digestive system 1+2+3

gastrointestinal tract

1. mouth

2. pharynx

3. esophagus

4. stomach

5. small & large intestines

accessory digestive organs

1. salivary glands

2. liver

3. gallbladder

4. pancreas

lips

• orbicularis oris muscle

• connective tissue

• skin

• numerous sensory receptors and blood vessels (hence red color)

cheeks

lateral walls of mouth

hard palate

roof — ____ ______ (bone)

maxilla and palatine bones

soft palate

• muscular arch: skeletal muscle

uvula

cone-shaped projection of soft palate

frenulum

• fold of tissue under tongue: restricts movement

intrinsic muscle

interwoven skeletal muscle of tongue

extrinsic muscle

• outside tongue, attached to base of tongue

• originate on hyoid and other structures

  • ex: hyoglossus, styloglossus, genioglossus

papillae

(dorsal surface)

• small raised areas

• contain taste buds

• create sensitive surface with some friction

lingual tonsil

• lymphoid tissue on posterior portion of tongue

taste map

the _____ ___ is wrong and outdated

• 5th flavor discovered: umami

  • savory (like steak, mashed potatoes)

crown

exposed portion of teeth

root

anchors tooth firmly in jaw

periodontal ligament

CT anchoring teeth to jaws

gingiva (gums)

mucous membrane of jaw

alveolus

socket (cavity) in bone that holds teeth

enamel

of teeth

• mostly CaPO4 (hydroxyapatite)

dentin

bone like material inside teeth

pulp

of teeth,

• nerves

• blood vessels

root canal

• canal of teeth in which pulp is found

saliva

• 99% water

• enzymes:

  • lysozymes: destroy bacteria

  • digestive enzymes

• mucous: lubrication

• salts

  • maintain proper pH for digestive enzymes

parotid glands

• located inferior and anterior to ear

• drains into oral cavity near 2nd upper molar

submandibular glands

• located just inside the mandible

• empties into the floor of the mouth

sublingual glands

• located under mucosa in floor of mouth

• empties into floor of mouth

mumps

viral infection that swells the salivary glands

pharynx

• structure:

  • lined with stratified squamous epithelium

  • mucous membrane (lubrication)

  • skeletal muscle

swallowing

__________ begins as a voluntary action

• sets off reflexive opening/closing of openings (ex. nasal cavity)

• past mid-esophagus: completely involuntary (under autonomic control)

mucosa (GI)

• epithelium (inner lining)

  • stratified squamous at beginning and end of tract

    • mouth, pharynx, esophagus, anal canal

• simple columnar in middle

  • stomach & small and large intestine

• lots of glands

submucosa (GI)

(CT)

• rich blood/nerve supply

• elastic and collagenous fibers allow GI tract to expand

• lacteals: lymphatic vessels—absorb fats

muscularis externa

of the GI tract

• moves materials along tract

• mechanical digestion

• multiple layers of smooth muscle

serosa

outer CT of GI tract

enteric

• special intrinsic nervous system of gut (intestines)

parasympathetic

• rest and digest nervous system of gut

• (sympathetic does opposite: inhibit digestion, movement, secretion)

submucosal plexus (meissner’s plexus)

• in the submucosa

• activates glands

• innervates layer of smooth muscle that squeezes mucosa and coaxes out secretions

myenteric plexus

• major nervous supply to muscularis

• peristalsis (involuntary constriction)

celiac trunk

• left gastric artery

• common hepatic artery

• splenic artery

supplies esophagus, stomach, spleen, liver, gallbladder

summary: most upper quadrant organs

superior mesenteric artery

• supplies duodenum, pancreas, jejunum, ileum, cecum, ascending colon, transverse colon

• summary: all small intestine, some of large intestine

inferior mesenteric artery

• supplies transverse colon, descending colon, sigmoid colon, rectum

• summary: large intestine + remainder of digestive tract

esophagus location

• posterior to trachea

• begins at larynx

• passes through hiatus in the diaphragm to join the stomach

esophagus structure

• stratified squamous epithelium

• submucosa—blood vessels and nerves

• muscularis externa

  • upper 1/3: skeletal muscle

  • middle 1/3: skeletal and smooth muscle

  • lower 1/3: smooth muscle

• serosa—outer CT layer

gastro-esophageal sphincter

• prevent stomach contents from entering esophagus

• smooth muscle

hiatal hernia

stomach bulges through the diaphragm

parietal peritoneum

lines body cavity—inner surface of the abdominal and pelvic walls

visceral peritoneum

covers outer surfaces of organs

peritoneal cavity

space between the two which contains a small amount of peritoneal fluid—same configuration as pleura/pleural cavity

peritoneum

same general principle as pleura: produces lubricative fluid

folds (double layers)

special peritoneal membranes

• isolate organs

• protect organs

• support organs and blood vessels

• attach organs to the body wall

• store fat

lesser omentum

special peritoneal membrane

• attaches lesser curvature of stomach to liver

greater omentum

special peritoneal membrane

• suspended from inferior curvature of stomach like an apron

falciform ligament

attaches liver to inferior diaphragm, anterior body wall

round ligament

remnant of umbilical vein (carried O2 rich blood from placenta)

mesentery

attaches and suspends small intestine from posterior abdominal wall & spine

mesocolon

attaches and suspends large intestine to posterior abdominal wall

retroperitoneal organs

(behind the peritoneum)

