Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GI GU Repro > Intestinal Absorption and Secretion of Fluids and Electrolytes > Flashcards

Intestinal Absorption and Secretion of Fluids and Electrolytes Flashcards

1
Q

What are the 2 key absorptive and secretory structures in the small intestine?

A

Absorptive - villi

Secretory - cryps of lieberkuhn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are each of the cells in this image and what are their functions?

A
  • Absorptive cell - at top of villi, absorb nutrients, electrolytes, fluid
  • Goblet cell - secrete mucous
  • Enteric endocrine cell - secreting cells, secrete CCK and secretin among other things
  • Stem / progenitor cell - replenish absorptive cells
  • Paneth cells - immune function (alpha defensin and lysozyme)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the turnover rate for absorptive cells on villi?

A

Slough off in 3-5 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Under what conditions (not an exhaustive list, just some to know) is the turnover of shedding absorptive cells and producing new ones from stem cells diminished?

A
  • Right after eating
  • During lactation
  • After intestinal resection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The absorptive cells that line the gut on the villi undergo rapid turnover. What does this make them susceptible to?

A

Vulnerable to radiation and chemotherapy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Brunner’s glands in the duodenum secrete what?

A

Alkaline mucus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q
  • Where are brunner’s glands located?
  • What is their function?
  • What benefit does this provide for the GI tract?
A
  • Pylorus –> sphincter of Oddi (place where pancreatic enzymes enter duodenum) –> ONLY IN DUODENUM
  • Mucus secretion with high HCO3- content
  • Protects duodenal wall and neutralizes acid in chyme from stomach
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  • What signals stimulate secretions from brunner’s glands?
  • What signals inhibit secretions from brunner’s glands?
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where are crypts of lieberkuhn located?

A

Throughout small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Within a crypt of Lieberkuhn, what are the 2 kinds of secretory cells that can be found and what do they secrete?

A
  • Crypt enterocyte –> Fluid and electrolytes (Na+, Cl-, HCO3-)
  • Goblet cell –> Mucous and HCO3-
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
  • Throughout the small intestine, what is the purpose of secrete fluid into the GI lumen?
  • How is fluid secretion accomplished?
A
  • The secreted fluid picks up nutrients making it easier for the nutrients to be absorbed as they are absorbed with the fluid by absorptive cell
  • The cells don’t actively secrete fluid. Instead they actively secrete Cl- and HCO3- and Na+ (both active and passive). Secretion of these ions into GI lumen causes osmotic movement of water into GI lumen as well –> fluid secretion.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the composition of fluid that is secreted by crypt enterocytes?

A

Isotonic, slightly alkaline for acid neutralization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where does most absorption in the GI tract occur?

A

Duodenum and Jejunum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

With regards to the secretory enterocytes in the crypts of Lieberkuhn, secretion of […] and […] is active while secretion of […] is both active and passive.

A

Cl-

HCO3-

Na+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

In the colon, […] are absent while […] are present.

A

Villi

Crypts of Lieberkuhn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The colon lacks villi. How does it accomplish absorption and what does it absorb?

A

Colon still has surface enterocytes that absorb fluid and electrolytes (mostly fluid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the function of crypt enterocytes in the colon?

A

Secretion of fluid and electrolytes (Na+, Cl-, HCO3-)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Are goblet cells found in the colon?

A

Yes –> secrete mucous and HCO3-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the purpose of having a large # of goblet cells in the colon to secrete mucus?

A

Helps with feces formation and mucosal protection of the colon wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Surface area in both the small and large intestines are amplified in order to facilitate absorption. By what mechanisms is this accomplished in the small intestine and large intestine?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where does most of the body’s fluid aborption occur?

A

Small Intestine

22
Q

Different sections of the GI tract have different permeability to water. What determines how permeable a section of the GI tract is?

A

Degree of resistance posed by epithelial tight junctions

23
Q

In column on right, state how permeable each section is to water.

A
24
Q

Describe the general mechanism by which fluid is absorbed and secreted throughout the GI tract.

A

Fluid follows solutes due to creation of osmotic driving force for water to be either reabsorbed or secreted.

25
Q

Fluid absorption in a particular region of GI tract is mostly due to net […] absorption

A

Na+, glucose, amino acids, and Cl-

26
Q

Fluid secretion in a particular section of GI tract is usually due to net […] secretion

A

Cl-

27
Q

What is the NET result of absorption and secretion in the small intestine and large intestine?

A
28
Q

Water is absorbed throughout the whole GI tract. What areas of the GI tract does most of the reabsorbing?

