Lecture 7

Question 1

mechanoreceptors

Answer 1

• small structures found in skin & organs that detect displacement, velocity & acceleration of organs
• brain perceives these as pressure, strecth or vibration

Question 2

types of mechanoreceptors

Answer 2

slowly adapting receptors
* merkel cells

rapidly adapting receptors
* meissner’s corpuscles
* pacnian corpuscle
* hair follicle

Question 3

merkel cells

Answer 3

• common in tips of fingers
• sensitive to displacement of skin; perceived as pressure

Question 4

meissner’s corpuscles

Answer 4

• nerve endings sensitive to light pressure
• detects slipping objects

Question 5

pacnian corpuscle

Answer 5

sensitive to mechanical pressure & vibrations (200-300Hz)

Question 6

hair follicle

Answer 6

sensitive to fine movements of hair on skin

Question 7

proprioception

Answer 7

• brain’s ability to discern the actual spatial location of each part of the body
• muslce spindle - meaure length
• tendon organs - measure tension
• important in spinal reflexes

Question 8

muscle spindles activated when stretched by :

Answer 8

• external forces - lifting a weight
• internal forces - activation of gamma motor neurones

stretched musle - ATP generated at increasing rate
unstretched musle - ATP generated at constant rate

Question 9

muscle stretch reflex -maintains muslce length

Answer 9

1. sensory neurons in spindle receptor send increasing ATP to SC
2. sensory neurons synapse with alpha motor neurons which excites fibres of the stretched muscle
3. stretched msucle contracts to maintain length
4. efferent neurons inhibits alpha motor neurons of antagonistic muscle so this muscle relaxes while the agonist contracts

Question 10

fast pain

Answer 10

• acute shap pain
• removes part of the organism from harm’s way to prevent further damage
• fast pain adapts, pain subsides
• transmission of nerve impulses over A delta fibres

Question 11

slow pain

Answer 11

• chronic, more intense pain
• debiliates the organism to prevent over-activity until injury repairs
• hyperglasia - increased sensitivity to pain
• transmission over non myelinated C fibres

Question 12

chronic pain

Answer 12

• particularly debiliating and can destroy quality of life
• neuropathic pain persisits in abscense of tissue damage
• sometimes after healing the CNS fails to rest itself and
  pain persists

Question 13

Nocioceptors

Answer 13

• detects a noxious stimulus
• important for fight or flight response

Question 14

nocioceptor activation

Answer 14

• physical distortion of membrane
• changes in pH
• chemicals released from damaged cells
• prostoglandins