The Senses Flashcards
What is transduction?
The process where receptors will convert sensory information into neural signals
What is the sensory process?
- Sensory organs collect the signal
- Sensory receptors convert the energy of the stimuli into neural signals
- The signal is transmitted to sensory brain areas
- The brain processes the signal
Where does transduction begin?
At the sensory receptor
How are sensory systems specialised?
To detect environmental stimuli
What is the step of receptor potentials?
Between the arrival of energy at the receptor cell and the initiation of an action potential
What does the thalamus do?
Relays sensory impulses from receptors to various parts of the body to the cerebral cortex
What does the pupil do?
Allows an opening for light to reach the retina
What does the iris do?
Vary the size of the pupil
What is the pupil and iris covered by?
Cornea
What is the optic nerve?
A nerve that carries axons from the retina, exits the back of the eye and passes through the orbit to reach the brain
What is the optic disk?
Where the optic nerve exits the retina
Why can’t the sensation of light occur at the optic disk?
Lack of photoreceptors
What happens when the eye captures light?
It focuses it on the visual receptors?
What do photoreceptors do?
Convert light energy into neural impulses which are sent to the brain
What does photoreceptors influence?
The membrane potential of bipolar cells
What are the two types of photoreceptors?
Rods and cones
What are the four types of neurones in the retina?
Ganglion cell, bipolar cell, amacrine cell, horizontal cell
What do ganglion cells do?
Fire action potentials to propagate to the optic nerve and then to the brain
What do amacrine cells do?
Input from bipolar cells and influence ganglion, bipolar and other amacrine cells
What do horizontal cells do?
Receive input from photoreceptors to influence bipolar cells and photoreceptors
What are the layers of the retina?
Photoreceptor layer, the intermediate layer, the ganglion cell layer
What vision does the rods and cones provide?
Rods- grey scale and cones- colour
What happens in the photoreceptor layer?
Phototransduction
What occurs when there is darkness in the photoreceptor layer?
The Na+ ion channel open from cGMP and the photoreceptor is depolarised from the influx of sodium which creates a dark current