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Physiology (MPP 3202) > Ch. 6 Interactions Between Cells and the Extracellular Environment > Flashcards

Ch. 6 Interactions Between Cells and the Extracellular Environment Flashcards

1
Q

What does the extracellular environment include?

A

Everything located outside the cell

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2
Q

Cells receive ____ from and release ____ into the extracellular environments.

A

Nourishment; wastes

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3
Q

How do cells communicate with each other using the extracellular environment?

A

By secreting chemical regulators into the extracellular environment

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4
Q

How to cells exchange things?

A

Inside cell –> extracellular

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5
Q

Does diffusion work better over a limited space? Why?

A

Yes b/c the exchange into extracellular environment occurs faster

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6
Q

What is the extracellular environment in endothelial cells?

A

The blood running by

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7
Q

True/False: Capillary beds are in close proximity to most cells in the body.

A

True

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8
Q

__% of our water is within cells in the intracellular compartment; intracellular fluid (ICF).

A

67% (2/3)

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9
Q

__% of our water is in the extracellular compartment (extracellular fluid, ECF).

A

33% (1/3)

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10
Q

__% of ECF is in blood plasma.

A

20%

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11
Q

__% of ECF makes up tissue fluid (or interstitial fluid).

A

80%

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12
Q

Interstitial fluid

A

aka tissue fluid

Connects the intracellular compartment with the blood plasma

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13
Q

What does extracellular matrix contain?

A

Protein fibers (structural support) of collagen and elastin, and ground substance (glycoproteins and proteoglycans)

Foundation to build cells upon; flexible

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14
Q

Protein fibers provide ____ ____.

A

Structural support

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15
Q

Integrins

A

Glycoproteins that extend from the cell cytoskeleton and bind to the extracellular matrix; linking cells to the matrix

Selective; different integrins recognize different extracellular matrix

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16
Q

What 3 things to integrins do?

A

Impart a polarity to cells
Affect adhesion and motility
Affect proliferation

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17
Q

Why is proliferation important? How can it go wrong?

A

Important: only need once cell covering basement membrane –> proliferation

Tumors are opposite: adding unnecessary cells to cover basement membrane

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18
Q

The plasma membrane is ____ ____.

A

Selectively permeable

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19
Q

Selectively Permeable plasma membrane

A

Allows some molecules to cross but not others

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20
Q

What is the plasma membrane generally not permeable to?

A

Proteins, nucleic acids, or other large molecules

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21
Q

What is the plasma membrane generally permeable to?

A

Ions, nutrients, and wastes

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22
Q

Non-carrier mediated membrane transport

A
  1. Simple diffusion of lipid-soluble molecules
  2. Simple diffusion of ions through nonspecific channels
  3. Simple diffusion of water = osmosis
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23
Q

Carrier-mediated membrane transport

A
  1. Facilitated diffusion

2. Active transport

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24
Q

Passive Transport

A

Molecules move from higher to lower concentration w/o using metabolic energy

  • -moves down concentration gradient
  • -equalize concentration
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25
Q

Active Transport

A

Molecules move from lower to higher concentration using ATP and specific carrier pumps

  • -selective movement
  • -move again concentration gradient
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26
Q

Diffusion: Plasma Membrane

A

Small, nonpolar (or uncharged) lipid-soluble molecules pass easily through the lipid portion of the membrane

  • -oxygen, carbon dioxide, and steroid hormones (estrogen, testosterone…)
  • -gas exchange: net diffusion of oxygen into cells and CO2 out of cells due to concentration gradients; opposite in lungs (offload CO2 and bring CO2 into lungs)
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27
Q

Aquaporins

A

Water can pass through these special channels in osmosis

–lipid membrane not water soluble, aquaporins help water move

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28
Q

Where does CO2 build up?

A

In Krebs cycle and Electron Transport

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29
Q

Osmosis

A

Diffusion of solvent instead of solute; unique

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30
Q

Why can water pass through the plasma membrane?

A

Because water molecules do not carry a charge, they can pass slowly

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31
Q

Where are Aquaporins found?

A

Kidneys, eyes, lungs, salivary glands, and the brain

–glaucoma (occurs from increased eye pressure) can occur b/c of issues w/ aquaporins

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32
Q

Osmotically Active

A

Solutes that cannot cross and permit osmosis

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33
Q

For osmosis to occur, must there be a solute concentration difference on either side of a membrane permeable to water?

A

Yes

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34
Q

For osmosis to occur, the membrane must be ____ to the solute, or the concentration difference will not be maintained.

