Exam 3 Lecture - Fluid Interaction Flashcards

1
Q

What is the universal physiological solvent?

A

water

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2
Q

What is concentration of a solution?

A

percentage or parts solute per hundred of solvent

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3
Q

What is the difference between molarity and molality?

A

molarity is moles per L of solvent and molality is moles per kg of solvent

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4
Q

Explain the concept of electrochemical equivalence.

A

Electrochemical equivalence reflects that not all solutes have the same charge
- one equivalent has the same charge as one mole of H+

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5
Q

Why is concentration important?

A

because differences in concentration drive the interaction between fluids and are critical to how the kidney works

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6
Q

What are cell membranes composed of?

A

lipid bilayers

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7
Q

What molecules cannot cross the lipid bilayer?

A

charged particles and polar molecules

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8
Q

What molecules can cross the lipid bilayer?

A

small polar molecules

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9
Q

What is the function of the cell membrane?

A

act as a potent barrier and separate fluids that may have very different properties on either side of the membrane

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10
Q

What are the four mechanisms by which solutes interact at the lipid bilayer?

A

diffusion, facilitated diffusion, active transport, and secondary active transport

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11
Q

What is diffusion?

A

the movement of the solute in question down or with its concentration; from high to low

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12
Q

Is energy required for diffusion?

A

no

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13
Q

In order for diffusion to occur, the membrane must be what?

A

permeable to the solute in question

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14
Q

How long will diffusion occur?

A

until equilibrium is reached

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15
Q

In diffusion and facilitated diffusion, the bigger the gradient, the ______ it happens.

A

faster

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16
Q

In diffusion and facilitated diffusion, the ____ ________ the membrane, the ______ it happens.

A

more permeable, faster

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17
Q

What is facilitated diffusion?

A

the movement of a solute down or with its concentration from high to low concentration

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18
Q

Is energy required for facilitated diffusion?

A

no

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19
Q

Why is facilitated diffusion different than diffusion?

A

the mechanism is used if the membrane is not permeable so the diffusion is facilitated by transporters or pores in the membrane

20
Q

How long does facilitated diffusion occur?

A

until equilibrium is reached

21
Q

What is a renal example of diffusion?

A

paracellular reabsorption of Cl in the late proximal tubule

22
Q

What is a renal example of facilitated diffusion?

A

Na, K, and Cl transport via NKCC2 in the macula densa to monitor glomerular filtration

23
Q

What is the electrochemical gradient?

A

the net gradient of charge and concentration

24
Q

What is active transport?

A

the movement of solute up or against its concentration gradient from low concentration to high concentration

25
Is energy required for active transport?
yes, energy provided by the hydrolysis of ATP
26
Aside from energy, what does active transport require?
a transport protein that moves the solute against its gradient; the transporter hydrolyses ATP
27
What is a renal example of active transport?
movement of Na at the basolateral membrane of proximal tubule (and other nephron sections) by NaK ATPase
28
What is secondary active transport?
the movement of solute up or against its concentration gradient from low to high concentration
29
How is secondary active transport different than active transport?
Energy is provided by the hydrolysis of ATP, however the transporter moving the solute does not hydrolyze ATP; instead it uses potential energy that has been generated by ATP-dependent processes elsewhere in the cell
30
What is osmosis?
the movement of water from an area where water concentration is high to an area where water concentration is low
31
In an area where the water concentration is high, what is the solute concentration like?
it is low
32
In an area where the water concentration is low, what is the solute concentration like?
it is high
33
For osmosis to occur, the membrane must ....
not be permeable to the solute in question
34
What is an effective osmole?
a solute that is unable to move across the membrane, creating the concentration difference between both sides
35
What is the difference between osmolarity and osmolality?
osmolarity is the concentration of osmotically active atoms per L of solvent Osmolality is the concentration of osmotically active atoms per Kg of solvent
36
How many osmotically active ions would NaCl have?
2 - one for Na, one for Cl
37
Is the osmolarity of a highly concentrated solution low or high?
high
38
What is tonicity?
the concentration of effective osmoles in a fluid
39
What is a hypertonic solution?
a solution with a higher effective osmolarity than another
40
If a cell with low osmolarity is placed into a hypertonic solution, what happens?
the water will move from inside the cell to the solution causing the cell to shrink
41
What is a hypotonic solution?
a solution with a lower effective osmolarity than another
42
If a cell with high osmolarity is placed into a hypotonic solution, what happens?
the water will move from the solution into the cell causing it to swell
43
What is an isotonic solution?
a solution with the same effective osmolarity as another; there is no osmosis generating pressure
44
What is a renal example of secondary active transport?
the movement of glucose and amino acids at the luminal membrane of the proximal tubule
45
How is the energy of the movement of glucose and amino acids at the luminal membrane of the proximal tubule provided?
the downhill movement of Na into the cell via the same transporter; the sodium is moving down a gradient that was establisged by NaKATPase which burns the ATP