Nervous System Physiology Part 7 Flashcards
Describe rods in vision
- Rods are our dim-light and peripheral vision receptors.
- They are more numerous and far more sensitive to light than cones are.
- They do not provide sharp images or color vision.
- Colors disappear and the edges of objects appear fuzzy in dim light and at the edges of our visual field.
Describe cones in vision
- Cones, by contrast, are our vision receptors for bright light and provide high-resolution color vision.
Compare the location in the retina for rod cells and cone cells.
- Rod Cells: Found around the periphery
- Cone Cells: Found around the central fovea
Compare the optimal light conditions for rod cells and cone cells.
- Rod Cells: Dim light (“night” vision)
- Cone Cells: Bright light (“day” vision)
Compare the visual acuity provided by rod cells and cone cells.
- Rod Cells: Low resolution (many rods converge onto one bipolar cell)
- Cone Cells: High resolution (one cone synapses with one bipolar cell)
Compare the color sensitivity of rod cells and cone cells.
- Rod Cells: All wavelengths (achromatic, black and white)
- Cone Cells: Certain wavelengths (red, green, blue)
Compare the type of vision provided by rod cells and cone cells.
- Rod Cells: Non-color
- Cone Cells: Color
Compare the number of types of photopigments in rod cells and cone cells.
- Rod Cells: One (all contain rhodopsin)
- Cone Cells: Three different iodopsin pigments
Compare the relative abundance of rod cells and cone cells.
- Rod Cells: Many
- Cone Cells: Fewer
Describe the optic pathways starting from the retinal ganglion cells.
Axons from retinal ganglion cells form the optic nerves and optic tracts, synapse in the lateral geniculate body of the thalamus, and ascend to the visual cortex in the geniculocalcarine tract.
How do hear stuff?
Sound waves enter the external auditory canal and the sound energy is transmitted from the tympanic membrane to the inner ear (cochlea) by the malleus, incus, and stapes in the middle ear.
What structures transmit sound energy from the tympanic membrane to the inner ear?
The malleus, incus, and stapes.
Through which canal do sound waves enter the ear?
The external auditory canal.
What is the cochlea almost completely divided by?
A membranous tube called the cochlear duct
What does the cochlear duct contain?
Sensory receptors of the auditory system.
What are the receptor cells in the organ of Corti called?
Hair cells
What type of receptors are hair cells?
Mechanoreceptors
What protrudes from one end of hair cells?
Hairlike stereocilia.
What membrane lies above the hair cells in the organ of Corti?
The tectorial membrane.
What is the function of stereocilia on hair cells?
They detect mechanical changes (vibrations) and convert them into neural signals.
Neural Pathways in Hearing
ongitudinal
• Cochlear nerve fibers enter the brainstem and synapse with
Lateral
Portary auditory
cus (halamus)
Inferior colliculus
interneurons there. Fibers from both ears often converge on the same neuron.
• From the brainstem, the
- Lateral lemniscus
information is transmitted via a polysynaptic pathway to the thalamus and on to the auditory cortex in the temporal lobe.
Where do cochlear nerve fibers synapse after entering the brainstem?
They synapse with interneurons in the brainstem
Where do auditory signals travel after the brainstem?
To the thalamus via a polysynaptic pathway, then to the auditory cortex in the temporal lobe.
What part of the brain is responsible for processing auditory signals?
A combination of involuntary reflexes (spinal cord) and voluntary actions (higher brain centers).
What does posture and movement depend on?
A combination of involuntary reflexes (spinal cord) and voluntary actions (higher brain centers).
Name the five components involved in motor control.
Spinal Cord, Brain Stem, Cerebellum, Basal Ganglia, Motor Cortex.
What is the function of the higher centers in the motor control hierarchy?
Form complex plans based on intention and communicate with the middle level.
What brain areas are associated with the higher centers?
Areas involved with memory, emotions, motivation, and the sensorimotor cortex.
What is the function of the middle level in motor control?
Converts plans from higher centers into programs for patterns of neural activation.
Which structures are part of the middle level?
Sensorimotor cortex, cerebellum, parts of basal nuclei, and some brainstem nuclei.
What is the role of the local level in motor control?
Specifies muscle tension and joint angles to execute movement.
Which structures are included in the local level?
Brainstem or spinal cord interneurons, afferent neurons, motor neurons.
