Somatosenses Flashcards
Somatosenses
provide info about what is happening on our body surface and insides
Cutaneous
skin senses; pressure, vibration, heating, cooling, tissue damage, pain
Proprioception
body’s posture
kinesthesia
body’s movement; receptors in joints and muscle length receptors
Organis senses
arise from receptors within inner organs; digestive system
epidermis
outermost layer of skin, hairy and glabrous skin
dermis
contains tough connective tissue, sweat glands, hair follicles
mechanoreceptors
vibration and touch sensitive
Mech: touch sensitive
merkel’s disks ane messiners corpuscles
Mech: vibration sensitive
ruffni corpuscles, pacinian corpsules
Touch
detected by mechanoreceptors, detection causes movement of dendrites which causes ion channels to open, flow of ions causes a change in membrane potential
temperature
warmth: deeply in skin. coolness: just beneath epidermis
pain
perception is accomplished by networks of free nerve endings in the skin
3 types of nociceptors
high threshold, TRPV1, and TRPA 1
high-threshold receptors
respond to intense pressure (pinch)
TRPV1 receptors
sensitive to heat, acids and presence of capsaicin
TRPA1 receptors
sensitive to pungent irritants
primary somatosensory cortex
receives body sense information; has a somatotopic arrangement
Info from nerves pathway
medulla, medial lemniscus, central posterior nucleus of thalamus, primary somatosensory cortex, association cortex
Dorsal column
carries touch and kinesthesia information
spinothalamic tract
carries pain and temperature information
3 components of pain
sensory (pure perception), immediate emotional (unpleasantness), and long term emotional ( the treat to well being)
Pain: Brain: sensory
spinal cord, ventral posterolateral thalamus, primary and secondary somatosensory cortex
Pain: brain: immediate emotional
mediated by pathways that reach the anterior cingulate cortex and the insular cortex
Pain: brain: longterm emotional
mediated by pathways that reach the prefrontal cortex
Somatosensory agnosia
caused by large lesions to parietal cortex
astereognosia
loss of ability to recognize objects by touch
asomatognoisa
loss of ability to recognize parts of ones own body
gustation
perception of taste
taste
sensation of different components of food
flavor
combination of taste and smell
5 qualities of taste
bitterness, sourness, sweetness, saltiness, and umami
how many taste buds do we have
10,000
how many receptors per tastebud?
20-50`
perception of taste
the tasted molecule binds to a receptor and changes the permeability of the membrane that cause receptor potentials; different molecules bind to different receptors producing different tastes
what is the stimuli for saltiness
sodium
what is the stimuli for sourness
hydrogen ions
what is the stimuli for sweetness
glucose/fructose
what is the stimuli for bitterness
plant alkaloids
what is the stimuli for umami
glutamate
taste neural pathway
gustatory receptors, medulla, ventral posteromedial thalamic nucleus, primary gustatory cortex, gustatory association cortex
taste is
ipsilateral
olfaction
helps us identify foods that are bad
where do olfactory receptor cells lie
the olfactory epithelium at the top of the nasal cavity
olfactory processing
olfactory receptors are bipolar neurons whose cell bodies lie within the bone at the base of the rostral part of the brain
each receptor sends a single axon to the olfactory bulb and forms synapses with mitral cells
the axons travel to the rest of the brain through olfactory tracks
axons project onto the amygdala, primary o cortex, and entorhinal cortex
Main neural pathways
olfactory tract to amygdala to the hypothalamus,
olfactory tract to primary olfactory cortex to hypothalamus and orbitofrontal cortex,
olfactory tract to entorhinal cortex to hippocampus
transduction of olfaction
molecules bind to o receptors, g proteins open sodium channels and produce depolarizing receptor potentials, humans can recognize up to 10,000 smells from only 339 receptors
