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Veterinary Physiology > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

Selectively Permeable

A

feature/function of the plasma membrane that maintains homeostasis by regulating the passage of some substances while preventing others from entering the cell.

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2
Q

Hydrophilic

A

water insoluble; “water-loving”

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3
Q

Hydrophobic

A

water soluble; “water-fearing”

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4
Q

Lipid bilayer

A
  • composed of two layers of polar phospholipids **A phospholipid contains a polar hydrophillic head and two hydrophobic tails (tails on the inside of the layer and heads on the outside)
  • membrane also contains proteins and cholesterol
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5
Q

Amphipathic

A

containing both a polar and non-polar portion

**phospholipids are amphipathic

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6
Q

Fluid-mosaic

A

Used to describe the feature of the plama membrane.

  • Fluid: the phospholipid are constantly moving and rearranging.
  • Mosaic: several different components of the membrane (different types of lipids, proteins, and carbohydrates).
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7
Q

Brownian movement (Diffusion)

A

random moving of particles; dependent upon temperature and mass of the molecule.
-Does not require ATP

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8
Q

Flux

A

quantity of molecules moving from one sector to another in a defined volume.
-dynamic equilibrium=flux is 0.

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9
Q

Permeability coefficient

A

“Diffusion” coeffecient (P); volume that will flow in an amount of time.
-takes into account: solubility, pore size of the membrane,membrane thickness

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10
Q

Osmotic pressure

A

the pressure that needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane

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11
Q

Isotonic

A

equal osmotic pressure

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12
Q

Hypertonic

A

having higher osmotic pressure than other solution

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13
Q

Hypotonic

A

has lower osmotic pressure than other solution

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14
Q

Crenate

A

Process in osmosis where red blood cells shrink; This happens if placed in a hypertonic solution

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15
Q

Hemolyze

A

Process in osmosis where red blood cells swell and burst ; this can happen if placed in a hypotonic solution

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16
Q

Electrogenic pump

A

pumps unequal numbers of like charges in opposite directions; some active pumps pump 3 Na+ out of the cell while only 2 K+ are moving into the cell.

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17
Q

Electroneutral pump

A

pumps equal numbers of like charges in opposite directions

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18
Q

Endocytosis

A

Cells absorb molecules by engulfing them;

  • pinocytosis= “cell drinking”, fluid endocytosis
  • receptor-mediated endocytosis= endocytosis mediated by recoptors on the surace of the membrane; ligand binds to a receptor protein; clathrin coated pit; membrane invaginates to form vesicle
  • phagocytosis
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19
Q

Exocytosis

A

mechanism where cell can release certain particles from the cell that are too large to pass the membrane.

20
Q

Tmax

A

Transport maximum; maximum amount of transported molecule. point at which increases in concentration do not result in an increase in movement of a substance across a membrane.

21
Q

Transduction

A

a major process of membranes that refers to the conversion of one form of energy to another.

22
Q

Translocation

A

a major process of membranes that refers to the selective movement of substances from one location to another.

23
Q

Phospholipids

A
  • derived from either glycerol (phosphoglycerides) or sphingosine (sphingomyelin)
  • hydrophobic fatty acid tails; probably what decreases the membrane’s permeability to polar molecules
  • hydrophilic heads
24
Q

Glycolipids

A

sugar containing lipids found mostly in plasma membranes.

-derived from sphingosine (like sphingomyelin)

25
Q

Cholesterol

A
  • Some plasma membranes contain one molecule of cholesterol for every molecule of phospholipid.
  • smaller cholesterol molecules serve to add stability to the membrane and tends to decrease its fluid nature and increase its viscosity.
  • Also prevents cystallization of fatty acyl chains by fitting between them.
  • Cholesterol is largely nonpolar, hydrophobic but when combined with protein, its solubility in water increases.
26
Q

Common activities of membranes

A
  1. Receptor sites- for hormones and other chemical messengers
  2. Energy Conversion- oxidative phosphorylation, which produces ATP, occurs on mitochondrial membranes
  3. Transcellular Transport and Extracellular Communication- molecules are transported through the membrane by a variety of ways (active and passive)
  4. Intracellular Compartmentalization- divides the cytoplasm into structures such as the nucleus, endoplasmic reticulum, and Golgi apparatus
27
Q

3 major classes of membrane lipids

A
  1. phospholipids
  2. glycolipids
  3. cholesterol
28
Q

Integral vs peripheral

A

Membrane proteins are classified as either integral or peripheral on the basis of how well they can be dissociated from the membrane.

29
Q

Integral Proteins

A
  • interact very extensively with the hydrocarbon chains; only be released by agents that can compete for these non-polar interactions (detergents); disruption of the bilayer is necessary to remove these.
  • membrane-spanning proteins man span the membrane once or a number of times.
  • have both hydrophobic and hydrophilic portions
  • provides a lot of the asymmetry of the membrane
  • some may serve as receptor sites; a class that serve as receptors for hormones, neurotransmitters, and some drugs are couple to G proteins and are termed G protein-coupled receptors; span membrane with 7 alpha-helical domains; outer portion contain ligand binding site, inner portion binds to G protein.
30
Q

Peripheral proteins

A
  • bound to membranes by electrostatic and hydrogen bonds; more easily disrupted
  • Water-soluble
  • some bound to surface of integral proteins
31
Q

Functions of cell membrane proteins

A
  1. structural elements- and within and between cells (tight junctions)
  2. enzymes- surface or cytoplam
  3. receptors- ligand will evoke intracellular changes
  4. transporters- carriers or channels
32
Q

Aquaporins

A

water channels in membrane

33
Q

Carbohydrate of cell membranes

A
  • cell membranes may contain 2-10% carbohydrate.
  • associated with either lipids or proteins on the outer surface of the cell
  • Function: interaction between cells, structural
34
Q

Osmosis

A

movement of water from an area of higher concentration to an area of lower concentration.

35
Q

Key determinants of Diffusion

A

lipid solubility, size, and charge

36
Q

Passive Transport

A
  • Does not require an input of chemical energy
  • Simple Diffusion
  • Facilitated Diffusion
37
Q

Simple Diffusion

A
  • type of passive transport
  • does not require an input of chemical energy
  • small, non-polar molecule passes through a membrane
38
Q

Facilitated Diffusion

A
  • does not require an input of chemical energy
  • movement of molecules from a higher concentration to a lower concentration with the help of proteins found in the membrane.
  • gated channels allow ions and small polar molecules to pass through at certain times.
  • Protein carriers assist larger molecules; important characteristic: specificity, saturation, competition
39
Q

Symporters (sodium, potassium, and chloride)

A

name for transporters that transport ions in the same direction

40
Q

Antiporters (sodium and hydrogen)

A

transport ions in opposite directions

41
Q

Uniporters (glucose)

A

transport only single molecules

42
Q

Active Transport

A
  • May also be called a pump
  • Movement of substances from an area of low concentration to an area of high concentration
  • ATP required
43
Q

ATPases

A

name for many of the active transporters

44
Q

Sodium/ Potassium pump

A
45
Q

Secondary active transport

A
  • takes advantage of the concentration gradient that exists for many ions
  • The downhill transport of one molecule provide the energy for the uphill transport of another molecule
  • countertransport= opposite direction
  • cotransport= same direction
46
Q

transcytosis

A

transport of substances across the cell; endocytosis and exocytosis

Veterinary Physiology (3 decks)

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