Basic cell physiology Flashcards

1
Q

What is ECF?

A

Extracellular fluid

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2
Q

What are homeostatic mechanisms?

A

A dynamic equilibrium that maintains a specific sets of thresholds compatible for life -> to detect and respond to deviations from pH 7.4

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3
Q

What is the osmolarity of blood plasma?

A

300 mOsM - equal amount of water in blood cell and plasma

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4
Q

What is osmolarity?

A

Concentration of osmotically active particles

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5
Q

What is tonicity of a solution?

A

Describes the cell volume change that occurs at equilibrium if the cell is placed in that solution

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6
Q

Explain hypotonic, hypertonic and isotonic solutions

A

Tonicity Osmolarity
- hypotonic - hypoosmotic
- hypertonic - hyperosmotic
- isotonic - isosmotic
hypo: cells swell - net influx of H2O into ICF at equilibrium
hyper: cells shrink - net H2O loss to ECF at equilibrium
iso: normal cells - no net movement between ICF and ECF

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7
Q

What determines whether a substance can pass through a cell membrane?

A

Lipid and protein composition

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8
Q

How is the membrane permeable or impermeable to a solution?

A

Membrane is permeable to solution if it allows it in.
Membrane is impermeable to solution if it doesn’t allow it in

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9
Q

What type of molecules can move easily across cell membranes?

A

Oxygen, carbon dioxide and lipids

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10
Q

What molecules move across cell membrane with more difficulty?

A

Polar molecules and large molecules (proteins)

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11
Q

What is diffusion?

A

Passive transport of molecules down a chemical (concentration) gradient -> higher concentration to lower concentration

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12
Q

Which is more likely to cross cell membrane by simple diffusion: fatty acid or a glucose molecule?

A

Fatty acid because it is lipophilic

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13
Q

What is osmosis?

A

Passive movement of water molecules from regions of relatively high H2O potential to regions of low H2O potential through a differentially permeable membrane

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14
Q

Do cell membranes have specific channels for molecules?

A

Yes. Example: glucose -> glucose transporter in membrane

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15
Q

Explain active transport

A

Moves molecules against their concentration gradient and requires energy
Primary active transport: ATP used
Secondary active transport: indirectly driven by ATP

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16
Q

Name two ways channels differ from carriers

A

Channel proteins form continuous connections between two sides of membrane and transport molecule faster

17
Q

What can pass through open channels?

A

Ions and water molecules

18
Q

What is the most important primary active transport?

A

Na+/K+ ATP (Sodium/Potassium ATPase)
- Pumps NA+ out and K+ into cell
- Maintain concentration gradient of Na+ and K+
- Transporter protein to pump 3NA+ out and 2K+ in

19
Q

True or false:
ICF has higher NA+ concentration than the ECF

A

False:
ICF: low Na+ / high K+
ECF: high Na+ / low K+

20
Q

Which are the protein-mediated transporters?

A

Structural proteins: maintain cell shape
Enzymes: catalyze chemical reactions and transport signals across membrane
Receptor proteins: part of body signaling system
Transporter proteins: move molecules in and out

21
Q

What is resting membrane potential?

A

-70 mV - electrical gradient that exists between ECF and ICF
- inside of cell negative

22
Q

What primary ion determines the resting membrane potential?

A

K+

23
Q

How does Na+/K+ ATPase help maintain the RMP?

A

Removing Na+ that leaks into cell and returning K+ that has leaked out