Human Phys 1.3 Flashcards

1
Q

What is diffusion?

A

Random molecular movement (move on their own)

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2
Q

How does diffusion always occur?

A

Down a concentration gradient (downhill)

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3
Q

What is simple diffusion determined by?

A

Amount of substance available

Velocity of motion

Number of size and openings (permeability)

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4
Q

What does facilitated diffusion always require?

A

Carrier protein

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5
Q

What is always true about flow down gradients?

A

There will always be an energy gradient (supports flow) and a resistance to flow

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6
Q

Flow

A

Movement of substances from one point in the system to another

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7
Q

Why does flow occur?

A

Due to the presence of an energy gradient

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8
Q

What can determine the direction of flow?

A

More than one gradient

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9
Q

What will there always be when it comes to flow?

A

Some form of resistance

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10
Q

What is true about resistance in flow?

A

It can be varied or physiologically controlled

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11
Q

Are there multiple gradients during flow?

A

Yes (working at same time)

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12
Q

What is osmosis?

A

Flow down gradient

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13
Q

How do molecules diffuse?

A

Independently of one another

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14
Q

Does the presence of a gradient mean flow will always occur?

A

No (due to resistance)

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15
Q

Chemical gradient

A

Flow occurs from higher to lower concentration

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16
Q

Electrical gradient

A

Flow occurs based on attraction between + and - charges

17
Q

What is it called when a chemical and electrical gradient are combined?

A

Electrochemical gradient

18
Q

Pressure gradient

A

Behaves same as chemical gradient (high to low pressure)

19
Q

Mole

A

6 x 10^23

20
Q

Equivalent

A

Used to describe the amount of charged (ionized) solute (moles x valence)

21
Q

Osmole

A

The number of particles into which a solute dissociates in solution

22
Q

Pores

A

Always open (non gated)

23
Q

What is selectivity of a pore based on?

A

Diameter and electrical charge

24
Q

Channel

A

Closed (gated)

25
Q

What are the types of gates that come with a channel?

A

Voltage gated

Ligand gated

Mechanically gated

26
Q

Voltage gated

A

Opens based on electrical charge

27
Q

Ligand gated

A

Opens due to molecule binding

28
Q

Mechanically gated

A

Opens due to change in pressure

29
Q

What limits the maximum rate of facilitated diffusion?

A

Saturation

Speed of conformational change

30
Q

Saturation

A

All carrier proteins have a limited number of binding sites (and limited number of carrier proteins)

(Seats available in boat)

31
Q

Speed of conformational change

A

The rate of transport can never be greater than the speed of conformational change (how fast the boat can go)

32
Q

What are the factors that affect net diffusion?

A

Concentration gradient

Partition coefficient

Diffusion coefficient

Thickness of the membrane

Surface area

33
Q

Partition coefficient

A

Decreases the solubility of a solute in oil relative to its solubility in water

34
Q

Diffusion coefficient

A

Depends on size of molecule and viscosity of the medium

35
Q

Thickness of membrane

A

The greater the distance of diffusion the lower diffusion rate

36
Q

Surface area

A

The greater the surface area available the higher rate of diffusion

37
Q

What are two factors that affect net diffusion if the solute is an electrolyte?

A

Potential difference

Diffusion potential

38
Q

When does a diffusion potential occur?

A

Only if the membrane is permeable to the electrolyte

39
Q

When will negatively charged molecules stop entering a positively charged cell?

A

When equilibrium is reached between both the chemical and electrical gradient