action potentials

Question 0

charges inside and outside cell (2)

Answer 0

1. outside cell is more positive because Na+

2. inside cell is more negative bc large (-) proteins dominate over K+

Question 1

Resting membrane potential

Answer 1

1. Difference in charge inside (-) and outside (+)

Question 2

nerve action potential graph (6)

Answer 2

1. resting stage
2. Na enters cell until hit threshold of action potentional
3. depolarization stage= membrane becomes permeable to Na and influx of sodium ions rush into cell to make less negative (and sometimes makes it positive because of overshoot)
4. repolarization= within milliseconds, sodium channels close and K channels open (starts fast, then slows down)
5. hyperpolarization = undershoot = K is transported also by leaky channels so potential undershoots threshold
6. Na-K pump gets potential back to baseline

Question 3

Na-K pump (proteins that make it work) (2)

Answer 3

1. works by protein NaK-ATPase

2. de-phosorylization of NaK-ATPase -> opens channel

Question 4

generator/ receptor potential (3)

Answer 4

1. generates action potential
2. does not propograte, can be summated
3. has no threshold and no refractory period

Question 5

refractory periods (2 def and when they occur) 5

Answer 5

1. absolute refractory period- no matter what cannot generate new action potential- cannot open Na gates
2. relative refractory period- can only generate new action potential when potential is > or = to previous potential
3. ** these are only for action potential**
4. absolute = right when depolarization starts
5. relative- around baseline during repolarization

Question 7

transmission of action potential down nerve fiber (3)

Answer 7

1. schwann (glia) cells wrap around axon = mylenation
2. where there is no mylenation = node of ranvier
3. this causes Saltatory conduction= jumping of action potential from node to node

Question 8

saltatory conduction (3)

Answer 8

1. electrical potential is moving along cytoplasm and inside axon in axoplasm
2. increases velocity of nerve transmission
3. conserves energy (by keeping in all the action potential)

Question 9

examples of secondary active transport (2)

Answer 9

1. Na-glucose
2. Na-amino acid
   in both cases Na is with gradient and glucose/aa are against gradient (makes a salt)

Question 10

how diffusion helps maintain homeostasis (4)

Answer 10

1. maintenance of cell volume (Na-K pump pumps out 3Na for every 2 K it pumps in)
2. resting membrane potential
3. general regulation of ion distribution (co-transport)
4. facilitation of nutrient intake)

Question 11

3 types of gradients

Answer 11

1. concentration (ions or molecules)
2. pressure
3. electrical charge

Question 12

excitation (2 def, 3 reasons)

Answer 12

1. process of eliciting new action potential
2. action potential can be elicited by any means that causes Na+ to enter cell
   reasons:
   
   3. mechanical disturbance of a membrane
   4. chemical effects
   5. passage of e