Lecture 23 & 24 & 25: Digestive System

Question 1

Digestive system

Answer 1

Organs involved in ingestion, digestion of food, absorption of nutrients, elimination of indigestible materials
Provides nutrients for cells for energy, growth, repair

Question 2

Alimentary canal

Answer 2

Muscular tube from mouth to anus, 9m long

Composed of oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum

Question 3

Accessory digestive organs

Answer 3

Assist in ingestion and digestion of food

Composed of teeth, tongue, salivary glands, liver, gallbladder, pancreas

Question 4

Oral cavity

Answer 4

Bound by mucosal folds (lips) made of orbicularis oris
Roof: anterior 2/3 hard palate (maxilla and palatine bones), and posterior 1/3 soft palate (separating the oral cavity and nasopharynx during swallowing)
Posterior border: uvula - conical soft tissue
Floor: suprahyoid muscle
Behind oral cavity is pharynx
Border between oral cavity and pharynx: oropharyngeal isthmus

Question 5

Dental arch

Answer 5

Vestibule: part of oral cavity outside dental arch (horse shoed shape)
Oral cavity proper: remaining space behind dental arch

Question 6

Frenulum

Answer 6

Short mucosal folds that attach lips or tongue to gum
Upper lip attached via superior labial frenulum
Lower lip attached via inferior labial frenulum
Tongue attached via lingual frenulum
Function: prevent excess movement of lips/tongue

Question 7

Palatoglossal arch

Answer 7

From posterior border of soft palate are 2 folds

Connects soft palate to tongue; anterior fold

Question 8

Palatopharyngeal arch

Answer 8

Connects soft palate to wall of pharynx; posterior fold

Question 9

Tonsilar fossa

Answer 9

Between the palatoglossal arch and palatopharyngeal arch

Contains the palatine tonsil

Question 10

Oral pharyngeal isthmus

Answer 10

Connects oral cavity proper to oropharynx

Formed by palatoglossal arches

Question 11

Composition of teeth

Answer 11

Crown: above level of gum/gingiva
Neck: narrow part of tooth in touch with gingiva connecting crown and root
Root: embedded in alveolar bone of upper/lower jaw; attaches cementum to alveolar bone via periodontal ligament

Question 12

Calcified tissues of teeth

Answer 12

Dentin: makes up core, calcified tissue
Enamel: extra protection in the crown region
Cementum: extra protection in the root region

Question 13

Pulp cavity

Answer 13

Large space in dentin
Contains loose connective tissue, blood vessles, nerves, lymphatic vessels
Root canal: extension of pulp cavity in root

Question 14

Nerve supply of teeth

Answer 14

Branches of CNV through root canal and pulp cavity

Question 15

Tongue

Answer 15

Superior surface: dorsal surface
Posterior end: epiglottis and entrance of larynx
Involved in swallowing, phonation, tasting, chewing

Question 16

Dorsal surface of tongue

Answer 16

Terminal sulcus: reverse V shaped line dividing tongue into posterior 1/3 or root of tongue or pharyngeal part of tongue, and anterior 2/3 or body of tongue or oral part of tongue

Question 17

Anterior 2/3 of tongue

Answer 17

Made of skeletal muscles
Has epithelial papilla
Circumvallate papilla: largest, single row in front of terminal sulcus
Foliate papilla: on L/R border of tongue
Fungiform papilla: evenly scattered on dorsal surface, looks like mushrooms
Filiform papilla: small, thin
All papillae except filiform papilla contain taste buds
Filiform papilla increase friction of tongue to move bolus around oral cavity more efficiently

Question 18

Posterior 1/3 of tongue

Answer 18

Primarily made up of lymphoid tissue

Contains lingual tonsils

Question 19

Nerve supply of tongue

Answer 19

Anterior 2/3:
CNVII provides special taste
CNV provides general sense (pain, touch, temperature)
Posterior 1/3:
CNIX provides special taste and general sense

Question 20

Esophagus

Answer 20

Muscular tube, 25cm
Starts at CVI (end of laryngopharynx) through neck, superior and posterior mediastinum, diaphragm, and ends at stomach at TXi

