Special Senses Flashcards
What are the general sense receptors? What do they do?
Chemoreceptors (chemical changes), Mechanoreceptors (pressure & movement) , Thermoreceptors (temp. change), Nociceptors (pain), Photoreceptors (light energy)
How does a sensory pathway work?
A stimulus generates a receptor potential –> the receptor potential triggers an action potential –> an action potentials travel to the brain
Where are taste buds found on the tongue?
Found in papillae
What are the epithelial cells that make up each taste bud? What is a characteristic of each?
Gustatory epithelial cells (have long microvilli called gustatory hairs) & Basal epithelial cells (stem cells)
How does a taste signal get to the CNS?
- Dissolved molecules in saliva enter taste pore
- Molecules bind to receptors on gustatory hair cells
- Action potentials are generated, sensory neurons stimulated, signals sent to CNS
What are the different types of tastes?
- Sweet
- Sour
- Salty
- Bitter
- Umami
What are the steps of the gustatory pathway?
Taste receptors –> sensory nerve fibers in cranial nerves –> brainstem –> thalamus –> gustatory cortex (insula)
Where are the olfactory receptors found? What epithelium?
Found in the olfactory epithelium, made of pseudo stratified columnar
What kind of neurons are olfactory sensory cells?
Bipolar neurons
What are the filaments of the olfactory nerve?
Extensions of sensory neurons that enter the CNS through the cribriform plate and synapse with mitral cells in olfactory bulb
How is olfactory information relayed? Where to?
Relayed from mitral cells via the olfactory nerve to the limbic system and the primary olfactory cortex in temporal lobe
What are the accessory structures of the eye? What are their functions?
Palebrae: eyelashes (keep foreign objects out), & Sebacous glands (lubricate surface of eye)
Palpebral Fissure: space b/w eyelids
Lacrimal Caruncles: Pink raised portion
What is the conjunctiva?
Transparent mucous membrane that covers the white of the eye
What is the lacrimal apparatus? What is it made out of?
Tear production; Lacrimal Gland and ducts that drain lacrimal fluid (tears)
What are the 3 layers of the eye?
3 tunics: Fibrous tunic (outermost), Vascular tunic, Sensory tunic (innermost)
What are the functions and characteristics of the Fibrous Tunic in the eye?
Outermost layer, provides protection and mechanical support; avascular, made out of sclera & cornea
What is the sclera? What is the cornea? What are they made out of?
Sclera: White part of the eye (dense IR CT)
Cornea: transparent (dense regular CT)
What are the parts of the Vascular Tunic? What do they do?
Choroid: vascular, dark surface that absorbs excess light
Iris: made of smooth muscle that contracts and enlarge pupil to regulate light entry to eye ball
Ciliary Body
Suspensory Ligaments: controls the shape of the lens
What is accommodation?
The lens changes shape when looking at things up close
How does parasympathetic control accommodation work? Sympathetic control?
Close objects, ciliary muscle contracts; distant objects, ciliary muscle relaxes
What are the layers of the Sensory Tunic? What do they do?
- Pigmented Layer: single epithelial layer, involved with absorbing light and nourishing neural layer
- Neural Layer: Contains 3 types of cells (photoreceptors, bipolar, ganglion)
What are the type of photoreceptors?
Rod cells: Most sensitive light, found mainly in the periphery of retina
Cone cells: Color vision, concentrated in central part of retina
What is the visual pathway in the retina?
Photoreceptors activate bipolar cells –> bipolar cells activate ganglion cells –> axons of ganglion cells form optic nerve –> brain
What is the role of the suprachiasmatic nucleus?
Contain a protein called melanopsin that regulate the body’s circadian clock
