study guide small intestine

Question 1

dietary carbs are composed of ?

Answer 1

polysaccharides and disaccharides

Question 2

give an example of a polysaccharide?

Answer 2

starches

Question 3

give an example of a disaccharide?

Answer 3

sucrose and lactose

Question 4

enterocytes can only absorb what?

Answer 4

monosaccharides

Question 5

a monosaccharide is also termed a?

Answer 5

simple sugar

Question 6

give examples of simple sugars?

Answer 6

glucose
galactose
fructose

Question 7

in the small intestine, on the surface of the brush border, digestion of starches begins in where? with what?

Answer 7

in the oral cavity

with salivary amylase

Question 8

in the small intestine, on the surface of the brush border, digestion of starches ends where? with what?

Answer 8

duodenum

pancreatic amylase

Question 9

describe how amylase creates disaccharides, trisaccharides, and oligosaccharides?

Answer 9

amylase cleaves internal bonds of polysaccharides forming these components

Question 10

amylase cleaves internal bonds of polysaccharides forming fragments known as what?

Answer 10

disaccharides
trisaccharides
oligosaccharides

Question 11

what enzyme digest disaccharides and oligosaccharides into monosaccharides? where does this occur?

Answer 11

hydrolase

brush border

Question 12

are monosaccharides water soluble or not?

Answer 12

they are water soluble

Question 13

what does it mean that monosaccharides are water soluble?

Answer 13

requires them to have assistance to cross the plasma membrane of the enterocytes by active transport proteins.

Question 14

lipids are almost entirely _____ in water, meaning they will do what in water?

Answer 14

insoluble

aggregate together

Question 15

what is the first step for lipid digestion?

Answer 15

emulsification

Question 16

what is emulsification?

Answer 16

a mechanical process producing a suspension of fine lipid droplets

Question 17

what helps the small intestine with emulsification of the lipids?

Answer 17

bile salts

Question 18

bile salts are released by?

Answer 18

the liver

Question 19

following emulsification, lipids are then chemically digested by what? where?

Answer 19

lipase

brush border of the small intestine

Question 20

name two other lipases that aid in lipid digestion?

Answer 20

phospholipase and cholesterol esterase

Question 21

phospholipase hydrolyzes what?

Answer 21

phospholipids

Question 22

cholesterol esterase breaks down what?

Answer 22

esters in cholesterol

Question 23

proteins in the small intestine must be digested into what? for what?

Answer 23

tripeptides
dipeptides
and individual amino acids
for transport into enterocytes

Question 24

the digestion of proteins begins in the __________. Where what happens?

Answer 24

stomach

where the acidic environment can hydrolyze peptide bonds

Question 25

chief cells release what?

Answer 25

pepsinogen

Question 26

pepsinogen is activated how? into what?

Answer 26

activated by a low pH | pepsin

Question 27

why is pepsinogen released in an inactive form?

Answer 27

to protect organs

Question 28

once pepsin is activated it can do what?

Answer 28

digest the target

Question 29

premature activation of pepsin can cause what?

Answer 29

damage of our intestinal lining and stomach lining

Question 30

what does pepsin hydrolyze in proteins?

Answer 30

the peptide bond following aromatic amino acids

Question 31

name three aromatic amino acids

Answer 31

phenylanine tryptophane tyrosine

Question 32

more complex digestion of proteins requires an additional _________ released by the _______.

Answer 32

protease | pancreas

Question 33

pancreatic proteases are released as inactive precursors known as __________ which are converted tot he active form ___________, which in return activates all other pancreatic proteases.

Answer 33

trypsinogen | trypsin

Question 34

final digestion of the resulting oligopeptides occurs at the brush border by _________ .

Answer 34

proteases

Question 35

protease digestion of oligopeptides, produces?

Answer 35

tripeptides dipeptides and individual amino acids

Question 36

the dipeptides, tripeptides, and individual amino acids are transported back into the cell by secondary transporters with what?

Answer 36

sodium or coupled with proton symporters

Question 37

dipeptides and tripeptides are digested by what into individual amino acids?

Answer 37

systolic peptidases

Question 38

where is the major site for water and electrolyte absorption?

