Chapter 5 Flashcards

1
Q

What is total body water made up of?

A

The sum of the intracellular and extracellular fluid volumes

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2
Q

What solute is abundant in the intracellular fluid?

A

K+

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3
Q

What solutes are abundant in the extracellular fluid?

A

Na+, Cl-

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4
Q

Every type of body fluid has the same?

A

OsmoLALITY & an equal number of positive and negative charges

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5
Q

At equilibrium, the chemical and electrical potential energy differences are?

A

Equal, but opposite

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6
Q

What equation accounts for the electromotive force on an ion?

A

Vm-Ex = Net driving force

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7
Q

In simple diffusion, the flux of an uncharged substance is directly proportional to?

A

The concentration difference of that substance

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8
Q

How large of a molecule can pass through a water-filled pore in the membrane?

A

45 kDa

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9
Q

What is similar between pores, channels, and carriers?

A

Their physical structures are similar

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10
Q

How many Na+ ions does the Na/K ATPase push out of the cell?

A

3 Na+ ions

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11
Q

How many K+ ions does the Na+/K+ ATPase push into the cell?

A

2 K+ ions

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12
Q

What are some other ATPase pumps besides the Na+/K+ pump?

A
  1. K+/H+ pump in the parietal cells of the gastric gland

2. Ca2+ pump in the SER (sarcoplasmic reticulum). Also known as SERCAs.

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13
Q

The F-type and V-type ATPases transport what?

A

H+ ions

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14
Q

What can ATP-acting binding cassettes act as?

A

Pumps, channels, and regulators

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15
Q

Cotransporters are usually driven by what solute?

A

Na+ concentration gradient energy (secondary active transport)

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16
Q

What is another type of transporter that utilizes secondary active transport, besides cotransporters?

A

Exchangers - exchange ions for one another. Another type of secondary active transports

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17
Q

What is the central role of the Na+/K+ ATPase pump?

A

To keep Na+ inside the cell low, and K+ high inside the cell

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18
Q

What are some of the channels that Cl- is associated with?

A

Cl-/HCO3- exchanger (in), Na+/K+/Cl- cotransporter (in), passive Cl- channel efflux (out).

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19
Q

What are some of the main channels utilized in pH regulation?

A

Na+/H+ exchanger, Na+/HCO3- transporter.

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20
Q

What causes water transport to occur?

A

Osmotic and hydrostatic pressure differences.

21
Q

What is a downstream effect of the Na+/K+ ATPase?

A

Maintenance of cell volume by generating osmotic pressures counteracting passive Donnan forces.

22
Q

If a cell’s volume changes, how does the cell respond?

A

Rapid changes in ion channel regulation (activity, #, etc.) in order to bring cell volume back to normal.

23
Q

What gradients determine osmotic flow?

A

Tonicity and osmolality

24
Q

What determines ECF volume?

A

How much Na+ there is in the entire body.

25
Q

What determines osmolality?

A

How much water there is in the entire body.

26
Q

Do apical and basolateral membranes of the epithelial cell have similar or different electrochemical gradients?

A

Different, because the ions and transporters that compose each membrane are different!

27
Q

“Water follows ____”

A

“solute”

28
Q

How can epithelial cells (in general) regulate transport across their membranes?

A

Controlling transport proteins, tight junctions, and the supply of transported substances.

29
Q

What is the anion gap?

A

Anion gap = [Na+] - ( [Cl-] + [HCO3-] )

30
Q

When is the membrane potential at equilibrium (by definition)?

A

When the electrochemical potential energy difference for an ion across the membrane is zero (0).

31
Q

What is the net flux equation (Fick’s Law)?

A

Net Flux = Jx = Px ( [X]o - [X]i )

Px = Permeability coefficient
X = name of ion
o/i = Outside vs. Inside
Jx = Flux
32
Q

Define an “occluded” ion.

A

Occurs when an ion is being facilitated through its respective ion channel. Occluded is the state when the ion is located within the channel and both the inner gate and the outer gates of the ion channel are closed (or inactivated), resulting in the trapping of the ion of interest in its channel - occlusion.

33
Q

Do pores have gates?

A

No. They are pathways that are always open

34
Q

What is the nuclear pore complex?

A

A fancy term for the pores that are located in the nucleus membrane. It is huge, so it can transport large molecules.

35
Q

What is perforin?

A

A pore-forming protein that is secreted by certain types of cells, such as cytotoxic T cells that polymerize within the target cell membrane and assembles to form a barrel, or pore, which will kill the target cell by allowing ions, and metabolites that are necessary for the cell to leak out of the cell

36
Q

Is the electrochemical driving force for Na+ positive or negative? What does that mean?

A

Strongly negative. This means that once the Na+ channels open to allow Na+ diffusion, Na+ will flow inwardly into the cell.

37
Q

What are the 4 components of gated channels?

A
  1. Gate that determines if the channel is open or closed.
  2. Sensors that respond to 3 different stimuli (1. Membrane voltage, 2. Second-messenger systems acting on the cytoplasmic side of the channel, 3. Ligands)
  3. Selectivity Filter, which determines what CLASS of ion (anion/cation) or particular ions (Na+, K+, Ca2+) that can access the pore.
  4. Open-channel Pore, the actual pore that the ion can flow into to access the other side of the channel
38
Q

Is the electrochemical driving force for K+ positive or negative? What does that mean?

A

Usually around zero, or somewhat positive. This means that K+ is either at equilibrium or tends to move out of the cell.

39
Q

Is the electrochemical driving force for Ca2+ positive or negative? What does that mean?

A

Strongly negative. This means that Ca2+ moves into the cell.

40
Q

Is the electrochemical driving force for H+ and its channels positive or negative? What does that mean? What is special about proton channels?

A

Negative. This means that H+ will move into the cell (if there are any channels open). However, proton channels tend to be closed under normal conditions and activate only when the membrane depolarizes or the cytoplasm acidifies - that is, when the driving force favors the outward movement of H+.

41
Q

Is the electrochemical driving force for Cl- and other anions positive or negative? What does that mean? What is the special case for anions?

A

Negative. This means that it will flow OUT from the cell (negative ion, so it’s opposite to conventional rules that have been developed for positive ions)

42
Q

What is an ionophore?

A

A fancy term for a channel that binds to an ION and then the channel moves to the other side of the membrane (as a boat or spaceship) and exports the ION to the other side. This does not exist in animal cells.

43
Q

How many conformation sites does the Na+/K+ ATPase pump have?

A

2

44
Q

What are the names of the two conformational sites of the Na+/K+ ATPase pump?

A

E1-P, and E2-P

45
Q

Which site does Ouabain, a common Na+/K+ ATPase pump inhibitor, bind to?

A

E2-P

46
Q

In what conformational state is the Na+/K+ ATPase pump in when 3 Na+ are able to bind to their binding sites?

A

E1-P

47
Q

Is ATP bound or a phosphate group bound when the E1-P conformational state of the Na+/K+ ATPase pump is open?

A

ATP

48
Q

Is ATP bound or a phosphate group bound when the E2-P conformational state of the Na+/K+ ATPase pump is open?

A

Phosphate group

49
Q

List 3 types of P-type ATPases.

A
  1. Na+/K+ ATPase pump
  2. H+/K+ ATPase pump (in parietal cell of gastric gland). AKA HKA
  3. Ca2+ ATPase pump (in SERCA). AKA PMCA