Lecture 19: Action Potentials

Question 1

what is a neuron

Answer 1

basic functional unit of nervous system

Question 2

what is the function of a neuron

Answer 2

conduct messages & integrate information

come in variety of shapes and sizes

Question 3

cell body of neuron

Answer 3

• contains organelles
  -soma

Question 4

dendrites

Answer 4

• many, short branched
• recieve info
• sends signals to cell body

Question 5

axon

Answer 5

• one, long
• axon hillock ( signals fenerated
• synaptic terminals ( tips of branches at the end)
• transmits away from cell body (produces responce to stimulus)
• nerve = axons of many neurons

Question 6

sensory neuron

Answer 6

• afferent neuron

- sensory receptor -> processing center

Question 7

interneuron

Answer 7

• intergration
• interact only with other neurons
• 90% of neurons in brain

Question 8

motor neuron

Answer 8

• efferent neurons

- processing center -> effector

Question 9

pathway of info processing

Answer 9

• sense organ
• sensory neuron
• interneuron
• motor neuron
• effector

Question 10

membrane potential

Answer 10

• all animal cells have selective permeable PM -> membrane is polarized
• potential to do WORK

Question 11

charge difference is

Answer 11

negative on the inside compared to the outside

Question 12

excitable cells

Answer 12

• generate rapid changes in membrane potential

- neurons and muscles

Question 13

voltage

Answer 13

• measurement of mp

- use voltmeter

Question 14

resting potential

Answer 14

• axon is at rest
• 70 mV
• result of NA+-K+ pump ion channels

Question 15

sodium-potassium pump

Answer 15

• membrane protiens, along with PM of cell body, dendrites, and axon

Question 16

one complete pumping cycle

Answer 16

• moves 3+ Na+ out for every 2 K+ moved in
• pumped against concentraion gradients ( active transport, requires ATP)
  (SALTY BANANA)

Question 17

ungated ion channels

Answer 17

• pores formed by clusters of specialized membrane-spanning proteins
• (selectively permeable)
• ions diffuse across membrane

-

Question 18

what generated mp

Answer 18

any net movement of + or - charge

Question 19

sodium channels

Answer 19

allow Na+ through

Question 20

potassium channels

Answer 20

• diffusion of potassium ions that tare critical for achieving resting potential
• may more K+ channels than Na+ channels, PM is 100x more permeable to K+ than to Na+

Question 21

potassium channel rules

Answer 21

• K+ pumped into cell can easily pass out, but once Na+ is out of cell, cannot easily come back in
• outside of cell becomes more positive (inside is more negative) -> major source of MP

Question 22

-70 mh (RP)

Answer 22

• potential E
• can be changed by stimulus
• any environmental factor which induces change MP
• example: Physical pressure, Chemical change

Question 23

Hyperpolarization

Answer 23

• MP moves below RP -> more negative, ex: -70 mV to -90 mV

- inhibitory: neurons ability to generate neural impulse

Question 24

depolarization

Answer 24

• MP becomes more positive -> closer to 0

- EX: from -70 mV to -50 mV

Question 25

threshold

Answer 25

• MP required to trigger an action potential

- most neurons: -55 mV

Question 26

action potential : change in MP

Answer 26

• massive change in voltage, depolarization reaches threshold

Question 27

voltage gated ion changes

Answer 27

• membrane protiens -> gate
• open & close
• shape regulated by changes in voltage

Question 28

control passage of specific ions

Answer 28

• facilitated diffusion

- follows concentration gradient (no ATP)

Question 29

types of channels

Answer 29

voltage- gated K+ channel

voltage- gated Na+ channel

Question 30

gate closed:

Answer 30

no ions flow across membrane

Question 31

gate opened:

Answer 31

ions flow through channel

Question 32

strong stimulus

Answer 32

• opens more voltage-gated sodium channels

- produces large change in permeability (depolarization) if memebrane reaches threshols (-55