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M2M exam 3 wk 1 > composition of cells > Flashcards

composition of cells Flashcards

1
Q

volumes of plasma

A

3 liters

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2
Q

volume extracellular fluid (ECF) ___ L

A

about 13 liters plus another 5 for the ‘third space’)

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3
Q

volume intracellular fluid (ICF) ____ L

A

27 liters

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4
Q

__% of all the chemical particles in the __ liters of body fluids are water molecules.

A

99%

45L

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5
Q

Of the remaining 1%, about 5 out of every 6 are simple

A

inorganic ions, principally Na+, K+, and Cl-. All of the rest – all carbohydrates, proteins, nucleic acids, lipids, and so forth – constitute a very small fraction of the total.

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6
Q

the fluids in the various body compartments _________;

A

do not have the same composition

the ion content of cells, for example, is vastly different from that of blood plasma.

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7
Q

The boundary between the intra- and extracellular fluids is

A

plasma membrane

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8
Q

extracellular fluid (ECF) comprises

A

plasma (~3 liters – plasma is whole blood without the cells), lymph, and interstitial fluid, all of which have nearly identical inorganic ion and water compositions.

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9
Q

ECF we will mean the

A

interstitial fluid.

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10
Q

Intracellular fluid (ICF) comprises

A

mitochondrial, vesicular, nuclear, and other subcompartments.

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11
Q

ICF

Na+

A

14

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12
Q

ICF K+

A

145

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13
Q

ICF

Cl-

A

5

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14
Q

ICF

A-n

A

126

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15
Q

ICF

H2O

A

~55,000

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16
Q

ECF

Na+

A

140

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17
Q

ECF K+

A

5

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18
Q

ECF

Cl-

A

145

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19
Q

ECF

A-n

A

~0

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20
Q

ECF H2O

A

~55,000

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21
Q

membrane permeability

Na+

A
  • (no)
22
Q

membrane permeability

K+

A

+ (yes)

23
Q

membrane permeability

Cl-

A

+ (yes)

24
Q

membrane permeability

A-n

A
  • (no)
25
Q

membrane permeability

H2O

A

+ (yes)

26
Q

A note on the word permeable: _____ are permeable (or impermeable) to solute,
while a _____ is permeant (or impermeant) or permeating (or nonpermeating)

A

membranes

solute

27
Q

Membranes are mostly _____, which are_______ to water and charged substance

A

lipid molecules

impermeable

28
Q

Lipids are also ‘strong’, in an _______. they can keep opposite _______.

A

electric sense.

electric charges separated, without collapsing

29
Q

he cytoplasm of nearly all cells is electrically ______, compared to the ECF, because:

A

negative

because cells contain a few more negative than positive ions.

30
Q

membrane potential, is caused by:

A

The excess anions create an electrical potential difference between the inside and the outside of the cell

31
Q

Membrane potential governs some:

A

vital cell processes, is wholly dependent on the integrity of the plasma membrane

32
Q

The ability of the membrane to withstand the imposed electric force (which has a whopping strength of about 100,000 volts/cm) is due to its_______

A

lipid composition.

33
Q

Many charged and polar molecules can cross membranes. Through:

A
  1. channels

2. transporters

34
Q

channels are ______ for particular ions

A

selective

35
Q

Sodium channels will pass ___________.

A

Na+ ions, but not K+, or Cl-, or other ions

36
Q

voltage gated channels depend on _____

The gate open when the membrane is _____

A

electric field across the membrane or membrane potential.

the gates open when the membrane is depolarized

37
Q

depolarized means

A

cell is less negative inside

38
Q

aquaporins

A

channel that has no gate,

39
Q

pumping means work, energy can come from

A
  1. directly from metabolism: primary active transport

2. other sources: secondary

40
Q

active transport

A

pump molecules across a membrane to concentrate them on one side against their energy gradient.

41
Q

primary active transport example

A

Na+ pump, which extrudes Na+ from the cell and requires ATP

42
Q

secondary active transport,

A

use the energy released when Na+ ions leak into cells, and the energy released is captured and used to pump another ion across the membrane.

43
Q

Transporters work ______ than channels, usually not exceeding _____

A

thousands of times slower

usually not exceeding several hundred transport cycles per second.

44
Q

by mutating only a few amino acid residues, a transporter of chloride and hydrogen ions, which pumps only about a hundred ions per second, can be turned into a _______

A

chloride-selective ion channel that allows the passage of tens of thousands of ions per second.

45
Q

From a functional standpoint, there are two kinds of proteins that mediate the transmembrane movements of charged substances:

A

channels and transporters.

46
Q

Understand the routes by which a given substance can traverse a membrane.

A
  1. diffusion
  2. passive transport: channels
  3. active transport: transporters
47
Q

Diffusion:

A

This is primarily for water, which crosses membranes through special channels called aquaporins.

Water always diffuses down its concentration gradient – there is no active transport for water.

48
Q

Passive transport: Channels

A
  • Charged and polar substances can cross membranes through these
  • passive pores/tunnels through the membrane
  • selective for specific ions/substances
  • Some are gated, and substances can only pass when the gate is open
49
Q

Active transport: Transporters

A

• substances cross membranes by binding to proteins and being escorted across
• big molecules, like glucose
• selective
• needed to pump molecules across a membrane, concentrating them on one side
against their energy gradient

– requires ATP

50
Q

dentify physical forces that can determine the gating properties of ion channels.

A
  • Electric field (membrane potential) across the membrane
  • Mechanical stimulation (stretching of the membrane)
  • Binding of a particular chemical
  • Temperature
51
Q

in secondary active transport, the transporter uses

A

the energy released when Na+ ions leak

into cells: the energy released is captured and used to pump another ion across the membrane

52
Q

Ultimately, secondary active transport also depends on

A

metabolism.

M2M exam 3 wk 1 (15 decks)

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