Question 21

Borders of esophagus

Answer 21

Posterior: lower cervical and thoracic vertebrae
Anterior: trachea and L atrium of heart
Left: arch of aorta which continues as descending aorta

Question 22

Peritoneum

Answer 22

Serous membrane that produces serous fluid to keep abdominal organs most and facilitate movement
(In lungs = pleural, heart = pericardium, joints = synovial membrane)

Question 23

Visceral peritoneum

Answer 23

Peritoneum in touch with viscera

Question 24

Parietal peritoneum

Answer 24

Peritoneum in touch with abdominal/pelvic cavity

Question 25

Intraperitoneal organs

Answer 25

Organs completely invested by peritoneum Relatively mobile Liver, stomach, transverse colon, coils of small intestine

Question 26

Retroperitoneal organs

Answer 26

Organs partially covered by peritoneum, located between parietal peritoneum and posterior abdominal wall Generally fixed in position and can't move Pancreas, duodenum, rectum urinary bladder

Question 27

Peritoneal reflections

Answer 27

Forms pathways for blood vessels and nerves to reach parts of the digestive system and eliminate risk of entanglement Coronary ligament: short double layer attached to superior surface of liver and diaphragm Lesser omentum (gastohepatic ligament): double layer between liver and stomach Greater omentum: quadruple layer from stomach indirectly to transverse colon Transverse mesocolon: double layer from posterior transverse colon to posterior abdominal wall Sigmoid mesocolon: from sigmoid colon to posterior abdominal wall Mesentery: largest; from coils of small intestine to posterior abdominal wall

Question 28

Stomach

Answer 28

Cardia: where esophagus meets stomach; guarded by cardiac sphincter; malfunction results in heart burn Fundus: above the level the cardia Body: between fundus and pyloric part Pyloric part: after body narrows (pyloric atrium, pyloric canal, pyloric sphincter/pylorus) - controls passage to duodenum Has lesser curvature (attachment of lesser omenutm) and greater curvature (attachment of greater omentum) Rugae: longitudinal folds enabling stomach to expand, will disappear when stomach is full

Question 29

Duodenum

Answer 29

Length and width are same (12 fingers side by side) 4 segments forming C shape: superior, descending, inferior, ascending Attaches to rest of small intestine Retroperitoneal organ

Question 30

Jejunum

Answer 30

Forms proximal/upper 2/5 of small intestine Found it in umbilical region Has thicker walls, narrow lumen, more blood supply than ileum Intraperitoneal organ

Question 31

Ileum

Answer 31

Forms distal 3/5 of small intestine Found in hypogastric region Intraperitoneal organ Joins large intestine at ileocecal junction

Question 32

Cecum

Answer 32

Receives appendix at the bottome (2-20cm) | Ileocecal valve controls passage between ileum and cecum

Question 33

Ascending colon

Answer 33

Found in R lumbar area | Continues to inferior surface of liver, and bends sharply as transverse colon at hepatic/ R colic flexure

Question 34

Transverse colon

Answer 34

Continues left of abdominal cavity Intraperitoneal organ Ends at splenic/L colic flexure to descending colon

Question 35

Descending colon - Anus

Answer 35

Found in L lumbar area Retroperitoneal Continues as sigmoid colon (intraperitoneal) to rectum in pelvic cavity (retroperitoneal) to anal canal guarded by external anal sphincter

Question 36

Teniae coli

Answer 36

3 bands of smooth muscles fibers along large intestine | During contraction, they produce pocket like folds = haustrum

Question 37

Rectum

Answer 37

Upper 2/3 is more dilated = ampiola | Distal 1/3 is more narrow and continues with anal canal

Question 38

Anal sphincters

Answer 38

Internal anal sphincter: involuntary (smooth muscle fibers, controlled by ANS) External anal sphincter: volunary (skeletal muscle, controlled by pudendal nerve); control passage of fecal material from rectum to external environment

