Senses & Perception

Question 1

What is the receptive field of a neuron?

Answer 1

The sensory surface of a neuron which is activated by a stimulus

Question 2

What happens to the size and overlapping of receptive fields as you move from the trunk to the periphery?

Answer 2

• Large on the trunk

- Small on the periphery

Question 3

What is two point discrimination and how do receptive fields relate?

Answer 3

The ability to recognise 2 separate mechanical stimuli applied simultaneously.

Because areas with smaller receptive fields (periphery) can distinguish 2 point discrimination better compared to areas with higher receptive fields.

Question 4

How is the stimulus transduced (converted) to an electrical impulse?

Answer 4

1) Stimulus
2) Change in receptor membrane permeability
3) Influx of cations (+ve)
4) Depolarisation: Receptor potential
5) Action Potential

Question 5

How is a stimulus coded through action potentials?

Answer 5

ALL AP ARE THE SAME!

Intensity = Greater - AP frequency, neurons activated

Duration = Duration of AP firing

Question 6

How does the body determine the location from which the stimulus is coming from?

Answer 6

Neural pathway goes to site specific part of brain depending on what region of the body the sensory receptor is activated at.

sensory homunculus

Question 7

What is the brachial plexus?

Answer 7

A plexus is network of nerves. The brachial plexus innervates the upper limb (upper torso, arms, hands)

Question 8

What are the types of nerve fibres?

Answer 8

4 types

A alpha, A beta, A delta, C fibres

Question 9

What are the properties of A alpha fibres and what’s their function?

Answer 9

• Largest in diameter as well as greatest myelination
• Greatest nerve impulse speed
• Proprioceptors of skeletal muscles - sensory to body position/movement

Question 10

What are the properties of A beta fibres and what’s their function?

Answer 10

• Smaller than A-alpha fibres in diameter and myelination
• Slower nerve impulse speed
• Mechanoreceptors of skin - mechanical sensation & differences in pressure

Question 11

What are the properties of A delta fibres and what’s their function?

Answer 11

• Smaller than A-beta fibres in diameter.
• SMALLEST MYELINATED fiber
• Pain & Temperature detection

Question 12

What are the properties of C fibres and what’s their function?

Answer 12

• SMALLEST diameter
• NO MYELINATION
• SLOWEST SPEED
• Convey dull aching pain

Question 13

SENSORY axons enter CNS via _____ roots

Answer 13

Dorsal (Rear)

closest to back (afferent/sensory nerves - dorsal root)

Question 14

MOTOR axons enter CNA via _____ roots

Answer 14

Ventral (Front)

abdominal side (efferent/motor nerves - ventral root)

Question 15

What is the makeup of Cranial Nerve V and what is each branch?

Answer 15

Sensory:
V1 - Ophthalmic Branch
V2 - Maxillary Branch

Motor + Sensory:
V3 - Mandibular Branch

Question 16

What is an overview of the somatosensory (touch, pressure, vibration, itch, tickle) pathway?

Answer 16

Contains 3 neurons

Primary Sensory Neuron - Periphery
Secondary Sensory Neuron - CNS
Tertiary Sensory Neuron - Thalamus

Question 17

What is the dorsal column/medial lemniscal pathway?

Answer 17

An ASCENDING pathway of the spinal cord - Sends info from receptors and Peripheral NS towards brain

Question 18

What is the spinothalamic pathway?

Answer 18

An ascending pathway of the spinal cord. Tt is one of the most important sensory pathways of the nervous system

Question 19

How are areas with high density of receptors represented in the cerebral cortex?

Answer 19

They are allocated more ‘brain space’ in the cortex

Question 20

What is stereognosis?

Answer 20

Ability to recognise objects by ‘the feel’ alone