sensory anatomy of the dog and cat
general types of stimuli
mechanical stimuli
thermal
electromagnetic (vision)
chemical
visceral sensations
vague and poorly localaised
hunger and thirst
include visceral stretch receptors in GI tract and urinary system
touch and pressure
tactile sense - sensation of something being in contact with the surface of the ody
pressure - sensation of something pressing on the body surface
temperature
superficial temp receptors
in the skin
detect upward or downward changes in skin temp
central temp receptors
in the hypothalamus
monitor blood temp
also called core body temp
pain
nociceptors - pain receptors
receptors are the most widely distributed receptors inside and on the surface of the body
pain processes - the four steps
transduction - conversion of painful stimulus into nerve impulse
transmission - conduction of nerve impulse to spinal cord
modulation - changes sensory nerve impulse
can amplify or suppress sensory impulse
perception - conscious awareness of painful stimuli
proprioception
sense of body position and movement
stretch receptors in skeletal muscle, tendons, ligaments and joint capsules sense movements of limbs, positions of joints, state of contraction of muscles, and the amount of tension being exerted on tendons and ligaments
taste
gustatory sense
chemical receptors - taste buds in oral cavity
papilllae -small elevated structures on tongue, lining of mouth and pharynx
smell
olfactory sense
very important in most nonhuman animals
olfactory cells and supporting cells in epithelial patches in nasal passage
hairlike processes project up for olfactory cells into the mucous layer that covers the nasal epithelium
odor molecules dissolve in mucus and contact sensory processes
nerve impulses are generated, travel to the brain and are interpreted as particular smells
hearing
auditory sense
converts vibrations of air molecules into nerve impulses
most structures of the ear are located in the temporal bones ie the tympanic bullae of the skull
external ear
acts as funnel to collect sound wave vibrations and direct to eardrum
middle ear amplifies and transmits the vibrations from the eardrum to the inner ear
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