Lecture 17 - Transport Across Membranes (Ch 12)

Question 1

The region of an ION channel that becomes narrow is called a __ __

Answer 1

selectivity filter

Question 2

What does ms. ion channel select her clients based on?

Answer 2

She chooses her clients based on how wide they are (ugh ik! but diameter), what shape they are (so discriminatory), and their charge (talk about highly selective!) $$$ but in AA side chains

Question 3

What does a stimulus do for ion channels>?

Answer 3

Stimulation opens the gates of the Gated Ion Channel

Question 4

What is faster in opening and closing/passing things, a channel or transporter? And by how much

Answer 4

A channel is 1000x faster

Question 5

Ions flow through an ion channel fast and lots at a time because of the electrochem gradient made in advance by:

Answer 5

pumps!

Question 6

What cation is highest outside the cell?

Answer 6

salt

Question 7

What cation is highest inside the cell?

Answer 7

potassium

Question 8

What helps balance some of the Na+ outside the cell?

Answer 8

Chloride anions

Question 9

What helps balance some of the K+ inside the cell?

Answer 9

Negative charges on inorg AND org ions

Question 10

What is our resting membrane potential and what does this mean for the charge inside the cell?

Answer 10

-20 milivolts to -200 millivolts; it means the inside of cell is more negative

Question 11

What channels are OPEN in RESTing cell; what is the purpose of this?

Answer 11

K+ Leak channel ONLY; it moves k out of cell until electrochem gradient (for K only) = 0 ->mem potential is now -20 to -200 mv range

Question 12

10x change in ion concentration changes membrane potential by how much

Answer 12

62 mv

Question 13

A pipette with wire help you tear off a single channel from a membrane to study it. you adding a wire can help make a circute. what is this technique called?

Answer 13

Patch clamp technique

Question 14

True or false, ion channels randomly open and close

Answer 14

True, and very fast too (they fully open and fully close, not in between)

Question 15

What are the different stimuli types that can affect membrane potential?

Answer 15

Ligand binding, mechanical stress, and membrane potential (aka voltage gating)

Question 16

Give two examples of mechanical (aka stress gated ) channels

Answer 16

Our ear stereocilium respond to the physical sound waves we hear! Also, the mimosa plant will close if you touch it (but this plant one is mech gated AND volt gated(depolarization))

Question 17

Whats the key to maintaining resting potential in cells?

Answer 17

K+ channels

Question 18

What part of the nerve cell recives signals?

Answer 18

THe dendrite, which is attached to the cell’s body (like a lil omlet with egg fratgments)

Question 19

How are signals delivered so that membrane potentials are spread efficiently?

Answer 19

The signal first gets delivered to the dentrite (localarea ->localized change) and cell body area, and travels through the axon (like the stalk of a dandelion!), and to the terminal

Question 20

How do volt gate ion channels respond to and affect membrane potential? name the 3 steps and what is ultimately created.

Answer 20

First, the voltgateion channel opens bc membrane potential has shifted a lil bit. Next, ions go through the channel to shift it even more. Lastly, the newly shifted mem potential trickles down activating more channels to open ‘em (making a circuit)

Question 21

Nerve impluses, aka ____, help membrane potential shifts to TRAVEL across the body to reach a certain area

Answer 21

nerve impulses

Question 22

describe how action potentials spread!

Answer 22

Na+ voltage gated channel opes and changes potential, opening more, and then after 1 msec they close

Question 23

For an action potential to actually happen, what has to happen to cross the threshold potential level?

Answer 23

You have to have enough power in you r initial depolarization stimulus that you reach the minimum (threshold) to spread (amplify) your signal!

Question 24

True or false, K+ leak channels repolarize the membrane.

Answer 24

false- they are not fast enough.

Question 25

What repolarizes the membrane.

Answer 25

Na-K pumps (3 na in 2 k out). Common W

Question 26

What brings the membrane to resting state?

Answer 26

Voltage gated K+ channels. resting = repolarized

Question 27

What channel converts electric to chem signals? where does this happen?

Answer 27

Voltage gated calcium; at a nerve terminal

Question 28

What neurotransmitters do exciting stuff? (excitatory synaptic signal)

Answer 28

acetylcholine and glutamate (both are cation channels)

Question 29

How does prozac work?

Answer 29

it blocks sodium symport so that serotonin is not taken up and can be used

Question 30

What channels stop signaling?

Answer 30

GABA (sedative) and glycine. both work in a cl- channel

Question 31

What do synapses connect?

Answer 31

They connect neurons to the cell they want to send a signal to (target cell)

Question 32

What molecule do synaptic vesicles house? how doees that molecule work?

Answer 32

they give housing to neurotransmitters (signalling molecules), and they fuse with the cleft when calcium channel tells them to

Question 33

How is a nt removd from the cleft once it did its job

Answer 33

after it bound to receptor on post synaptic cell, enzymes destroy and return remnants to terminal

Question 34

How does the chem go back to electric signal?

Answer 34

transmitter gated ion channels

Question 35

Whats the difference between k leak and k voltage gated channels

Answer 35

k leak maintains resting state of membrane, but k volt repolarizes/returns to rest AFTER action potential happens

Question 36

Whats the job of ca channel?

Answer 36

Releases neurotransmitters

Question 37

Give 2 toxin examples that act on nt receptors

Answer 37

curare- blocks acetylcholine receptor to cause paralyze in surgery, strynchine blocks glycine - can kill - BAD