Epithelial Transport Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What are examples of specialized environments created by epithelial tissue?

A

– Blood vessel endothelium - plasma
– Blood-brain barrier – cerebrospinal fluid
– Blood-bone barrier – bone fluid (promotes bone
mineralization)
– Blood-testis barrier – promotes
spermatogenesis
– Kidney – cortical-medullary osmotic gradient
and the formation of urine

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

What structures restrict movement of membrane lipids/proteins, and allows them to carry out selective transport?

A

Tight Junctions

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

Which structures help to provide mechanical strength by adjacent linking cells together with the underlying cytoskeleton?

A
  • Adherens
  • Desmosomes
  • Hemidesmosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which side of epithelial tissueare NA_+/K+ ATPase localized?

A

Basolateral

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

Which location contain specialized epithelium which contain Na+/K+ ATPase on the apical side?

A
  • Choroid plexus

- Retinal pigment epithelium

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

What are the two types of transport from the renal filtrate to the blood?

A
  1. Transcellular: Across epithelium via a variety of transporters
  2. Paracellular: Occurs between cell through “leaky” tight junctions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the action of Canagliflozin, Dapagliflozin, and similar drugs?

A
  • Inhibit SGLUT2 reabsorption in the kidneys

- Used to treat diabetes II by decreasing blood glucose levels

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

How does Vibrio Cholerae affect the lower GI tract?

A

• V. cholerae is a bactria that can attach to cells of the small intestine and produce a complex protein
rapid dehydration that can be fatal without proper treatment (“The blue death”) toxin, part of which is a enzyme that can permanently ribosylate the Gs alpha subunit of G- proteins
• This results in constitutive cAMP production,
which in turn leads to the secretion of water, sodium, potassium, and bicarbonate into the lumen of the small intestine
• The resulting watery diarrhea of cholera leads To rapid dehydration that can be fatal without proper treatment (“The blue death”)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where does 70% of Mg get absorbed? What are the affects of loop diuretics?

A

Thick ascending limb; Decreases reabsorption of

Mg++, Ca++, and K+

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

Which of the following is an true statement about the reabsorption of Mg++ by the kidney? [select all that apply]
A. The reabsorption of Mg++ by the kidney occurs via
transcellular mechanisms only.
B. The reabsorption of Mg++ by the kidney occurs via
paracellular mechanisms.
C. Loop diuretic drugs increase reabsorption of Mg++ by
the kidney.
D. The reabsorption of Mg++ by the kidney is affected by
the electrical potential difference across the epithelium.
E. Genetic forms of hypomagnesemia can be caused by
the mutation of tight junction proteins.

A

B. The reabsorption of Mg++ by the kidney occurs via
paracellular mechanisms.

D. The reabsorption of Mg++ by the kidney is affected by
the electrical potential difference across the epithelium.

E. Genetic forms of hypomagnesemia can be caused by
the mutation of tight junction proteins.

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

What affect does aldosterone have on regulating tight junctions?

A

Aldosterone stimulates expression of a tight junction protein which reduces backward leaking of Na+

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

What is the defining external characteristic of Cystic Fibrosis?

A

Individuals homozygous for CF gene mutations secrete excessive salt in their sweat, whereas heterozygous individuals have sweat that contains slightly more salt than wild type (normal) individuals

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

What is the main driving force for paracellular reabsorption of Mg++?

A

The net + transepithelial potential difference

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

Which nutrient is the exception, and does. Not get primarily absorbed n the PCT?

A

Mg; absorbed in Thick ascending limb

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

What affect does furosemide have?

A

Inhibits specific transporters, thus resulting in decreased transepithelial potential

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

What is the significance of Paracellin 1/Claudin 16?

A
  • Paracellin 1 is expressed in the thick ascending limb tight junctions, and plays a role on control of paracellular reabsorption of Mg and Ca.
  • Mutations in the gene which code for it result in autosomal recessive conditions known as familial hypomagnesemia, Hypercalcuria, and neprocalcinosis
17
Q

Which of the following is an example of local regulation of epithelial transport? [select all that apply]

A. The increase in water reabsorption by the kidney produced by vasopressin.
B. The increase in Ca++ reabsorption by the kidney produced by low free Ca++ .
C. The increase in Na+ reabsorption by the kidney and sweat glands produced by vasopressin.
D. The increase in water reabsorption by the intestine produced by increased Na+ and glucose content in food.
E. The increase in sweat production caused by the release of acetylcholine by sympathetic nerves.

A

B. The increase in Ca++ reabsorption by the kidney produced by low free Ca++ .

D. The increase in water reabsorption by the intestine produced by increased Na+ and glucose content in food.

18
Q

Explain the regulation of ENaC in epithelial asorption of N+

A
  • ENaC are not voltage-gated when unphosphorylated
  • PKA phosphorylates ENaC to initiate possible activation
  • PKC inhibits regardless of phosphorylation
19
Q

Eccrine sweat glands produce sweat by secreting Na+, Cl- and water into the gland. Much of the Na+ and Cl- is reabsorbed in the sweat duct, but little or no water is reabsorbed by the duct. Which of the following is probably true of the duct cells? [select all that apply]

A. The apical membrane of duct cells contains a large number of aquaporins. B. The apical membrane of duct cells contains very few aquaporins.
C. Eccrine sweat gland duct cells have very “leaky” tight junctions.
D. Eccrine sweat gland duct cells have very “tight” tight junctions.

A

D. Eccrine sweat gland duct cells have very “tight” tight junctions