lecture 34: digestive 2

Question 1

main functions of oesophagus

Answer 1

• fast transport
• protection against abrasion

Question 2

structure of oesophagus

Answer 2

• thick many layered stratified squamous epithelium, sacrificial outer layer
• cells replaced by basal stem layers slowly migrating outwards (7 day renewal time)

Question 3

oesaphagus modifications to the gut tube

Answer 3

• as well as smth mxl, upper oesophagus muscularis externa has skeletal muscle
• contains fibrous adventitia rather than serosa

Question 4

function of stomach

Answer 4

• food storage so you can eat faster than you can digest.
  -acid, enzyme, mucous secretion,
• protein digestion
• some absorption
• protectiosn against microbes and its own secretions
• transport/mixing

Question 5

4 regions of the stomach

Answer 5

• cardia (mucous glands mostly)
• fundus (acid, enxyme, mucous sectretion)
• body (acid, enxyme, mucous sectretion)
• pylorus (mucous glands mostly)

Question 6

gross anatomical features of stomach

Answer 6

• rugae (longitudinal folds)
• pyloric sphincter (muscularis externa inner layer thickening) to allow chyme to go to duodenum
• lower oesophageal sphincter (failure causes reflux)

Question 7

gastric pits of stomach muscosa

Answer 7

• surface mucous cells (secrete alkaline mucous to protect mucosa from acid + pepsin)

Question 8

glands of stomach mucosa

Answer 8

• parietal cells (secrete H+ and Cl- ions, also intrinsic factor, kill microbes and living cells)
• chief cells (secrete pepsinogen and gastric lipase)
• enteroendecrine cells (gastrin secretion)
• undifferentiated cells (stem cells)

Question 9

intrinsic factor function

Answer 9

needed for vit. b12 absorptions needed for RBC haematopoiesis (prevent anaemia)

Question 10

pepsinogen

Answer 10

converted to pepsin which splits proteins by acid in the gastric gland lumen

Question 11

function of gastrin secretion

Answer 11

• stimulate acid and pepsinogen secretion
• increase stomach muscle contractions
• relax pyloric sphincter

Question 12

major functions of liver

Answer 12

500 different functions including:
- glycogen/glucose storage+release
- RBC recycling
- bile synsthesis + secretion
- plasma protein synthesis
- blood toxin removal

Question 13

hepatocytes requiremnts

Answer 13

carry out all functions of the liver. require:
- access to nutrient laden blood drained from intestinal walls
- access to oxygenated blood
- access to ducts to drain bile to the gallbladder

Question 14

hepatocyte structure:

Answer 14

• brick shaped with cut outs for bile caniculus
• lined with fenestrated epithelium
• surrounded by wide sinusoids
• lymph space of disse between microvilli and sinusoid endothelium

Question 15

how are hepatocytes placed in relation to blood and bile spaces

Answer 15

• columns of hepatocyts in radiating colums with bile canaliculi between that drain bile to ductules and then ducts.

Question 16

structure of liver lobule

Answer 16

• hexagonal units of the liver
• surrounded by connective tissue
• space containing portal triad
• columns of hepatocytes
• central vein fed by sinusoids
• adjacent to hepatic portal veing bring nutrient rich blood
• hepatic artery brinsg oxygenated blood

Question 17

function of bile

Answer 17

emulsify fats to smaller globules so pancreatic lipases have more surface area to work on when digesting. also helps with the absorption