Week 2: Introduction to the Visual System Flashcards
Describe the conceptual stages how sensory systems convey messages to the brain?
Using the common sequence of events (psychophysics)
- Energy (external stimulus)
- Receptor
- Electrophysiological signal (movement of ions)
- Brain
- Perception
List the features of the sensory system
- Vestibular cortex
- Somatosensory cortex
- Olfactory cortex
- Gustatory cortex
- Audiotory cortex
- Visual cortex
Vestibular cortex
Balance (in the ear)
Somatosensory cortex
Touch (pain response)
Olfactory cortex
Smell (nose)
Gustatory cortex
Taste (tongue)
Auditory cortex
Hearing (ears)
Visual cortex
Seeing (eyes)
Anatomical Plan Pathway
- Receptor
- Thalamus (relay station for reorganisation)
- Cortex
Physiological Processing Plan Pathway
- Reception
- Transduction
- Coding
- Output
Describe the basic sensory visual processing pathway
- Photoreceptors
- Retinal ganglion cells
- Optic nerve
- Thalamus (LGN)
- Optic radiations
- Visual cortex
What information is important for the visual system to detect and process?
- Colour contrast
- Illumination
- Motion
- Attention
Sagittal Plane
- Divides body/object into R and L parts
- Side to side
Transverse Plane
- Divides body/object into superior and inferior parts
- Top and bottom
Coronal/Frontal Plane
- Divides body/object into front and back parts
- Front to back
Anterior/Rostral
Front
Posterior/Caudal
Back
Superior/Dorsal
Top
Inferior/Ventral
Bottom
Proximal
Closer to the origin of the structure
Distal
Further from the origin of the structure
Medial
Towards the midline
Lateral
Away from midline
Ipsilateral
Same side of body
Contralateral
Opposite side of body
Name the chambers of the human eye
- Anterior chamber
- Posterior chamber
- Vitreous chamber
Anterior chamber: what is it filled with and measurement, depth, anterior and posterior limit
- Filled with aqueous humour (0.2 mL)
- Measures 3 mm at greatest depth centrally
- Anterior limit: cornea & sclera
- Posterior limit: iris & lens
Posterior chamber: what is it filled with and measurement, anterior, posterior and peripheral limit
- Filled with aqueous humour (0.06 mL)
- Anterior limit: iris
- Posterior limit: lens & zonules
- Peripheral limit: ciliary processes
Vitreous chamber: what is it filled with and measurement, anterior and posterior limit
- Largest chamber and filled with vitreous humour (6.5 mL)
- Anterior limit: lens & zonules
- Posterior limit: retina
What are the layers of the human eye?
- Internal nervous layer (retinal layer)
- Intermediate vascular pigmented layer (uvea)
- External, fibrous layer (cornea & sclera)
What are the components in the internal nervous layer (retinal layer)
- Photoreceptors = rods for capturing light and 3 cones for capturing light in bright illumination (daylight, colour vision)
- Bipolar cells
- Ganglion cells
- Foveal area = devoid of blood vessels & very tightly packed with photoreceptors (helps with creating sharp images)
What are four functions of the internal nervous layer (retina layer)?
- Nourishment
- Waste removal
- Protection
- Sharp imagery & fixation
What are the components in the intermediate vascular pigmented layer (uvea) and their functions?
- Iris
- To control the amount of light entering the pupil
- To allow light in, in dim light conditions - Ciliary body
- Production of the aqueous humous and lens zonules
- Holds lens in place
- Facilities accomodation - Choroid
- Supplies blood to the retina and pigmented epithelium
What are the components in the External fibrous layer. Describe its characteristic and function
- Sclera
- Anteriorly forms ‘white’ of the eye
- Function: protection, fixation & teaming - Cornea
- Characteristic: transparent
- Function: main refractive power of the eye
What are the four sections of the optic nerve and its measurements with their position?
- Intraocular/optic nerve head: 1 mm long
- Intraorbital: 25 mm long
- loosely held bounded by sclera anteriorly & optic canal posteriorly - Intracanalicular: 10 mm long
- begins at optic foramen, ends at insertion to intracranial cavity - Intracranial: 15 mm long
- extending from intracranial cavity to optic chiasm
What are the functions for optic nerve?
- Anterior extension of white matter of the brain
- Carries axons of ganglion cells of the retina to the lateral geniculate (LG) body then to the visual cortex
