27: Small Intestine

Question 1

length of Small intestine

Answer 1

10 ft in live people

19.7 in cadavers due to muscle tone loss

Question 2

length of the 3 sections

Answer 2

duodenum: 10 inches
jejunum: 8..2 feet
ileum: 11.5 feet
ends at ileocecal valve

Question 3

absorptive cells

Answer 3

microvilli

most absorption happens at surface of microvilli

Question 4

goblet cells

Answer 4

has signficant area where secretion can hapen

Question 5

eteroendcorine cell

Answer 5

secretes secritin, cholecystokin, GIP (hormones)

Question 6

cell type (epithelium)

Answer 6

simple columnar epi

Question 7

4 cell types of SI

Answer 7

absorptive cell
goblet cell
enteroendocrine cell
paneth cell

Question 8

paneth cell

Answer 8

secretes lysosome and capable of phagocytosis

Question 9

Villi/Microvilli functions

Answer 9

inc SA for abs
brush border enzymes on surface–> chem breakdown (carbs and proteins_
cell division at base: new cells that move up

Question 10

Carb digestion enzymes

Answer 10

mouth: salivary amylase
stomach: mechanical
duodenum: pancreatic amylase
brush border enzymes: maltase, sucrase, lactase

Question 11

brush border enzymes:

Answer 11

maltase, sucrase, lactase
produce monosaccharides from disaccarides
lactose intolerance: no lactase: bacteria ferment the sugar

Question 12

Glucose and galactose absorption into epicells:

Answer 12

glucose and galactose: sodium symporter (2ndary active transport)

Question 13

movement of monosacchs out of epis into bloodstream

Answer 13

facilitated diffusion

Question 14

Protein digestion locations

Answer 14

stomach
SI
brush border enzymes

Question 15

Protein digestion in stomach

Answer 15

HCl denatures proteins

pepsin turns into peptides (AA chains)

Question 16

Protein digestion in SI

Answer 16

pancreatic enzymes: split peptide bonds between different AAs

Question 17

Protein digestion in brush border enzyme

Answer 17

aminopeptidase: split AAs at amino end
dipeptidase: split dipeptides

Question 18

absorption of amino acids and dipeps into epicells of duodenum and jejjunm

Answer 18

active transport (2ndary) with Na+ or H+ ions (symporters)

Question 19

movement into blood stream of amino acids

Answer 19

diffusion

Question 20

Lipid digestion locations

Answer 20

mouth
stomach
SI

Question 21

Lipid digestion in mouth

Answer 21

lingual lipase

Question 22

Lipid digestion in stomach

Answer 22

gastirc lipase

infants

Question 23

Lipid digestion in SI

Answer 23

emulsification by bile from liver–> miscells
pancreatic lipase: split triglyccerides into FAs and monoglycerides
no lipase in brush border!

Question 24

Water absorption

Answer 24

9 L enter GI tract daiily
SI absorbs 8 L
LI absorbs 90% of last liter
abs by osmosis through cell walls into vascular capps in villi

Question 25

Absorption of vitamins

Answer 25

fat soluble water soluble B12: problem causer

Question 26

abso of fat soluble vitamins

Answer 26

travel in micelles and absorbed by simple diffusion with lipids

Question 27

abso of water soluble vitamins

Answer 27

diffusion

Question 28

B12 abs

Answer 28

has to combine with intrinsic factor from stomach p-cells b4 transport to ileum. abs by receptor mediated endocytosis

Question 29

electrolyte sources

Answer 29

``` GI exocrine secretions foods and liqueds diffusion by diffusion and 2ndary AT NA and K Cl-, iodine, nitrate iron, magnesium, phosphate CA++ ```

Question 30

sodium and potassium abso

Answer 30

active transport

Question 31

chloride, iodide, nitrate abso

Answer 31

passive

Question 32

iron, magnesium, phospate

Answer 32

active transport

Question 33

intestinal Ca++

Answer 33

requires vit. D and PTH

Question 34

abso of small/short chain fatty acids

Answer 34

simple diffusion into abso cells and bloodstream | b/c easy to get through lipid bilayer

Question 35

abso of larger lipids/long chain FAs/ monoglycerides

Answer 35

seqestered w/in micelles after emulsification (bile) | enter cells by simple diffusion, leave bile salts in gut

Question 36

fat soluble vitamins

Answer 36

ADEK | enter cell with the lipid

Question 37

lipids inside epi cells

Answer 37

fats rebuilt into triglycerides, coated with proteins to make chylomicrons

Question 38

chylomicrons leave...

Answer 38

by exocytosis into a lacteal travel in lymph system to reach subclavian veins removed from blood by liver and fat tissue

Question 39

fructose absorption into epicells:

Answer 39

facillitated diffusion