivary glands

• pancreas

pancreas as exocrine gland

1. secretes HCO₃^-

2. lipase

3. trypsin

why is it beneficial to have non-keratinized start squamous in mouth, esophagus, and anus?

many layers, resistant to abrasions, resilient to friction

why is it beneficial to have simple columnar epithelium in the stomach, small intestine, and large intestine?

one way absorption of molecules, goblet cells secrete mucus to reduce friction and protect stomach

what does apical side of simple columnar epithelium face? (stomach and intestines

lumen of GIT

what does basal side of simple columnar epithelium face? (stomach and intestines

bloodstream

functions of saliva

• cleanses mouth

• dissolves chemicals

• moistens food; bolus!

• begins breakdown with amylase - starch!

parotid salivary gland

anterior to ear, external to masseter

submandibular salivary gland

medial to body of mandible

sublingual salivary gland

anterior to submandibular gland

what is it called when the process of chewing tears and grinds food into smaller fragments

mastication

primary dentition

20 deciduous (baby) teeth; 6-24 months

how many teeth do adults have

32 (16 upper, 16 lower)

incisors function

rip/tear flesh

canines function

pierce flesh

premolars (bicuspids) function

grind flesh

molars

best at grinding flesh

propulsion

involuntary, smooth muscle contractions propel food through GI tract

what does propulsion involve

peristalsis and segmentation

peristalsis

adjacent segments of ali canal alternately contract/relax; primarily propulsive, but some mixing

segmentation

nonadjacent segments of the ali canal contract and relax; primarily mixes, some propulsion

deep to superficial layers of digestive organs

1. mucosa

2. submucosa

3. muscularis externa

4. serosa

mucosa function

secretes, absorbs, protects

submucosa function

• structural/elastic

• blood and lymph vessels

• nerve fibers

muscularis externa

deep circular layer (sphincters) and longitudinal layer (superficial) for peristalsis and segmentation

serosa function

made up of visceral peritoneum

peritoneum

serous membranes of abdominal cavity

visceral peritoneum

membrane on external surface of most digestive organs

parietal peritoneum

membrane that lines body wall

mesentery

• double layer of peritoneum

• pathway for blood vessels, lymphatics, nerves

• holds organs in place; stores fat

retroperitoneal organs

outside (posterior) to peritoneum

• pancreas, duodenum, parts of LI

pharynx

• strat squamous epi w mucus

• external muscle layers

  • inner = long

  • outer pharyngeal constrictors = encircle wall of pharynx

esophagus

laryngopharynx → stomach

gastroesophageal sphincter

• keeps orifice closed when food not being swallowed

• mucus cells on both sides of sphincter help protect from acid reflux

what is small intestine located between

pyloric sphincter + ileocecal valve

small intestine characteristics

• 20ft long relaxed

• duodenum = 10 ft

• jejunum = 8 feet

• ileum = 12 feet

mods to SI that make it good for nutrient absorption

• circular folds

• villi

• microvilli

circular folds

permanent folds that force chyme to slowly spiral through lumen, for more nutrient absorption

villi

fingerlike projections of mucosa

microvilli

cytoplasmic extensions of mucosal cell; fuzzy appearance called brush border that has enzymes

large intestine gross anatomy

• teniae coli

• haustra

• epiploic appendages

teniae colo

3 bands of long smooth muscle in muscularis

haustra

pocket-like sacs caused by tension of teniae coli

epiploic appendages

fat-filled pouches of visceral peritoneum

cecum

1st part of large intestine

appendix

• masses of lymphoid; part of MALT

• bacterial storehouse

colon

1. ascending = up right side

2. transverse

3. descending = travels down left side

4. sigmoid = through pelvis

rectum

• 3 rectal valves

• retroperitoneal

anal canal

• ends at anus

• internal sphincter = smooth muscle

• external sphincter = skeletal

what are cecum, appendix, rectum, ascending/descending colon in terms of location?

retroperitoneal