Lecture 13 and 14

Question 1

Pathway of neuronal stimulus

Answer 1

stimulus > sensor/integrator neuron > muscle or other effector > response

Question 2

Who discovered that biological tissues have “animal electricity” within them?

Answer 2

Luigi Glavani

Question 3

What nerve did we observe for frogs in lab?

Answer 3

the sciatic nerve

Question 4

What units do we measure potential energy in?

Answer 4

volts

Question 5

The individual cells the potential energy is measured in…

Answer 5

millivolt (mV)

Question 6

In cells, this generates 20% of potential energy?

Answer 6

ATPase, 3Na+ ions out, 2 K+ ions in

Question 7

In cells this generates 80% of potential energy?

Answer 7

Facilitated diffusion of ions via leak channels

Question 8

There is always more (Na+ or K+) outside the cell and more (Na+ or K+) inside the cell.

Answer 8

Na+; K+

Question 9

When is equilibrium potential reached?

Answer 9

when potential (electrical gradient) = potential (chemical gradient)

Question 10

Potential charge for potassium

Answer 10

-90 mV

Question 11

Potential charge for sodium

Answer 11

+60 mV

Question 12

Potential charge for sodium potassium

Answer 12

-70 mV

Question 13

Signals are transmitted within the neuron by two kinds of potentials

Answer 13

Passive: Graded potentials
Active: Action Potentials

Question 14

What happens to the amplitude of the passive potentials over time?

Answer 14

the amplitude decreases

Question 15

What happens when voltage-gated Na+ channels open?

Answer 15

the membrane potential depolarizes

Question 16

Absolute refractory period

Answer 16

no amount of current injection will make an action potential

Question 17

Relative refractory preiod

Answer 17

injecting lots of current might generate an action potential

Question 18

What are ways to increase the conduction velocity of action potentials?

Answer 18

increase axon diameter, insulate axon (via schwann cells = oligodendrocytes

Question 19

What is mutliple sclerosis?

Answer 19

destruction of oligodendrocytes

Question 20

Signal comes from the _______ neuron and is transmitted to the ______ neuron.

Answer 20

presynaptic; postsynaptic

Question 21

In vertebrates, the neurotransmitter at neuromuscular synapses…

Answer 21

Acetylcholine (Ach)

Question 22

What are two neuromuscular diseases?

Answer 22

myasthenia gravis and muscular dystrophy

Question 23

Tonix that cause muscle paralysis

Answer 23

tetrodotoxin and pumiliotoxin B

Question 24

What does tetrodotoxin do?

Answer 24

Blocks the opening of Na+ channels, mainly on muscle

Question 25

What does pumiliotoxin B do?

Answer 25

Binds to Ca2+ channels, causing calcium ions to be released from storage which inhibits calcium re-uptake into storage.

Question 26

What does botox stand for and how is it produced?

Answer 26

Botulinum toxin (produced by the bacterium clostridium botulinum)

Question 27

What does botox do?

Answer 27

interferes with release of neurotransmitter vesicles at neuromuscular junctions, temporarily preventing muscle contraction and thus relaxing facial muscles

Question 28

What is electromyography (EMG)?

Answer 28

Diagnostic technique for recording and evaluating the electrical activity produced by skeletal muscles

Question 29

electrical source of the EMG is

Answer 29

the muscle membrane potential

Question 30

What is Weber’s Law?

Answer 30

k = delta I/I (I = intensity of stimulus) (delta I = the change in stimulus) (k = constant of the ratio of change in intensity over the initial intensity)

Question 31

The change in intensity is a _______ (on the graph) but our perception of the intensity is _______

Answer 31

linear equation; logarithmic