Answer 38

small intestine

Question 39

water absorption is ______ and occurs via paracellular route known as _____

Answer 39

passive | aquaporins

Question 40

water can move in both directions across the mucosa depending on?

Answer 40

osmotic gradient

Question 41

duodenum and jejunum tight junctions are leaky but become progressively tighter in the _____ or _____.

Answer 41

ileum or colon

Question 42

depending on the intestinal contents, osmolarity of the duodenal contents may be?

Answer 42

hypertonic | hypotonic

Question 43

by the time the contents enter the jejunum, the content's osmolarity is similar to ?

Answer 43

plasma

Question 44

sodium is absorbed mainly how in the small intestine?

Answer 44

transcellular traveling through the cell passing through apical and basolateral membranes

Question 45

sodium potassium ATPase has a basolateral membrane , and maintains a ________ intracellular concentration of sodium. why?

Answer 45

low | allowing for luminal sodium to enter the enterocyte

Question 46

sodium transport is coupled with?

Answer 46

glucose and amino acids

Question 47

a diet high in _______ could inadvertently drive sodium reabsorption?

Answer 47

glucose | thing of patients with HTN dash diet, limit sugar

Question 48

some sodium and chloride ions are absorbed through the __________ route

Answer 48

paracellular

Question 49

quadions are reabsorbed through the ________ ______.

Answer 49

antiporter exchanger

Question 50

following quadions being reabsorbed into the antiporter exchanger, then ______ ions are secreted into the lumen.

Answer 50

bicarbonate

Question 51

bicarbonate acts to protect epithelial cells in most proximal sections of the ?

Answer 51

duodenum

Question 52

the movement of electrolytes and nutrients from the intestinal lumen back into the blood creates what? which helps with what?

Answer 52

osmotic gradiant that drives water absorption | helps contents to pass more freely

Question 53

fluid and electrolytes secretions act to protect the mucosal layer by?

Answer 53

flushing bacterial products and toxins away from epithelial cells

Question 54

although the net movement of water and electrolytes in the small intestin is primarily absorptive, electrolyte secretion can occur. give an example

Answer 54

some potassium is secreted through potassium channels into the intestinal lumen

Question 55

chloride ions are secreted into the intestinal lumen via?

Answer 55

chloride channels located in the apical membrane

Question 56

the movement of negatively charged ions provides an electrical gradiant in which, ___ ions are also secreted through a paracellular route

Answer 56

sodium

Question 57

numerous ________ and paracine signaling molecules stimulate fluid and electrolyte secretion in both healthy individuals as well as those suffering from a disease

Answer 57

neural

Question 58

intestinal smooth muscle in the muscularis layer, mix chyme with what?

Answer 58

pancreatic bile and intestinal secretions

Question 59

intestinal smooth muscle in the muscularis layer propel food through the small intestine in two different ways, name them?

Answer 59

segmentation contractions | peristaltic waves

Question 60

segmentation contractions describe them?

Answer 60

nonadjacent segments of the intestine rhytmically contract and relax moving food in both directions, mixing intestinal contents with cell secretions.

Question 61

segmentation ______ transit, increasing ____ time.

Answer 61

slow transit, increasing contact time between the chyme and epithelial cells allowing for absorption to occur.

Question 62

peristaltic waves describe?

Answer 62

adjacent segments of intestinal alternatively contract and relax, propelling the food forward along the track

Question 63

peristalsis occurs _______ in the digestive process. why

Answer 63

late | after most nutrients have been absorbed.

Question 64

name for functions of the large intestine/

Answer 64

complete digestion absorb most of the remaining water and electrolytes secrete mucus store the unabsorbed material until it can be eliminated from the body

Question 65

describe how the wall of the large intestine differs from the small intestine?

Answer 65

few folds no villi virtually no cells that secrete digestive enzymes large number of goblet cells which secrete mucus

Question 66

little digestion occurs in the large intestine, but name one that does.

Answer 66

small amounts of digestion by the intestinal microbial flora.

Question 67

water absorption in the large intestine is coupled to?

Answer 67

electrolytes, particularly sodium and chloride movement