Neuronal communication

Question 1

Define a sensory receptor

Answer 1

A specialised cell that converts one form of stimulus into an action potential

Question 2

Define a neurone

Answer 2

A specialised cell that can transmit an action potential

Question 3

Define homeostasis

Answer 3

The regulation of internal conditions inside cells or organisms to maintain optimum conditions for biological function in response to internal and external changes, often through negative feedback mechanisms

Question 4

give 3 characteristics of a good communication system

Answer 4

• covers the whole body
• enables rapid communication
• can allow short and long-term response to a stimulus

Question 5

Key differences between the endocrine and neuronal communication systems

Answer 5

Nervous system has much faster and specific responses transmitted chemically compared to glandular responses

Question 6

Define neurones

Answer 6

Specialised cells that conduct electrical impulses through the body

Question 7

Define nerves

Answer 7

Bundles of neurones

Question 8

Should be able to draw and label a sensory, relay and motor neurone!!!!!!!

Question 9

Define action potentials

Answer 9

Movements of charged ions along the neurone

Question 10

Explain the phrase ‘polarised membrane’

Answer 10

Creating a potential difference across the membrane

Question 11

Define the resting potential

Answer 11

When the potential difference is -70mv inside a neuron

Question 12

Define a voltage gated channel

Answer 12

A protein in a cell membrane that opens and closes in response to changes in the membrane’s electrical potential

Question 13

Define threshold potential

Answer 13

The minimum level of membrane depolarization required to trigger an action potential in a neuron, around -55mv

Question 14

Define the refractory period

Answer 14

The brief time after an action potential where a neuron’s membrane cannot be stimulated to generate another impulse

Question 15

Define the electrochemical gradient

Answer 15

The combination of a concentration gradient (difference in solute concentration) and an electrical gradient (difference in charge) across a biological membrane, driving the movement of ions

Question 16

receptor/ generator potential

Answer 16

A temporary, localized change in the electrical potential across the membrane of a sensory receptor cell, such as the Pacinian corpuscle, in response to a stimulus like pressure or light

Question 17

How is an action potential transmitted (6)

Answer 17

• Voltage gated Na+ channels open
• Na+ diffuse in2 neurone down an electrochemical gradient depolarising the membrane (action potential begins)
• Na+ inside neurone diffuse along its length known as a local current
• Movement of Na+ down the neurone starts to depolarise the membrane further along the neurone
• once pd across this part of membrane reaches the threshold, voltage gated Na+ channels open
• process repeats transmitting action potential along the neurone

Question 18

How do voltage gated channels open?

Answer 18

Opened by changes in voltage across the membrane

Question 19

What is an energy transducer?

Answer 19

they convert one form of energy to another (RECEPTORS)

Question 20

How do action potentials start?

Answer 20

• receptor cells respond to changes in their environment
• When stimulated, they cause some sodium gates in the receptor to open an the end of the neurone

Question 21

What is the all or nothing law?

Answer 21

If a threshold voltage is reached an action potential is always generated, if not reached then there is no action potential generated

Question 22

Define saltatory conduction

Answer 22

action potentials appear to jump from one node to the next

Question 23

Should be able to label a synapse!!

Question 24

How does an action potential cross the synapse?