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Week 1 Physiology > Week 1 Physiology > Flashcards

Week 1 Physiology Flashcards

1
Q

Total Body Water

A

The total amount of fluid or water and accounts for 50%-70% of body weight. This correlates inversely with body fat.

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2
Q

Intracellular fluid (ICF)

A

contained within the cells and 2/3s of total body water

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3
Q

Extracellular fluid (ECF)

A

is outside the cells and is 1/3 fo total body water

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4
Q

What separates ICF and ECF

A

cell membranes

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5
Q

What are the 2 subcompartments of ECF?

A

Plasma and Interstitial fluid

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6
Q

Plasma

A

is the fluid circulating in the blood vessels and is smaller to the two ECF subcompartments

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7
Q

Interstitial fluid

A

is the fluid that actually bathes the cells and is the larger of the two subcompartments

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8
Q

What separates the Plasma and Interstitial Fluid?

A

Capillary Wall

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9
Q

Interstitial fluid is WHAT of the plasma?

A

Ultrafiltrate and is formed by filtration processes across the capillary wall

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10
Q

Interstitial Fluid contains very little

A

Protein

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11
Q

What are the units for amounts solutes?

A

Moles and osmoles

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12
Q

What are the units for conentrations of solutes?

A

moles per liter (mol/L) and equivalents per liter (Eq/L)

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13
Q

1 mole =

A

6x10^23

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14
Q

1 millimole=

A

1/1000 or 10^-3

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15
Q

Equivalent

A

is used to describe the maount of charged (ionized) solute and is the number of moles of the solute multiplied by its valence

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16
Q

Osmole

A

is the number of particles into which a solute dissociates in solution

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17
Q

Osmolarity

A

is the concentration of particles in solution expressed as osmoles per Liter

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18
Q

What happens if a solute doesnt dissociate in its solution?

A

Then its osmolarity is equal to is molarity

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19
Q

What happens when a solute does dissociate into more than one particle in a solution?

A

then its osmolarity equals the molarity multipled by the number of particles in solution

ex) a solution containing 1 mmol/L NaCl is 2mOsm/L because NaCl dissociates into two particles

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20
Q

pH

A

a logarithmic term that is used to express hydrogen (H+) concnetration

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21
Q

what does the negative sign mean in pH?

A

pH decreases as teh concentration of H+ increases and pH increases as teh concentration of H+ decreases (pH=-log10[H+]

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22
Q

Principle of Macroscopic Ele ctroneutrality

A

each compartment must have the same cconentration, in mEq/L of positive charges (cations) as of negative charges (anions).

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23
Q

What is the major cation in ECF?

A

sodium (Na+) and the balancing ions are chloride (Cl-)

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24
Q

What are the major cations in ICF?

A

Potassium (K+) and Magnesium (Mg2+) and the balancing anions are proteins and organic phosphates

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25
Q

What are the differences in composition between between ECF and ICF

A
  1. Major cation in ECF is Na + in ICF its K+ ang Mg2+
  2. ICF the composition of CA2+ is very low and in ECF its higher
  3. ICF is more acidic (lower pH) than ECF. Thus substances found in high concentration in ECF are found in low concentration in ICF
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26
Q

Is the total solute concentration (Osmolarity) the same in ICF and ECF?

A

Yes, because water flows freely across cell membranes

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27
Q

What is the Na+-K+ ATPase (Na+-K+ pump)

A

this transports Na+ from ICF to ECF and transports K+ from ECF to ICF. Both are transported against their electrochemical gradients which means ATP is required

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28
Q

What would happen if a cell membrane were freely permeable to all solutes?

A

The gradients would quickly dissipate

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29
Q

What are the physiological functions for the differences in composition between ICF and ECF?

A
  1. The resting membrane potential of nerve and muscle critically depends on the difference in concentration of K+
  2. The upstroke of the action potential of these same excitable cells depends on the differences in NA+ concentration across the cell membrane
  3. Excitation-contraction coupling in cells depends on the differences in CA2+ concentration across the cell membrane and the membrane of the sarcoplasmic reticulum (SR)
  4. Absorption of essential nutrients depends on the transmembrane NA + concentration gradient
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30
Q

What are the differences between Plasma and Interstitial Fluid?

