Part 3 Sensory function of the nervous System
Part 3 Sensory Function of the Nervous System
Sensory pathways o Sensory systems allow us to detect, analyze and respond to our environment ascending pathways o Carry information from sensory receptors to the brain o Conscious reach cerebral cortex o Unconscious do not reach cerebral cortex o Sensations from body reach the opposite side of the brain
I Sensory pathways ⚫ Sensory systems allow us to detect, analyze and respond to our environment ⚫ “ascending pathways” ⚫ Carry information from sensory receptors to the brain ⚫ Conscious: reach cerebral cortex ⚫ Unconscious: do not reach cerebral cortex ⚫ Sensations from body reach the opposite side of the brain
1. Sensory receptors A: Free nerve endings(pain, temperature) 060 A B: Pacinian corpuscle(pressure) C: Meissner's corpuscle(touch) B C D: Muscle spindle(stretch)
1. Sensory receptors A: Free nerve endings (pain, temperature) B: Pacinian corpuscle (pressure) C: Meissner’s corpuscle (touch) D: Muscle spindle (stretch) A B C D
Hairy skin Glabrous skin Merkels disk Epidermis Epidermal dermal border Free nerve ending Dermis Meissner corpuscle Hair follicle receptor Pacinian corpuscle Ruffini's ending Ruffini's endings respond to tension and stretch in the skin
Ruffini's endings respond to tension and stretch in the skin
2. Sensory pathways: 3 neurons o 1st: enters spinal cord from periphery o 2nd: crosses over(decussates ), ascends in spinal cord to thalamus o 3rd: projects to somatosensory cortex
2. Sensory pathways: 3 neurons ⚫ 1 st: enters spinal cord from periphery ⚫ 2 nd: crosses over (decussates), ascends in spinal cord to thalamus ⚫ 3 rd: projects to somatosensory cortex