Exam 3: The Special Senses Flashcards
General Senses
- Include:
- Somatic sensations (tactile, thermal, pain, and proprioceptive)
- visceral sensations
- Scattered throughout the body
- simple structures
Special Senses
- Include
- smell
- taste
- vision
- hearing
- equilibrium
- concentrated in specific locations in head
- anatomically distinct structures
- complex neural pathway
How many receptors does Olfactory epithelium contain?
10-100 million receptors
Olfactory epithelium is made up of 3 types of cells:
- Olfactory receptor cells
- Supporting Cells
- Basal Cells
Olfactory Receptor Cells
- a bipolar neuron with cilia called olfactory hairs
- respond to chemical stimulation of an odorant molecule
Supporting Cells
Provide support and nourishment
Basal Cells
Replace olfactory receptors
How many different odors can be detected by Olfaction?
10,000
What are the 11 steps of Olfaction?
- Odorant molecule binds to the receptor of an olfactory hair
- Receptor linked to G protein; Odorant binding causes G-protein activation
- G-Protein activates adenylate cyclase
- Adenylate cyclase produces cAMP
- cAMP causes the opening of ligand gated Na+ channels
- Open Na+ channels allow the inflow of Na+
- Inflow of Na+ causes generator potential
- Generator potential turns into nerve impulses along olfacroty nerves
- nerve impulse travels to the olfactory bulbs
- Nerve impulse travels to the olfactory tract
- Nerve impulse travels to the primary olfactory area of the cerebral cortex
From the olfactory tract sensory information reaches:
- Cerebral cortex- allowing for consious smell
- Hypothalamus- controlling visceral reactions
- Amygdala- odor recognition and emotional association
What is another name for taste?
Gustation
The taste bud is made up of three types of epithelial cells:
- Supporting Cells
- Gustatory Receptor Cells
- Basal Cells
About per taste bud
50 Gustatory cells
Where are taste buds found?
Papillae
Three types of papillae with taste buds:
Vallate (circumvallate)
Fungiform
Foliate
Which type of taste bud doesnt have taste buds, but only mechanical function?
Filliform
What are the 5 basic taste sensations?
- Sweet
- Salt
- Sour
- Bitter
- Umami
Sweet
produced by organic compouds; e.g sugar or artificial sweeteners
Salt
produced by metal ions; e.g Na+ and K+
Sour
Associated with acids: e.g vinegar
Bitter
Produced by alkaloids; e.g unsweetened chocolate
Umami
taste related to amino acids to produce meaty flavor
What are the factors that affect taste?
Texture
Temperature
Adaptation
Olfaction
Thresholds
Gustatory Pathway
- Tastant binding to specific cell membrane proteins
- G proteins activated by sweet, bitter, and umami stimuli
- works through second messenger
- results in depolarization by salt and sour stimuli
- initiates action potentials and neurotransmitter release
What is the relay center for all your sensations?
Thalamus
Neural Pathways for taste
cranial nerves ⇒ Medulla ⇒ Thalamus →parietal lobe
→Hippocampus (emotion/memory vomiting)
→ Hypothalamus (salvation, gagging)
What are the three layers of the eye?
– Fibrous tunic- outer layer
• Sclera “white” of the eye
• Cornea-transparent coat
– Vascular tunic or uvea- middle layer
• Choroid
• Ciliary body consists of ciliary processes and ciliary muscle
• Iris
– Retina(sensory) - inner layer
• Optic disc
• Macula lutea- fovea centralis
What does the lens divide the eyeball into?
Anterior cavity- filled with aqueous humor
Posterior cavity- filled with vitreous body
What does the outer segment of a rod and cone contain?
photopigments
transduction of light energy into receptor potential
What does the inner segment of a rod/ cone contain?
nucleus, golgi complex, mitochondira
What are the two parts to a pigment?
opsin (four types: 3 in cones and 1 in rod)
retinal (light absorbing part)
Rod photopigment
rhodopsin
cone photopigments
red, blue, green
what happens with absorption of light to a photopigment?
structural changes in retinal
Photobleaching steps
Isomerization
Bleaching
Regeneration
Isomerization
In darkenss: retinal has a bent shape called cis retinal
Absorption of a photon causes straigtening of the retinal into trans retinal
Bleaching
trans-retinal separates from opsin
Regeneration
trans-retinal turns back into cis retinal
What are the steps of vision in the dark?
- ) In the outer segment of the rod (on disks), Cis-retinal is bound to opsin: With cis-retinal bound, opsin cannot block the production of cGMP. A whole bunch of cGMP is made
- ) Binding of cGMP(ligand) on sodium channels opens the channels allowing sodium to flow in
- )This causes a graded potential to travel down the rod.
- )Graded potential at the axon terminal bulbs causes release of the neurotransmitter glutimate
- ) Glutimate is an INHIBITORY neurotransmitter. It’s effect on the bipolar cell is hyperpolarization: it opens ligand gated chloride ion channels.
- )Chloride ions (negative charge) flow into the bipolar cell making it even more negative than resting membrane potential. This stops the bipolar cell from depolarizing and sending an action potential
- ) No action potential stimulated on ganglion cells
What happens in the light?
- )A photon of light is absorbed by cis-retinal. It changes from cis-retinal to trans-retinal.
- )Trans-retinal separates from opsin (photobleaching) Opsin then interacts with molecules inside of the outer segment and shuts off the production of cGMP.
- )Without cGMP (the ligand for the ligand gated sodium
channels) , the sodium channels remain closed. This stops the inflow of sodium and the rod does not generate a graded potential.
4.)Without a graded potential, the inhibitory neurotransmitter glutimate is not released from the rod. Without glutimate binding to the bipolar cell, the bipolar cell depolarizes and generates an action potential.
5.) Excitatory neurotransmitters are released by the bipolar
cell. The excitatory neurotransmitters cause the ganglion cells
to depolarize and an action potential is sent along the optic nerve toward the brain.
What are the three main regions of the ear?
External
Middle
Internal
External Ear
- auricle or pinna
- external auditory canal
- tympanic membrane
- Ceruminous glands
Middle Ear
- auditory ossicles: malleus, incus and stapes
- auditory (eustachian) tube
Internal Ear
• Labyrinth: bony and membranous
– Bony labyrinth- perilymph
– membranous labyrinth- endolymph
– Oval window and round window- membranous regions.
What are the three parts that compose the inner ear
Semicircular canals
vestibule
cochlea
What is the ampulla?
stem/root of the semicircular canals
what two sacs does the vestibule consist of?
utricle and saccule
What is our audible sound range?
20-20,000 Hz
What is the pathway for hearing?
- Sound waves→
- Auricle/Pinna→
- external auditory canal→
- tympanic membrane→
- malleus→ incus→ stapes→ oval window→
- perilymph of the scala vestibuli→
- vestibular membrane→
- endolymph in the cochlear duct→
- basilar membrane →
- hair cells against tectorial membrane →
- bending of hair cell stereocilia→
- receptor potential→
- nerve impulse
- Sound wave → scala tympani→ round window
What are the two tyoes of equilibrium?
Static
Dynamic
Static Equilibruim
Maintenance of the body position relative to the force of gravity
Dynamic Equilibruim
Maintenance of body position (mainly head) in response to rotational acceleration and deceleration
What are the receptors for equilibruim? what are they collectively called?
hair cells in the utricle, saccule and semicircular canals and are collectively called vestibular apparatus
What are the three channels of the cochlea?
Cochlear duct
scala vestibuli
scala tympani
What composes the cochlea?
The three channels
Helicotrema
Vestibular membrane
Basilar membrane
Spiral organ of corti: hair cells
