EXAM 5 digestive 2 (SMALL INTESTINE)

villi

collection of protrustions/peaks

villi purpose

increase surface area for absorption

villi contains

goblet cells, capillaries, lacteals and microvilli

goblet cells

secretes mucus

capillaries

absorb monomers

leacteals

absorbs fat

microvilli

folds/minicells within villi protrusions

microvilli purpose

further surface area expansion, hydrolyzes chyme macromolecules into monomers

small intestine secretions

mucus (lubrication and protection). water (hydrolysis) (NO ENZYMES - those are at villi)

fats in small intestine

Breakdown is within the lumen, Enzymes into Bile and Pancreatic Lipase, Monomers into Monoglycerides, Fatty Acids

carbohydrates in small intestine

Location in lumen, Enzymes into Pancreatic Amylase (Dual breakdown with Microvilli) Monomers into Monosaccharides

proteins in small intestine

Location also lumen, Enzyme into Proteolytic (Pepsins, Aminopeptidase) Monomer into amino acids

other nutrients in small intestine

based upon bodies requirements, only takes what it needs to take

transepithelial transport

how carbs and proteins are transported in small intestine (fats form micelles making hard)

fat nutrient transport

micelles re-synthesized into triglycerides, through interstitial fluid, then needs further breakdown

migration motility complex

movement complex after most absorption had occured, occurs in-between meals

motility seuqence

segmentation stops (chyme stationary), digestive system then initiates peristaltic waves

peristaltic waves

weak but repetitive waves from the stomach down to the ileum (short distance contractions to slowly push food/bolus/chyme to the end)

segmentation

combination of propulsive/mixing motility, chyme is moved either forward or backward

propulsive/mixing motility

regions of contracted and relaxed sections, alternates between contracted and relaxed

how does overall movement happen then

duodenum has pacemaker cells that depolarize faster than the ileum, gradually chyme will move through

small intestine

primary absorption of nutrient monomers, 3 structures/regions

duodenum

beginning (carbs, lipids, amino acids, calcium, iron etc.)

jejunum

middle (same as duodenum)

ileum

end (vitamin B12, water, electrolytes)