Week 1 (lecture 4)- Sensory Receptors and Ascending Pathways Flashcards
what are the ascending pathways?
neural pathways by which sensory information from peripheral nerves is transmitted to the CNS
what are the 4 steps of ascending pathways? (3rd order)
receptor
SC
decussation, and ascends thalamus
projects to cortex
(each order is between each stage)
define receptors?
specialised cells that respond to environmental stimuli
what are the 3 classifications of receptors?
function location structure
what are the 4 types of receptors under functional classification, and what do they detect?
mechanoreceptors (deformation e.g. touch, pressure; subcategory of proprioceptors)
photoreceptors (light)
thermoreceptors (heating/cooling)
chemoreceptors (substances released by cells; subcategory of nociceptors)
what are the 3 types of receptors under location classification, and what do they detect?
externoreceptors (detect environmental stimuli)
internoreceptors (detect internal stimuli)
proprioceptors (detect static position/movement; found in muscles, tendons etc)
what can be used to subdivide receptors based on structure?
complexity (most are simple; complex ones typically found at sensory organs)
name 3 unencapsulated receptors, and what they do?
free dendric endings (small diameter allows sensation of ‘crude touch’)
modified free (e.g. merkel disks- light touch)
root hair plexuses (detects displacement of hair)
name 3 types of unencapsulated receptors at skin level, and their role?
Meismers corpuscles (light touch/vibration; small receptive field)
Pacinian Corpsucles (subcutaneous fine touch/vibration; large receptive field)
Ruffinis corpuscles (stretch)
name 3 proprioceptors that are responsible for detecting muscle/joint related actions?
muscle spindles (muscle length/speed of lengthening)
golgi tendon organs (muscle/tendon tension)
joint kinaesthetic receptors (modified receptors in joint capsule/ligaments)
describe joint kinaesthetic receptors in joint capsule?
Ruffini type endings detect extremities of joint range; Pacinian corpuscles detect movement
describe joint kinaesthetic receptors in ligaments?
receptor stimuli similar to golgi tendon organs detect tension
what are the 5 steps of a simple reflex arc?
detection of stimulus by receptors
activation of afferent neurone (by an AP starting in the PNS and entering the CNS via dorsal root ganglion into the dorsal horn of grey matter)
information processing/integration (within grey matter of SC)
activation of efferent neurone (via anterior horn of grey matter)
effector response (i.e. muscles)
what 2 ways can the automatic function of the reflex arc be?
somatic (e.g. spinal reflexes leading to muscle movement)
visceral (e.g. activating glands)
what is the difference between inborn and learned reflex activity?
inborn= rapid, involuntary and stops us having to think about it i.e. to get out of danger quicker
learned= developed over repetitive practice (e.g. driving)
