Exam 3 Lecture - Fluid Interaction

Question 1

What is the universal physiological solvent?

Answer 1

water

Question 2

What is concentration of a solution?

Answer 2

percentage or parts solute per hundred of solvent

Question 3

What is the difference between molarity and molality?

Answer 3

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

Question 4

Explain the concept of electrochemical equivalence.

Answer 4

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

Question 5

Why is concentration important?

Answer 5

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

Question 6

What are cell membranes composed of?

Answer 6

lipid bilayers

Question 7

What molecules cannot cross the lipid bilayer?

Answer 7

charged particles and polar molecules

Question 8

What molecules can cross the lipid bilayer?

Answer 8

small polar molecules

Question 9

What is the function of the cell membrane?

Answer 9

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

Question 10

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

Answer 10

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

Question 11

What is diffusion?

Answer 11

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

Question 12

Is energy required for diffusion?

Answer 12

no

Question 13

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

Answer 13

permeable to the solute in question

Question 14

How long will diffusion occur?

Answer 14

until equilibrium is reached

Question 15

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

Answer 15

faster

Question 16

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

Answer 16

more permeable, faster

Question 17

What is facilitated diffusion?

Answer 17

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

Question 18

Is energy required for facilitated diffusion?

Answer 18

no

Question 19

Why is facilitated diffusion different than diffusion?

Answer 19

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

Question 20

How long does facilitated diffusion occur?

Answer 20

until equilibrium is reached

Question 21

What is a renal example of diffusion?

Answer 21

paracellular reabsorption of Cl in the late proximal tubule

Question 22

What is a renal example of facilitated diffusion?

Answer 22

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

Question 23

What is the electrochemical gradient?

Answer 23

the net gradient of charge and concentration

Question 24

What is active transport?

Answer 24

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

Question 25

Is energy required for active transport?

Answer 25

yes, energy provided by the hydrolysis of ATP

Question 26

Aside from energy, what does active transport require?

Answer 26

a transport protein that moves the solute against its gradient; the transporter hydrolyses ATP

Question 27

What is a renal example of active transport?

Answer 27

movement of Na at the basolateral membrane of proximal tubule (and other nephron sections) by NaK ATPase

Question 28

What is secondary active transport?

Answer 28

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

Question 29

How is secondary active transport different than active transport?

Answer 29

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

Question 30

What is osmosis?

Answer 30

the movement of water from an area where water concentration is high to an area where water concentration is low

Question 31

In an area where the water concentration is high, what is the solute concentration like?

Answer 31

it is low

Question 32

In an area where the water concentration is low, what is the solute concentration like?

Answer 32

it is high

Question 33

For osmosis to occur, the membrane must ….

Answer 33

not be permeable to the solute in question

Question 34

What is an effective osmole?

Answer 34

a solute that is unable to move across the membrane, creating the concentration difference between both sides

Question 35

What is the difference between osmolarity and osmolality?

Answer 35

osmolarity is the concentration of osmotically active atoms per L of solvent
Osmolality is the concentration of osmotically active atoms per Kg of solvent

Question 36

How many osmotically active ions would NaCl have?

Answer 36

2 - one for Na, one for Cl

Question 37

Is the osmolarity of a highly concentrated solution low or high?

Answer 37

high

Question 38

What is tonicity?

Answer 38

the concentration of effective osmoles in a fluid

Question 39

What is a hypertonic solution?

Answer 39

a solution with a higher effective osmolarity than another

Question 40

If a cell with low osmolarity is placed into a hypertonic solution, what happens?

Answer 40

the water will move from inside the cell to the solution causing the cell to shrink

Question 41

What is a hypotonic solution?

Answer 41

a solution with a lower effective osmolarity than another

Question 42

If a cell with high osmolarity is placed into a hypotonic solution, what happens?

Answer 42

the water will move from the solution into the cell causing it to swell

Question 43

What is an isotonic solution?

Answer 43

a solution with the same effective osmolarity as another; there is no osmosis generating pressure

Question 44

What is a renal example of secondary active transport?

Answer 44

the movement of glucose and amino acids at the luminal membrane of the proximal tubule

Question 45

How is the energy of the movement of glucose and amino acids at the luminal membrane of the proximal tubule provided?

Answer 45

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