Word Bank Terms Exam 2

Question 1

Channel

Answer 1

Transmembrane protein that does not undergo conformational changes
Hydrophilic pore which opens with selectivity filter and regulated by gate for ions to flow through cell membrane
Can only do passive transport
High rate of transport of molecules

Question 2

Transporter

Answer 2

Transmembrane protein that undergoes conformational changes to transport specific molecules and ions (hydrophilic) that can not diffuse across cell membrane
Can complete active or passive transport
Lower rate of transport of molecules

Question 3

Active transport

Answer 3

Nonspontaneous transport of molecules from low to high concentration (against concentration gradient)
Requires energy (ex ATP or gradient)
Only Transporters

Question 4

Passive transport

Answer 4

Spontaneous transport of molecules from high to low concentration (with concentration gradient)
Does not require energy
All channels
Some transporters

Question 5

Coupled transport

Answer 5

a process that moves molecules across a cell membrane by linking the movement of one molecule to the movement of another

Question 6

Na+/K+ pump

Answer 6

ATP driven pump which maintains the negative charge inside the cell and ion concentration differences between Na+ and K+
Transports 3 Na+ out, K+ in

Question 7

Glucose/Na+ symport

Answer 7

Found on the apical side of the gut lumen by tight junctions
Transports low glucose concentration from gut lumen into high glucose concentration in intestinal cells (active transport)
Coupled transport as active transport of glucose into cell coupled with high electrochemical gradient of Na+
Symport: Na+ and glucose transported in same direction

Question 8

Membrane potential

Answer 8

voltage (charge) difference between inside and outside the cell

Question 9

Dendrite

Answer 9

short extensions from cell body that receives signal (from another neurons)

Question 10

K+ leak channel

Answer 10

makes minor adjustments to maintaining resting membrane potential
usually open for K+ to travel outside the cell down concentration gradient
Unbalanced negative charges create voltage gradient for K+ to be pulled back in
when K+ leak channel reaches no movement, K+ electrochemical gradient is 0 and resting membrane potential is maintained

Question 11

Axon

Answer 11

long extension that branches at end of cell body to send electrical signal away from cell body to target cells

Question 12

Cell body

Answer 12

contain nucleus and most organelles

Question 13

Nerve terminal

Answer 13

End of axon that sends signals (neurotransmitters) to target cells

Question 14

Action potential

Answer 14

initial explosion of electrical activity at cell body when signal exceeds threshold
depolarizing stimulus exceeds threshold with open of voltage gated Na+ channels for Na+ to flow into cell and action potential to initiate

Question 15

Depolarization

Answer 15

Explosion of electrical activity that represents an action potential and involves rapid increase in membrane potential
Cell membrane becomes less negative
Caused by opening of voltage gated Na+ channels for influx of positive Na+ ions
For neuron signaling: excitatory neurotransmitters bind to ligand gated sodium ion channels that increase membrane potential and promote opening of voltage gated Na+ channels

Question 16

Refractory period

Answer 16

voltage gated Na+ channels inactive (closed) even though cell is still depolarized

Question 17

Repolarization

Answer 17

Return to resting membrane potential
Voltage gated channels inactive shortly after being opened which stops Na+ to come into the cell
Voltage gated K+ channels (delayed K+ channels) activate after depolarization for K+ have high electrochemical gradient and transport to outside cell

Question 18

Hyperpolarization

Answer 18

Cell membrane potential becomes less negative
Prevents firing of neuron (generation of action potential) by decreasing membrane potential
Neuron signaling: inhibitory neurotransmitters bind to ligand gated ion (CI-) channels and release negative ions into the post synaptic cell to decrease membrane potential

Question 19

voltage gated Na channel

Answer 19

channel opens and allows Na+ to enter cell when charge inside cell is positive
channel closed at resting membrane potential (charge inside cell is negative)
helps initiate action potential, and increase membrane potential to pass threshold
involved with depolarization

Question 20

voltage gated K+ channel

Answer 20

activate after depolarization
charge inside cell is positive = channel open
allows K+ to travel outside cell and maintain resting membrane potential
involved in repolarization

Question 21

voltage gated Ca2+ channel

Answer 21

found on presynaptic neuron on nerve terminal
arrival of action potential to nerve terminal, opens voltage gated Ca2+ channels for Ca2+ to rush into neuron (down electrochemical gradient) and triggers membrane fusion between synaptic vesicle and nerve terminal for neurotransmitter is released

Question 22

Ligand gated Na+ channel

Answer 22

When released neurotransmitters crosses synaptic cleft and binds to ligand gated Na+ channel on post synaptic neuron
Changes membrane potential (depolarizing) and can help action potential occur
Observed in neuromuscular junction

Question 23

Ligand gated CI- channel

Answer 23

Inhibitory transmitters bind to ligand gated CI- channels and transport ions to post synaptic cell and decrease membrane potentiak
Prevents firing of neuron and decrease probability of action potential
Hyperpolarization

Question 24

Neuromuscular junction

Answer 24

synapse between motor neuron and muscle cell

Question 25

Synaptic cleft

Answer 25

space between cell sending message (presynaptic neuron) and cell receiving message (post synaptic neuron)

Question 26

Valium

Answer 26

binds to CI- channels and increase activity of inhibitory neurotransmitter
Inhibits action potential by making cell more negative

Question 27

Curare

Answer 27

toxin that binds to acetylcholine receptors on muscle cells and causes paralysis
inhibits action potential

Question 28

Excitatory neurotransmitter

Answer 28

Increase probability of action potential and excites post synaptic neuron
Ex. Acetylcholine and glutamate which activate ion channels which transport positive ions (Na+) into cell
Pushes cell towards threshold potential for action potential to occur
Promotes depolarization

Question 29

Inhibitory neurotransmitter

Answer 29

Decrease probability of action potential and inhibit post synaptic neuron
Ex. GABA and glycine which bind to ligand gated CI- channels to increase influx of negative ions into cell and causes cell to move away from threshold for action potential

Question 30

Neurotransmitter

Answer 30

small secreted molecules that serve as chemical signal at synaptic cleft
stored in nerve terminals within membrane enclosed synaptic vesicles in presynaptic neuron
released upon arrival of action potential at nerve terminal