Question 39

Hemorrhoidal veins

Answer 39

Veins are anal canal to shunt blood from portal system to anal system; during pathology of liver, they dilate causing hemorrhoids

Question 40

Blood supply to digestive system

Answer 40

Celiac artery to stomach, liver, spleen, pancreas, upper duodenum Superior mesenteric artery to lower duodenum, jejunum, ileum, cecum, ascending colon, R 2/3 of transverse colon Inferior mesenteric artery to L 1/3 of transverse colon, rectum

Question 41

Nerve supply to digestive system

Answer 41

Sympathetic fibers from thoracic splanchnic nerves Parasympathetic fibers from vagus nerve (until junction at R 2/3 and L 1/3 transverse colon), after innervated by pelvic splanchnic fibers (S2-S4)

Question 42

Parotid gland

Answer 42

Largest deep to skin by ear, pierces mucosal membrane of oral cavity against 2nd upper molar, and drains into vestibule of oral cavity Secretion carried by parotid duct Controlled by parasympathetic fiber of CNIX

Question 43

Submandibular gland

Answer 43

Deep to mandible Submandibular duct opens to floor of oral cavity behind incisor tooth Controlled by parasympathetic fiber of CNVII

Question 44

Sublingual gland

Answer 44

Smallest Under tongue Secretion released to floor of oral cavity by numerous ducts Controlled by parasympathetic fiber of CNVII

Question 45

Liver

Answer 45

Largest gland In R hypochondriac, epigastric, L hypochondriac region Falciform ligament divides anterior surface into large R lobe and smaller L lobe (closely related to inferior vena cava and stomach) Gallbladder sticks out from inferior border of liver Porta hepatis in between 2 layers of lesser omentum attaching stomach and liver

Question 46

Ligaments of liver

Answer 46

Coronary ligament: peritoneum reflects on itself under diaphragm; attaches superior liver to inferior diaphragm Falciform ligament: reflection on anterior surface; attaches liver to diaphragm and posterior surface of abdominal wall Round ligament of liver: remnant of fetal blood vessels which turns into a ligament after birth

Question 47

Surfaces of liver

Answer 47

Diaphragmatic surfaces: superior R anterior and posterior surfaces of liver in touch with diaphragm Visceral surface: inferior surface; contains porta hepatis which includes common bile duct, hepatic portal vein, hepatic artery proper

Question 48

Lobes of liver

Answer 48

Caudate lobe: contains L side of inferior vena cava Quadrate lobe: contains L side of gallgladder Caudate and quadrate lobe are part of L lobe functionally (even though located on the R side of the falciform ligament

Question 49

Gallbladder

Answer 49

Pear shaped structure Receives and dilutes bile from liver, concentrates it, and releases it to 2nd part of duodenum when needed Composed of fundus, body, neck

Question 50

Process of bile production

Answer 50

Liver and duodenum = biliary system L/R hepatic duct: 2 small bile ducts drain bile from L/R lobe; they join together to form common hepatic duct Common hepatic duct and cystic duct from gallbladder form common bile duct L/R hepatic duct and common hepatic duct carry dilute bile from liver, and pass the dilute bile to gallbladder when joining the cystic duct (sphincter at the beginning of the common bile duct preventing passage of dilute bile into duodenum) Bile goes to gallbladder to become concentrated, and if needed, goes through common bile duct At the end of common hepatic duct, sphincter prevents passage of concentrated bile back to liver, so it goes to duodenum

Question 51

Pancreas

Answer 51

Dual gland with endocrine (hormones) and exocrine (digestive enzymes) secretions; 98% exocrine Composed of head (almost encircled by duodenum), body (moves L), tail Tails touches hilum of spleen Before common bile duct empties bile into duodenum, it joins with pancreatic duct which carries exocrine secretions of pancreas, and will open to 2nd part of duodenum at major duodenal papilla

Question 52

Blood supply for liver and pancreas

Answer 52

Branches of celiac artery

Question 53

Nerve supply for liver and pancreas

Answer 53

ANS celiac plexus: Sympathetic fibers - thoracic splanchic nerves Parasympathetic fibers - CNX