Neural Communication

Question 1

Luigi Galvani

Answer 1

Discovered electrical properties in the nervous system

Question 2

Alessandro Volta

Answer 2

Replicated Galvani’s experiment, trying to dismiss that there was something special. He was right and determined that no electricity is conducted in the nervous system.

Question 3

Diffusion

Answer 3

The distribution of ions in a medium. Spread of ions towards a uniform concentration. Reaching equilibrium is an equal spread of the ions.

Question 4

Current

Answer 4

Is created by creating a difference of positive and negative charges across a barrier

Question 5

Osmosis

Answer 5

The diffusion of molecules from a high concentration gradient to a low concentration gradient. Movement

Down a concentration gradient

Question 6

Semi permeable membranes

Answer 6

Can create differences in diffusion in a medium. Pores of a certain size that allows some to pass through

Question 7

Electrochemical attraction

Answer 7

Can influence the movement of ions towards one another. Gradients and forces which create a second force for ions to move to opposite charges.

Question 8

Active transport

Answer 8

Carries molecules across a membrane usingprotien carriers. Dependent on energy being put into the system.

Question 9

Plasma membrane

Answer 9

Allows axons to generate electrical potential. Allows for different concentrations inside and outside the cell.

Question 10

How does resting potential happen?

Answer 10

Surrounding the neurons are countless Lons, there is a tiny excess of negative charged lons inside. [ all neurons at rest are negatively charged [- 5 to-100]] the resting potential depends on the type of neuron.

Question 11

Semi - permable plasma membrane

Answer 11

Ion channels can pass different kinds of ions between them, semi-personable allows certain ions to enter or exist. Leaky nature cot plasma membranes causes it to remain open and positive charges can leave and enter as they please. Excess charges line up on the plasma membrane.

Question 12

Action potential

Answer 12

Parts of an action potential needs energy to be inserted. 2-graded potential looking at sodium ions which causes a depolarization. 3-all or nothing channels go through a cycle of opening and closing. The more Na that rushes in the more depolarization. 4- sodium channels close but potassium channels remain open and allow k to leave the concentration gradient.

Question 13

Triggering the action potential

Answer 13

Sensory activity: son channels open up when deflected by pressure, which allows sodium ions to enter. Depolarization: causes channels to open up in n all or nothing cascade.
Channel opens: external stimuli are transformed to a neural signal through sensory receptors. One after another they open and result in an electrical potential down an axon.
K+ channels open: causes a return to normal state.

Question 14

Voltage gated sodium channels

Answer 14

The action potential rising phase occurs because the neuronal membrane contains voltage gated Na + channels that open in a regenerative manner. The action potential rising phase ends because the voltage gated Na + channels inactivate. Creates a Plato of action potential.The action potential falling phase occurs because the voltage gated k+ channels open (with a delay) in response to depolarization.

Question 15

Speed of action potential probation

Answer 15

Estimation of 500 action potentials per second. Max. 1200 action potentials per sec. After voltage gated channels open and close, they can open up again, but they have to over come hyperpolarization.
Unmyelinated - slower conduction
Myelinated - faster conduction

Question 16

What determines the speed of an action potential?

Answer 16

The axon is leaky = Low membrane resistance. Causes a change in polarization. Poor job separating certain ions.
The axon is sticky = high membrane capacity.
The axon is thin = high axoplasmic resistance. Slows down movement at ions.
Myelin is a physical barrier that increases space between the inside and outside of the membrane causing less electrical charge attraction and less leaky channels.

Question 17

Graded potentials

Answer 17

The brief changes in the membrane potential of the postsynaptic cell.
Excitatory postsynaptic potential: produces a small local depolarization as Na + channels open, pushing the cell closer to threshold. (Depolarization)
Inhibitory postsynaptic potential: produces a small hyper polarization, pushing the cell further away from threshold. (Hyperpolarization)

Question 18

Spatial summation

Answer 18

Is the summing of potentials that come from different parts of the cell.

Question 19

Temporal summation

Answer 19

Is the summing of potentials that arrive at the integration zone at different times