Lecture 18 Flashcards
Sensory processes
What do sensory systems provide animals with?
Sensory systems provide animals with information about their external and most of their internal environments.
What are the key features of sensory systems?
They depend on specialized sensory receptor cells that respond to stimuli and convert energy into electrical signals. These systems vary in sensitivity (signal intensity) and specificity (type of signal).
How are sensory receptor cells organized?
Sensory receptor cells are often clustered together to form sense organs (e.g., the eye). Together with the nervous system, they form the sensory system.
What is sensory transduction?
Sensory transduction is the process by which sensory receptor molecules convert stimulus energy into electrical signals.
What is a graded potential?
A graded potential is a short-distance signal triggered by ion-gated channels that initiates a local change in membrane potential.
What is an action potential?
An action potential is a long-distance signal generated by voltage-gated channels, enabling the transmission of signals over long distances.
How are sensory receptors classified?
Sensory receptors can be classified by:
- Sensory modality – the subjective nature of the stimulus.
- Stimulus energy – electromagnetic, mechanical, or chemical.
- Signal transduction – how the receptor converts stimulus energy into electrical signals.
- Location relative to the body – exteroceptors (external stimuli) vs interoceptors (internal stimuli).
What is the difference between taste and olfaction in terrestrial animals?
Taste involves stimuli in liquid form and is detected by chemoreceptors near the mouth.
Smell involves airborne stimuli that dissolve in liquid and are detected in specialized structures (nose or antennae).
How is chemoreception different in aquatic animals?
In aquatic animals, the distinction between taste and smell is less clear, with taste typically detecting high concentrations of stimuli during feeding and smell detecting low concentrations for navigation.
Where are taste and touch receptors found in insects?
Taste and touch receptors are located in sensilla (bristles), found on mouthparts, antennae, legs, wings, and ovipositors.
What is the function of a mechanoreceptor cell in insects?
The mechanoreceptor cell is attached to the base of the bristle shaft. When the bristle moves, it deforms the mechanoreceptor cell membrane, opening stretch-activated channels.
How do insect taste receptors work?
Insect taste receptors detect changes in frequency and intensity of signals (graded potentials) when compounds enter tiny holes in the sensilla.
How do mammalian taste receptors work?
Epithelial sensory cells in taste buds transduce taste stimuli into electrical signals, which are sent to the brain’s taste centers.
What are the different types of cells in taste buds?
Taste buds contain 50-150 cells, including:
Type I (astrocyte-like cells),
Type II (sweet, bitter, and umami receptors),
Type III (sour receptors),
Type IV (basal cells).
Salt receptors don’t fit neatly into these categories.
How is salt and sour taste detected in mammals?
Salt and sour tastes are detected through ionotropic signaling via type III receptor cells, where sodium or proton influx depolarizes the cell.
