Physio-Exam 1

Question 1

What type(s) of molecules can diffuse through a cell membrane?

Answer 1

Small, neutral-polar

Small, lipid soluble

Question 2

True/False, proteins can increase the permeability of a membrane?

Answer 2

TRUE

Question 3

Where are the least body fluids found?

Answer 3

Lymph and transcellular

Question 4

What kind of amino acid is an integral protein made of that transverses the cell membrane?

Answer 4

Non-polar

Question 5

Is energy required for movement of large polar molecules from ECF to ICF?

Answer 5

Yes, energy is needed for vesicle formation and movement

Question 6

What is selective uptake of large molecules called?

Answer 6

Receptor-mediated endocytosis

Question 7

What is selective uptake of a multi-molecular particle called?

Answer 7

Phagocytosis

Question 8

What is non-selective uptake of ECF called?

Answer 8

Pinocytosis

Question 9

Why can glucose passively diffuse through a cell membrane?

Answer 9

It is relatively small

Question 10

Where does inhibition of an action potential occur on a neuron?

Answer 10

Axon hillock

Question 11

When an ion reaches its equilibrium potential what does it mean?

Answer 11

The net flux of the ion is zero

Question 12

What are the purposes of exocytosis?

Answer 12

1. Secrete large molecules (proteins and hormones)

2. Allows cell to add protein/carbs to the membrane

Question 13

What is osmosis?

Answer 13

The diffusion of water down its concentration gradient

Question 14

How is hydrostatic pressure and osmotic pressure related?

Answer 14

If there is movement of water down its gradient due to an imbalance of solutes across a membrane impermeable to those solutes, water will increase on one side and decrease on the other. Osmotic pressure = the minimum hydrostatic pressure needed to make the net water flux zero

Question 15

Define osmolarity?

Answer 15

Concentration of all dissociated particles. Examples:

• -1 M CaCl2 = 3 osM CaCl2
• -1 M NaCl = 2 osM NaCl

Question 16

Define tonicity?

Answer 16

The effect a solution has on cell volume

Question 17

What type of solutes contribute to osmotic pressure at steady state?

Answer 17

Membrane impermeable solutes (aka, osmotically active solutes)

Question 18

How do kidneys help regulate osmolarity of the blood?

Answer 18

By manipulating the osmolarity of urine

Question 19

What two forces move water in the body?

Answer 19

Osmotic pressure

Hydrostatic pressure

Question 20

How does secondary active transport work?

Answer 20

An ion gradient is generated by primary active transport, which is then used to drive secondary active transport.

Question 21

What is the function of the Sodium-Potassium ATPase pumps?

Answer 21

• -Establishes Na+ and K+ concentration gradients across the plasma membrane of all cells, but is especially important for nerve and muscle cells
• -Helps regulate cell volume

Question 22

What are the two mechanisms of secondary active transport?

Answer 22

1. Symport (co-transport)

2. Antiport (counter transport)

Question 23

Is membrane potential present on all cells, and can all cells rapidly change membrane potential?

Answer 23

Yes, all cells have a membrane potential, BUT only EXCITABLE cells can rapidly change membrane potential

Question 24

Define potential as it applies to a membrane’s electrical potential?

Answer 24

Potentials are a measure of the size of the electrical forces inside the membrane pushing/pulling ions through the membrane

Question 25

Is potassium or sodium more permeable to the cell membrane at rest?

Answer 25

Potassium is MUCH more permeable

Question 26

What is the Nernst Eqn?

Answer 26

61*log(Co/Ci)

Question 27

What causes the net flux of a given ion to equal zero?

Answer 27

When the electrical gradient equals the concentration gradient

Question 28

What is the equilibrium potential for potassium?

Answer 28

-90mV

Question 29

What is the equilibrium potential for sodium?

Answer 29

+60mV

Question 30

What is the equilibrium potential for chloride?

Answer 30

-70mV

Question 31

Where do graded potentials happen?

Answer 31

Dendrites and cell body

Question 32

Where do graded potentials begin?

Answer 32

Dendrites

Question 33

What are the voltage-gated K+ channels doing at threshold?

Answer 33

Delayed opening is triggered at threshold

Question 34

When are K+ channels open?

Answer 34

From peak potential (+30 mV) until after hyper polarization (-80 mV)

Question 35

When are Na+ channels closed and not capable of opening?

Answer 35

During the absolute refractory period (+30 mV to -70 mV)

Question 36

Name the eight steps of an action potential:

Answer 36

1- Depolarizing/triggering event 2- Na+ channel opens 3- Na+ influx, depolarizing to +30 mV, K+ begins opening (but isn't fully open until +30 mV) 4- Na+ inactivation gate closes and K+ opens 5- K+ eflux 6-Na+ inactivation gate opens, but activation gate closed (capable of opening) 7-Hyperpolarization 8-K+ channel closes and resting potential is reached

Question 37

What molecule in the body decreases current (flow of charges)?

Answer 37

Lipids

Question 38

What causes some potentials to be graded?

Answer 38

``` Electrical resistance Current loss (ions diffuse through membrane through leak channels) ```

Question 39

Can ions move through the membrane without channels?

Answer 39

NO, they require ion channels to traverse the membrane

Question 40

What is the acronym for the different categories of graded potentials, and what does it stand for?

Answer 40

``` Post-synaptic potentials Receptor potentials End-plate potentials Pacemaker potentials Slow-wave potentials ```

Question 41

Where are slow-wave potentials found?

Answer 41

Gastrointestinal tract

Question 42

What direction(s) can a graded potential polarize, and how is this different from an action potential?

Answer 42

Depolarization OR Hyperpolarization | Action potentials always depolarize first and there is a reversal of charges

Question 43

Do graded potentials have a refractory period?

Answer 43

NO

Question 44

What exist at the Nodes of Ranvier?

Answer 44

Voltage-gated Na+ and K+ channels

Question 45

Why does myelination increase conduction velocity?

Answer 45

There aren't voltage channels where myelination exists, so current (movement of charge) is forced to flow within the ICF until it reaches Nodes of Ranvier

Question 46

Why isn't the entire length of a neuron myelinated?

Answer 46

Because the ions would have to diffuse the entire length of the neuron, which would actually take much longer than have the Nodes of Ranvier

Question 47

What are gap junctions made of and how are gap junctions useful?

Answer 47

- -Made from Connexons | - -Allows passage of ions and small molecules between cells VERY rapidly