receptors ms answers Flashcards
The fovea of the eye of an eagle has a high density of cones. An eagle focuses the image of its prey onto the fovea.
Explain how the fovea enables an eagle to see its prey in detail.
high visual acuity
each cone connected to single neurone
cone send separate set of impulses to brain
The retina of an owl has a high density of rod cells.
Explain how this enables an owl to hunt its prey at night.
high visual sensitivity
several rods connected to single neurone
spatial summation to overcome threshold
Explain how the resting potential of –70 mV is maintained in the sensory neurone when no pressure is applied.
membrane is more permeable to potassium ions and less permeable to sodium ions
sodium ions actively transported out
potassium ions in
Multiple sclerosis is a disease in which parts of the myelin sheaths surrounding neurones are destroyed. Explain how this results in slower responses to stimuli.
no saltatory conduction
impulse cant jump from node to node
more depol along full length of membrane
After the student had stared at a purple square, he saw a green afterimage.Suggest why.
stared at square, red nd blue cones are stimulated
green isnt stimulated
red and blue cone cells become exhausted and stop working
so green cone cells start working
what time of stimuli might receptors in the eye respond to
pressure
temp
light
smell
blink rate producing means that are not significantly different. Explain why.
standard deviations overlap
The blink reflex can be stopped by drugs which prevent the opening of sodium ion channelproteins in the axons of motor neurones.
Suggest how these drugs affect the passage of nerve impulses along the axons.
low influx of sodium ions
so no depol and action potential
what causes vision to be in colour and have a high visual acuity
three different types of cone cells which are sensitive to different wavelengths
impulses are set along separate neurone from each receptor cell
how wold the distribution of rod and cones differ in a nocuturnal animal and a human
nocturnal animal would have rods only as they are highly sensitive to light
humans - cones
rhodopsin bleach at low light intensity
