GIT Physiology

two plexuses of the enteric nervous system

myenteric, submucosal

exception to statement that sympathetic NS has inhibitory role in GIT

sphincters

what type of cholinergic receptor is stimulated for secretion of gastric acid

M1

submucosal plexus is called...

Meissner's plexus

myenteric plexus is called...

Auerbach's plexus

Auerbach's or Meissner's plexus controls motility

Auerbach's

what does Meissner's plexus control

secretion, blood flow

how much saliva is produced daily

750-1500ml

when saliva is secreted, is it hyper/hypo/isotonic

isotonic

striated ducts make saliva...

hypotonic

what effect does parasympathetic innervation have on saliva

increases volume

what effect does sympathetic innervation have on saliva

thickens

what type of papillae have most taste buds

valiate papillae

which type of papillae have no taste buds

filiform papillae

disorder of the oesophagus - bird beak oesophagus and impaired/absent peristalsis

achalasia

un-coordinated peristalsis, impaired motility

corkscrew oesophagus

transient lower esophageal sphincter relaxation

GORD

2 hormones produced by enteroendocrine cells

gastrin, ghrelin

what do parietal cells of stomach produce

HCl, intrinsic factor

optimum pH of intrinsic factor

7

intrinsic factor required for the absorption of which vitamin

vitamin B12

what does vis B12 bind to in stomach

haptocorrin

autoimmune disease caused by intrinsic factor deficiency

pernicious anaemia

which type of enteroendocrine cells release gastrin

G-Cells

which enteroendocrine cells secrete somatostatin

D-cells

3 phases of gastric acid secretion

cephalic, gastric, intestinal

what % of gastric acid released in cephalic phase

35

which empties more quickly from stomach - liquids or solids

liquids

which empties slowest: fatty/protein/carbohydrate

fatty

particles with diameter less than ___ empty from stomach very slowly if not at all

7mm

release of plasma enterogastrones in response to increase in acidity, fat, amino acids, distension in duodenum

negative enterogastric reflex

two duodenum derived hormones that inhibit gastric emptying

secretin, CCK

basal electrical rhythm in stomach

3/min

basal electric rhythm in duodenum

12/min

basal electric rhythm in ileum

8-9/min

basal electric rhythm in colon

3/min

name of cells that generate slow waves

interstitial cells of Cajal

receptor tyrosine kinase expressed by ICC cells

Kit

name for grouping of pacemaker currents

unitary current

summation of unitary currents

slow wave

name for large fold in duodenal lumen

plicae circularis

which mucous secreting cells become more abundant as you move down GIT

goblet cells

defensive cell types lining small intestinal mucosa

Paneth cells

absorptive cells lining small intestinal mucosa

enterocytes

hormone cells lining small intestinal mucosa

enteroendocrine cells

name for glands opening on to duodenal lumen

crypts of Lieberkuhn

mucous producing glands unique to duodenum

Brunner's glands

main secretory product of small intestine

isotonic, chloride rich secretion

static contractions to break up the chyme in the small intestine

segmentation

what nervous system mediates peristalsis

ENS

slow migration of undigested food

migrating myoelectrical complex

what hormone stimulates migrating myoelectrical complex

motilin

contribution of vagus to GIT motility increases/decreases as you descend the GIT

decreases

name of muscle which wraps like a sling around colon

puborectalis

what type of epithelium is seen in anal canal

stratified squamous, keratinised

tone at ileocaecal canal is decreased by what hormone

gastrin

invagination of a part of the intestine on to itself, early childhood

ileoileal intussusception

name for three aggregations of longitudinal muscle on colon

taenia coli

pouches occurring in colon because taenia coli are shorter than colon

haustra

pouches in colon

diverticulosis

when out pouches in colon become inflamed

diverticulitis

squirting of contents, kneading faecal mass, movements over short distances in colon

haustral shuttling

how many mass movements per day

1-3

what 5 things increase basal electric rhythm

stretch, ACh, histamine, substance P, 5-HT

what two hormones decrease basal electric rhythm

Ad, NAd

what antibodies are present in saliva

IgA

bacteria that can withstand low pH, found in stomach

H. pylori

T cells that maintain tolerance to self antigens in the gut mucosa

T reg cells

which cells can extend their processes out through tight barriers to the lumen (immune function - sample bacteria)

dendritic cells

what two protective secretions do Paneth cells of the GIT secrete

defensins, IgA

what does M stand for in M cell

microfold

function of M cells

antigen sampling system

two pathogens that can enter M cells without being endocytosed

salmonella, shigella

which two signalling molecules are Nod-like receptors associated with

caspases, NFkappaB

mutations in what receptor make someone more susceptible to IBD

NOD2

hospital acquired disease, can follow broad spectrum antibiotic use, focal transplant as treatment

c. difficile colitis

which three sympathetic ganglia contribute to innervation of GIT

coeliac, sup mesenteric, inf mesenteric

which cholinergic receptor is activated by parasympathetic NS to induce secretions from glands

M3

which receptor controls contraction of sphincters by the Sympathetic NS

alpha 2 adrenoceptor

mastication is governed by a group of neurons in the CNS that execute complicated task without need for continuous input called

CPG

third phase of masticatory cycle called

intercuspal phase

5 muscles involved in swallowing

medial and lateral pterygoids, buccinator, masseter, orbicularis oris

which three cranial nerves innervate muscles of mastication and salivary glands

V, VII, IX

what enzyme is produced by the parotid gland

amylase

what enzyme is produced by the submandibular glands

lysosyme

which main salivary gland does not produce mucous

parotid

which substance, found in saliva, maintains fungiform taste buds

epidermal growth factor

which two chemicals are higher in saliva than in plasma

K+, bicarbonate

taste receptors for salty food are

ENaC

what channels are blocked by H+ ions from sour foods, allowing you to taste 'sour'

K+

what is primary peristalsis initiated by

swallow

what is secondary peristalsis initiated by

distension of oesophagus

can peristalsis occur after vagotomy

yes

what occurs after multiple rapid swallows

deglutitive inhibition

what neurotransmitter contracts the muscle behind the bolus in peristalsis

ACh

what neurotransmitter relaxes muscle after the bolus in peristalsis

NO

what % of blood supply to liver is from hepatic portal vein

75%

what % of hepatic blood supply is from hepatic artery

25%

major cell type involved in liver fibrosis

hepatic stellate cells

small space between sinusoids of liver and hepatocytes called

space of Disse