Somatosensory

Question 1

What are the 4 sensory pathways?

Answer 1

Fine Touch (discriminative)
Proprioception
Pain
Temperature

Question 2

Touch : Stimulus? Receptor? Sense Organ?

Answer 2

Mechanical deformation
Skin Mechanoreceptors
Pacinian Corpuscle

Question 3

Proprioception : Stimulus? Receptor? Sense Organ?

Answer 3

Mechanical Deformation
Mechanoreceptors
Muscle Spindl, Golgi Tendon Organs, Joint Receptors

Question 4

Temperature :Stimulus? Receptor? Sense Organ?

Answer 4

Thermal Energy
Hot/Cold Thermoreceptors
Nerve Endings in Skin

Question 5

Pain :Stimulus? Receptor? Sense Organ?

Answer 5

Noxious Stimulus - extreme mechanical, thermal, chemical energy
Nociceptors - Mechanoreceptive, thermal, chemoreceptive, polymodal
Nerve endings in the skin

Question 6

What is Adequate Stimuli?

Answer 6

Differential sensitivity of sensory receptors

Question 7

What is a Pacinian Corpuscle?

Answer 7

Rapidly Adapting Mechanorecptor
Depolarization occurs via stretch-activated Na+ channels
Detects mechanical pressure vibrations of 200-300Hz

Question 8

What is Receptor Potential?

Answer 8

The depolarizing or hyper polarizing response to a sensory stimulus

Question 9

Other Sensory Receptors

Answer 9

Hyperpolarization is due decreased Na current (photoreceptors) or increased K+ current (auditory mechanoreceptors)

Question 10

Stereotypic encoding of stimulus intensity

Answer 10

The intensity of the stimulus in encoded by the frequency (number per time) of action potentials (AP)

Question 11

What is frequency code?

Answer 11

Temporal Summation: increase in AP frequency of a single fiber associated with the sensory receptor

Question 12

What is population code?

Answer 12

Spatial summation of is when more sensory receptors and their fibers are activated and Fire APs

Question 13

What is Transduction?

Answer 13

The process of changing physical energy into electrical signals

Question 14

What is a generator potential for transduction?

Answer 14

Change in membrane potential of the sensory receptors, caused by stimulus; may be depolarization (mechanoreceptors) or hyperpolarization (photoreceptor)

Question 15

What is a first order neuron?

Answer 15

The first neuron to fire an action potential after stimulation

Question 16

Labeled Line Code of Sensory Modality

Answer 16

Quality of the Stimulus is encoded by pathway of transmission
- quality = modality = sensory channel

Question 17

What is a sensory modality?

Answer 17

A communication channel that is associated with individual senses e.g. Touch, smell, vision

Question 18

What is Adaptation?

Answer 18

Nerves adjust to repetitive stimuli

Question 19

Hyperalgesia

Answer 19

Heightened sensation of pain - Endogenous chemicals (prostaglandins) from damaged tissue directly activate or sensitize (lower activation threshold) nociceptors. Others are histamine, substance P, serotonin, and bradykinin

Question 20

Neuralgia

Answer 20

Severe persistent pain in the distribution of a spinal or cranial nerve. Trigeminal neuralgia is treated by: tractotomy, injection of alcohol into the Trigeminal nerve, oral anticonvulsants

Question 21

Thalamic Pain Syndrome

Answer 21

Lesions of Posterior Thalamus

Question 22

Peripheral Neuropathy

Answer 22

Numbness and ulcers in limbs often seen in diabetic patients (stocking glove). Mechanism not well understood.

Question 23

Referred Pain

Answer 23

Pain arising from deep visceral structures is felt at sites at the periphery of body.

Question 24

Phantom Limb Pain

Answer 24

Limb removal leads to sensation of pain in missing limb

Question 25

Analgesia

Answer 25

Inability to feel pain while still conscious

Question 26

Sedation

Answer 26

A sedative is a drug that calms a patient down, easing agitation and permitting sleep, reducing irritability. Sedatives depress cardiovascular and respiratory functions, cannot be used with alcohol, and can become additive

Question 27

Anesthesia (A State of Unconsciousness)

Answer 27

Has three components:

• analgesia: pain relief
• amnesia: loss of memory
• immobilization

Question 28

Hereditary Sensory Autonomic Neuropathy Type 5

Answer 28

Loss of ability to feel pain, heat, or cold. Loss of deep pain perception - unable to feel broken bone, ligaments or muscle