(9) somatosensory, vestibular and olfactory systems Flashcards
-Sensory projections ascend from the
spinal cord into the brain through the brainstem.
When sensory projections travel through the thalamus, they act as…
which acts as a relay processing station of signals to other brain regions
What is a pathway?
Pathway is the receptor to the brain
What are the skins three layers?
- Epidermis: thin outer layer
- Dermis (thick inner layer)
- Hypodermis
What is Glabrous Skin?
- Smooth, thick skin on palms and soles of our feet , e.g. finger tips
- Epidermis = 1.5 mm Dermis = 3 mm
What is Hairy Skin?
- Thin skin populated with hair follicles, widespread
- Epidermis = 0.1 mm Dermis = 1-2 mm
What are sweat glands?
- Eccrine – secrete saline (heat regulation)
- Sebaceous – secrete complex cell cytoplasm
- (Primary source of human body odour!)
What are Meissner Corpuscles?
Small receptive fields, fast adapting
What are Merkel Cells?
Small receptive fields, slow adapting
What are Ruffini Endings?
large receptive fields, slow adapting
What are Pacinian Corpuscle?
large receptor fields, fast adapting
What is the ‘Two point discrimination test’ for?
which skin region is more accurate
The receptive field of an individual sensory neuron is the
particular region of the sensory space in which a stimulus will modify the firing of that neuron
Bell-Megendie Law, in the dorsal the sensory afferents or efferents?
-dorsal= sensory afferents
Bell-Megendie Law, in the ventral the sensory afferents or efferents?
-ventral= motor efferents
Whats a Dermatome?
an area of skin in which sensory nerves derive from a single spinal nerve root
Somatosensory signals are sent through the spinal cord via the dorsal column pathway to the
primary somatosensory cortex (S1) in the brain.
What is somatotopy?
Each part of the skin surface is represented by a specific region of primary somatosensory cortex
What is “sensory homunculus”?
(little man) The area devoted to each body part reflects the receptor density in that part
What is Cortical magnification?
The receptive fields and cortical representations give more acuity to fingers, mouth, nose and tongue
Pain and touch are processed by
separate neural systems, Pain is detected by special receptors in the skin
What are Nociceptors (free nerve endings)?
Signal mechanical & chemical pain
What are Thermoceptors?
Signal hot and cold pain, Ending of unmyelinated C-fibers