GI tract Flashcards
Buccal cavity -
smash food mechanically and add saliva t produce a soft bolus
Mastication to break into smaller SA ease swallowing
uses chew reflex as stretch receptors cause mouth to close
saliva -
alpha amylase breaks down starches
muscles that mechanical break
masseter
temoralis
pterygoids (tregemical CNV)
Oesophagus
firbomuscular tube
20-25 cm long
lined with mucosa
upper 3rd skeletal muscle, lower 2/3rds is smooth
posterior to trachea
peirces diaphragm before entering stomach
muscular layer perform peristaltic movement controlled by CN 9 and 10
stomach
1l food,elastic pouch, upper left abdominal cavity, releases HCL, peristalsis to produce chyme that is released is small quantities into the duodenum via sphincter
food stretches stomach, vasovagal reflex - reduces muscular tone and bulges it out so more food
gastric juices from the gastric glands mixes with food due to waves
Duodenum
c shaped, 25cm, enzymatic breakdown of chyme, regulates stomach emptying via hormones secretin and cholecytokinen that causes sphyncter to open and close
jejunum
absorption, villi , ph more than 7
nutrient reabsorption
passive for fructose
active fro glucose , aa , small peptides
Ileum -
lumen diameter is smaller, following jejunum , thinner walls
Mesentry ?
membrane that tethers GI tract to abdomen
Peyers Patchers
on the intestine, contain lymph nodes with immune cells
Large intestine
absorbs water and electrolytes and eliminates waste
caecum -
chyme through ileocaecal valve
rectum -
store for faces follows she of sacrum with stretch receptors which cause desire to defecate
Barrett’s disease -
change in cells in oesophagus stratified scams replaced with columnar. causes acid reflux and heart burn etc
Gastrin hormone role
stimulates secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the pyloric antrum of the stomach, duodenum, and the pancreas. … Its release is stimulated by peptides in the lumen of the stomach.
Peptic ulcer -
damge to te wll due to HCL. Use a proton pump inhibitor whch reduces acid and allows ulcer to heal
Folds of Keckring
increase SA in duodenum and jejunum along with villi
Small intestine reabsorbtion -
water moves down concentration gradient, sodium actively transported through mucosa so less than 0.5% in faeces, cotransported with glucose, aa or H
Cl- dragged along due to attraction to Na+
Food breakdown -
starch main food - to monosaccharides
Fats - monoglycerides and free Fatty acids that are emulsified by the liver in bile micelles that are soluble in chyme as charged exterior, they diffuse with epithelial cell, micelle recycled, MG and FFA taken up by smooth ER, form triglycerides and combine with protein to chylomicrons that enter lacteal (lymph capillary) and taken to blood
Amino acids - active transport to blood
large intestine role and regions
remove water, salt super, vitamins
regions - caecum , ascending, transverse, descending, sigmoid
Have no villi but lots of goblet cells to produce mucus
Tight junctions prevent back flow
Tenia Coli
3 bands longitudinal muscle
Faesces -
brown colour - stercobilin and urobilin
Odour - bacteria and colonic flora
3% protein, 30% undigested food, 30 % dead bacteria, 10-20% inorganic matter and 20 % fat
Hormone cholecytokinin
released in duodenum mucosal layer to signal stop eating
Leptin
released by brown fat cells, apdipse issue, ‘plenty of fat in store stop eatingg” sent to hypothalamus
Gherelin
peptide hormone to increase food intake made by stomach cells
PYY3-36
decrease food intake peptide hormone made by intestinal cells . More calories you eat the more of it made
