Small Intestine and Pancreas Flashcards Preview

SF4 Exam I > Small Intestine and Pancreas > Flashcards

Flashcards in Small Intestine and Pancreas Deck (80):
1

the intestinal structure amplifies what?

surface area

2

transport of water and solutes across living membrane depends on what process?

diffusion

3

the longitudinal folds on the surface of the small intestine are known as what?

folds of Kerckring (plicae circulares)

4

what projects from the folds of kerckring

villi

5

what lines the entire mucosal surface of small intestine

villi

6

what protrudes from the surface of intestinal cells?

microvilli

7

the appearance of the microvillus gives them the term?

brush border

8

what projects down into the surface at base of each villus

crypt

9

how many crypts are there per villus

3

10

name the cell types found in the small intestine

enterocytes
goblet cells
crypt cells

11

enterocytes of small intestine (what type of cell are they, where are they found, and what feature do they have)

columnar epithelial cells
in villus
microvilli protrude from apical surface

12

enterocytes of small intestine (name the functions it performs)

digestion, absorption, secretion

13

what location in the villus are enterocytes of the small intestine best at digestion and absorption

those found at the tip of the villus than at the base

14

goblet cells of small intestine (where are they, what do they do)

interspersed with enterocytes in villus
secrete mucus

15

crypt cells (where are they found, what do they do)

found in crypts at base of villus
secrete fluids and electrolytes

16

what cells are proliferative cells in the intestine and what do they form

crypt cells
can form both enterocytes and goblet cells

17

what are the functions of the small intestine

mix chyme with digestive juices and bile to facilitate digestion and absorption
further reduce size of chyme particles, which increases solubility
bring chyme into contact with absorptive surface of microvilli
propel chyme from duodenum to colon

18

what types of contractions occur in the small intestine

segmentation
peristaltic
migrating myoelectric complex

19

what is the most common type of intestinal contraction

segmentation

20

segmentation contraction (what is contracting and what does that contraction do)

circular smooth muscle of isolated wall contracts
forces chyme toward both stomach and colon

21

segmentation contraction (upon relaxation of the circular smooth muscle what happens to chyme and what is the effect of this)

returns to original segment
effect is mixing of chyme with digestive juices

22

is there net movement of chyme in segmentation contraction (if so which direction and why)

net movement of chyme toward colon
due to higher frequency of contraction in proximal than distal intestine

23

peristaltic contractions (function, and where do they occur)

serve to propel chyme down small intestine
occur only over short distances

24

migrating myoelectric complex (what does it do, when does it occur)

clears remaining chyme in small intestine
occurs about every 90 minutes

25

intestinal slow waves require what for contractions to occur

action potentials

26

what happens to slow wave frequency going from proximal to distal intestine

slow wave frequency decreases distally

27

peristaltic reflex/rush (what is it, what initiates it)

contraction that moves intestinal contents along small intestine
initiated by chyme in intestine which either distends wall or greatly irritates mucosa (also severe cases of infectious diarrhea)

28

intestinointestinal reflex (what is it and what does it prevent)

overdistention of one segment of intestine inhibits contractile activity in rest of intestine
prevents moment of material into already beverly distended section of bowel

29

gastroileal reflex (what triggers it, what does it do)

gastric secretion and emptying triggers increased peristalsis in ileum
causes relaxation of ileocecal sphincter and moment of ill contents into large intestine

30

what reflex moves intestinal contents along small intestine

peristaltic reflex/rush

31

what reflex cases relaxation of ileocecal sphincter and movement of ill contents into large intestine?

gastroileal refelx

32

what reflex causes the urge to defecate shortly after starting a meal

gastrocolic reflex

33

gastrocolic reflex (what does it do, what triggers it, what is eventual outcome)

urge to defecate shortly after starting meal
presence of food in stomach triggers increased colonic motility
eventually leads to evacuation of colon to make way for remains of next meal

34

what types of cells are found in the pancreas

acinar cells
centroacinar cells
duct cells

35

what do acinar cells of the pancreas do?

produce:
peptidases- digest proteins
lipases- digest fat
amylases- digest carbohydrates

36

what do centroacinar cells of the pancreas do?

secrete pancreatic juice containing high concentration of HCO3- (neutralizes gastric acid in duodenum and brings contents within pH range for enzymatic digestion)

37

pancreatic juice secreted from centroacinar and duct cells has a high concentration of what and why?

HCO3- (neutralizes gastric acid in duodenum and brings contents within pH range for enzymatic digestion)

38

what do duct cells of pancreas do?

secrete pancreatic juice containing high concentration of HCO3- (neutralizes gastric acid in duodenum and brings contents within pH range for enzymatic digestion)

39

pancreatic juice tonicity is what compared to plasma (and at what rates of secretion)

isotonic
at all rates of secretion

40

at low flow rates what is the primary composition of pancreatic juice?

Na+
Cl-

41

at high flow rates what is the primary composition of pancreatic juice?

