Brainscape's Knowledge GenomeTM

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


See full index

BioSci107 Finals > Epithelial Transport of Glucose > Flashcards

Epithelial Transport of Glucose Flashcards

1
Q

What effects transepithelial transport

A

Combining different types of transport proteins

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

Epithelial tissues
- Consist of cells arranged in ______ sheets in either ___ or ____ layers
- Cells sit on a _____ membrane
- Form the _____ between the body’s organs or between the ___ and _____ environment
- Subject to physical breakdown and ____ … therefore undergo ____ and rapid renewal process

A

Epithelial tissues
- Consist of cells arranged in CONTINUOUS sheets in either SINGLE or MULTIPLE layers
- Cells sit on a BASEMENT membrane
- Form the BOUNDARY between the body’s organs or between the BODY and EXTERNAL environment
- Subject to physical breakdown and INJURY… therefore undergo CONSTANT and rapid renewal process

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

What are epithelial cells separated from the neighbours by

A

Lateral intercellular space

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

How are epithelial cell held together

A

Their luminal edges by tight junctions

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

What type of junction is composed of thin bands that encircle the cell and make contact with thin bands from adjacent cells

A

Tight junctions

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

Appearance of freeze fracture tight junctions

A

Interlocking network of ridges in the PM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why tight junctions act as a barrier and a fence

A

To separate the epithelial cells into 2 distinct membrane domains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Name the 2 distinct membrane domains

A
  1. Apical (luminal or mucosal)
  2. Basolateral
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Tight junctions act as a barrier or a fence when “they restrict the movement of subst. through the intercellular space between cells”

A

Tight junctions act as a BARRIER

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

Tight junctions act as a barrier or a fence when “they prevent membrane proteins from diffusing in the plane of the lipid bilayer”

A

Tight junctions act as a FENCE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What membrane domain faces the lumen of the organ/body cavity

A

Apical (luminal or mucosal)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The basolateral membrane…

A

Adheres to the adjacent basement membrane and interfaces with the blood

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

Why do we need the distinct membrane domains

A

So different transport proteins can be inserted into either the apical or basolateral membrane

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

True or false, “transport can occur via the paracellular OR transcellular pathway OR both”

A

TRUE

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

What laws is paracellular transport governed by

A

Laws of diffusion and tightness of junctions

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

True or false, “the electrical resistance to ion flow through tight junctions can’t be measured”

A

FALSE… electrical resistance to ion flow through tight junctions CAN be measured

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

What happens to number of tight junction strands holding the cell together if there’s higher electrical resistance to ion flow

A

Greater number of tight junction strands holding the cell together

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

Epithelial tissues functional classifications

A
  1. Leaky epithelium = paracellular transport dominates
  2. Tight epithelium = transcellular transport dominates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What changes in proximal to distal direction in GI tract and kidney

A

Tight junction resistance

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

Features of the proximal direction

A
  • Leaky epithelium
    • Low electrical resistance
    • Low # of strands
    • Bulk transport (paracellular)
      e.g duodenum/proximal tubule
21
Q

Features of the distal direction

A
  • Tight epithelium
    • High electrical resistance
    • High # of strands
    • Hormonally controlled (transcellular)
      e.g. colon/collect duct
22
Q

What is transcellular transport

A

Epithelial cells use 1o and 2o active transport often in combination with passive diffusion through ion channels to produce transport across the epithelial tissues

23
Q

Transcellular transport can either be

A
  • Absorption = transport from lumen to blood
  • Secretion = transport from blood to lumen
24
Q

4 areas transepithelial transport is broken down into

A
  1. Entry and exit steps
  2. Electrochemical gradient
  3. Electroneutrality
  4. Osmosis
25
Q

What area of transepithelial transport “the entry step for absorption is the apical but for secretion is the basolateral membrane”

A

Entry and exit steps

26
Q

The electrochemical gradient area of transepithelial transport does…

A

Entry or exit step passive or active

27
Q

What area of transepithelial transport “movement of a positive or negative ion will attract a counter ion”

A

Electroneutrality

28
Q

Osmosis area of transepithelial transport does…

A

The net movement of ions will establish a difference in osmolarity that will cause water to flow by osmosis

29
Q

What do epithelial cells use to mediate either secretion or absorption

A

Different collections of transporters and channels

30
Q

Step 1 of glucose absorption

A

Tight junctions divide cells into apical and basolateral membrane domains

31
Q

Step 2 of glucose absorption

A

Na-pump sets up ion gradients

32
Q

Step 3 of glucose absorption

A

The sodium glucose symporter (SGLT) uses the energy of the Na gradient to actively accumulate glucose above its conc. gradient

33
Q

Step 4 of glucose absorption

A

Facilitative glucose transporter (GLUT) mediates glucose exit across the basolateral membrane via passive diffusion down its gradient

34
Q

Step 5 of glucose absorption

A

Na take up via the glucose exits via the basolateral Na-pump

35
Q

Step 6 of glucose absorption

A

The transport of Na and glucose across the epithelium induces paracellular Cl and water influxes

36
Q

The ability of glucose to enhance the absorption of Na+ and Cl- and water is exploited in…

A

Oral rehydration therapy

37
Q

What causes glucose-galactose malabsorption syndrome

A

A mutation to the glucose symporter in the small intestine means that sugar is retained in the intestine lumen

38
Q

What is induced due to the associated increase in lumen osmolarity

A

Induces a water efflux

39
Q

The increased water flow produces

A

Pronounced diarrhea

40
Q

What is the treatment for glucose-galactose malabsorption

A
  • Remove glucose and galactose from diet
  • Use fructose as source of carbohydrate
41
Q

What utilises a facilitative transporter (GLUT5) that is specific for fructose

A

Therapy for glucose-galactose malabsorption

42
Q

What fructose uses to exit across the basolateral membrane

A

GLUT2

43
Q

In the kidney ____ in the ____ is filtered and needs to be _____ or it will appear in the ___

A

In the kidney GLUCOSE in the PLASMA is filtered and needs to be REABSORBED or it will appear in the URINE

44
Q

Name for when glucose is in the urine

A

Glucosuria

45
Q

What is the most common cause in diabetes mellitis as insulin activity is deficient and blood sugar too high (over 200mg/mL)

A

Glucosuria - glucose in the urine

46
Q

What happens to glucose symporter in diabetes

A

Can not absorb glucose fast enough and glucose appears in the urine

47
Q

What happens to urine if glucose absorption is impaired or the transporter is saturated

A

Glucose will appear in the urine

48
Q

Glucose in urine - transporter kinetics
- All filtered ____ is reabsorbed until the ___ threshold is reached
- Once the renal ____ is reached ____ appears in the ____

A

Glucose in urine - transporter kinetics
- All filtered GLUCOSE is reabsorbed until the RENAL threshold is reached
- Once the renal THRESHOLD is reached GLUCOSE appears in the URINE

49
Q

What does renal threshold reflect

A

Transport maximum of SGLT (sodium-glucose linked transporters)

BioSci107 Finals (11 decks)

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