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Physiology > Chapter 3: The Plasma Membrane And Membrane Potential > Flashcards

Chapter 3: The Plasma Membrane And Membrane Potential Flashcards

1
Q

Plasma Membrane

A
  • extremely thin layer that forms the outer boundary of every cell
  • encloses the intracellular contents
  • acts as a mechanical barrier
  • determines cell composition
  • controls entry of nutrients and molecules and exit of waste products
  • maintains differences in ion concentrations inside and outside the cell
  • is a fluid lipid bilayer embedded with proteins
  • consists mostly of lipid and proteins plus small amounts of carbohydrates
  • phospholipids are the most abundant membrane lipids
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2
Q

Cholesterol in Membrane

A
  • contributes to both the fluidity and the stability of the membrane
  • molecules are tucked between the phospholipid molecules
  • prevent fatty acid chains from packing together and crystallizing
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3
Q

Membrane Proteins

A
  • proteins are inserted within or attached to the lipid bilayer
  • integral, transmembrane, and peripheral proteins
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4
Q

Function of the Lipid Bilayer

A
  • forms basic structure of the membrane
  • hydrophobic interior is a barrier to passage of water soluble substances between ICF and ECF
  • responsible for the fluidity of the membrane
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5
Q

Functions of Membrane Proteins

A
  • different specialized functions
  • channels for passage of small ions
  • carriers for transport of substances
  • docking-marker acceptors for secretary vesicles
  • membrane-bound enzymes
  • receptors for response to chemical messengers
  • cell adhesion molecules that hold cells together
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6
Q

Membrane Carbohydrates

A
  • serve as self-recognition markers

Involves in tissue growth

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7
Q

Cell-to-Cell Adhesion

A
  • extracellular matrix binds cells together
  • consists of collagen, elastin, and fibronectin
  • some cells are directly linked by specialized cell junctions
  • Desmosomes, tight junctions, and gap junctions
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8
Q

Desmosome

A
  • a rivet or bolt that uses biological tissue to make a thick plaque area
  • tight junction
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9
Q

Tight Junction

A
  • several sown areas of claudin proteins
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10
Q

Gap Junctions

A
  • channel that bind two cell membranes together

- allows a small area for passage of ions

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11
Q

Membrane Transport

A
  • substances can cross the membrane
  • membrane is permeable to that substance
  • substance cannot cross the membrane
  • membrane is impermeable to it
  • selectively permeable plasma membrane
  • allows some particles to pass while preventing others
  • lipid-soluble substances and small water-soluble substances
  • permeate the plasma unassisted
  • active forces use energy to move particles across the membrane
  • passive forces do not
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12
Q

Unassisted Membrane Transport

A
  • particles that can penetrate the membrane on their own are passively driven across the membrane
  • diffusion down a concentration gradient
  • simple diffusion and net diffusion
  • Fick’s Law of Diffusion
  • movement along an electrical gradient
  • ions that can permeate the membrane
  • move passively along their electrical gradient
  • osmosis is the net diffusion of water down its own concentration gradient
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13
Q

Permeable Vs Impermeable

A

Permeable
- diffusion can occur
Impermeable
- no diffusion

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14
Q

Tonicity

A
  • effect the concentration of non-penetrating solutes in a solution has on cell volume
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15
Q

Unassisted Membrane Transport Solutions:

Isotonic Solution

A
  • same concentration of non-penetrating solutes as normal body cells
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16
Q

Unassisted Membrane Transport Solution:

Hypotonic Solution

A
  • below-normal concentration of non-penetrating solutes
17
Q

Unassisted Membrane Transport Solution:

Hypertonic Solution

A
  • above-normal concentration of non-penetrating solutes
18
Q

Assisted Membrane Transport

A
  • Carrier-mediated transport
  • carrier protein spans the thickness of the plasma membrane
  • can change shape so that specific binding sites within the carrier are alternately exposed to the ECF and the ICF
  • Specificity, saturation, and competition
  • facilitated diffusion is passive carrier-mediated transport
  • uses carrier to facilitate the transfer of a particular substance across the membrane “downhill” from high to low concentration
  • active transport is carrier mediated and uses energy
  • primary and secondary active transport
19
Q

Assisted Membrane Transport Protein:

Symport

A
  • has a driving ion that enters cell (low concentration on the inside of cell and high on outside) that also pulls another ion (high concentration on inside and low on outside)
20
Q

Assisted Membrane Transport Protein:

Antiport

A
  • uses driving ion that enters cell (low concentration on inside and high on outside) to transport another ion that has (low concentration on the inside and high on the outside) out of the cell
21
Q

Assisted Membrane Transport Protein:

Vesicular Transport

A
  • material is moved into or out of the cell wrapped in membrane
  • Endocytosis and exocytosis
  • rates of ^ must be kept in balance to maintain constant membrane surface area
22
Q

Membrane Potential

A
  • cell plasma membranes are polarized electrically
  • a separation of opposite charged across the plasma membrane
  • results from differences in the concentration and permeability of key ions
  • balance of passive leaks and active pumping at resting membrane potential
  • at resting potential neither K+ nor Na+ is at equilibrium
  • concentration gradients and permeabilities for Na+ and K= remain constant in resting state
  • resting membrane potential established by these forces remains constant
  • chloride movement at resting membrane potential doesn’t have an effect
  • membrane potential passively influence the distribution of Cl-
23
Q

Effects on Membrane Potential

A
  • Na+ - K+ pump
  • movement of K+ alone
    Equilibrium potential for K+
  • movement of Na+ alone
    Equilibrium potential for Na+
  • simultaneous K+ and Na+
  • RESTING POTENTIAL IS -70
  • HYPER-POTENTIAL IS -90
  • HYPO-POTENTIAL IS +60
24
Q

Specialized Use of Membrane Potential

A
  • in nerve and muscle cells
  • can rapidly and transiently alter their membrane permeabilities to the involved ions in response to appropriate stimulation
  • bringing about fluctuations in membrane potential
  • responsible for producing nerve impulses in nerve cells and for triggering contraction in muscle
25
Q

After a long day, you soak in the tub for several minutes to relax. As you dry off, you notice that your fingers and toes are very wrinkled. What happened?

A

-

26
Q

What happens when humans drink salt water?

A

-

27
Q

If a person has an abnormally low concentration of proteins in his/her plasma, edema (accumulation of fluid in the tissues) will occur. Why?

A

-

Physiology (7 decks)

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