Lecture 23 & 24 & 25: Digestive System Flashcards
Digestive system
Organs involved in ingestion, digestion of food, absorption of nutrients, elimination of indigestible materials
Provides nutrients for cells for energy, growth, repair
Alimentary canal
Muscular tube from mouth to anus, 9m long
Composed of oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum
Accessory digestive organs
Assist in ingestion and digestion of food
Composed of teeth, tongue, salivary glands, liver, gallbladder, pancreas
Oral cavity
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
Dental arch
Vestibule: part of oral cavity outside dental arch (horse shoed shape)
Oral cavity proper: remaining space behind dental arch
Frenulum
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
Palatoglossal arch
From posterior border of soft palate are 2 folds
Connects soft palate to tongue; anterior fold
Palatopharyngeal arch
Connects soft palate to wall of pharynx; posterior fold
Tonsilar fossa
Between the palatoglossal arch and palatopharyngeal arch
Contains the palatine tonsil
Oral pharyngeal isthmus
Connects oral cavity proper to oropharynx
Formed by palatoglossal arches
Composition of teeth
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
Calcified tissues of teeth
Dentin: makes up core, calcified tissue
Enamel: extra protection in the crown region
Cementum: extra protection in the root region
Pulp cavity
Large space in dentin
Contains loose connective tissue, blood vessles, nerves, lymphatic vessels
Root canal: extension of pulp cavity in root
Nerve supply of teeth
Branches of CNV through root canal and pulp cavity
Tongue
Superior surface: dorsal surface
Posterior end: epiglottis and entrance of larynx
Involved in swallowing, phonation, tasting, chewing
Dorsal surface of tongue
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
Anterior 2/3 of tongue
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
Posterior 1/3 of tongue
Primarily made up of lymphoid tissue
Contains lingual tonsils
Nerve supply of tongue
Anterior 2/3:
CNVII provides special taste
CNV provides general sense (pain, touch, temperature)
Posterior 1/3:
CNIX provides special taste and general sense
Esophagus
Muscular tube, 25cm
Starts at CVI (end of laryngopharynx) through neck, superior and posterior mediastinum, diaphragm, and ends at stomach at TXi
Borders of esophagus
Posterior: lower cervical and thoracic vertebrae
Anterior: trachea and L atrium of heart
Left: arch of aorta which continues as descending aorta
Peritoneum
Serous membrane that produces serous fluid to keep abdominal organs most and facilitate movement
(In lungs = pleural, heart = pericardium, joints = synovial membrane)
Visceral peritoneum
Peritoneum in touch with viscera
Parietal peritoneum
Peritoneum in touch with abdominal/pelvic cavity
Intraperitoneal organs
Organs completely invested by peritoneum
Relatively mobile
Liver, stomach, transverse colon, coils of small intestine
Retroperitoneal organs
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
Peritoneal reflections
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
Stomach
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
Duodenum
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
Jejunum
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
Ileum
Forms distal 3/5 of small intestine
Found in hypogastric region
Intraperitoneal organ
Joins large intestine at ileocecal junction
Cecum
Receives appendix at the bottome (2-20cm)
Ileocecal valve controls passage between ileum and cecum
Ascending colon
Found in R lumbar area
Continues to inferior surface of liver, and bends sharply as transverse colon at hepatic/ R colic flexure
Transverse colon
Continues left of abdominal cavity
Intraperitoneal organ
Ends at splenic/L colic flexure to descending colon
Descending colon - Anus
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
Teniae coli
3 bands of smooth muscles fibers along large intestine
During contraction, they produce pocket like folds = haustrum
Rectum
Upper 2/3 is more dilated = ampiola
Distal 1/3 is more narrow and continues with anal canal
Anal sphincters
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
Hemorrhoidal veins
Veins are anal canal to shunt blood from portal system to anal system; during pathology of liver, they dilate causing hemorrhoids
Blood supply to digestive system
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
Nerve supply to digestive system
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)
Parotid gland
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
Submandibular gland
Deep to mandible
Submandibular duct opens to floor of oral cavity behind incisor tooth
Controlled by parasympathetic fiber of CNVII
Sublingual gland
Smallest
Under tongue
Secretion released to floor of oral cavity by numerous ducts
Controlled by parasympathetic fiber of CNVII
Liver
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
Ligaments of liver
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
Surfaces of liver
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
Lobes of liver
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
Gallbladder
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
Process of bile production
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
Pancreas
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
Blood supply for liver and pancreas
Branches of celiac artery
Nerve supply for liver and pancreas
ANS celiac plexus:
Sympathetic fibers - thoracic splanchic nerves
Parasympathetic fibers - CNX
