Somatosensory, Vestibular and Olfactory systems Flashcards
define stimulus
energy source Internal External
define receptor sense organ
structures specialized to respond to stimuli
define transducers
-stimulus energy converted into action potentials
deine conduction
Afferent pathway Nerve impulses to the CNS
how amny epidermal cells do humans shed a day?
50 million
outline the skin
Glabrous Skin Smooth, thick skin on palms and soles of our feet
Epidermis = 1.5 mm
Dermis = 3 mm
Hairy Skin Thin skin populated with hair follicles Epidermis = 0.1 mm Dermis = 1-2 mm
Sweat Glands Eccrine – secrete saline (heat regulation) Sebaceous – secrete complex cell cytoplasm (Primary source of human body odor!)
what are the 4 types of touch receptors?
Meissner corpuscle -Touch Small receptive fields Fast adapting
Merkel cells - Touch Small receptive fields Slow adapting
Ruffinin ending -Stretch Large receptive fields Slow adapting
Pancininan corpuscle Vibrations Large receptive fields Fast adapting
what is the receptive field?
“The receptive field (RF) of an individual sensory neuron is the particular region of the sensory space in which a stimulus will modify the firing of that neuron”
what effects the RF’s spatial resolution
Size: Smaller RF à Higher Resolution Density: Higher Density à Higher Resolution
ouline the Ascending nervous pathway
afferent sensory information enters CNS
Innervation via Spinal Nerve
effeent signles to muscles and glands via ventral root
what is the dorsal horn and ventral root?
DORSAL HORN = Afferent sensory information VENTRAL HORN = Efferent motor signals
Bell-Magendie Law
The fact that anterior spinal nerve roots contain only motor fibers and posterior roots only sensory fibers.
Dorsal: signals to brain
Ventral: motor-efferent pathway transmits motor information from brain to body.
name the mapping of the sesnory system
Dermatome: Adermatomeis an area of skin that is mainly supplied by a single spinal nerve Although there are 31 pairs of spinal nerves in humans, there are only 30 dermatome
outline the ascending pathway
Tactile signals are sent through the spinal cord via the dorsal column pathway to the primary somatosensory cortex (S1) in the brain Ascending pathway
TACTILE PATHWAY Dorsal column Thalamus Primary somatosensory cortex(S1) Secondary somatosensory cortex(S2) Other brain areas (parietal areas)
where is somatosensory cortex one?
by the cetral sulcus
what does the somatosensory cortex do for mapping?
Each part of the skin surface is represented by a specific region of primary somatosensory cortex somatotopy
“Sensory Homunculus” little man
The area devoted to each body part reflects the receptor density in that par
little man
The area devoted to each body part reflects the receptor density in that part
Cortical Magnification
The receptive fields and cortical representations give more acuity to fingers, mouth, nose and tongue