physiological organisation + control II

Question 1

what types of light can some animals detect

Answer 1

some animals can detect IR and UV light, as opposed to humans who can only detect visible light

Question 2

how does photoreceptor sensitivity vary

Answer 2

photoreceptors are more sensitive in low ambient light eg nocturnal tipula, and less sensitive in high ambient light eg diurnal sarcophagia

Question 3

how does light affect flying speed

Answer 3

in high ambient light images are made quickly to they can fly fast. in low ambient light images are generated slowly using summation so they must fly slower in order to prevent blurred vision

Question 4

what happens if insects fly in both high and low ambient light

Answer 4

eg bees they only have one type of photoreceptor but adapt by flying slower. this allows time for summation to generate images to prevent blur. it also helps account for the decrease in signal: noise ratio where the image is more difficult to identify against background ‘noise’

Question 5

describe lateral inhibition

Answer 5

the inhibition of neighbouring neurones to enhance contrast at the edge of an object

Question 6

how are pink helmet jellyfish innervated

Answer 6

pacemakers regulate innervation of motor giant rootlets (aka inner ring) which coordinates the contraction of the myoepithelium (muscle) via 8 motor giant axons

Question 7

describe conduction in slow swimming of pink helmet jellyfish

Answer 7

conduction speed of the axons is around 0.4m/s and the muscle contracts around every 2 seconds

Question 8

describe conduction in fast swimming of pink helmet jellyfish

Answer 8

conduction speed of axons is around 3.0m/s and is initiated by hair cells detecting vibrations of contact. speed is due to short chemical synaptic delay

Question 9

how do pink helmet jellyfish detect tilt

Answer 9

8 statocysts detect the mechanoreception of an internal statolyth which allows interpretation of its relative position

Question 10

how do pink helmet jellyfish feed

Answer 10

with nematocysts, either via ambush (passive) or feeding current (active)

Question 11

describe the ionic basis of slow swimming in pink helmet jellyfish

Answer 11

a slow rise/ decay of EPSP causes slow electrical transmission and therefore slow swimming. the weak Ca2+ action potentials -30mV fail to reach the threshold for faster Na+ potentials

Question 12

describe the ionic basis of fast swimming in pink helmet jellyfish

Answer 12

a fast rise/ decay of EPSP causes fast electrical transmission and therefore fast swimming. larger Ca2+ action potentials -100mV are sufficient to reach threshold for faster Na+ potentials