Special Senses (chapter 15) Flashcards
Occurs when a physical or chemical stimulus is converted into a neural signal that can be interpreted by the brain.
Transduction
Sense of smell
Olfaction
A small patch of specialized epithelium located in the superior region of the nasal cavity
Olfactory epithelium
Modified bipolar neurons that detect the chemical substances we perceive as odors
Olfactory neurons
Chemical substances in the air that can be transduced into signals the brain can interpret
Odorants
A sensory receptor that responds to a change in the concentration of a specific chemical in the air or the body fluids
Chemoreceptors
A structure located in the brain just superior to the ethmoid bone and inferior to the frontal lobe of the brain
Olfactory bulb
Carries olfactory information to further parts of the brain for analysis
Olfactory tract
Stem cells that develop into olfactory neurons; lifespan 10-14 days
Basal cells
Columnar cells that support and surround the olfactory neurons; have no role in taste sensation
Supporting cells
Responsible for the awareness and identification of an odor; the only sensory pathway that has no synapse in the thalamus
Primary olfactory cortex
Lack of olfaction (smell)
Anosmia
Reduce olfactory sensitivity
Hyposmia
Sense of taste
Gustation
Clusters of receptor cells and supporting cells on the tongue that detect taste sensations
Taste buds
Round projections that covers the tongue
Papillae
The largest and most dome-shaped; each contains hundreds of taste buds
Vallate (circumvallate) papillae
Mushroom-shaped and contain only a few taste buds
Fungiform papillae
Ridges on the sides of the tongue and contain taste buds only in childhood
Foliate papillae
Long, thin cylinders scattered across the tongue; they do not contain taste buds but have sensory nerve endings that detect texture and temperature of food
Filiform papillae
Specialized epithelial cells with microvilli that contain receptors that detect different tastes
Gustatory (taste) cells
Small pocket on the surface of the papilla
Taste pore
Simple sugars such as glucose and fructose
Sweet tastes
Produced by hydrogen ions, found in the citric acid of lemon juice
Sour tastes
this taste is due to the presence of metal ions such as sodium and potassium ions
Salty tastes
Flavors are imparted by many nitrogen-containing compounds and are often found in rancid or poisonous substances
Bitter taste
A taste often associated with meat or broth, is produced by glutamate or other amino acids
Umami taste (savory)
Pathway:
*facial, glossopharyngeal, vagus nerves carry taste to the CNS
- axons of the 3 nerves terminate in the solitary nucleus in the medulla by synapsing onto central sensory neurons
- axons from the nucleus synapses on neurons in the thalamus, which then send the taste signals to the primary gustatory cortex in the parietal lobe
The Gustatory Pathway
Two thin folds that cover the anterior part of the orbit, prevents objects from entering the eye, and distribute tears across the eye when blinking
Eyelids (Palpebrae)
A thin piece of dense regular collagenous connective tissue that the eyelid is stiffened by
Tarsal plate
Modified sebaceous glands that are located in the tarsal plate and secrete oil to prevent the eyelids from sticking together
Tarsal glands
A fleshy structure found at the medial commissure that contains sebaceous glands that secrete a whitish lubricating substance
Lacrimal caruncle