• organs that only have visceral peritoneal on their anterior surface OR do not come in contact with the peritoneum at all

• parts of pancreas

• kidneys

• duodenum

• ascending & descending colon

chyme

acidic paste of stomach

• mechanical mixing of food and production of ______

• initiates major protein digestion

• storage of _____ until it passes into the duodenum

• minimal absorption (e.g. some drugs, alcohol)

stomach location

upper left quadrant between esophagus and small intestine

stomach borders

• lesser curvature: superior

• greater curvature: inferior

stomach regions

• cardia: immediately follows esophagus

• fundus: superior dome

• body: main central region

• pylorus: entry to small intestine

pyloric sphincter

relaxes to let chyme exit stomach & enter small intestine

mucosa (stomach)

(layers of stomach wall)

simple columnar epithelium

submucosa (stomach)

(layers of stomach wall)

nerves and blood vessels

inner oblique, middle circular, outer longitudinal

(layers of stomach wall inner to outer) — muscularis

3 layers of smooth muscle

• _____ _______

• ______ _______

• _____ ____________

• 3 layers: better 3D compression/churning

serosa (stomach)

(layers of stomach wall)

connective tissue

rugae

• folds of mucosal layer

• permit stomach to distend

• increase surface area for secretion and digestion

• disappear as stomach expands

parietal cells

• produce HCl which decreases the pH of stomach contents

• produce intrinsic factor required for B12 absorption

chief cells

zymogenic cells

• produce inactive pepsinogen

• converted to active enzyme pepsin for protein digestion by HCl

gastric mucous cells

• produce bicarbonate-rich mucous

• protects stomach lining from HCl

• (mucus produced by goblet cells in intestines)

digestive hormones

• communication between system and CNS

• communication among organs

enteroendocrine cells

stomach & intestines

• hormone producing cells

• example:

  • gastrin (from G cells): increase GI activity + acid secretion

small intestine

• major site of chemical digestion

• mechanical mixing

• major site for absorption of nutrients

• propels undigested nutrients or materials to large intestine

small intestine location

• extends from pyloric sphincter (A) to large intestine (B)

• occupies central and lower portion of abdominal cavity

• primary functions

  • digestion and absorption

duodenum

region of small intestine

• C-shaped region

• first 10 inches of small intestine

• retroperitoneal

• duodenal papilla

  • opening in ________

  • bile from common bile duct

  • enzymes from pancreatic duct

brunner’s glands

secrete alkaline solution

• protects intestinal (duodenal) lining from acidic chyme

plicae circulares

• deep folds of submucosa

• increase surface area for digestion and absorption

• do NOT disappear as intestine expands (unlike gastric rugae)

villi

• small finger-like projections

• emerge off of plicae

• further increase surface area

• capillary network

• lacteal: transports digested fats

• PC: plica circularis

microvilli

even more absorptive surface area on each cell in the intestinal wall

jejunum

region of small intestine

• middle section

• slightly larger lumen

• many plicae circulares

ileum

region of small intestine

• third region of small intestine

• very few plicae circulares

• contains peyer’s patches

  • clusters of lymphatic tissue

peristalsis

• involuntary wave-like movement

• entire tract from esophagus to large intestine

• functions to mix and propel food through GI tract

• involves muscularis layer

segmentation

• occurs primarily in intestine

• localized contraction in areas where food is present

• mixes food with enzymes

  • aid in digestion & absorption

intestinal glands

• found on surface of villi and in crypts at base of villi

• enzymes

  • digestive

  • antibacterial

• hormones

  • affects GI function

large intestine location

• begins at end of ileum in lower right quadrant

• extends superiorly to liver

• runs left to spleen

• descends on left pelvis

• terminates at anus

ascending colon

right side

transverse colon

passes from right to left

descending colon

left side

sigmoid colon

• S-shaped

• from left side to center of body

rectum

in midline, leads to anal canal

cecum

• dilated pouch at junction of small & large intestines (projects off appendix)

• lower right quadrant

• ileocecal valve guards opening

anal canal

• of large intestine

  • passageway leading to the anus (external opening)

  • sphincters guard opening

    • internal anal sphincter — smooth muscle

    • external anal sphincter — skeletal muscle

neat and tidy

the colon is not as ____ ___ ____ in an actual body

taenia coli

structural specialization of large intestine

• long strip of smooth muscle

• forms stripe along large intestine

haustra

sac-like regions in large intestine

epiploic appendages

• fat-filled pouches of large intestine

large intestine function

• completes absorption of water

• formation, storage, and explusion of feces

• contains “normal flora” (bacteria)

• manufacture vitamins

• fat soluble A, D, E, K

appendix

• location

  • lower right quadrant

  • usually retro-cecal (behind cecum)

• structure

  • finger-like projections (2-3 inches long)

  • blind pouch

  • contains lymphatic tissue

• appendicitis

  • bacterial infection

liver

• metabolism of nutrients

• detoxification: toxins, drugs

• synthesis of major blood proteins: albumin, fibrinogen, etc.

• storage

  • fat

  • glycogen

  • iron

  • vitamins

  • production of bile by hepatocytes

bile

yellowish-green fluid composed of water, cholesterol, bile pigments (bilirubin) & bile salts

function

• emulsification of fat

• bile is NOT produced in the gallbladder