Na+
HCO3-

42

compared to plasma what is the [HCO3-], [Cl-], and [K+] of pancreatic juice

[HCO3-]- higher in pancreatic juice than plasma
[Cl-]- lower in pancreatic juice than plasma
[K+]- about the same as in plasma

43

as flow rate increases what happens to [HCO3-], [Cl-], [Na+] and [K+] of pancreatic juice

[HCO3-]- increases
[Cl-]- decrease
[Na+]- stays the same
[K+]- stays the same

44

what produces initial pancreatic juice and what is its primary composition

acinus produces small volume initial pancreatic juice
primarily Na+ and Cl-

45

what modify the initial pancreatic juice produces by acinus (and how)

ductule and centroacinar cells
secreting HCO3- and absorbing Cl-

46

in ductule and centroacinar cells how is HCO3- formed

HCO3- and H+ are formed from H2O and CO2 via carbonic anhydrase

47

venous blood from actively secreted pancreas is what compared to a nonnsecreting pancreas

lower pH in actively secreting pancreatic venous blood (H+ in blood from carbonic anhydrase reaction)

48

H+ is transported out of ductule and centroacinar cells to where, in exchange for what, and by what?

H+ goes into blood
in exchange for Na+
via Na+/H+ antiporter

49

what happens to H+ once in the blood

reforms CO2 with HCO3- (the CO2 can then freely reenter the cell and become HCO3-)

50

HCO3- in ductule and centroacinar cells is exchanged to where, for what?

HCO3- transported across apical membrane to lumen
exchange for Cl-

51

how does Cl- enter lumen

through channel in apical membrane

52

what is messed up (in regards to pancreas) in cystic fibroses

the apical Cl- channel is mutated

53

the rate of HCO3- secretion in ductule and centroacinar cells is dependent on what

Cl- being present in lumen

54

what happens to the Na+ inside ductule and centroacinar cells

actively pumped out of cell via Na/K ATPase (keeps intracellular Na+ low for the Na/H antiporter)

55

what follows HCO3- into lumen and why?

Na+
to preserve electrical neutrality

56

how does water move into lumen of pancreas?

somatic gradient (b/c pancreatic ducts are permeable to water)

57

in terms of water movement what is difference between pancreatic duct and salivary duct

pancreatic duct is permeable to water
salivary duct is not preamble to water

58

what protects pancreas from autodigestion

trypsin inhibitor secretion

59

pancreatic lipase and amylase are secreted in what form

active

60

pancreatic proteases (trypsin and chymotrypsins) are secreted as what?

inactivated forms

61

pancreatic proteases (trypsin and chymotrypsins) are activated where?

small intestine

62

during cephalic and gastric phases of digestion what regulates pancreatic secretion (what cell are acted on and by what, what triggers control and by what reflex, what is it mostly controlled by)

ACh acting on acinar and ductule cells
distention of stomach initiates vagovagal reflex (stimulates secretion)
mostly digestive enzymes

63

during intestinal phase of digestion what stimulates regulates pancreatic secretion

stimulated by acid and by fat and protein digestion products in duodenum

64

during what phase of digestion is the majority of pancreatic control

intestinal

65

during intestinal phase of digestion what does acid do to pancreatic section

acid releases secretin from S cells in duodenum
secretin acts on ductule cells to increase HCO3- secretion (neutralizes acid)

66

during intestinal phase of digestion what do protein and fat digestion products do to pancreatic section

release cholecystokinin (CCK) from I cells in duodenum
CCK acts on acinar cells to increase enzyme secretion

67

secretin acts on what type of pancreatic cells and does what?

secretin acts on ductule cells to increase HCO3- secretion (neutralizes acid)

68

CCK acts on what type of pancreatic cells and does what?

CCK acts on acinar cells to increase enzyme secretion
act on duct cells to potentiate action of secretin

69

during intestinal phase of digestion what do protein and fat digestion products as well as acid initiate what reflex and what does that do

vagovagal reflex
stimulates acid secretion

70

what potentiates the action of secretin on ductal cell secretion

CCK and ACh

71

Cystic Fibrosis (whats wrong, and what does that lead to)

mutation occurs in Cl- channel in apical membrane of cell
reduces secretion of both aqueous and enzymatic component of pancreatic juice (lack of aqueous secretion leads to concentration of pancreatic juice, which block secretion of enzymatic compartment)

72

malabsorption and steatorrhea are common in patients with?

cystic fibrosis

73

what is most commonly caused by chronic alcoholism or gallstone (can be caused by high triglycerides and smoking)

pancreatitis

74

what are the symptoms of acute pancreatitis

severe abdominal pain
swollen and tender abdomen
nausea and vomiting
diarrhea
fever

75

greatly elevated serum lipase and amylase levels are indicative of what?

pancreatitis

76

what is the issue in pancreatitis

activated enzymes digest pancreatic tissues

77

in US what is mot common cause of chronic pancreatitis

repeated episodes of acute pancreatitis induced by alcohol abuse

78

high protein concentration in pancreatic juice is indicative of what?

chronic pancreatitis

79

How does Na+ from pancreatic juice enter lumen of small intestine

between pancreatic ductal cells

80

an example of negative feedback in the pancreas would be?

Acid stimulates secretin which then stimulates bicarbonate which reduces the acidity