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Pharmacology > Membrane Permeability and Transport > Flashcards

Membrane Permeability and Transport Flashcards

1
Q

What is a semi- permeable membrane?

A

A layer through which only allowed substances a can pass

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2
Q

What types of molecules can pass through a phospholipid bilayer?

A

Hydrophobic, small, uncharged and polar molecules

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3
Q

Why does glucose only pass through the phospholipid bilayer very slowly?

A

As it’s a large molecule

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4
Q

Why can water pass through phospholipid bilayer easily?

A

Water diffuses across as a gas

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5
Q

What is the affect of temperature on the movement of molecules

A

As temperature increases the movement of molecules increases

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6
Q

What are 4 important roles of transport processes?

A
  1. Maintenance of ionic composition
  2. Maintenance of intracellular pH
  3. Regulation of cell volume
  4. Expelling of waste and toxic substances
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7
Q

What types of transport has a negative value for Gibbs Free Energy?

A

PASSIVE

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8
Q

What type of transport have a positive value for Gibbs Free Energy?

A

ACTIVE

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9
Q

Why are Gated pores inefficient?

A

It takes a long time for the molecules to be transported

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10
Q

Are Gated pores an example of active or passive transport

A

PASSIVE

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11
Q

What are the different methods of facilitated diffusion?

A

Ligand Gated Ion Channels, Voltage Gated Ion Channels and protein Channels

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12
Q

How do Voltage Gated Ion Channels work?

A

The positively charged amino acids residues in the protein channel are attracted to the opposite negative charges of the inside of the membrane so the Channels are closed. When depolarisation occur the now positive membrane repels the channel, causing it to open.

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13
Q

What is membrane transport dependant on?

A

Concentration and membrane potential

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14
Q

What is active transport?

A

The movement of ions or molecules against a concentration gradient using energy directly or indirectly from the hydrolysis of ATP

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15
Q

What is a primary Active Transporter?

A

A transporter that uses ATP directly

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16
Q

What does Uni-Transport mean?

A

Only one molecule at a time can be transported

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17
Q

What is a Co-Transporter?

A

When more than one molecule can be transported at a time

18
Q

What type of transporter is the Sodium Glucose Cotransporter?

A

A symport co-transporter

19
Q

What is a symport transporter?

A

A co-transporter that transport the molecules in the same direction

20
Q

What is an Antiport co-transporter?

A

A co-transporter that transports molecules in opposite directions

21
Q

Give an example of an Antiport cotransporter

A

Sodium potassium ATPase pump

22
Q

What is the difference between a pump and a transporter?

A

A pump is found on the plasma membrane whereas a transporter is found in the membranes of organelles

23
Q

What is the most important mechanism for maintaining the resting potential of cells?

A

Potassium diffusion across Channels outside of the cell

24
Q

What is the resting potential of s cell?

A

-70mV

25
Q

How does the Na/K ATPase pump work?

A

It moves 3 Na ions out and 2 K ions in.

26
Q

What is the structure of the Na/K ATPase?

A

It has an alpha subunit where phosphorylation, movement of ions and blocking occurs.
There is also a beta subunit which glycoproteins are attached which anchor and direct pump to membrane surface.

27
Q

Why is the Na/K ATPase also called a P-Type ATPase

A

As ATP phosphorylate aspartate producing a phosphoenzyme intermediate

28
Q

What happens when the CFTR (cystic fibrosis transmembrane conductance regulator) stops working?

A

Chloride ions are not moved out of the cell and so they accumulate inside the cell, creating an electrochemical unbalance. The chloride can’t help produce mucus and so it’s harder to breath.

29
Q

What happens when the CFTR increases its function and what causes this?

A

More chloride ions leave the cell as so water water meaning that you become more dehydrated and get diarrhoea. This is caused by the cholera infection as it activates PKA which then activate the CFTR

30
Q

Why can Chloride, Sodium, Potassium and Calcium ions be classed as osmolytes?

A

As one Ion moves it takes 6 moles of water with it.

31
Q

What terms describes a transporter that results in a net change of charge?

A

Electrogenic

32
Q

Give 2 examples of acid extruded transporters

A

Na/H Exchanger (NHE) and the sodium bicarbonate cotransporter (NBC)

33
Q

Give an example of a base extruder

A

Cl/HCO3 Exchanger (anion Exchanger-AE)

34
Q

How does the Na/H Exchanger work?

A

Exchanges 1 extracellular sodium for one intracellular proton (electronetural 1:1 exchange) so makes the inside of the cell more basic

35
Q

Is the Na/H Exchanger a primary or secondary active transporter?

A

Secondary as it doesn’t use ATP directly

36
Q

How does the Sodium Bicarbonate transporter work?

A

It moves sodium and bicarbonate inside the cell and a proton and chloride Ion outside the cell. This makes the cell more basic

37
Q

How does the AE work?

A

It transports bicarbonate out of the cell and chloride into the cell. This makes the cell more acidic.

38
Q

What can a cell do to decrease swelling(?

A

It can transport ions outside of the cells so that water will follow out by osmosis, shrinking the cell

39
Q

What can a cell do to increase its size?

A

Transport ions into the cell, so that water moves in by osmosis causing the cell to swell to its original size.

40
Q

What are diuretic drugs used for?

A

Block transporters that reabsorbed sodium, so more sodium is lost in the urine. This means that more water follows the sodium into the urine, so you lose water. This helps to treat oedema

41
Q

Why is all the bicarbonate reabsorbed in the kidneys?

A

To retain the base when controlling cell pH levels

42
Q

Why is all the sodium reabsorbed in the kidneys?

A

Na/K ATPase pump sets up a low intracellular sodium concentration and so sodium moves back into cells and so it’s all reabsorbed.

Pharmacology (12 decks)

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