A

Impermeable

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35
Q

Osmotic Pressure

A

Force surrounding a cell required to stop osmosis

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36
Q

Osmolality

A

Total molality of a solution when you combine all of the molecules within it

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37
Q

Pure water has an osmotic pressure of ____.

A

Zero

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38
Q

A higher solute concentration would require a ____ osmotic pressure.

A

Higher

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39
Q

Tonicity

A

The effect of a solute concentration on the osmosis of water

Literally how a cell is going to react in a solution

40
Q

Hypoosmotic and Hypotonic

A

Solutions with a lower solute concentration than the cell

Will pull water into the cell; cell will swell and could lyse

41
Q

Hyperosmotic and Hypertonic

A

Solutions with a higher solute concentration than the cell

Will pull water out of the cell; cell will shrivel up and crenate

42
Q

Osmoreceptors

A

In hypothalamus; detect increases in osmolality (due to dehydration).

Triggers:

  • -thirst
  • -decreased excretion of water in urine
43
Q

Decreasing the solute will ____ osmolality.

A

Increase

44
Q

Anti-diuretic hormone

A

Tells kidneys to retain water when dehydrated

45
Q

Constant osmolality must be maintained, or ____ will be damaged.

A

Neurons

46
Q

With a lower plasma osmolality, osmoreceptors are not ____, so more water is excreted in urine.

A

Stimulated

47
Q

Gated

A

Refers to plasma membrane in which things may only be moved at certain times

Opened and closed by a number of stimuli

48
Q

Channels: Plasma Membrane

A

Charged ions (small) can pass through ion channels that cross the plasma membrane that may always be open or gated

49
Q

How do larger polar molecules cross the plasma membrane?

A

They cannot pass through the membrane by simple diffusion, so they need special carrier proteins in order to cross

50
Q

Can molecules that are large or polar diffuse across the membrane?

A

No; carrier proteins within the plasma membrane move these molecules across

51
Q

What molecules cannot diffuse across the membrane?

A

AA, glucose, and other organic molecules

52
Q

What are characteristics of the carriers?

A

Specific to a given molecule
–e.g. Glucose transporter moves glucose only

May be competition for similar carriers or molecules
–e.g. Antibiotics: must figure out which ones are going to be eliminated in urine and which ones won’t

Saturation - number of carriers is limited
–eventually all the carriers are being used and we can’t move anything else

53
Q

Facilitated Diffusion

A

Powered by the random movement of molecules - no ATP used

Move from high to low concentration

Requires specific carrier-mediated proteins

Transport proteins may always exist in the plasma membrane or be inserted when needed

54
Q

Active Transport

A

Molecules must be moved from an area of low concentration to an area of high concentration
–against concentration gradient

Requires expenditure of ATP

also called pumps

55
Q

Primary Active Transport

A

Occurs when hydrolysis of ATP is directly responsible for carrier protein function

Transport protein is also an ATPase enzyme that will hydrolyze ATP

Pump activated by phosphorylation using a phosphate from ATP

56
Q

Na+/K+ Pump

A

Found in all body cells

ATPase enzyme pumps 3 NA+ out of the cell and 2 K+ into the cell

57
Q

What 3 functions does the Na+/K+ Pump serve?

A
  1. Provides energy for coupled transport of other molecules
  2. Produces electrochemical impulses in neuron and muscle cells
  3. Maintains osmolality
58
Q

Discuss Na+ and K+ concentrations inside and outside of the cell.

A

High K+ concentration in cell, low K+ concentration outside cell

Low Na+ concentration in cell, high Na+ concentration outside cell

59
Q

Secondary Active Transport

A

Aka coupled transport

Energy needed to move molecules across their concentration gradient is acquired by moving sodium back into the cell

60
Q

Secondary Active Transport: Cotransport or Symport

A

Other molecule is moved with sodium. Common way of transporting glucose

61
Q

Secondary Active Transport: Countertransport or Antiport

A

Other molecule is moved in the opposite direction from sodium.

e. g. Sodium hydrogen antiport
- -kidneys move sodium in, we move hydrogen out

62
Q

Absorption

A

Transport of digestive products across intestinal epithelium into the blood
–pulling things in from gut

63
Q

Reabsorption

A

Transport of molecules out of the urinary filtrate back into the blood
–referring to renal fxn; kidneys filter blood, reabsorb water and sodium

64
Q

Transcellular Transport

A

Movement of molecules through the cytoplasm of the epithelial cells
–moving things through cell

65
Q

Paracellular Transport

A

Movement across tiny gaps between cells

–moving things between cells

66
Q

Transport usually involves what type of cells?