A

the presences of proteins

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31
Q

Why do Proteins not readily cross the capillary wall?

A

Their large molecular size

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32
Q

What are the consequences of proteins not being in interstitial fluid?

A

Gibbs-Donnan Equilibrium

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33
Q

Gibbs-Donnan Equilibrium

A

The plasma proteins are negatively charged, and this negative charge causes a redistriubution of small, permeant cations and anions across teh capillary wall

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34
Q

Gibbs-Donnan ratio

A

gives teh plasma concentration relative to the interstital fluid concentration for anions and Interstitial fluid relative to plasma for cations

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35
Q

The plasma compartment contains what?

A

impermeant negatively charged proteins and has a slightly lower concentration of small anions and a slightly higher concentration of small cations than the interstitial fluid becuase of the need of electoneutrality

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36
Q

What are Cell membranes primarily made of?

A

Lipids and proteins.

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37
Q

What do Lipids consists of?

A

Phospholipids, cholesterol, adn glycolipids

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38
Q

What are Lipids responsible for?

A
  • The high permeability of cell membranes to lipid-solubel substances such as carbon dioxide, oxygen, fatty acids, and steroid hormones
  • the low permeability of cell membranse to water-coluble substances suhc as ions, glucose, adn amino acids
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39
Q

What to proteins consists of?

A

Transporters, enzymes, hormone receptors, cell surface antigens, and ion and water channels

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40
Q

What do Phospholipids consist of

A

Phosphorylated glycerol ack bone (head) and two fatty acids (tail)

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41
Q

Are the Glycerol backbons hydrophilic or Hydrophobic?

A

Hydrophilic (water soluble)

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42
Q

Are the fatty acid tails hydrophilic and hydrophobic?

A

Hydrophobic (insoluble)

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43
Q

What are phospholipd molecules?

A

Amphiathic (both hydrophilic and hydrophobic)

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44
Q

What happens at an oil water inerface with phospholipids?

A

the molecules form a monolayer and orient themselves so that the glycerol back bone dissolves in the water phase and the fatty acid tails dissolve in the oil phase

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45
Q

How do phospholipids orient themselves in cell membranes?

A

the lipid coluble fatty acid tails face each other and the water soluble glycerol heads point away from each other dissolving in the aqueous solutions of the ICF or ECF, this creates a lipid bilayer

46
Q

What can protein cell membranes be?

A

Integral or peripheral, depending on whether they span the membrane or whether they are present on only one side

47
Q

Fluid mosaic model

A

explains various observations regarding the structure of functional cell membranes.

48
Q

Integral Membrane Proteins

A

They are embedded in and anchored to teh cell membrane by hydrophobic interactions. To remove an integral protein from the cell membrane, its attachmetns to the lipid bilayer must be disrupted

49
Q

Transmembrane Proteins

A
  • They span the lipid bilayer one or more times, adn are in contact with ECF adn ICF ex) ligand binding receptors, transport proteins, pores, ion channels, cell adhesion molecules, and GTP binding proteins
  • embedded in the lipid bilayer of the membrane but does not span it
    associated with membrane proteins but is not embedded in the lipid bilayer
50
Q

Peripheral Membrane Proteins

A

are not embedded in the membrane adn are not covalently bound to the cell membrane compents. They are loosely attached to either the intracellular or extra cellular side of the cell membrane by electrostatic interaction and can be removed with mild treatments that disrupt ionic or hydrogen bonds

51
Q

What is an example of peripheral membrane protein?

A

Ankryin, which “anchors” the cytoskeltion of red blood cells to an integral membrane transport protein, the Cl- HCO3- exchanger (band 3 protein)

52
Q

What do Downhill transport occur by?

A

Diffusion (simple or facilitated diffusion) and do not require engery

53
Q

What do Uphill transport occur by?

A

Active Transport (Primary or Secondary) they need energy to work

54
Q

What type of energy source does Primary transport need?

