Receptors

Question 1

What is the role of a receptor

Answer 1

To convert stimulus energy into a generator potential acting as a transducer

Question 2

What is a pacinian corpuscle ?

Answer 2

Transduces mechanical energy into a generator potential

Question 3

Describe the structure of the pacinian corpuscle

Answer 3

A single sensory neurone foynd deep within the skin surronded by layers of tissue with a viscous gel in between

Question 4

How does the pacinian corpuscle work?

Answer 4

The neurone contains stretch mediated sodium channels,
Their permeability varies dependant on the shape
At rest narrow Na+ channels so doesnt allow sodium in therefore at resting potential
Pressure increases membrane permeability and so sodium ions diffuse
Neurone depolarises = generator potential
Creates an action potential

Question 5

What colours of light do rod cells detect?

What pigment do they contain?

Answer 5

Black and white

Rhodopsin

Question 6

Describe the effect of one sensory neurone being attached to many rod cells

Answer 6

Helps to make sure that the threshold is met as more impulses from receptors meet the same sensory neurone
Allows the generator potential to be reached
But low visual acuity because the sensory neurone sends the same impulse is irrespective of the specific rod cell

Question 7

Where are rod cells found?

Answer 7

In the outer areas of the eye

Question 8

What colours do cone cells allow us to see?

What pigment is present?

Answer 8

Colour (not black and white)

Iodopsin

Question 9

Describe why cone cells have greater visual acuity than rod cells

Answer 9

They have an individual neurone each, therefore one cone cell produces a more specific generator potential

Question 10

Give two reasons why cone cells emit signals in higher intensities of light than rod cells

Answer 10

Individual cone cells have an individual neurone attached, requires greater energy to overcome the threshold to produce a generator potential.
Iodopsin breaks down in greater intensity light than rhodopsin

Question 11

Where is light focused in the eye? What cells are present here? Where is the other type of cell found?

Answer 11

Focused on the fovea in the centre where there are more cone cells, where as the rod cells are present in the peripherys

Question 12

Define the terms sympathetic and parasympathetic nervous system. State the type of relation between the two

Answer 12

Sympathetic nervous system: stimulates effectors to increase activity
Parasympathetic nervous system: inhibits effectors slows activity down
Antagonistic

Question 13

Which part of the brain is responsible for controlling heart rate?

Answer 13

Medulla oblongata

Question 14

Where is the medulla oblongata attached to in terms of rate rate regulation?

Answer 14

The sinoatrial node

Question 15

The heart muscle is myogenic, what does this mean?

Answer 15

Its contraction is initiated from within the muscle its self

Question 16

Where is the sino atrial node?

Answer 16

On the wall of right atrium

Question 17

Describe from the point where adrenaline meets the SAN how the heart beats

Answer 17

SAN sends wave of electrical excitation
Across the atria causing them to contract
Atrioventricular septum is a layer of non conducive tissue prevents the excitatory wave from entering the ventricles
Excitatory wave reaches AVN - atrioventricular node
Found between the atria
AVN causes a slight delay
Converys the impulse across purkyje fibres - purkyge factors combine to a bundle of his
Bundle of his continues impulse
Causes ventricles to contract

Question 18

What two receptors control the signals sent to the SAN? Where are they found?

Answer 18

Chemoreceptors that are sensitive to blood pH found in the carotid arteries
Pressure receptors detect the blood pressure, in aorta
They send signals to the medulla oblongata to either reduce the number of impulses or increase