Chapter 16 - Nervous System: Senses Flashcards
what is each unique type of sensation called?
sensory modality
what are the general senses?
Somatic senses -Tactile - touch, pressure, vibration, itch, tickle -thermal sensations - warm / cold -Pain -proprioception Visceral senses -Info about internal organs **scattered throughout body **simple structures
what are the special senses?
Smell taste vision hearing equilibrium and balance **concentrated in specific locations in the head **anatomically distinct structures **form complex pathways
where does sensation begin?
- sensory receptor = specialized cell OR dendrites of a neuron
- *Receptors are selective – only respond to one type of stimulus
Exteroceptors
near external surfaces of body respond to eternal stimuli
Interoceptors (visceroceptors)
internal environment (In blood vessels, organs, muscles)
proprioceptors
tells you position of limbs and body in space
Muscles, tendons, joints, inner ear
what are the 3 sensory receptors named by location?
Exteroceptors
Interoceptors (visceroceptors)
proprioceptors
what are the 6 sensory receptors named by action?
1) Mechanoreceptors – responds to deformation
2) Thermoreceptors- respond to temperature
3) Nociceptors – respond to pain
4) Photoreceptors – respond to light
5) Chemoreceptors - respond to chemicals (tastes, smells)
6) Baroreceptors - respond to pressure
what is unique about tactile receptors?
thermo, mechano- or nociceceptors located in the skin
describe nociceptors
- chemoreceptive, free-nerve endings
- Activated by tissue damage from intense thermal, mechanical or chemical stimuli
- Little adaptation – pain tends to linger
- In every tissue in the body except the brain
fast pain
(acute, well localized) occurs rapidly – myelinated axons
slow pain
- gradually increases in intensity
- Burning, aching, throbbing
superficial somatic pain
Receptors in skin
deep somatic pain
Muscles, joints, tendons, fascia
Visceral pain
-Nociceptors in visceral organs
-Pain is felt in or just deep to the skin that overlies the organ
OR pain felt far from affected organ = referred pain
referred pain
pain felt far from affected organ
Ex) heart attack – chest pains and pain felt far from area (arm)
sensory pathway: first-order / primary somatosensory neurons
Into brain stem or spinal cord
sensory pathway: Second-order / secondary neurons
to thalamus
sensory pathway: Third-order neurons
From thalamus to cortex
describe the distribution of somatic sensory neutrons in the body
not distributed evenly in the body
where does motor activity begin?
in the primary motor areas of the primary motor cortex and other cerebral integrative centers
Upper motor neuron (UMN)
-Motor neuron not responsible for stimulating muscle contraction -Connects brain to the upper level in spinal cord
lower motor neurons (LMNs)
descend to innervate skeletal muscle