2-Neurohistology Flashcards
pathways for sensory input
- conciousness- stimulus > receptors > pathway of series of neurons > brain > conscious sensory experience
- reflex/unconscious- stim > receptors > spinal cord > reflex resp
pseudounipolar neuron
- dendrites @ skin, muscles, tendons, ligaments, joint capsules, periosteum, bone, arteries, mucous membranes, visceral structures
- nerve impulse down peripheral process bypass cell body
- axon terminals to CNS @brainstem or spinal cord
cell body in dorsal root ganglia
neurons with sensory receptors
- bipolar
- pseudounipolar
bipolar neurons
@olfactory epithelium, retina (rods/cones), vestibular apparatus (hair cells inner ear), cochlea
aka special senses
encapsulated dendrites
can be in
-meissner corpuscles
-pacinian corpuscles
-ruffini end organs
-muscle spindles
-golgi tendon organs
multipolar neurons
dendrites of multipolar neurons not have sensory receptors, neurotransmitter receptors instead
sensory receptor criteria
- location in body
- morphology
- velocity of conduction
- modality they carry
cranial nerve modalities
- olfaction
- vision
- gustation
- audition
cranial nerves only
cranial + spinal nerve modalities
- tactile sensation- touch, pressure, vibration
- nociception
- temperature
- proprioception
touch types
- light - crude, non descriptive, don’t know what it is
- discriminative- fine, detailed, know info about what you’re touching
stimulus path general
- stimulus elicits physiologic resp- visual, auditory, chemical, mechanical, thermal
- receptor activated by stimulus transduced into electric signal
- electric signal transmitted to nerve terminal for action potential gen
- CNS
receptive field of receptor
area of territory where receptor resides/ is activated by a stim
large number of receptors in skin of face and hand
-less in skin of other parts like legs
-smaller receptive field = more detail/precise
receptor classifications- stimulus source
- exteroceptors
- proprioceptors
- interoceptors
exteroceptors
either
1. teloreceptors- DISTANCE so light and sound stim
2. contact receptors- tactile, nociceptive, thermal, chemical
close to body surface and resp to external environ
proprioceptors
are static, kinesthetic, position sense receptors
@ vestibular apparatus, skin, muscles, tendons, joint capsules
interoceptors
detect sensory info from bodys internal environ
-chemoreceptors @ hypothalamus for PH, carotid body for O2, CO2
-baroreceptors @ carotid sinus for BP, bladder
receptor classification by modality
- nociceptor
- thermoreceptor
- mechanoreceptor
nociceptors
have free nerve endings
-mechanosensitive (xs mech stim or tissue injury)
-temp sensitive (intense heat/cold)
-polymodal (various noxious stim)
-pruriceptors (resp to histamine)
unpleasant/injurious stim aka pain
thermoreceptors
have free nerve endings
-cold and warmth receptors, can detct inc in temp
-temp sensitive (intense heat/cold)
-nociceptors
mechanoreceptors
can be
1. nonencapsulated- free nerve endings, peritrichial nerve end (root of hair follicle), tactile (Merkel)
2. encapsulated- meisner, pacinian, ruffini, muscle spindles (proprio), golgi tendon organs (proprio)
meissner corpuscle
has 2 point discrimination
1. epidermis
2. nerve ending
pacinian corpuscle
non-neural tissue surrounds nerve ending
-senses flutter/vibration
extrafusal fibers
@skeletal muscle that contract to produce move
-motor inn by alpha motor neurons
-sensory inn by pseudounipolar
intrafusal fibers
enclosed by muscle spindles (mechano) that monitor length
- nuclear bag fibers- noncontractile region + contractile portion, can be static (length) or dynamic (rate of length change)
- nuclear chain fibers- noncontract + contractile mostly sensitive to changes in muscle length
