Digestive part 2 Flashcards
What do the mesentery regions associate with
Greater omentum:small and large intestine
Lesser omentum:liver+lesser curvature
Falciform ligament:liver
Mesentary proper: jejunum and illium
Mesocolon: posterior wall
Gastric mixing and emptying steps
- muscle contractions mix bolus and gastric juice making chyme
- peristalsis wave creates pressure gradient towards pylorus
- force increases on pyloric sphincter
- sphincter opens, allowing chyme into duodenum
- sphincter closes
Cephalic phase of digestion
Triggered by sensory input such as sight or smell. Received by medulla -> nerve signals down to stomach. Increased force of contractions and secretions
Gastric phase of digestion
Initiated by food in stomach. Baroreceptors detect stretch/chemoreceptors detect protein or higher pH. Nerve signals to medulla > Increases force of contraction and secretions. Additionally gastrin is released.
Intestinal phase of digestion
Initiated by presence of acidic chyme in duodenum.
chemoreceptors in intestinal wall detect pH change > decreased nerve signals to medulla > decreased signals to stomach > stomach decreases force of contraction and decreases secretion. Additionally CCK is released, inhibiting contraction and secretin inhibits secretions
digestion of carbohydrates
begins in oral cavity with salivary amylase and is further broken down in the small intestine by pancreatic amylase and brush border enzymes
digestion of lipids
begins in oral cavity with lingual lipase but isn’t actually activated until stomach. Lingual lipase begins to break down in the stomach and gastric lipase breaks down other fats. Pancreatic lipase breaks down stuff in small intestine too
digestion of proteins
none in oral cavity
pepsin in stomach, continues in small intestine with pancreatic juices and brush border enzymes
digestion of nucleic acids
only in small intestine
internal anal sphincter
Involuntary smooth muscle at
base of anal canal
External anal sphincter
Voluntary skeletal muscle
Sphincters normally closed off but relax during defecation
Peristalsis in the large intestine is
slow
Gastrocolic reflex
Initiated by stomach distension
o Causes a mass movement