A
29
Q

Na+ and Cl- are absorbed throughout the small and large intestines. What areas of do most of the absorbing?

A
30
Q

Bicarb is absorbed or secreted along the length of the small intestine and colon.

  • Where is it secreted?
  • Where is it absorbed?
A
  • Secreted - Duodenum, Ileum, colon
  • Absorbed - jejunum
31
Q

K+ is secreted and absorbed throughout small intestine and colon.

  • Where is it secreted?
  • Where is it absorbed?
A
  • Secreted - Ileum, colon
  • Absorbed - Duodenum, jejunum, colon
32
Q

Where in the small intestine is:

  • Ca2+ absorbed?
  • Fe2+ absorbed?
A
  • Duodenum, jejunum
  • Duodenum
33
Q

Describe how Ca2+ is absorbed in the small intestine.

A
  • Occurs in duodenum and jejunum.
  • These parts of SI have leaky tight junctions, so Ca2+ can diffuse paracellularly –> Passive
  • Can also have active transport when VitD (calcitriol) is around –> upregulates insertion of Ca2+ channels into apical and basolateral membranes of intestinal epithelium –> Ca2+ enters and binds to calbindin to maintain Ca2+ gradient and keep intracellular available Ca2+ regulated –> calbindin delivers Ca2+ to basolateral membrane where Ca2+ is pumped into blood via a number of transporters –> Active / transcellular
34
Q

Describe the absorption of Iron

A
  • Occurs in duodenum
  • Ingestion of iron from either heme sources (Fe2+) or non-heme sources (Fe3+)
  • Heme enters via heme transporter, free Fe3+ reduced to Fe2+ by apical membrane cytochrome, then enters via DMT1
  • Cells either
    • Store the iron as ferritin (which is lost)
    • Release iron into the body via transport through ferroportin on the basal epithelial membrane.
  • Transported Fe2+ is oxidized to Fe3+(by Hephaestin); Fe3+ binds transferrin for travel in the blood
  • Utilized or stored in liver
35
Q

Describe intestinal absorption of Na+ and Cl- in the FED STATE

A
  • Important to note - mostly duodenum and jejunum that are affected by fed/fasting
36
Q

Describe intestinal absorption of Na+ and Cl- in the FASTING STATE

A
  • Important to note: this diagram illustrates how the duodenum and jejunum handle absorption of Na+ and Cl- in fasting but it illustrates how ileum and colon handle absorption all the time, regardless of fed/fasting conditions
37
Q

How is Na+ and Cl- absorbed in the distal colon?

A
38
Q

Aldosterone regulates Na+ absorption in the […]

A

Distal colon

39
Q
  • Describe how Cl- is secreted in the intestine (small and large, is same mechanism)
  • Why is chloride secreted in intestines?
  • What is the relationship between presence of cholera toxin and Cl- secretion?
A
40
Q

K+ is absorbed in the […] and secreted in the […]

A

Small/large intestine

Distal colon

41
Q

Describe K+ absorption in small intestine.

A
42
Q
  • Describe K+ secretion in the distal colon.
  • What transporter drives this secretion?
  • What hormone is this affected by?
  • How is this influenced when in hypovolemic?
A
43
Q

Describe the effects of aldosterone in the distal colon.

A

Aldosterone stimulates the increased activity and # of Na+/K+ ATPase and ENac channels in the distal colon cells as well as the increased activity and # of the Na+/K+/2Cl- transporter. This results in net Na+ absorption and K+ secretion. It is important to note that these mechanisms are not coupled –> they occur by different mechanisms and I assume in different cells, unlike in the kidney where they were directly coupled. Thus when a person is having really bad diarrhea, they are losing a lot of volume –> triggers aldosterone secretion –> increases Na+ absorption and K+ secretion –> hypernatremic and hypokalemic.

44
Q

What 4 things regulate absorption and secretion in GI tract?

A

ENS/ANS

Paracrine factors

Endocrine factors

Immune cells

45
Q

How does the ENS/ANS regulate secretion/absorption?

What is the stimulus?

A
46
Q

How do paracrine factors regulate secretion/absorption?

What is the stimulus?

A
47
Q

How do endocrine factors regulate secretion/absorption?

What is the stimulus?

A
48
Q

How do immune cells regulate secretion/absorption?

What is the stimulus?

A
49
Q

What is the definition of diarrhea

A

Increased stool volume > 0.2L/day due to:

  • Increased bowel movements
  • Decreased stool consistency
50
Q

What are the different types of diarrhea?

A
51
Q
A

C - glucose

Na+, Cl-, K+

GI GU Repro (58 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions