Ch.15 Flashcards
What is general sense and not a special sense?
Touch
Special Senses
- Smell
- Taste
- Sight
- Hearing
- Equilibrium
- Each have specialized receptors that send sensory information to the brain
* Receptors are highly localized for their function
Smell-Olfactory Receptors
- Receptors located in epithelium covering cribriform plate and superior nasal concha
- 10-100 million Bipolar neurons
- Receptors on hairs
Basal Cell
- Stem cell
- to make more olfactory Neurons (30-60 dys)
Supporting cells
- Insulate the olfactory cells
- Have cilia to move mucus
Physiology of Smell
Ordorant binds receptor
→ Axons of olfactory neurons send axons through cribiform plate → synapse in olfactory bulb → olfactory tract → olfactory cortex (and limbic system)
Sensory adaptation
within a sec of stimulation intensity drop 50%, in a min receptors are insensitive ex living with a smoker
Taste
Function:
- Triggers reflexes that prepare the GI tract for activity
- Induce vomit if food is bad
Taste Anatomy
- Receptor = Taste buds
- Located on tongue and oral cavity
- Tongue has 3 type of raised projections (papillae)
Taste Physiology
Tastant binds receptor → gustatory cells transmit signal to neurons (of cranial nerve VII, IX, X) → medulla → thalamus → gustatory cortex (and limbic system)
5 primary taste sensations:
- sweet: carbs
- sour: acids
- salt: inorganic salts
- bitter: organic/inorganic salts
- unami: amino acids - glutamate
Eyelids
Vision Anatomy
- Protection
- Shade eyes for sleep
- Spread lubricant
- Anchor orbicularis oculi
Eyelash
Vision Anatomy
Trigger blink reflex
Lacrimal Apparatus
Vision Anatomy
Produces tears = mixture of mucus, antibodies, lysozyme
Conjunctiva
Vision Anatomy
- Thin mucous membrane lines inner side of lids and whites of the eyeball
- For protection
Extrinsic eye muscles
Vision Anatomy
- originate from bony orbit and insert on eyeball
- Superior, inferior, lateral, and medial rectus: Enable eye to follow moving objects, maintain shape of eyeball, and hold it in orbit
– names indicate movements - Superior and inferior oblique muscles: move eye in vertical plane and rotate eyeball
Lateral rectus
Extrinsic Eye Muscle
- moves eye laterally
- VI (abducens)
Medial rectus
Extrinsic Eye Muscle
- moves eye medially
- III oculomotor
superior rectus
Extrinsic Eye Muscle
- elevates eye and turns it medially
- III (oculomotor)
inferior rectus
Extrinsic Eye Muscle
- depresses eye and turn it medially
- III (oculomotor)
inferior oblique
Extrinsic Eye Muscle
- elevates eye and turns it laterally
- III (oculomotor)
superior oblique
Extrinsic Eye Muscle
- dperesses eye and turns it laterally
- IV (trochlear)
Vision – Eye Ball
- Hollow sphere filled with fluids (humors)
- Has anterior and posterior poles
- Walls have 3 layers (tunicas)
- Lens divides sphere into anterior and posterior cavities
Sclera Venous Sinus
Eye ball
- Drains aqueous humor –> Returns it to blood
- Glaucoma when plugged
Aqueous humor
Eye Ball
- made by ciliary body (by filtering blood, similar to plasma)
- Flows through chambers to nourish tissue
Vitreous Humor
Eye Ball
- Helps hold eye ball shape
- Keeps tunicas pressed together
- Maintains internal pressure (to counterbalance to extrinsic eye muscles)
Lens
Eye Ball
- Focuses light on the rods and cones
- Biconvex disk
- Transparent, flexible, avascular
- Contains crystallin (protein that keeps it transparent)
- Encapsulated by a thin layer of elastic connective tissue
- Ciliary muscles adjust shape for focus
- Cataracts (clouding of lens)
Outer Fibrous Tunica
Eye Ball
Avascular connective tissue
What are the two regions of Outer Fibrous Tunica?
- Sclera: white, opaque
- Maintains shape of eyeball
- Anchors the extrinsic muscles
- Continuous with dura mater - Cornea: transparent
- Covered internal and external with epithelium
- Regenerates quickly
Regions of Vascular Tunica (uvea)
- Choroid
- Rich blood supply nurtures other tunicas
- Highly pigmented (melanin) - Ciliary Body
- Contains ciliary muscles attached by fibers to lens
- Contains ciliary process that makes aqueous humor - Iris
- Donut-shaped, hole is pupil
- Contains melanin (brown pigment)
- Made of smooth muscle to adjust size of pupil
Regions of Sensory Tunica (retina)
- Pigmented layer
- One cell layer
- Pigment absorbs light
- Stores vitamin A
– (Deficiency cause nightblindness) - Neural Layer
- Rods and Cones
- photosensitive
Pathway of light through eye
Light goes through air
↓
Cornea
↓
aqueous humor
↓
lens
↓
vitreous humor
↓
photoreceptors in retina
Macula lutea
contains the fovea centralis
Fovea centralis
Only cones, area of sharpest focus
optic disk
lacks photoreceptors
Auricle
External Ear
- Funnel shape
- Elastic connective tissue inside
- Directs sound vibrations into ear
External auditory canal
- Formed by the auditory meatus in the temporal bone
- Lined with skin that contains ceruminous glands
ear drum (tympanic membrane)
External Ear
- Divides outer and middle ear
- Made of thin connective tissue membrane
- It transfers sound waves to middle ear
Middle Ear
- Air filled cavity
- Lined with a mucous membrane
- Located in petrous region of temporal bone
- Auditory tube: extends from floor opens into nasal pharynx
– Allows equalization of pressures - 3 ossicles are suspended from ceiling - Attached to each other by synovial joints
- They transmit vibrations from ear drum to oval window (inner ear)
3 Regions of the Inner Ear
- Vestibule
- Semicircular canals
- Cochlea
Vestibule
Inner Ear
- Egg shaped cavity
- Filled with perilymph (like the CSF) 2 sacs inside
- Both sacs contain equilibrium receptors
Utricle
Inner Ear
Continuous w/ semicircular canals
Saccule
Inner Ear
Continuous w/cochlea
Semicircular Canals
Inner Ear
- Project posterior from the vestibule
- Orientated in the 3 planes of space
- Ampulla = swelling at base
- Each ampulla has an equilibrium receptor
Cochlea
Inner Ear
Spiral chamber that extends anterior
Cochlear duct
- in the cochlea
- Membranous sac
- Has a blind end
- Houses the Spiral Organ of Corti (hearing receptor)
How does sound travel through the ear
- Sound waves vibrate the tympanic membrane
- Auditory ossicles vibrate
- pressure is amplified - Pressure waves created by the stapes pushing on th oval window move through fluid in the scala
4a. Sounds with frequencies below hearing travel through the helicotrema and do not excite hair cells
4b sounds in hearung range go through cochlear duct, vibrating the basilar membrane and defecting hair cells
