Friday 2 - fitz sensory physiology & somatosensation

Question 1

Two “essential” steps in transduction

Answer 1

1. conformational change in transducer protein

2. Opening of ion channel (or closing)

Question 2

When a receptor is the primary afferent in a system (i.e. free nerve endings), where does the first action potential in that system occur?

Answer 2

At the first node of ranvier

Question 3

What is one type of “inadequate” stimulus in a neurological system

Answer 3

pushing on your eyes and seeing stars, stimulating a nerve ending in a way that it is not used to and getting an effect that it thinks it is “supposed” to be.

Question 4

Acuity

Answer 4

The ability to precisely localize a stimulus

Question 5

The more intense a stimulus, the (Less or more?) precisely it can be localized.

Answer 5

less

Question 6

Two ways in which “stimulus intensity” is encoded.

Answer 6

Frequency coding - firing rates of sensory neurons increase as the intensity of the stimulus increases

Population coding - Number of primary afferents increases (recruiting)

Question 7

Define the process of adaptation in neurons and two types of adaptation with regards to how fast they happen

Answer 7

Adaptation is the process by which the response of a receptor to a CONSTANT stimulus DECLINES over time. If the change in receptor potential occurs SLOWLY, the response is called TONIC; if it occurs RAPIDLY, it is called PHASIC.

Question 8

What maintains acuity in the face of a large stimulus?

Answer 8

Lateral inhibition of neurons.

Question 9

3 types of pain from class and how they happen

Answer 9

Nociceptive (acute) - sensation = perception. TRP V1 receptors

Inflammatory - tissue dmg

neuropathic - synapses change

Question 10

example of Allodynia

Answer 10

person with a peripheral neuropathy reports sharp pain when a brush is lightly passed over his skin.

Question 11

example of Hyperalgesia

Answer 11

person reports being more sensitive to pain for an extended period of time after being stung (by a platypus)

Question 12

molecular mech of benzos and barbituates

Answer 12

sensitize chloride channels

Question 13

3 ways to activate TRP V1 gated channels

Answer 13

H+
>43C
capsacin

Question 14

2 ways to sensitize TRP V1 channels

Answer 14

1. Prostaglandins (NSAIDS block this)

2. Bradykinins

Question 15

Is there a change in “adequate stimulus” with “referred pain”

Answer 15

NO

Question 16

What is referred pain

Answer 16

Pain from the heart, lungs, gut, etc gets transported to the spinal cord where it is perceived as pain from the skin, muscle, etc.

Question 17

What order of neuron (i.e. primary, secondary, or tertiary) do inhibitory neurons work on?

Answer 17

second order

Question 18

What function is first to be blocked by low concentration of a local anaesthetic?

Answer 18

pain