Senses Flashcards
What types of stimuli do thermoreceptors, chemoreceptors, photoreceptors, and nociceptors detect?
thermoreceptors: temperature
chemoreceptors: chemicals
photoreceptors: light
nociceptors: injured & damaged tissue
What is transduction?
When a physical stimulus acts on a sensory receptor cell specifically designed to respond to that stimulus, then the energy of the stimulus (e.g. mechanical, chemical, light) is transduced into an electrical response.
What stimuli do mechanoreceptors detect, and what receptors are classified as such?
Mechanoreceptors detect direct stimuli such as vibration, touch, and pressure. Tactile receptors, proprioceptors, and baroreceptors are classified as mechanorecptors.
What type of receptors are muscle spindles and Golgi tendon organs?
Mechanoreceptors, more specifically proprioceptors.
What are the five special senses, and why are they considered “special”?
Smell, taste, balance, hearing, vision; They are considered special because they are confined to the head and have specialized structures for detection.
By what other names are the general senses known?
Somatosensory senses.
Where are the receptors for general senses that detect sensory stimuli like pain located?
In the receptive endings of sensory neurons (first-order neurons)
Where are the sensory receptors for the special senses located?
In specialized receptor cells that are not neurons.
What are the main differences between tactile discs and tactile corpuscles?
Tactile corpuscles are more associated with dynamic touch, while tactile discs are more involved in the detection of sustained pressure
The following names: Meissner, Krause, Ruffini, and Pacinian, are associated with which receptors?
Meissner: tactile corpuscles
Krause: end bulbs
Ruffini: bulbous corpuscles (continuous pressure)
Pacinian: lamellar corpuscles (vibration)
What are the three categories into which pain is classified?
Nociceptive, neuropathic, nociplastic.
What is nociceptive pain, and does it involve the activation of nociceptors?
Nociceptive pain is pain that arises from actual or threatened damage to non-neural tissue and is due to the activation of nociceptors.
How is nociceptive pain further classified?
It is further classified into visceral pain (originating from the viscera, internal organs) and somatic pain (arising deep within bones, joints, or muscles, or superficial pain from the skin).
What type of pain can mucosal injury or obstruction or capsular distension produce? Provide specific examples.
All these conditions can produce nociceptive pain. Examples include peptic ulcer for mucosal injury, and kidney stones for visceral obstruction.
In neuropathic pain, where is the origin of the noxious stimulus or damage located?
The origin of the noxious stimulus or damage in neuropathic pain is within the nervous system itself.
In nociplastic pain, can you observe tissue damage or a clear lesion of the nervous system? What are the two most typical examples of nociplastic pain?
No, you cannot observe tissue damage or a clear nervous system lesion in nociplastic pain. Two typical examples are fibromyalgia and irritable bowel syndrome.
What are the seven endogenous molecules that contribute to the generation of pain signals by stimulating nociceptors in the periphery?
Histamine, bradykinin, prostaglandin, protons, substance P, calcitonin gene-related peptides (CGRP).
What two molecules are released as part of the “axon reflex, “ and what are their effects?
Substance P and calcitonin gene-related peptides (CGRP) are released by nociceptors at the site of tissue injury, leading to vasodilation and the subsequent release of bradykinin, histamine, and serotonin. This process is unconventional as it occurs in the opposite direction to the usual pathway of a sensory neuron.
Which two neurotransmitters are released in the spinal cord by the first-order neuron and contribute to the transmission of pain signals?
Substance P and glutamate (an excitatory neurotransmitter) are released in the spinal cord by the first-order neuron.
Which molecules do descending analgesic fibers synapsing with interneurons in the spinal cord release to inhibit the second-order pain neuron?
Enkephalins, which belong to the opiate family, are released by descending analgesic fibers to inhibit the second-order pain neuron.
What are taste buds, and where are they located?
Taste buds are the taste organs containing gustatory receptor cells, also known as taste cells. They are located within the tongue papillae.
Among the tongue papillae, which one does contain taste buds?
Fungiform papillae and vallate papillae.
What types of cells can be found in a taste bud?
Taste buds consist of supporting cells, basal cells (stem cells capable of replacing other taste bud cells), and gustatory receptor cells, which are not neurons.
What are the five primary taste sensations, and how are they produced?
- Saltiness, metal ions
- Sweetness, carbohydrates
- Sourness, acidic substances
- Bitterness, spoiled food and alkaloids
- Umami, amino acids
Which taste sensations involve sodium channels? Which ones involve GPCR receptors?
Salty and sour taste involve sodium channels. Sweet, bitter, and umami taste involve GPCR receptors.
How do taste cells stimulate the axons of the sensory neurons corresponding to the vagus nerve, glossopharyngeal nerve, and facial nerve? Where do these axons travel to in the medulla?
Taste cells stimulate the axons of sensory neurons by releasing neurotransmitters that bind to receptors in these cranial nerves. These axons travel to the nucleus of the solitary tract in the medulla oblongata.
Where is the gustatory cortex located?
The gustatory cortex is situated in the insula of the brain.
Where is the olfactory mucosa or epithelium located, and what does it contain?
The olfactory mucosa is located on the roof of the nasal cavity and contains basal cells, supporting cells, and olfactory receptor cells.
Where are the receptor proteins that detect odorants located?
They are located in the dendrites of olfactory receptor cells and are often referred to as olfactory hairs due to their appearance.
The olfactory nerve synapses with which neurons at the glomerulus?
The olfactory nerve synapses with tufted and mitral cells at the glomerulus in the olfactory bulb.
What is a glomerulus, and where is it located?
A glomerulus is the site in the olfactory bulb where the axons of olfactory receptor cells containing receptors for the same odors synapse with tufted and mitral cells. Glomeruli are located in the olfactory bulb.
The axons of which neurons form the olfactory tracts?
The axons of tufted and mitral cells form the olfactory tracts.
What three brain areas constitute the primary olfactory cortex in the temporal lobe?
The piriform cortex, amygdala, and entorhinal cortex.
What is the role of the orbitofrontal cortex, also known as the secondary gustatory-olfactory cortex?
The orbitofrontal cortex integrates taste, smell, and sight signals; resulting in the perception of flavor and discrimination
What other brain areas are associated with the olfactory pathway?
The hippocampus is involved in olfactory memory. The hypothalamus and brainstem are related to triggering autonomic responses associated with appetite, salivation, and gastric contraction.
What are granule cells located, and what is their function?
Granule cells are found in the olfactory bulb, and they release the inhibitory neurotransmitter GABA. Their function is to inhibit mitral and tufted cells, the principal relays of olfactory information, thereby enhancing olfactory discrimination.
