Module 1.3

Question 1

cell membrane helps cells maintain ___________ -
stable internal balance

Answer 1

homeostasis

Question 2

the cell membrane maintains homeostasis through balancing the ________ (4) through active and passive transport

Answer 2

pH, temperature, glucose (sugar intake), water balance

Question 3

if a solution’s pH is unbalanced, it is corrected with a

Answer 3

BUFFER

Question 4

direction of diffusion

Answer 4

high to low

Question 5

direction of osmosis

Answer 5

high water to low water
low solute to high solute

Question 6

When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to _____.

Answer 6

shrivel

Question 7

When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to _____ and possibly explode.

Answer 7

swell

Question 8

is a distribution of charge across the cell membrane

Answer 8

membrane potential

Question 9

Membrane potentials

A. The body as a whole is electrically _____

B. All of the cells of body have an _______ across their membrane (_______) known as the membrane potential

C. Membrane potentials develop because of differing _________ between the inside and outside of the cell

Answer 9

neutral
electrical potential ; Voltage difference
ion concentrations

Question 10

The exact value measured for the resting membrane
potential varies between cells, but ______ is a commonly reported value

Answer 10

-70 mV

Question 11

________ is determined by the difference in charge between two points
- membrane potential,
- influence transport

Answer 11

Potential difference

Question 12

Principals of electricity

1. Units of electrical potential are in ______ or for biological system _______
2. Voltage is always measured between two points (________)

Answer 12

volts (V) ; millivolts (mV) ; 1 V = 1000mV
Potential difference

Question 13

flow of electrical charges from one point to another

Answer 13

current

Question 14

B. Current

1. Like charges repel unlike attract
2. Ions tend to move from areas of greater concentration to areas of least concentration
3. Movement of a positive ion from one side of a membrane to the other implies a _______ is left behind

Answer 14

negative charge

Question 15

the voltage across a conductor is directly proportional to the current flowing through it, provided all physical conditions and temperature, remain constant.

Answer 15

Ohm’s Law (I = E / R)
R = resistance
I = current flow
E = electrical potential

Question 16

C. Current Flow

1. Cell - Aqueous solution + good ________ (Ions and water)
2. Lipid membrane - A few charged groups can not carry current - high electrical resistance - _________
3. ECF and ICF - both have _________

Answer 16

good conductor (ions)
good insulator (lipid membrane)
low electrical resistance (ECF and ICF)

Question 17

describes the steady state of the cell

Answer 17

Resting Membrane Potential

Question 18

By convention (Resting MP) - ECF (outside of the cell) is assigned a voltage of

Answer 18

zero

Question 19

Polarity of the membrane is stated in terms of the sign of the ________ inside of the cell

Answer 19

excess charge inside of the cell

Question 20

Types of channels (2)

Answer 20

1. Leak Channels
2. Na+/K+ ATPase Pump

Question 21

Open all of the time - slow leak of ions, simplest type of ion channel, in that their permeability is more or less constant (neurons)

Answer 21

Leak channels

Question 22

channel that transports sodium, potassium & chlorine

Accounts for 95% of the resting membrane potential

Answer 22

Leak channels

Question 23

These channels open and close at random, allowing ions to pass through when they are open.

Answer 23

Leak channels

Question 24

_______ :
a. Unequal transport of positive ions makes the ICF more _______ than it would be from diffusion alone
b. ________ pump
c. Accounts for 5% of resting membrane potential

Answer 24

Na+K+ATPase Pump;

negative,
Electrogenic

Question 25

Other types of channels (4)

Answer 25

a. Resting K+ channel b. Voltage-gated channel c. Ligand-gated channel d. Signal-gated channel

Question 26

- channel that is always open - are responsible for generating the resting potential across the membrane.

Answer 26

Resting K+ channel

Question 27

- channel that opens (transiently) in response to change in the membrane potential - are responsible for propagating action potentials along the axonal membrane

Answer 27

Voltage-gated channel

Question 28

opens (closes) in response to a specific extracellular neurotransmitter

Answer 28

ligand-gated channel

Question 29

opens (closes) in response to a specific intracellular molecule

Answer 29

signal-gated channel

Question 30

Two types of ion channels in dendrites and cell bodies are responsible for generating electric signals in postsynaptic cells

Answer 30

ligand-gated channel and signal-gated channel

Question 31

What are the complications of high potassium?

Answer 31

Hyperkalemia = too much K+ in the blood

Question 32

What are the two forms of ion gradients? Together these form what is known as the __________

Answer 32

1. Chemical Concentration Gradient 2. Electrical concentration gradient (Charge buildup and charge differential) electrochemical gradient

Question 33

Membrane potential: 75% more permeable to ____ (K+/Na+) than ____(K+/Na+) due to leak channel

Answer 33

K+ than Na+

Question 34

In all cells a potential difference across the membrane exists a. Inside is ______ (Na+K+ATPase) b. Membrane potentials usually within ___ to ___ mv

Answer 34

negative because Na+/K+ ATPase; -40 to -90

Question 35

A cell with a resting membrane potential is said to be

Answer 35

polarized

Question 36

if resting MP, Both the inside and the outside of the cell are

Answer 36

electrically neutral

Question 37

Factors that determine the resting membrane potential (4)

Answer 37

Selective permeability of the of the plasma membrane Leak channels Na+K+ATPase pump Differences in ion concentrations

Question 38

Many substances are in the cell but the mobile ions _________ (4) play the most important roles

Answer 38

Na+, K+, Ca++ and Cl-

Question 39

ECF: ____ helps to balance ____ ICF: _____ balance ____

Answer 39

Cl-, Na+ Proteins (Neg charge), K+

Question 40

At rest - Slightly permeable to Na+ 75 times more permeable to ___, and freely permeable to ___

Answer 40

K+, Cl-

Question 41

_________ or ______ at which ion movements in both directions across the membrane are exactly balanced (net movement = zero)

Answer 41

Equilibrium potential or electrochemical potential

Question 42

At equilibrium point, the ion flux = ____

Answer 42

0 (implies no net ion movement)

Question 43

Equilibrium potential or also known as

Answer 43

Nernst potential

Question 44

the value of the equilibrium potential (__________) for any ion depends on the concentration gradient across the membrane for that ion

Answer 44

Nernst potential