EXAM 4 digestion and reproduction Flashcards
Fats are also called _______. They break down into what 2 groups when digested?
lipids: triglycerides and cholesterol
Chewing is also called ______. Why do it?
increases surface area for enzymes
What substances does chewing mix food with, and what does each do?
saliva (lubricates), mucus, (lubricates), amylase (begins carb digestion), lingual lipase (attaches for later lipid digestion)
Time from swallow to stomach:
7 sec.
What happens in the stomach, and how long does it take? What happens when it is done?
food mixes with acid and pepsin, 3 hours, then chyme is “spoon-fed” into duodenum
Name the phases of gastric activity.
1) cephalic 2) gastric 3) intestinal
What happens in the cephalic phase of gastric activity?
Thoughts of food lead to a signal travelling through vagus nerve (X) that release hydrochloric acid and start contraction.
What happens in the gastric phase of gastric activity?
pH goes up and walls stretch, both signalling more HCl secretion, more pepsin secretion, and more contraction
What is the pH of an empty stomach?
2.0
What happens in the intestinal phase of gastric activity?
controlled emptying (spoon-feeding) into duodenum
Bile is made where? Stored where?
liver: gall bladder
Draw the busy intersection.
duodenum: include chyme from stomach, HCO3- from pancreas, digestive enzymes from pancreas, and bile
Chyme is made up of:
partly digested carbs with their salivary amylase, proteins with the pepsin that digests proteins, fats, with lingual lipase and bile that digest fats, plus acid
Name the pancreatic enzymes and the part of chyme they digest.
pancreatic amylase (carbs), pancreatic protease (proteins), pancreatic lipase, HCO3-
After passing through the doudenum, what is the progress of digestion?
All but few chunks are broken into particles.
What is added for carbohydrates to chyme in the duodenum? What does this cause?
Glucose-dependent Insulinotropic peptide: causes pancreas to secrete insulin.
What is added for protein and fats to chyme in the duodenum? What does this cause?
cholecystokinin; causes 1) gallbladder contraction, 2) relaxation of hepatopancreatic sphincter, 3) pancreas to release digestive enzymes, 4) pyloric sphincter contraction 5) signals sateity to the hypothalamus
What is added for acid to chyme in the duodenum? What does this cause?
secretin; causes 1) pancreas to release HCO3- (which neutralizes some acid) and relaxes hepato-pancreatic sphincter
Why don’t carbs make you feel full like fats and proteins?
They don’t cause secretion of cholecystokinin, which contracts the pyloric sphincter, slowing stomach emptying, and also signal satiety to the hypothalamus.
What does the suffix “trophic” mean?
all it does is cause another substance to be secreted
Draw a segment of small intestine with layers
include villi, capillaries, mucosa, submucosa, muscularis mucosa. muscularis externa, and serosa… and the capillaries send nutrient-rich blood to the liver
describe the condition of absorbable food in the small intestine
glucose, amino acids and a few still connected disaccharides and dipeptides
What is VIP and what does it do?
vasoactive intestinal peptide makes villi capillaries dilate to accept nutrients
Serosa is aka
viseceral peritoneum
WHat is the role of dead villi cells in intestine.
secrete brush border enzymes that break up still connected disaccharides and dipeptides
muscularis externa does this
contracts to move food along
role of visceral peritoneum
covers internal organs
this enzyme breaks down lactose- what does it break it down into? What breaks down sucrose, and what are the results.
lactase, breaks it into glucose and galactose
sucrase, breaks sucrose into glucose and fructose
Why do fats have special digestive chemicals? What makes it possible to digest fat?
fats are not water soluble, but the enzymes to process it are. Bile (a detergent) makes it possible todigest fats.