Epithelial Transport Flashcards
What are examples of specialized environments created by epithelial tissue?
– 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
What structures restrict movement of membrane lipids/proteins, and allows them to carry out selective transport?
Tight Junctions
Which structures help to provide mechanical strength by adjacent linking cells together with the underlying cytoskeleton?
- Adherens
- Desmosomes
- Hemidesmosomes
Which side of epithelial tissueare NA_+/K+ ATPase localized?
Basolateral
Which location contain specialized epithelium which contain Na+/K+ ATPase on the apical side?
- Choroid plexus
- Retinal pigment epithelium
What are the two types of transport from the renal filtrate to the blood?
- Transcellular: Across epithelium via a variety of transporters
- Paracellular: Occurs between cell through “leaky” tight junctions
What is the action of Canagliflozin, Dapagliflozin, and similar drugs?
- Inhibit SGLUT2 reabsorption in the kidneys
- Used to treat diabetes II by decreasing blood glucose levels
How does Vibrio Cholerae affect the lower GI tract?
• 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”)
Where does 70% of Mg get absorbed? What are the affects of loop diuretics?
Thick ascending limb; Decreases reabsorption of
Mg++, Ca++, and K+
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.
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.
What affect does aldosterone have on regulating tight junctions?
Aldosterone stimulates expression of a tight junction protein which reduces backward leaking of Na+
What is the defining external characteristic of Cystic Fibrosis?
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
What is the main driving force for paracellular reabsorption of Mg++?
The net + transepithelial potential difference
Which nutrient is the exception, and does. Not get primarily absorbed n the PCT?
Mg; absorbed in Thick ascending limb
What affect does furosemide have?
Inhibits specific transporters, thus resulting in decreased transepithelial potential
