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Flashcards in GI Deck (145)
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Describe the main components of saliva

-Hypotonic solution containing water, mucous and electrolytes, antibodies, amylase and lysozyme, lymphocytes and neutrophils


Give 3 consequences of failure of continuous saliva secretion (xerostomia)

-poor dentition
-Bacterial over growth


What physical mechanisms trigger the release of saliva from the major salivary glands?

-Senses ie sight, smell, taste and thought of food


Describe the location of the 3 major paired salivary glands and state whether their secretions are mainly serous, mucus or mixed

-Parotid = in front of ears (preauricular) -> serous
-Sublingual =under tongue -> mucous
-Submandibular = floor of mouth -> mixed


What are the main purposes of saliva?

-Lubrication of food for swallowing
-Maintenance of teeth integrity by neutralising acid
-Iodide is a bacteriostatic
-Initiate digestion of foods by amylase/lipase


Name the ducts of parotid and submandibular glands

-Parotid = stensons (second molar tooth of maxilla)
-Submandibular = whartons (either side of lingual frenulum)


Describe the general secretory units of a salivary gland and what each component does to produce saliva

-Acinus -> secretion of fluid isotonic with plasma
-Striated ducts -> ductal modifiction of isotonic solution by removing Na and Cl and adding K+, I-and HCO3-. ducts are impermeable so water cannot follow


Describe the difference between unstimulated and stimulated saliva

-Unstimulated -> low flow rate provides lots of time to remove Na/Cl and basal hco3 added.
-Stimulated -> high flow rate means limited time to remove Na and lots of HCO3- added


What does the gag reflex test?

-Sensation of soft palate
-Motor innervation of soft palate


Name the two arches anterior and posterior to the palatine tonsils

-Anterior = palatoglossus
-Posterior = palatopharyngeal


Describe the three phases of swallowing

-Oral -> food chewed to form bolus, pushed to back of mouth causing reflex activation of pharyngeal phase
-Pharyngeal -> involuntary control - pharyngeal receptors communicate with swallowing centres in brain causing soft palate to raise and close off nasopharynx, hyoid bone and larynx raise closing epiglottis, food passes into oesophagus
-Oesophageal -> passage through upper oesophageal sphinter causing constriction of sphincter and peristaltic wave causing relaxation of lower oesophageal sphincter


What is achalasia?

-Failed relaxation of lower oesophageal sphincter causing dysphagia


Give 3 common causes of dysphagia

-Stroke causing paralysis of muscles on one side
-Benign stricture
-Pharyngeal pouch


What is a pharyngeal pouch?

-also known as zenkers diverticulum
-diverticulum of oesophagus through killians dehiscence between cricopharyngeus and inferior pharyngeal constrictor


How does the autonomic nervous system affect salivary glands?

-Parasympathetic -> stimulates acinus and ductal cells to add HCO3-
-Sympathetic -> reduction in bloodflow to glands limits salivary flow


describe the differences in voluntary and unvoluntary control of the oesophagus

-Upper 1/3 voluntary striated muscle
-Lower 2/3 unvoluntary smooth muscle


Describe the results on the GI system of lateral and craniocaudal folding

-Lateral = ventral body wall and pinching from yolk sac
-Craniocaudal = blind ended primitive gut tube from stomatoduem to proctoduem with opening at umbilicus


Of what tissue origin are epithelial linings and musculature of gut wall?

-Epithelia = endoderm
-Musculature = splanchnic mesoderm


What are the adult derivatives of the foregut, midgut and hindgut?

-Foregut -> Oesophagus, stomach, 1st part duodenum, liver, gallbladder, pancreas
-Midgut -> distal 3/4 of duoedenum to 2/3 transverse colon
-Hindgut-> distal 1/3 transverse colon to upper anal canal. also internal lining of bladder and urethra


Describe the branches of the coeliac trunk and which art og the gut it supplies

-Splenic artery (left gastroepiloic, fundus)
-Common hepatic -> proper hepatic (R/L hepatic, cystic), gastroduodenal (superior pancreaticoduodenal, right gastroepiploic) right gastric
-Left gastric (oesopagus)


Describe the main branches of superior mesenteric artery and which part of the gut it supplies

-Inferior pancreaticoduodenal
-Right Colic
-Middle colic


Describe the main branches of inferior mesenteric artery and which part of the gut it supplies

-Left colic
-Continues as superior rectal


Which structures in the gut have a dual blood supply by CT and SMA?

-Duodenum (gastroduodenal and sup. pancreatico duodenal from CT and inf. pancreaticoduodenal from SMA)
-Pancreas (sup. pancreatico duodenal from CT and inf. pancreaticoduodenal from SMA)


What is a mesentery and why is it important? What is the embryonic origin of mesentery? Describe the locations of the dorsal and ventral mesentery

-Double layer of peritoneum which attaches the gut to the abdominal wall
-Allows blood and nerve supply to organs
-Splanchnic mesoderm
-Dorsal along length of gut tube, ventral only to foregut


What are omenta and describe their formation?

-Double folds of mesentery formed during rotation of the stomach
-As the stomach rotates clockwise in longitudinal axis it drags the dorsal and ventral mesentery with it producing double folds forming greater and lesser omenta.
-As it rotates on an obligue (AP) axis it puts the omenta into their anatomical positions -> greater hangs from greater curvature of stomach, lesser from lesser curvature of stomach


What lays in the free edge of the lesser omentum?

-Portal triad


Where does the liver develop? How does the liver help anatomical positioning?

-Within the ventral mesentery
-Grows so fast and so large within cavity that pushes stomach to left


What is retropetitoneal/secondary retroperitoneal and what organs?

-Retroperitoneal -> organs never within the peritoneum/enveloped in mesentery - abdominal aorta and kidneys
-Secondary retroperitoneal > once within the peritoneum and covered in mesentery but got pushed dorsally and became fused with posterior abdominal wall to loose its mesentery -> distal 3/4 duodenum, ascending/descending colon


Explain the association between the foregut and the respiratory tract

-Resp tract started as a blind diverticular ventral outpuching from the foregut.
-Tracheoesophageal septum gows and separates resp diverticulum from foregut. puts trachea ventrally and oesophagus dorsally


Describe the development of the duodenum and problems which can arise during development

-Grows rapidly and pulled into a c-shape as stomach rotates
-Growth is so rapid that lumen is obliterated and recanalised
-Failed recanalisation causes duodenal atresia (usually upper, problem with vasculature commonly causes lower duodenal atresia)