Physiology - Alimentary Canal Flashcards
what causes the circular muscle in alimentary canal to contract
release of Ach and substance P from excitatory motor neurone
what causes the circular muscle in alimentary canal to contract relax
release of VIP and NO from inhibitory motoneuron
what causes the longitudinal muscle in alimentary canal to contract
release of Ach and substance P from excitatory motoneurons.
what causes the longitudinal muscle in alimentary canal to relax
release of VIP and NO from inhibitory motoneuron
what muscle are sphincters made of
smooth and skeletal
function of mouth and pharynx
chop and lubricate food
start carbohydrate digestion
delivers food to oesophagus
function of oesophagus
propels food to the stomach
function of stomach
stores and churns food
continues carbohydrate digestion
initiates protein digestion
regulators delivery of chyme to duodenum
function of small intestine
principle site of digestion and absorption of nutrients
function of large intestine
colon reabsorbs fluids and electrolytes
stores faecal matter before delivery to rectum
function of rectum, anal canal, anus
regulates expulsion of faeces.
accessory structures of alimentary canal
salivary glands, pancreas, liver, gall bladder
4 layers of GI tract
mucosa
submucosa
musculares externa
serosa
What is mucosa made of
mucous membrane, lamina propria, muscalris mucosa
what is submucosa made of
connective tissue, larger blood and lymph vessels, glands, sub mucous plexus
what is muscarlis externa made of
circular smooth muscle layer, myenteric plexus, longitudinal smooth muscle layer
serosa
connective tissue
4 major functions of alimentary Canal
motility, secretion, digestion, absorption
circular smooth muscle contraction
lumen becomes narrower and longer
longitudinal smooth muscle
intestine becomes shorter and fatter
muscularis mucosae contraction
change in absorptive and secretory area of mucosa
where are interstitial cells of Cajal found
between circular and longitudinal muscle layers
what is the parasympathetic supply to GI tract mediated by
Vagal and Pelvic nerves
what part of GI tract do Vagal nerves innervate
oesophagus to and including ascending colon
what part of GI tract do Pelvic nerves innervate
descending colon to anus
excitatory influences of parasympathetic supply
increased gastric, pancreatic, small intestinal secretion.
increased blood flow
smooth muscle contraction
inhibitory influences of parasympathetic supply
relaxation of some sphincter
receptive relaxation of stomach
where do the pelvic nerves leave
S2-S4
what are the pre vertebral ganglion
celiac, superior mesenteric and inferior mesenteric.
where do preganglionic fibres from sympathetic region send out axons from
thoraco-lumbar region
excitatory influences of sympathetic division
increased sphincter tone
inhibitory influences of sympathetic division
decreases motility, secretion, blood flow
which plexus mainly regulates motility and sphincters
myenteric plexus (Auerbach’s)
which plexus mainly modulates epithelial and blood vessels
sub mucous plexus (Meissner’s)
what type of reflex is peristalsis
local reflex
is a local reflex intrinsic or extrinsic
intrinsic
is a short reflex extrinsic or intrinsic
extrinsic
is a long reflex extrinsic or intrinsic
extrinsic
which type of reflex is the intestine-intestinal inhibitory reflex
short reflex
what type of reflex is the gastroileal reflex
long reflex
what is the powerful sweeping contraction that forces faeces into the rectum known as
colonic mass movement
what is the powerful sweeping contraction from stomach to terminal ileum known as
migrating motor complex
what has low pressure tonic contractions
organs with a major storage function
what has high pressure tonic contractions
sphincters
what muscle is the UOS made of
skeletal
which sphincter relaxes to allow swallowing
UOS
which sphincter closes during inspiration
UOS
which sphincter relaxes to permit entry of food to stomach
LOS
which sphincter closes to prevent reflux of gastric contents to the oesophagus
LOS
which sphincter regulates gastric emptying
Pyloric sphincter
which sphincter usually prevents duodenal gastric reflex
Pyloric
which sphincter regulates flow from ileum to caecum
ilocaceal valve
what muscle is the internal anal sphincter
smooth
what muscle is the external anal sphincter
skeletal
which sphincter allows communication between bowl duct and upper part of duodenum
Sphincter of Oddi
