GI tract

Question 1

Buccal cavity -

Answer 1

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

Question 2

saliva -

Answer 2

alpha amylase breaks down starches

Question 3

muscles that mechanical break

Answer 3

masseter
temoralis
pterygoids (tregemical CNV)

Question 4

Oesophagus

Answer 4

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

Question 5

stomach

Answer 5

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

Question 6

Duodenum

Answer 6

c shaped, 25cm, enzymatic breakdown of chyme, regulates stomach emptying via hormones secretin and cholecytokinen that causes sphyncter to open and close

Question 7

jejunum

Answer 7

absorption, villi , ph more than 7

Question 8

nutrient reabsorption

Answer 8

passive for fructose

active fro glucose , aa , small peptides

Question 9

Ileum -

Answer 9

lumen diameter is smaller, following jejunum , thinner walls

Question 10

Mesentry ?

Answer 10

membrane that tethers GI tract to abdomen

Question 11

Peyers Patchers

Answer 11

on the intestine, contain lymph nodes with immune cells

Question 12

Large intestine

Answer 12

absorbs water and electrolytes and eliminates waste

Question 13

caecum -

Answer 13

chyme through ileocaecal valve

Question 14

rectum -

Answer 14

store for faces follows she of sacrum with stretch receptors which cause desire to defecate

Question 15

Barrett’s disease -

Answer 15

change in cells in oesophagus stratified scams replaced with columnar. causes acid reflux and heart burn etc

Question 16

Gastrin hormone role

Answer 16

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.

Question 17

Peptic ulcer -

Answer 17

damge to te wll due to HCL. Use a proton pump inhibitor whch reduces acid and allows ulcer to heal

Question 18

Folds of Keckring

Answer 18

increase SA in duodenum and jejunum along with villi

Question 19

Small intestine reabsorbtion -

Answer 19

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+

Question 20

Food breakdown -

Answer 20

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

Question 21

large intestine role and regions

Answer 21

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

Question 22

Tenia Coli

Answer 22

3 bands longitudinal muscle

Question 23

Faesces -

Answer 23

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

Question 24

Hormone cholecytokinin

Answer 24

released in duodenum mucosal layer to signal stop eating

Question 25

Leptin

Answer 25

released by brown fat cells, apdipse issue, ‘plenty of fat in store stop eatingg” sent to hypothalamus

Question 26

Gherelin

Answer 26

peptide hormone to increase food intake made by stomach cells

Question 27

PYY3-36

Answer 27

decrease food intake peptide hormone made by intestinal cells . More calories you eat the more of it made