A

Epithelial cells

67
Q

What are the 3 types of cell-cell adhesion?

A
  1. Tight junctions
  2. Adherens junctions
  3. Desmosomes

All 3 hold epithelial cells together

68
Q

Tight Junctions

A

Do not allow easy diffusion

Limit paracellular transport

69
Q

Adherens Junctions

A

Cell patterning/cell recognition

–space between plasma membrane

70
Q

Desmosomes

A

Lots of skin movement

–space between plasma membrane

71
Q

Bulk Transport: Exocytosis

A

Large molecules such as proteins, hormones, and neurotransmitters are secreted

Requires ATP

Involves fusion of vesicle w/ plasma membrane
–we can dump out a lot of molecules at once

72
Q

Bulk Transport: Endocytosis

A

Movement of large molecules such as cholesterol into the cell

Can be receptor-mediated (selective)

Usually a transport protein interacts with plasma membrane proteins to trigger endocytosis

73
Q

Why is there a difference in charge on each side of the plasma membrane?

A
  1. Permeability of the membrane
  2. Action of Na+/K+ pumps
  3. Negatively charged molecules (lot of proteins) inside cell
74
Q

Potential Difference

A

Difference in charge [of plasma membrane]

Makes inside of cell negative compared to outside

75
Q

Why does K+ accumulate at high concentrations in the cell?

A
  1. Na+/K+ pumps actively bring in K+
  2. Membrane is very permeable to K+
  3. Negative anions inside cell attract cations outside the cell
  4. Limited by strong concentration gradient

K+ concentration inside is 150 mEq/L and out is 5 mEq/L

76
Q

How do we measure the potential difference?

A

Measured as voltage

77
Q

K+ Equilibrium

A

Inside of cell has a voltage 90mV lower than the outside; this is the voltage needed to maintain 150 mM K+ inside and 5mM K+ outside

78
Q

Is the resting potential for our cells on the negative or positive side?

A

Negative side

79
Q

Na+ Equilibrium

A

Concentration of sodium in a normal cell is 12mM inside and 145mM outside

To keep so much sodium out, inside would have to be positive to repel sodium ions

Equilibrium potential for sodium is +66mV

80
Q

The membrane is less permeable to ____, so the actual membrane potential is close to that of the more permeable ____.

A

Na+; K+

81
Q

Resting Membrane Potential

A

Membrane potential of a cell not producing any impulses

Depends on:

  1. ratio of concentrations of each ion on either side of the membrane
  2. specific permeability to each ion
82
Q

Which ions contribute to the resting potential? Which ion has the greatest influence?

A

K+, Na+, Ca2+, and Cl- contribute

K+ has greatest influence b/c it’s most permeable

83
Q

T/F: A change in the permeability of the membrane for any ion will change the resting potential.

A

True

84
Q

T/F: A change in the concentration of any ion inside or outside the cell will change the resting potential.

A

True

85
Q

Does every cell have a resting membrane potential?

A

Yes

Occurs when there are no impulses: no neurons firing, no muscles contracting…

86
Q

What are the 4 types of cell signaling?

A
  1. Gap junctions
  2. Paracrine signaling
  3. Synaptic signaling
  4. Endocrine signaling
87
Q

Gap Junctions

A

Allow adjacent cells to pass ions and regulatory molecules through a channel between cells

Cardiac cells, muscle cells

88
Q

Paracrine signaling

A

Cells w/in an organ secrete molecules that diffuse across the extracellular space to nearby target cells; often called local signaling

One cell signals another w/in the same organ

89
Q

Synaptic signaling

A

Involves neurons secreting neurotransmitters across a synapse to target cells

90
Q

Endocrine Signaling

A

Involves glands that secrete hormones into bloodstream; these can reach multiple target cells

91
Q

Receptors

A

Allows cells to recognize signals, cells must have the specific receptor proteins either on the plasma membrane (outside cell) or inside the cell

92
Q

Nonpolar Regulator

A

Receptors on inside

Steroid hormones, thyroid hormone, and nitric oxide gas

93
Q

Polar Regulator

A

Receptors on outside (plasma membrane)

Epinephrine, acetylcholine, and insulin

94
Q

cAMP

A

Cyclic adenosine monophosphate

Signaling molecule; common second messenger

95
Q

How does cAMP work?

A
  1. Signaling molecule binds to a receptor
  2. Activates an enzyme that produces cAMP from ATP
  3. cAMP activates other enzymes
  4. Cell activities change in response

Physiology (MPP 3202) (32 decks)

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