Alimentary canal Flashcards
what are the 4 functions of the digestive system
digestion (by process of absorption and secretion)
secretion
absorption
motility
function of gallbladder
stores and concentrates bile
function of small intestine
chemical digestion and nutrient absorption
what is the structure of the alimentary canal like?
continuous hollow tube
varying diameter
starts at oesophagus and ends at the rectum
what are the 4 layers of the alimentary canal called?
mucosa
submucosa
muscularis externa
serosa/adventitia
3 layers of mucosa
epithelium
lamina propria
muscularis mucosae (thin smooth muscle layer)
what type of epithelium is in the mouth, oesophagus and anal canal?
stratified squamous
what type of epithelium is in the stomach, small and large intestine?
simple columnar
what is the submucosa
thick, irregular connective tissue that supports mucosa
contains neurones, blood vessels and lymphatic vessels
where are there submucossal glands? (2 places)
oesophagus
duodenum
what does the adventitia do outside the peritoneal cavity?
Adventitia attaches oesophagus and rectum to surrounding structures
what does the serosa do inside the peritoneal cavity?
Serosa surrounds the liver, the stomach, spleen, start of the small intestine and the ileum, the transverse colon and the sigmoid colon.
muscularis externa 2 layers are made of what types of muscle?
smooth muscle
inner layer - circular muscle - constricts the tube
outer layer - longitudinal. When they contract the tube shortens
what is the plexus called between circular and longitudinal muscle
myenteric
what is the enteric nervous system made up of? what is it’s function/ significance
submucosal and myenteric plexuses
independent control of gut function - like the gut’s own brain
autonomic control of alimentary function
long parasympathetic and short ENS reflexes
parasympathetic control of alimentary function is carried out by what?
vagus nerve
N.B parasympathetic = peace = rest and digest
so it is therefore stimulatory
stimulatory - increases secretion and motility
what nerves are used for salivation
facial and glossopharyngeal
sympathetic control of alimentary function
splanchnic nerve
inhibitory (except salivation) decreases secretion and motility
3 branches of abdominal aorta?
Celiac trunk
superior mesenteric artery
inferior mesenteric artery
which organs does the celiac trunk supply?
Stomach
Small intestine
Pancreas
Liver
which organs does the superior mesenteric artery supply?
Small intestine
Caecum
Ascending colon
Transverse colon
ie the midgut
which organs does the inferior mesenteric artery supply?
Descending colon
Sigmoid colon
Rectum
ie the hindgut
where does the heptaic portal vein drain to?
the hepatic vein which in turn drains to the inferior vena cava
Blood from the stomach drains into which veins?
gastric veins
Blood from the pancreas drains into which veins?
splenic veins
where does blood from the Small intestine, Caecum, Ascending colon and Transverse colon drain to?
superior mesenteric vein
where does blood from the descending colon, sigmoid colon and rectum drain to?
inferior mesenteric vein
lymphatic system link with gut?
products of fat digestion go through this
what is the myenteric plexus?
nerve network between circular and longitudinal muscle
true or false: there is no conscious control of gut function?
true - it is all done automatically
some reflexes occur just within the ENS whereas some also involve the CNS
