Transport Mechanisms Flashcards Preview

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Flashcards in Transport Mechanisms Deck (28):
1

What determines the specific function of the different parts of the nephron?

Based on the cells that make up that portion of the tubule

2

What is urine?

The products that they body needs to rid it of and that the body no longer needs

3

What % fluid does the proximal tubule filter?

65% is filtered and reabsorbed
-Na, K, Cl, H2O, AA Glucose

4

What % fluid does the loop of Henle filter?

20% is filtered and reabsorbed

5

What does each side of the loop of Henle filter?

Descending Loop --> H2O and minimal Na

Ascending Loop --> Na, K, Cl

6

What %R fluid does the Distal tubule and Collecting duct filter?

14% is filtered and reabsorbed
-Distal: Na, K, Cl, Ca
-Collecting: Na, H2O *fine tunes these depending on hormone balance

7

What is the tubule made up of?

Single layer of epithelial cells linked by junctions

8

What is the apical/luminal membrane?

The membrane of a tubule epithelial cell facing the inside of the tubule

9

What is the basolateral membrane?

The membrane of a tubule epithelial cell facing the outside of the tubule

10

What are the 2 forms of tubule transport?

1. Reabsorption
2. Secretion

11

What are the 2 kinds of reabsorption?

1. Paracellular
2. Transcellular

12

What is paracellular transport?

When ions/substances within the tubule move in-between tubule cells
-1 step process

13

What is Transcellular transport?

When ions/substances within the tubule move through tubule cells
-2 step process passing through luminal and basolateral membrane

14

What is secretion in terms of tubule transport?

When substances from the capillaries enters the tubule usually always transcellular

15

What are the 3 transport mechanisms?

1. Channels
2. Transporters
3. Primary active transporters

16

Describe the transport mechanism for channels?

-Simple diffusion mechanism
-Basic ion channel
-Protein lined pores that allow specific substances through
-Driven by [] gradient or electrochemical gradient

17

What are the 3 types of transporters?

1. Uniporters
2. Symporters
3. Antiporters

18

What is a uniporter?

Permits the movement of a single molecule through the membrane via protein configuration
-protein carrier that binds the molecule
-can become saturated

19

What is a symporter?

Permits the movement of 2 molecules in the same direction across a membrane
-at least 1 molecule must move down its [] gradient to move both molecules

20

What is secondary active transport?

When one molecules energy derived [] gradient is used to do work without ATP

21

What are antiporters?

Permits the movement of 2 molecules in opposite directions across a membrane.
-molecule must move down [] gradient for the other molecule to move

22

What is a Primary Active Transporter

Requires ATP to move molecules against their [] gradient
-protein carrier embedded in the membrane

23

What are the 3 ways in which transporters are regulated in the kidney?

1. Regulation at the level of Gene Expression
2. Regulation at the level of Cellular Location
3. Regulation at the level of Activity

24

What does it mean when you have a regulated transporter?

A specific transporter/channel is changed in its function in response to a hormone

25

What does it mean when you have a non-regulated transporter?

Transport occurs at a constant rate

26

What is Regulation at the level of Gene Expression?

When you take the DNA sequence and make more transporters/channels
-can express the channel/transporter more or less depending on the hormone level

27

What is Regulation at the level of Cellular Location?

Protein carriers can only work when they are in the membrane. If they are floating around they are not able to perform their function

28

What is Regulation at the level of Activity?

When it is possible to make the transporter/channel better, faster or slower depending on hormone levels