Lecture 21: Special Senses Flashcards
What are the 5 types of special senses?
Olfaction (smell)
Gustation (Taste)
Audition (hearing)
Vision (sight)
Equilibrioception (touch and balance)
What are the 2 types of senses?
Special Senses- balance vision, hearing, taste, smell
Somatic (general) Sensory = tactition, pain, proprioception and visceral senses.
What is “sensation” and what are the 4 criteria which indicates that the sense is perceived.
Sensation is the conscious or subconscious perception of changes in the external or internal environment.
In order for this change to be perceived:
- Stimulus
- Sensory Receptor
-
Sensory impulse
- Integration
Structurally classify the sensory receptors:
+ Free Nerve Endings → Bare dendrites
+Encapsulated nerve endings → enclosed within CT capsule
+ Separate Cells → Release neurotransmitters from receptor
Functionally classify the sensory receptors
Mechanoreceptor → changes in pressure and touch
Nociceptor → Painful stimuli
Thermoreceptor → Changes in temperature
Photoreceptor → Change in light, colour and movement
Chemoreceptor → Detects chemical change
What are the 3 receptors depending on the origin of the stimulus?
= exteroceptor
= interreceptor
= Proprioceptor
Where is the functional classifications of sensory receptors located?
Mechanoreceptor → Skin for touch and pressure
Nociceptor → Present in almost all organs
Thermoreceptor → Receptors in skin and hypothalamus
Photoreceptor → Retina of the eye
Chemoreceptor → Taste receptors in tongue, smell in nose, in blood vessels
Where is the special sense for olfaction located? What cells is it composed of?
→ Located in the superior nasal concha and upper nasal septum (olfactory epithelium)
Cells: Supporting Cells (support and nourishment
Basal Cells
Olfactory receptor cell- Bipolar neurons with cilia projecting from dendrite
Highlight the pathway for the olfaction sense:
- Odour molecules dissolve into olfactory hairs
- Olfactory cell receptor sends info travelling axon to the ethmoid bone
- Penetrates cribriform plate to the olfactory bulb
Where is the gustation special sense located and what cells is it composed of?
→ Located in taste buds!
Made up of epithelial cells: basal cells, supporting cells, gustation receptor cells (Long microvilli hairs detect food molecules → sends info to afferent nerve)
Has around 50 gustatory receptor cells per taste bud
Where are taste buds normal found on the tongue?
PAPILLAE
→ Circumvallate papillae : Back of tongue (100-300) taste buds
→ Foliate Papillae : Sides of tongue taste buds degenerate over time
→Fungiform Papillae : Scattered over with 5 taste buds each
→ Filiform Papillae : tactile receptor, no taste buds
What are the 5 traditional types of taste?
Bitterness
Saltiness
Sweetness
Umami-ness
Sourness
Outline the gustatory pathway
Gustatory receptors in taste buds are picked up by Facial (VII) glossopharyngeal (IX) and Vagus (X) nerves and sent to the medulla oblongata
What is the role of the ear in terms of special senses?
Receptor organ for sense of hearing and equilibrium
Composed of outer, middle and inner ear
What are the main functions of the external and inner ear?
external : Hearing only
Inner: Hearing and equilibrium
Describe the pathway of sound throughout the ear
OUTER:
→ Sound filtered by auricle → travels via external acoustic meatus → Hits tympanic membrane
MIDDLE:
→ Vibrations transmitted to auditory ossicles (malleus, incus, stapes)
INNER:
→Bony labyrinth, membranous labyrinth, make up cochlear
MEMBRANOUS CONTAINS AUDITORY RECEPTORS
Label the main features of the inner ear
Describe how audition is perceived by the brain
Ear provides a passage for vibrational energy to travel from one medium to another (air to perilymph in cochlea)
→ Conversion of vibrational energy to electrical energy is called TRANSDUCTION
→ Interpretation of these action potentials in the brain
Describe the components of the organ of corti and its main function
Function: Where transduction occurs
Bony labyrinth composed of Scala vestibuli and Scala tympani surrounding the main cochlear duct.
What is the function of equibrioception?
Allows an organism to sense body movement, direction + acceleration and maintain posture.
What parts of the inner ear maintain balance?
Bony labyrinth and vestibular apparatus
What part of the inner ear maintains static equilibrium
VESTIBULE:
- Saccule and utricle - Hair cells located in maculae detect linear motion
Outline how the macula works
Statoconia crystals of the otolithic membrane feel the force of gravity when head it tilted.
Pulls on the gelatinous layer in the same direction causing sensory hairs to bend.
What part of the inner ear maintains dynamic equilibirum?
SEMICIRCULAR CANALS:
Anterior, posterior and lateral - hair cells located in crista ampullaris detect angular acceleration in 3 planes
Outline how dynamic equilibrium impulses are received by the crista ampullaris`
- Head movement
- Movement of fluid in semi-circular ducts and hair cells
- Inertia of endolymph make hair bundles bend
- Receptor potential
- Nerve impulses carried by vestibula cochlear.
Label all important accessory structures around the eye
Describe the flow of tears:
Lacrimal gland → excretory lacrimal duct → superior or inferior lacrimal canal → Lacrimal sac → Nasolacrimal duct → Nasal cavity
What are your extrinsic eye muscles and what are their functions?
→ Superior Rectus (moves up and in) Inferior Rectus (moves down and in)
Lateral Rectus (Look out)
Medial Rectus (Look in)
What are the 3 layers of the eyeball?
- Fibrous Tunic
- vascular tunic
- Retina
What is the function of the ciliary body
Ciliary muscle ; shapes lens for viewing objects
Ciliary process ; will control pupil for light entry (aperture)
What constricts the pupil aperture
Vascular tunic
Pupil CONSTRICTS as circular muscles of iris contract - PARASYMPATHETIC NERVOUS\
Pupils DILATE as radial muscles of iris contract- SYMPATHETIC
What is the fovea?
Point on retina where cones are in highest density
Head and eyes move when looking at something is to mainly concentrate light on the fovea.
Label the classifications of the retina as light is incident
What are the functions of rods and cones?
Rods: Detect monochromatic vision
Cones: Detect colour vision
Where transduction of light energy to electrical potentials occur
Describe the visual; pathway
Optic nerve → Optic chiasm → Optic tract → lateral geniculate nucleus of thalamus → Optic Radiations → Primary Visual Area
