Chapter 13 - Neuronal communication

Question 1

What kind of response is admitted via neurones?

Answer 1

Electrical responses

Question 2

What is homeostasis?

Answer 2

The coordination of all organ functions in order to maintain a relatively constant internal environment

Question 3

What is cell signalling in animals?

Answer 3

Cellular communication via chemicals which target certain cells

Question 4

How do cells signal?

Answer 4

• Locally, via neurones at the synapse (neurotransmitter)
• Across a large distance, via hormones

Question 5

In what order does a nervous response occur?

Answer 5

Receptor > sensory neurones > relay neurone > motor neurone > effector cell

Question 6

What is the role of a sensory neurone?

Answer 6

Moves an impulse from sensory receptor cells to a relay neurone, motor neurone or the brain

Question 7

What is the role of a relay neurone?

Answer 7

Moves an impulse between neurones

Question 8

What is the role of a motor neurone?

Answer 8

Moves an impulse from a relay neurone to an effector

Question 9

What is the myelin sheath?

Answer 9

A layer of plasma membranes made by specialised schwann cells which surround the neurone which act as an insulating layer and allow electrical impulses to be conducted at a much faster speed

Question 10

What are the gaps between the myelin sheaths and what do they do?

Answer 10

Nodes of Ranvier, assists the travel of an electrical impulse down a neurone at a faster speed

Question 11

What are some features of a sensory neurone?

Answer 11

• They are specific to a single type of stimulus
• They act as a transducer

Question 12

What is a mechanoreceptor?

Answer 12

A receptor that detects pressure and movement (eg. skin, pacinian corpuscle)

Question 13

What is a chemoreceptor?

Answer 13

An olfactory receptor that detects chemicals/ scents (eg. nose)

Question 14

What is a thermoreceptor?

Answer 14

A receptor that detects heat (eg. tongue)

Question 15

What is a photoreceptor?

Answer 15

A receptor that detects light wavelengths (eg. eye)

Question 16

What is the role of a transducer?

Answer 16

To convert one type of energy to another (eg. thermal stimulus into electric impulse for signalling)

Question 17

What is a pacinian corpuscle?

Answer 17

A specific sensory receptor that detects mechanical pressure, located at the end of neurones

Question 18

What ions are present in the neurone and corpuscle?

Answer 18

Na+ and K+

Question 19

What type of channel is present in the corpuscle?

Answer 19

Stretch-mediated sodium channel

Question 20

What is the resting potential in a neurone?

Answer 20

-70 mv (3Na+ exchanged for 2K+ at the sodium-potassium pumps)

Question 21

What potential is needed to be reached to release an action potential?

Answer 21

-55 mv is the threshold value needed to be reached to fire an action potential

Question 22

Describe the neurone in a resting potential state

Answer 22

• Sodium-potassium pumps actively transports Na+ and K+ out/into the axon
• More K+ ions present inside the axon than outside, so Na+ ions diffuse back into the axon down the electrochemical gradient and K+ ions diffuse out
• More positive charge outside the axon, causing the resting potential of -70 mv

Question 23

Describe what is occuring during an action potential