Lecture 11-Control of digestion Flashcards
What is probiotic bacteria?
- bacteria that can get through the stomach to the colon -stomach is a big barrier
What is the gut-brain axis?
-brain and gut communicate= 2 directional communication
What happens in the digestive process, simply?
- Food taken into mouth 2. Broken down into ever smaller components, eventually into individual molecules 3. Separated chemically( and physically= as fat rises to the top in the stomach as it is lighter and gets emptied into the intestine last) into different nutrients that can be absorbed 4. Bi-products transported along the intestinal tract for further processing and recovery of key materials 5. Waste products excreted
How is fat important in digestion?
–fat activates lot of receptors in the mucosa -and the overall satisfaction with the food is dependent on fat -enough nutrients= duodenum= says that -we can overcome that= by apetite (thalamus)
What os vomiting for?
-if take in something noxious= vomit -evolved to be used for purposes of getting rid of noxius material in as short time as possible
What components are proteins, sugars and fats broken down into?
-proteins= amino acids -sugars and starches into simple sugars= glucose, fructose and galactose -lipids into fatty acids and glycerol
Where does most of the compounds breakdown happens?
-the breakdown happens mostly in upper duodenum and distal stomach, very little elsewhere (mouth)
What is the fermentation in animals used for?
-many species use bacterial fermentation to breakdown cellulose-into short chain fatty acids and sugars -if you’re a herbivore= deal with food that is indigestible, cellulose in plants -plants and leaves make their way through the duodenum, reach distal gut= process of fermetation occurs (not breaking down the food, it is converting it to sth else) = into short fatty acids)= extremely inefficient, herbivores are larger due to this -even humans use cellulose breakdown, the production of short chained fatty acids, = these activate things in the brain -represent about 30% of energy requirement in the distal gut
Where in humans do the short chain fatty acids play an important role?
-in the energy metabolism of mucosa in the ascending colon
What is the diet of animals with active life-styles like?
-tend to depend on foods high in simple sugars and protein= as those are easy to digest
What neurons are involved in digestion?
-both somatic and visceral -also endocrine system! (gut is the biggest endocrine organ)
What does the somatic nervous system control in digestion?
-conscious control -chewing, swallowing, peristalsis in esophagus and opening key sphincters -as soon as you get to oesophagus= mostly visceral control
What do the visceral neurons control in digestion?
-involved in salivation, primary peristalsis, all functions from stomach to anus
What visceral neurons are involved in digestion?
-sympathetic and parasympathetic nervous systems, many types of visceral afferents and the enteric nervous system
What happens when we see or smell food?
-cephalic phase of digestion -salivation, gastric relaxation, gastric acid secretion -happens via NS (vagus) in particular -no food needs to be digested -depends on hunger and appetite (depends on the hypothalamic regions of hunger) -food in mouth gives same behaviours=but also activates gustation and olfaction
How does the palatability of the food effect cephalic phase?
- more palatable the food, the greater the response (use memory as part of the process) -partly determined by nature of food previously eaten
What does hypothalamus do?
-regulates hunger
What happens when food is in the mouth?
-chewing -movement of tongue -swallowing