6- small intestine

Question 1

which is smallest and largest
duodenum
jejunum
ileum

Answer 1

small: duodenum
longest: ileum

Question 2

what is ferritin

Answer 2

a protein complex that acts as a storage form of iron

Question 3

what is transferrin

Answer 3

plasma protein that carries iron

Question 4

what do absorptive/enterocytes do

Answer 4

absorb

brush border enzymes

Question 5

what do most cells from the stem cells end up becoming

Answer 5

absorptive cells

Question 6

what do goblet cells do

Answer 6

secrete mucous

Question 7

what is the role of ileum

Answer 7

digest and absorb (less important)

secrete intrinsic factor for B12 and absorbs bile acid

Question 8

what do paneth cells do

Answer 8

secrete antibacterial proteins

Question 9

what are the major cell types in villus

Answer 9

goblet, endocrine and absorptive cells

Question 10

what are the major cell types in crypts

Answer 10

stem and paneth cells

Question 11

what is a brush border

Answer 11

small microvilli projections of epithelial cells that cover the villi, major absorptive surface of the small intestine

Question 12

what kind of molecules do brush border enzymes break down

Answer 12

carbs and peptides

Question 13

what do brush border enzymes durn maltose and limit dextrins into

Answer 13

glucose

Question 14

why do brush border enzymes need to break these sugars down to glucose

Answer 14

because the intestine can only absorb monosaccharides

Question 15

how does glucose/ galactose get from the intestinal lumen into epithelial cells

Answer 15

2ary cotransport with sodium

Question 16

how does glucose/ galactose get from the epithelial cells into the blood

Answer 16

facililated transport

Question 17

how does fructose get from the intestinal lumen into epithelial cells

Answer 17

facilitated diffusion

Question 18

how does fructose get from the epithelial cells into the blood

Answer 18

facilitated diffusion

Question 19

why does lactose intolerance cause diarrhea

Answer 19

decrease water absorption in gut because lactose produces an osmotic gradient

Question 20

how does glucose/ galactose get from the epithelial cells into the blood

Answer 20

facilitated transport

Question 21

how do small peptides get absorbed into epithelial cell

Answer 21

2 active coupled to H+

Question 22

what happens once small peptides enter the cytosol

Answer 22

they are hydrolyzed by peptidases into amino acids

Question 23

how to amino acids enter the blood

Answer 23

facilitated diffusion

Question 24

what happens once fatty acids enter the enterocyte and why

Answer 24

ER processes them back into triglycerides

Question 25

what are chylomicrons

Answer 25

proteins that were packed by Golgi and secreted via exocytosis

Question 26

what does the ER do to the triglycerides

Answer 26

triglycerides that aggregated and coated with amphipathic proteins

Question 27

what are chylomicrons and what do they contain

Answer 27

extracellular fat droplets | triglycerides, phospholipids, cholesterol and far soluble vitamins

Question 28

what does the ER do to the triglycerides

Answer 28

triglycerides that aggregated and coated with amphipathic proteins

Question 29

what happens once the triglycerides are coated with amphipathic proteins

Answer 29

packaged in Golgi and secreted via exocytosis

Question 30

where do large chylomicrons go

Answer 30

into the lymphatic system

Question 31

what do lymphatics enter the systemic circulation

Answer 31

the thoracic duct

Question 32

are capillaries or lacteals more leaky

Answer 32

lacteals thats why chylomicrons can fit

Question 33

what does lipoprotein lipase on endothelial cells of blood vessels release

Answer 33

triglycerides from chylomicrons as monoglycerides and free fatty acids which can be taken up by tissues

Question 34

how is iron transported into the enterocyte

Answer 34

2 active

Question 35

what happens once iron is in the enterocyte

Answer 35

incorporated into ferritin

Question 36

what happens to iron that is not stored

Answer 36

it is released into the blood and is attached to transferring

Question 37

what happens to iron bound to ferritin

Answer 37

it sheds after a few days

Question 38

what happens where there are ample iron stores

Answer 38

ferritin is upregulated so there is a reduced absorption of iron

Question 39

what happens when there are depleted stores of iron

Answer 39

less ferritin made so that more iron is absorbed

Question 40

what happens where there are ample iron stores

Answer 40

ferritin is up-regulated so there is a reduced absorption of iron

Question 41

where does majority of the water in the intestines come from

Answer 41

organs that drain into the intestine (liver, pancreas)

Question 42

how much fluid is handled in the GI tract daily

Answer 42

8-9 L

Question 43

what happens to most of the fluid in the GI tract

Answer 43

reabsorbed in the small intestine

Question 44

where is water absorption happening

Answer 44

in the villi

Question 45

where is secretion happening

Answer 45

crypts

Question 46

how does water get across epithelium

Answer 46

paracellular transport (tight junctions) due to osmotic gradient

Question 47

which are important electrolytes for water transport

Answer 47

Na Cl HCO3

Question 48

what electrolytes are important for water absorption | what kind of transport

Answer 48

Na gradients generated in secondary active nutrient uptake (glucose and amino acids)

Question 49

what electrolytes are important for water secretion | what kind of transport

Answer 49

Cl- gradient made by secondary active transporter | triggered by cAMP production

Question 50

what causes cholera

Answer 50

increases cAMP in crypt epithelium, which activates Cl- secretion into lumen and water follows

Question 51

what is the most common motion in the small intestine

Answer 51

segmentation

Question 52

what is the MMC and what does it replace

Answer 52

replaces segmentation, it is the migrating myoelectrical complex a pattern of peristaltic activity overlapping waves

Question 53

what is the purpose of MMC

Answer 53

push any undigested material and bacteria into the small intestine

Question 54

what is motilin

Answer 54

intestinal hormone released by small intestine cells that initialy MMC

Question 55

what inhibits motilin

Answer 55

eating