Lecture 9 - The Brain And Species Senses Flashcards
Sensory Receptor Definition
Dendrites of Sensory Neurons
Sensation Definition
Arriving Information into the CNS
Perception Definition
Conscious Awareness of a Sensation
Percentage of info that reaches conscious awareness
~1%
6 General Senses
Temperature
Pain
Touch
Pressure
Vibration
Proprioception (Body Position)
5 Special Senses
Smell
Taste
Vision
Hearing
Balance
Difference between General/Special Senses
General Senses use receptors all over the body
Special Senses use receptors from specific sensory organs
Organs used in Olfaction
Olfactory Organs
2 Parts of Olfactory Organs
Olfactory Epithelium
Olfactory Glands
Nerve used in Olfaction
Olfactory Nerve (I)
Steps of Olfaction
Air swirls within nasal cavity
Lipid/Water Soluble chemicals diffuse into the mucus
Olfactory Receptors stimulated
Chemicals interact with odorant binding receptors on cilia
Binding of odorants produces action potentials
Info relayed to CNS
Contents of Olfactory Epithelium
Receptor Cells
Supporting Cells
Olfactory Gland Function
Secretes mucus to coat face of olfactory organs
2 Mucus Function in Olfaction
Protects receptors on cilia from potent smells
Can dissolve chemicals
Common Cold Definition
The overstimulation of Olfactory Glands
Odorant Definition
Chemicals that stimulate olfactory receptors
Density of Olfactory Receptor Cells
Between 10/20 million olfactory receptor cells packed into ~5cm2
Pathway of info to CNS
Olfactory Nerve (CN I) reaches Olfactory Bulb
Axons travel along olfactory tract to olfactory cortex
Trend in receptor density/smell
Higher Surface Area of Receptors = Heightened Sense of Smell
Location of Olfactory Cortex
In Temporal Lobe
Location of Taste Receptors
Superior surface of the Tongue
Taste Buds Location
Sides of papillae
Papillae Definition
Epithelial Projection of the Tongue
3 types of Papillae
Filiform - No Taste Buds
Fungiform - ~5 Taste Buds
Circumvallate - ~100 Taste Buds
Location of Fungiform Papillae
Front of Tongue
Location of Circumvallate Papillae
Back of Tongue
2 Contents of Taste Buds
Gustatory Cells
Supporting Cells
Taste Pore Definition
Area of where microvilli of gustatory cells extend to surrounding fluid
6 Taste Sensations
Bitter
Sweet
Sour
Salty
Umami
Water
Function of Water Taste Sensation
Monitors hydration levels
Water Receptor Location
Pharynx
3 Steps of Taste Mechanism
Dissolved Chemicals contact microvilli
Change in membrane potential
Results in Action Potential
Pathways of Taste Mechanism
Use Facial (CN VII), Glossopharyngeal (CN IX), Vagus (CN X)
Cranial Nerves will synapse with medulla oblongata
Info sent to the Thalamus
Location of Gustatory Cortex
In Temporal Lobe
Diameter of Eye
~24mm
4 Parts of eye contacting light (in order)
Cornea
Pupil
Lens
Retina
Location of sensory neurons in the Eye
Retina
Function of Cornea
Causes Light Refraction
Refraction Definition
The bending of light as it travels from one medium to another
Cause of Short Sightedness
Not enough refraction of light
Cause of Long Sightedness
Too much refraction of light
Number of rods and cones in an Eye
~100 Million Rods
~5 Million Cones
2 types of Photoreceptors
Rods
Cones
Function of Rods (2 points)
Predominate periphery vision
Detect absence/presence of light
Function of Cones (2 points)
Predominate Central vision
Detect colour
Photopigments Definition
Light sensitive molecule in Photoreceptors
Rhodopsin Definition
Main component of Photopigments
2 Components of Rhodopsin
Opsin
Retinal
Rhodopsin reaction to light
In the presence of light, Rhodopsin splits
This alters the flow of electrical current
Thus, action potential is produced
5 Steps of Vision Mechanism
Light refracted by Cornea
Light interacts with photopigments in photoreceptors
Rhodopsin splits
Electrical flow is altered
Action Potential is produced
Pathways of Vison Mechanism
2 Optic Nerves (CN II) reach Diencephalon
Nerves cross over in optic chasm
Pass through the Superior Colliculus
Nerve Reach Thalamus on the opposite side of the brain
Info reaches visual cortex
Binocular Vision Definition
Field of view where both eyes are used
Location of Visual Cortex
In Occipital Lobe
Receptors used in Hearing/Balance
Mechanoreceptors
3 Parts of the Ear
External Ear
Middle Ear
Inner Ear
Location of Hearing Receptors
Cochlea
Location of Balance Receptors
Semicircular Canals
3 Components of Auditory Ossicles
Malleus
Incus
Stapes
Tympanic Membrane Definition
Membrane separating Middle Ear from ear canal
Auditory Ossicle in contact with Tympanic Membrane
Malleus
4 Components of Cochlea
Vestibular Duct
Cochlear Duct
Tympanic Duct
Organ of Cocti
2 windows in Bony Labyrinth of Cochlea
Round Window = Base of Tympanic Duct
Oval Window = Base of Vestibular Duct
Components of Organ of Cocti
Basilar Membrane
Tectorial Membrane
Movement of Stereocilia in Organ of Cocti
Vibration causes movement of tectorial membrane
Causes movement of cilia on receptors
Generates action potential
6 Steps of Hearing Mechanism
Sound waves arrive at Tympanic Membrane
Movement of Tympanic Membrane causes displacement of auditory ossicles
Movement of Stapes at the Oval window establishes pressure waves in perilymph of the vestibular duct
Basilar membrane distorted
Vibration of Basilar Membrane causes hair cell vibration against Tectorial Membrane
Action Potential Generation
Auditory/Equilibrium Pathways
Sensory Neurons located in spiral ganglion
Use Vestibulocochlear Nerve (CN VIII)
Enter Medulla Oblongata
Pass through Inferior Colliculus, Thalamus to reach Auditory Cortex
Layers of Semicircular Canals
Bony Labyrinth
Perilymph
Membranous Labyrinth
Endolymph
3 Semi-circular Canals
Anterior
Posterior
Lateral
Steps of Mechanism of Balance
Receptors respond to rotational movement
Movement leads to Fluid in cupula
Hair Cells in Cupula move
Action Potential Generation
2 Otoliths
Utricle = Horizontal Linear Accelerations
Saccule = Vertical Linear Accelerations
Function of Otoliths
Sense Gravity and Linear Acceleration
4 Functions of Vestibular Nuclei
Integrate sensory information arriving from each side of the head
Relay information to cerebellum
Relay information to cerebral cortex
Send commands to motor nuclei in brain stem and spinal cord