Lecture 9: Sensory Systems - Special Senses Flashcards
Vestibular Sensation
Organism’s sense of spatial orientation and balance`
Sensory transduction
Converting a stimulus into an electrical signal in the nervous system
Sensory Receptor
A cell or cell process that is specialized to engage with and detect a specific stimulus.
Used in the first type of cellular system that performs sensory transduction
Reception
First step in sensation
Activation of sensory receptors by stimuli
Receptive field
Region in space in which a given sensory receptor can respond to a stimulus
Intense Stimulus
May produce a rapid train of action potentials and reducing the stimulus will likewise slow the rate of production of action potentials.
A second way in which an intense stimulus is encoded is by the number of receptors activated. This may initiate action potentials in a large number of adjacent receptors.
Olfactory Epithelium
Collection of specialized olfactory receptors in the back of the nasal cavity
Olfactory Receptor
Dendrite of a specialized neuron
Responds when it binds certain molecules inhaled from the environment by sending impulses directly to the olfactory bulb of the brain.
Olfactory Neuron
Bipolar neurons
Each neuron has a single dendrite buried in the olfactory epithelium.
Each has one type of receptor on its cilia and they are specialized to detect specific odorants.
Olfactory Stimulation
The only sensory information that directly reaches the cerebral cortex, whereas other sensations are relayed through the thalamus.
Pheromone
Chemical released by an animal that affects the behaviour or physiology of animals of the same species.
Signals aren’t sent to olfactory bulb but are sent to a neural structure that projects directly to the amygdala.
The Vomeronasal Organ
VNO
Jacobson’s Organ
Tubular, fluid-filled olfactory organ present in many vertebrate animals that sits adjacent to the nasal cavity
Sensitive to Pheromones
Connected to the nasal cavity by a duct
Taste Bud
Primary organ of taste
A cluster of gustatory receptors that are located within the bumps on the tongue called papillae
Filiform Papillae
Located across the tongue
Are tactile
They provide friction that helps the tongue move substances
Contain no taste cells
Fungiform Papillae
Located mainly on the anterior two-thirds of the tongue
Each contain one to eight taste buds
Have receptors for pressure and temperature.
Circumvallate Papillae
Large, contains up to 100 taste buds
Forms a V shape near the posterior margin of the tongue.
Wall-like papillae
Each is surrounded by a groove
Each contains about 250 taste buds
Foliate Papillae
Leaf-like papillae
Located in parallel folds along the edges and toward the back of the tongue
Contain about 1300 taste buds within their folds
Five Primary Tastes in Humans
Salty Tastant
Sour Tastant
Sweet Tastant
Bitter Tastant
Umami Tastant
Salty Tastant
Provides the Na+ ions that enter the taste neurons and excite them directly.
Sour Tastant
Acids that belong to thermoreceptor family.
Binding of a sour molecule or acid triggers a change in the ion channel and these increase hydrogen ion concentrations in the taste neuron, hence depolarizing them.
Sweet, Bitter and Umami Tastant
Require a G-protein coupled receptor
Bind to respective receptors, thereby exciting the specialized neurons associated with them
Glomeruli
Neural clusters in the olfactory bulb
Each receives signals from one type of olfactory receptor.
Each is specific to one odorant
Audition
Hearing
Enables an organism to detect and receive information about danger
Sound waves
Auditory Stimuli
Mechanical, pressure waves that move through a medium.