A

They require direct input of metabolic energy

55
Q

What type of energy source does Secondary transport need?

A

They utilize an inderct input of metabolic energy

56
Q

Simple Diffusion is the only form of transoprt that…

A

is not carrier mediated

57
Q

Facilitated diffusion, primary and secondary active transport all involve…

A

integral membrane proteins and are called carrier mediated transport

58
Q

What three feature do all forms of carrier mediated tranport share?

A
  1. Saturation: based on the concept that carrier proteins have a limited number of binding sites for solute. At low solute concentrations many bonding sites are available. At high solute concentration low bonding sites are available
  2. Stereospecificity: The binding sites for solute on the transport proteins are stereospecific
  3. Competition: Although the binding sites for transported solutes are quite specific, they may recognize, bind, and even transport chemically related solutes
59
Q

Transport Maximum (Tm)

A

when all of the binding sites are occupies saturation is achieved at a point

60
Q

Simple Diffusion

A

Occurs as a result of the random thermal motion of molecules

61
Q

Net diffusion of the solute is called?

A

flux or flow

62
Q

What is the driving force for net diffusion?

A

Concentration gradient. The larger the difference in solute the greater the driving force adn the greater the net diffusion and if the concentrations in the two solutions are equal, there is no driving force and no net diffusion

63
Q

Partition Coefficient (K)

A

teh solubility of a solute in oil relative to its solubility in water. The greater the relative solubility in oil, the higher the K and the more easily the solute can dissolve in the cell membrane’s lipid bilayer

64
Q

Properties of Nonpolar solutes

A

soluble in oil and have high values for partition coefficents

65
Q

Properties of Polar Solutes

A

Insoluble in oil and have low values for partition coefficient

66
Q

How can the partition coefficent be measured?

A

K= oil/water

67
Q

What characteristic does diffusion coefficient depnd on?

A

size of the solute molecule and the visscosity of the medium

68
Q

What does diffusion coefficient incersely correlate with

A

molecular radius of the solute and teh visscosity of the medium

69
Q

What happens when there is a potential difference across the mebrane?

A

the potential differnece will alter the net rate of diffusion of a charged solute

70
Q

What happens when a solute diffuses down a concentration gradient?

A

the diffusion can itself generate a potential differnce across a membrane (diffusion potential)

71
Q

What happens at higher concentrations for facilitated diffusion? Lower conentration?

A
  1. the carriers become saturated and facilitated iffusion will level off
  2. proceeds faster than simple diffusion
72
Q

3 examples of primary active transport in physiologic systems?

A
  1. Na+ K+ in all cell membranes
  2. Ca2+ SR and endoplasmic reticulum
  3. H+ -K+ ATPase
73
Q

What is Na+-K+?

A
  • Present in all membrane of all cells and it pumps Na+ from ICF to ECF and K+ from ECF to ICF
  • Each move against its respective electrochemical gradient
  • Stoichiometry varies but typically 3 Na+ ions are pumped out of the cell and two K_ ions are pumped into the cell
    (More positive charge is pumped out of the cell than negative pumped in)
  • Electrogenic because it creates a charge separation and a potential difference
  • Is responsible from maintaining concentration gradients for both Na+ and K+ across the cell membrane, keeping the intracellular Na+ low and K+ high
74
Q

Cell (plasma) membranes contain this?

A

Ca2+ ATPase, or plasma membrane Ca2+ (PMCA)

75
Q

What is the function of PMCA?

A

to extrude Ca2+ from the cell against an electrochemical gradient; one Ca2_ ion is extruded for each ATP hydrolyzed

76
Q

What is PMCA responsible for?

A

Maintaining the very low intracellular Ca2+ concentration

77
Q

What do the Sarcoplasmic reticulum (SR) of muscle cells and the endoplasmic reticulum of other cells contain what?

A

variants of Ca2+ ATPase that pump two Ca2+ ions (for each ATP hydrolyzed) from ICF into the interior of the SR or endoplasmic reticulum

78
Q

What is SERCA

A

SR and endoplasmic reticulum CA2+

79
Q

Where is H_ K+ ATPase found?

