Receptors+ Control Of Heart Rate

Question 1

What type of receptor is pacinian corpuscle

Answer 1

Baro receptor

Question 2

Where is pacinian corpuscle found

Answer 2

In the skin
E.g fingers soles of feet
And also tendons ligaments and joints

Question 3

What is pacinian corpuscle made up of

Answer 3

Lamellae

Question 4

Explain how applying pressure to Pacinian corpuscle changes membrane potential

Answer 4

Pressure causes membrane to be stretched
Sodium ion channel proteins open and Na+ diffuse in
Greater pressure means more channels open and more Na+ diffuse in

Question 5

What is the maximum frequency of action potentials limited by

Answer 5

Refactory period

Question 6

RODS

Answer 6

Evenly distributed throughout the maculla
Sensitive to all wavelengths of light (rhodopsin is the light sensitive pigment)
High visual sensitivity to low levels of light intensity
Low visual acuity- image unclear
Retinal convergence- several rods share a single bipolar neuron
Generator potentials combine to reach theeshold

Question 7

Cones

Answer 7

Densely packed in fovea
Each cone cell (3) detects a specific wavelength of light
3 types of iodopsin
Iodopsin less sensitive than rhodopsin so requires higher light intensity
High visual acuity givin sharp image
This is because each cone cell is connected to a single bipolar neurone
Cone cells send separate impulses to the brain

Question 8

What do photons do

Answer 8

Cause the light pigment to break down altering chemical structure
Leading to generator potential

Question 9

What does retinal convergence lead to

Answer 9

Spatial summarion

Question 10

What summation is cones an example of

Answer 10

Temporal

Question 11

Heart muscle is myogenic
What dies this mean

Answer 11

Can iniate its own contraction

Question 12

Heart controls and coordinates the regular contraction of the atria ventricles
How

Answer 12

SAN sends out an electrical impulse causing the atria to contract
Layer of non conductive tissue preventing it reaching the ventricles
Electrical impulse reaches the AVN
0.1 seconds to allow atria to empty out blood
AVN sends another electrical impulse
This travels down the bundle of His
Up the purkinje fibres
Ventricles contract from the apex of the heart upwards

Question 13

Which nervous system is heart rate controlled by

Answer 13

Autonomic nervous system

Question 14

What is the autonomic nervous system split into
Relation of the two branches

Answer 14

Sympathetic
Parasympthetic
Antagonistic- opposing effects

Question 15

Neurotransmitter for sympathetic system

Answer 15

Noradrenaline

Question 16

Neurotransmitter for parasympathetic nervous system

Answer 16

Acetylcholine

Question 17

Membrane potential is the same whether medium or heavy pressure applied
Why

Answer 17

Threshold reached
So maximal response given /all or nothing principle

Question 18

Parts of the myelin sheath are destroyed
Explain how this results in slower responses to stimuli

Answer 18

Less saltatory conduction/action potential
Impulses unable to jump from node to node
More depolarisation over area of membrane

Question 19

Describe how pacinian corpuscle produces generator potential when stimulates

Answer 19

Increased pressure deforms the stretch mediated Na+ channel proteins
Causing them
To open
Na+ diffuse in
Depolarisation

Question 20

When light falls on cell 3 no light seen. Bur when light falls on cell 3+4+5 light seen
Why

Answer 20

1 unit subthreshold whereas 3 units are above threshold
1 unit no impulses are sent to brain
3 units lead to an impulse sent /spatial summarion

Question 21

Explain what causes vision in the fovea to be in colour

Answer 21

3 different types of cone cells sensitive to different wavelengths of light

Question 22

Disadvantage of taking the drug in a pill

Answer 22

Drug would be destroyed by acid in stomach

Question 23

What is the role of atp in myofibril contraction

Answer 23

Allows binding of myosin to actin
Atp provides energy which changes shape of myosin head
(Atp hydrolysed into Adp + Pi by Atp hydrolase) this provides the energy

Question 24

Tropomyosin

Answer 24

Moves out of the way when Ca2+ bind
Allowing myosin to bind to actin forming crossbridge

Question 25

Role of Myosin in myofibril contraction

Answer 25

Head of myosin binds to actin
Myosin detaches from actin and resets
This uses Atp
(Atp binds to myosin breaking cross bridge and Atp releases energy which changes shape of myosin head )

Question 26

Describe what is meant by threshold

Answer 26

When threshold reached
Causes maximal response// all or nothing principle

Question 27

Explain how fovea increases detail of an image

Answer 27

High visual acuity
Each cone connected to single bipolar neurone
Each cone sends separate impulses to the brain

Question 28

People with red-green blindness are unable to distunguish between red and green
Why

Answer 28

Green sensitive pigment/cone non functional
3 diff types of cone
Other colours seen due to stimulation of more than one pigment

Question 29

Explain how nervous control in a human can cause increased cardiac output

Answer 29

Increase in nerve impulses sent to the cardiac control centre in the medulla
Increased impulses along sympathetic nerve
To SAN
Release of noradrenalin
More impulse sent from SAN to atria
Increases heart rate

Question 30

Explain why increased cardiac output is an advantage ti exercise

Answer 30

Higher CO- increase O2 delivery
Increases glucose supply
More Atp produced via aerobic respiration
Increase CO2 removal
Delays formation of lactate

Question 31

What does the frequency of action potentials relate to

Answer 31

Intensity of the stimulus

Question 32

Explain how the connection of several rods to a single bipolar neurone
Influences visual acuity

Answer 32

Spatial Summation means cannot distinguish between stimuli from different rods linked to same bipolar cell
Decreases acuity