Pain

What is pain a major type of in the somatosensory system?

Non-discriminative somatic information.

What are the two types of information in pain perception?

Discriminative (specific) and non-discriminative (broad/general).

Which types of perceptions are included in the somatosensory system?

Exteroception, mechanoreception, thermoreception, nociception, proprioception, and introception.

What types of structures can pain arise from?

Both deep structures (like muscles) and cutaneous structures (like skin).

What are the three components of the pain experience?

Sensory coding of stimuli, motivational/affective component, cognitive/cultural component.

What does the motivational/affect component of pain refer to?

Whether your brain wants to attend to the painful input or is otherwise occupied.

What is the cognitive/cultural component of pain?

Whether your brain has learned to ignore painful input.

Are nociceptors slow or fast conducting nerve fibers?

Slow.

What types of fibers are nociceptors primarily made of?

C fibers (unmyelinated) and A-delta fibers (thinly myelinated).

How much denser are nociceptors compared to touch and thermoreceptors?

Nociceptors are 9x as dense as touch receptors and 15x for thermoreceptors.

What types of stimuli do nociceptors respond to?

Noxious stimuli only at injurious levels.

What ion channel is commonly associated with pain perception?

TRPV1 channel.

At what temperature is TRPV1 activated?

Above 43°C.

What is allodynia?

Where non-painful stimuli are felt as painful.

What is primary hyperalgesia?

Where painful stimuli cause more intense pain.

What does the term 'A-delta fibers' refer to?

Lightly myelinated nerve fibers that conduct fast pain sensations.

What does the term 'C fibers' refer to?

Unmyelinated nerve fibers that conduct slow pain sensations.

What can cause changes at the site of tissue injury?

Release of inflammatory agents (e.g., histamine) from cells into damaged tissues.

Why do we feel pain from normally non-painful stimuli after an injury?

Due to increased sensitivity of nociceptor endings from chemicals released during damage.

What are the consequences of excess Ca++ influx in nociceptors?

Leads to various detrimental effects for the cell such as burning or stinging sensations and localised defunctionalisation

What can TRPV1 bind to that makes certain foods spicy?

Capsaicin (in chillies), allyl isothiocyanate (in mustard/wasabi), and allicin (garlic).