A

parietal cells of the gastric mucosa and in the alpha-interclated cells of the renal collecting duct

80
Q

What does H+ K+ ATPase do in the stomach?

A

it pumps H+ from the ICF of the parietal cell sin to the lumen of the stomach, where it acidifies the gastric contents

81
Q

Omeprazole

A

an inhibitor of gastricc H+K+ATPase, can be used therapeutically to reduce the secretion of H+ in the treatment of some types of peptic ulcer disease

82
Q

Secondary Active Transport

A
  • indirect utilization of ATP as an energy source.
  • when the transport of two or more solutes is coupled. When one moves down its electrochemical gradient and the other solute move against its electrochemical gradient. The downhill movement provides energy for the uphill movement
83
Q

Why does secondary active transport processes diminish by inhibitors of the Na+ K+ ATPase?

A

their energy, Na+ gradient, is diminished

84
Q

What are the two types of secondary active transport?

A
  • Cotransport (symport)

- countertransoprt, antiport, or exchange

85
Q

Cotransport (symport)

A
  • if the uphill solute moves in the same direction as Na+
  • Na+ moves into the cell on the carrier down its electrochemical gradient
  • ex) SGLT1
86
Q

Countertransport, antiport, or exchange

A
  • the uphill solute moves in the opposite direction of Na+

- Na+ moves into the cell on the carrier down its electrochemical graident

87
Q

Osmosis

A

the flow of water across a semipermeable membrane because of difference in solute concentration

88
Q

Why does Osmosis occur?

A

because of a osmotic pressure difference

89
Q

Osmolarity

A

concentration of osmotically active particles (osmoles/L)

90
Q

Osmolality

A

concentration of osmotically active particles (osmoles/kg of water)

91
Q

Isotonic

A

When two solutions separated by a semipermeable membrane have the same osmotic pressure

92
Q

Hyptonic

A

The solution with the lower effective osmotic pressure (swells)

93
Q

hypertonic

A

the solution with the higher effective osmotic pressure (shrinks)

94
Q

What are ion channels?

A

selective and allows ions with specific characteristics to move through them

95
Q

What are ion channels controlled by?

A

gates

96
Q

Conductance

A
  • the degree to which an object conducts electricity

- the higher the probability that the channel is open, the higher is its conductance

97
Q

What 3 sensors control the gates?

A
  1. has sensors that respond to changes in membrane potential ( Voltage gated channels)
  2. changes in signaling molecules (second messenger gated channels)
  3. changes in ligands such as hormones or neurotransmitters (ligand gated channels)
98
Q

Diffusion potential

A

potential difference generated across a membrane when a charged solute (ion) diffuses down its concentration gradient

99
Q

What is causes a diffusion potential?

A

diffusion of ions

100
Q

Magnitude

A

depends on the size of the concentration gradient where the concentration gradient is the driving force

101
Q

Sign

A

Depends on the charge of the diffusing ion

102
Q

Equilibrium Potentail

A

is the diffusion potential that exactly balances or opposes the tendency for diffusion down the concentration difference

103
Q

Electrochemical equilibrium

A

the chemical and electrical driving forces acting on an ion are equal and opposite and no further net diffusion occurs

104
Q

Nernst Equation

A

is used to calculate the equilibrium potential for an ion at a given concentration difference

105
Q

When dealing with uncharged solutes what is the driving force?

A

the concentration difference of the solute across the cell membrane

106
Q

When dealing with charged solutes what is the driving force?

A

the driving force for net diffusion must consider both concentration difference adn electrical potential difference across the cell membrane

107
Q

Driving Force

A

it is the difference between the actual membrane potential and the value the ion would like the membrane potential to be

108
Q

Ionic Current

A

current flow occurs when there is movement of an ion across the cell membrane

109
Q

What are the 2 conditions for an ion to move across a cell membrane

A
  1. there is a driving force on the ion

2. the membrane has conductance to that ion

110
Q

What determine the direction of ionic current?

A

direction of the driving force

111
Q

What determines the magnitude of the ionic current

A

size of the driving force and the conductance of the ion

Week 1 Physiology (6 decks)

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