3.6.1.2 receptors

Question 1

structure of pacinian corpuscle

Answer 1

capsule
lamellae separated by viscous gel
sensory neurone
meylin sheath

Question 2

what does the pacinain corpuscle detect

Answer 2

pressure

Question 3

what is action potential

Answer 3

change in charge across the axon membrane, from -70mv to -55mv

Question 4

what is generator potential

Answer 4

depolarisation of the membrane of the receptor cell

Question 5

what is depolarisation

Answer 5

when Na+ diffuse through the stretch mediated sodium ion channels, making the voltage less negative

Question 6

what happens when the pacinian corpuscle detects a stimulus

Answer 6

detecting pressure, the lamellae become stretched and deformed.
this opens the stretch mediated sodium ion channels.
making the membrane more permeable to Na+
this allows more sodium ions to diffuse into the membrane making the voltage less negative.
resulting in generator potential

Question 7

how does action potential occur

Answer 7

if the generator potentaial reaches the threshold point of -55mv, this generates action potential

Question 8

what does action potential cause

Answer 8

an electrical nervous impulse to be transmitted across the sensory neurone to the CNS

Question 9

rod cells

Answer 9

contain the rhodopsin pigment, which is broken down at low light intensities.
multiple rod cells are connected to one bipolar cell = retinal convergence
do not detect colour.
low visual acuity

Question 10

cone cells

Answer 10

three different cone cells.
contain different types of iodopsin pigment which absorbs different wavelengths (red,blue or green) and is broken down at high light intensities.
one cone cell connected to one bipolar cell, high visual acuity and no retinal convergence.

Question 11

visual acuity

Answer 11

ability to distinguish between separate light sources of light.
higher visual acuity = more detailed and focused vision

Question 12

distribution of rod and cone cells

Answer 12

rod cells are located in the peripheral retina. none are found in the fovea or optic nerve.
cone cells are located in the fovea, densely packed

Question 13

what is spatial summation

Answer 13

present in rod cells.
when 3 rod cells send information to 1 bipolar neurone, allows for high sensitivity to light

Question 14

why do cone cells have high visual acuity

Answer 14

1 cone cell is connected to 1 bipolar cell, easily distinguish between separate light sources

Question 15

why do cone cells give colour vision

Answer 15

3 types of cone cells with 3 types of iodopsin pigment.
each pigment absorbs a different wavelength (red, green or blue) different proportions allow for different shades.