6.3 Receptors

Question 1

what causes vision using fovea to be in colour

Answer 1

three different types of cones for different colours

Question 2

what causes vision using fovea to have high visual accuity

Answer 2

each receptor cell connects to a seperate nuerone

Question 3

why does it take time for rod cells to recover their sensitivity to light after moving into darkness

Answer 3

rhodopsin pigment has been broken down by light

must wait for pigment to resynthesise

Question 4

role of the sino atrial node (SAN)

Answer 4

sinoatrial node acts as a natural pacemaker
sends an electrial impulse out to the atria

Question 5

exercise causes an increased heart rate. describe the role of receptors and of the nervous system in this process (4)

Answer 5

chemoreceptors detect a rise in co2

they send an impulse to medulla

more impulses sent to SAN

by synaptic nerve

Question 6

describe how a pacinian corpuscle produces a generator potential when stimulated (3)

Answer 6

applying pressure causes membrane to stretch and change shape

stretch mediated sodium channels open and sodium enters

which causes depolorisation allowing a generator potential to be reached

Question 7

the cardiac cycle is controlled by the sinoatrial node (SAN) and the atrioventricular node
describe how.

Answer 7

sinoatrial node acts as a natural pacemaker

SAN sends an electrical impulses atrium

atria contracts

AVN transfers electrical impulses to bundle of HIS

fiborous, non conductive nature of bundle of HIS allows for delay so that ventricles can fill

bundle of HIS conducts impulse to purkyne fibres

ventricles contract together from base upwards

Question 8

when a wave of electrical activity reaches the AVN, there is a short delay.
explain the importance of this (2)

Answer 8

allows for atria to empty and ventricle to fill

before ventricle contracts