Special Senses Flashcards
1
Q
Special senses
A
- smell, taste, vision, hearing, equilibrium
- housed in complex sensory organs
- olfaction and gustation: chemical receptors
2
Q
Olfactory epithelium
A
-covers superior nasal cavity and cribriform plate of the ethmoid bone
3
Q
Olfaction: sense of smell cells
A
- olfactory receptor cells
- bipolar neurons with non motile cilia
- contain olfactory receptors
- supporting cells
- columnar epithelium
- basal cells: stem cells
- replace receptors monthly
- olfactory (bowmans glands)
4
Q
Olfactory pathway
A
- axons from olfactory receptors from the olfactory nerves (cranial nerve I) that synapse in the olfactory bulb
- pass through foramina in cribriform plate
- second order neurons within the olfactory bulb for the olfactory tract that reaches the olfactory cortex
- olfactory sensation are the only sensation that reach the cerebral cortex without first synapsing in the thalamus
- some fibres form the olfactory tract project to the limbic system
- emotional response to odors
5
Q
Gustatory Sensation: taste
A
- taste requires dissolving of substances
- five classes of stimuli: sour, bitter, sweet, salty, and unami
- taste buds found on tongue, soft palate and epiglotis
- found on sides of gallate, foliage and fungiform papillae
6
Q
Anatomy of taste buds
A
- an oval body consisting of 3 cell types: supporting, receptor and basal
- supporting cells: contain microvilli and surround a group of about 50 gustatory receptor cells
- gustatory receptor cells: have gustatory microvilli that pass to the external surface through the taste pores
- basal cells: stem cells that produce supporting cells. The supporting cells then develop into gustatory receptor cells, which have a life span of about 10 days
7
Q
Why do you lose your sense of smell/taste when sick
A
- flavour of food involves both smell and taste
- odors from food pass upward from the mouth into the nasal cavity, where they stimulate olfactory receptors
- olfaction is much more sensitive than taste
- when you are sick your olfaction is blocked
8
Q
Gustatory pathway
A
- dissolved substance contacts gustatory hairs
- nerve impulse formed in 1st order neuron
- first order gustatory fibres found in cranial nerves
- CN VII (facial) serves posterior 1/3 of tongue
- CN IX (glossopharyngeal) serves posterior 1/3 of tongue
- CN X (vagus) serves palate and epiglottis
- signals travel to brain steam and thalamus or limbic system and hypothalamus
- taste fibres extend from the thalamus to the primary gustatory area on parietal lobe of the cerebral cortex
- providing conscious perception of taste
9
Q
Visual sensations
A
- accessory structures of the eye
- eyelids protect and lubricate eye
- eyelashes and eyebrows protect from foreign materials, perspiration and sunlight
- lacrimal glands
- palpebral fissure is gap between the eyelids
- sebaceous glands found at base of eyelashes
10
Q
Lacrimal apparatus
A
- about 1 ml of tears produced per day.
- spread over eye by blinking
- contains bactericidal enzyme called lysozyme
11
Q
Extraocular muscles
A
- muscles that move the eyeball
- innervated by CN III IV & VI
- superior rectus muscle
- interior oblique muscle
- inferior rectus muscle
12
Q
Tunics (layers) of eyeball
A
- fibrous tunic (outer layer)
- vascular tunic (middle layer)
- nervous tunic (inner layer)
13
Q
Fibrous tunic - cornea
A
- nonvascular
- transparent
- helps focus light
- parallel collagen fibres
- transplants are common, no blood vessels so no antibodies to cause rejection
- nourished by tears and aqueous humour
14
Q
Fibrous tunic - Sclera
A
- white of eye
- dense irregular connective tissue layer: collagen and fibroblasts
- provides shape and support
- at the junction of the sclera and cornea is an opening (sclera venous sinus)
- posteriorly pierced by optic nerve (CN II)
15
Q
Vascular Tunic - choroid
A
- pigmented epithelial cells (melanocytes) and blood vessels
- provides nutrients to retina
- black pigment in melanocytes absorb scattered light
16
Q
Vascular tunic: ciliary body
A
- ciliary processes
- folds on ciliary body
- secrete aqueous humour
- ciliary muscle
- smooth muscles that alters shape of lens
- suspensions ligaments attach lens to ciliary process
- ciliary muscle contrails tension on ligaments and lens
17
Q
Vascular tunic: iris
A
-coloured portion of eye
-shape of flat donut suspended between cornea and lens
-hole in centre is pupil
Function is to regular amounts of light entering eye