Receptors And Control Of Heart Rate

Question 1

Structure of pacinian corpuscle

Answer 1

Lamella
Axon
Myelin sheath
Nodes of ranvier

Question 2

Describe the pacinian corpuscle?

Answer 2

1.pressure stimulus deforms the lamellae of pacinian corpuscle surrounding axon
2. Causing deformation of sodium ion stretched mediated channels
3. This causes channels to open and sodium ions to diffuse in
4. This causes depolarisation of the membrane leading to generator potential
5. If stimuli build up to reach threshold potential

Question 3

Describe the introduction of muscles that causes the pupil to constrict ( narrow )? Cc

Answer 3

1. Circular muscles contract
2. Radial muscles relax

Question 4

Describe the interaction of muscles that caused the pupil to dilate ( widen) ?

Answer 4

Circular muscles relax
Radial muscles contract

Question 5

What are the two types of receptor cells in the eye?

Answer 5

Rods and cones

Question 6

Where are the rods in the eye ?

Answer 6

Evenly distributed throughout the macula

Question 7

Where are the cones in the eye?

Answer 7

Densely packed in the fovea

Question 8

Describe my vision using the fovea gives high detailed images?

Answer 8

1. High Density of only cones in the fovea
2. Each cone is connected to a single bipolar neuron
3. This is temporal summation as impulse from each cone is kept separate
4. Cones pigment which is iodopsin breaks downs leading to generator potential to send impulse to brain
5. This gives high visual acuity

Question 9

What is high visual acuity ?

Answer 9

Sharpness/ clarity of vision

Question 10

Describe how we can see colour using cones?

Answer 10

1. High density of cones in the fovea
2. Colour detected by cones
3. Humans have 3 types of cones -red/blue/green which are each sensitive to different wavelengths of light due to different amount of pigment iodopsin
4. Different colours can be seen due to stimulation of more than one cone

Question 11

Describe cone photo receptor exhaustion?

Answer 11

This is when After staring at a image for a long time, one type of cone is stimulated eg blue and other 2 are not which are red and green as not sensitive to that colour
Iodopsin is broken down (bleached ) at high light intensities which cause the cones to become exalted so stop working due to exhaustion of pigment and exhaustion of neurotransmitters and exhaustion of ATP

Question 12

Describe how an organisms vision can be adopted to find a mate in the dark?

Answer 12

1. High density of rods in the medulla in the retina which contain rhodopsin pigment which is sensitive to all wavelengths of light
   Light breaks down rhodopsin leading to generator potential
   Several rods connected to a single bipolar neuron which is special summation as gives enough neurotransmitter to reach threshold Impulse sent to optic nerve / brain giving high visual sensitivity

Question 13

Rod cell recovery

Answer 13

Rhodopsin pigment sensitive to all wavelengths of light and but absorbs certain wavelengths more readily. Light breaks down rhodopsin in rod cells at low light intensities stimulating the bipolar neuron through spatial summation
In the dark it will be re synthesised

Question 14

Difference between rod cells and cone cells

Answer 14

Densely packed in macula vs densely packed in fovea
Rhodopsin pigment vs iodopsin pigment
Sensitive to all wavelengths of light vs sensitive to specific wavelength of light
Low visual acuity vs high visual acuity
High visual sensitivity vs low visual sensitivity
One type of rod cell vs 3 types of cone cells
Special summation vs temporal summation

Question 15

Describe the coordination of a heart beat ?

Answer 15

1. Sino atrial node sends a wave of depolarisation/ electrical activity across both atria
2. Both atria contract
3. Layer of non conductive tissue prevents wave reaching ventricles
   4.Wave of electrical activity reaches atrio ventricular node
4. P.1 second delay to allow atria to empty and ventricle to fill with blood
5. Wave of electrical activity sent from from atrio ventricular node down to bundle of his to the base (apex) of the ventricles up the pukinje fibres
6. Causing the ventricles to contract from the apex of the heart upwards

Question 16

What is the autonomic nervous system?

Answer 16

A typical heart rate in a human is 70bpm by it can be altered in response to changing demands of respiring tissue oxygen for example exercise

Question 17

What are the two branches of the autonomic nervous system?

Answer 17

Sympathetic= speed up the heart rate
Parasympathetic = Slows down the heart rate

Question 18

Describe how the heart rate is controlled by the autonomic nervous system: sympathetic?

Answer 18

1. The medulla oblongata which is the cardiac centre of the brain coordinates the heart rate by sending nerve impulses/action potentials along the sympathetic nerve
2. They release neuro adrenaline to the sinoatrial node which increases impulses from sinoatrial to increase his heart rate

Question 19

Describe how the heart rate is controlled by the autonomic nervous system: parasympathetic?

Answer 19

The medulla oblongata which is the cardiac centre of the brain coordinates the heart rate by sending impulses along the parasympathetic nerve
The parasympathetic nerve releases acetylcholine to the atrial node which decreased impulses from electron which decreased hear rate

Question 20

What is the medulla oblongata ?

Answer 20

Cardiac Centre of the brain which coordinates the heart rate

Question 21

What does the sympathetic nerve release?

Answer 21

Noradrenaline

Question 22

What does the parasympathetic nerve release?

Answer 22

Acetylcholine

Question 23

What are the two receptors important in the control of heart rate?

Answer 23

Baro receptors
Chemo receptors

Question 24

Where are these receptors found?

Answer 24

Aorta and carotid arteries = baro
Carotid body = chemo

Question 25

What does baro receptors detect?

Answer 25

Change in blood pressure

Question 26

What does chemo receptors detect?

Answer 26

Change in pH of blood

Question 27

Describe how a decrease in blood pressure results and an increase in the rate of heartbeat? You want to do opposite

Answer 27

1. Baroreceptors in car tide arteries/aorta, detect a decrease in blood pressure 2. They send impulses to the medulla oblongata which is the cardiac centre of the brain. 3. They send increased frequency impulses by sympathetic nerve to the sinoatrial node 4. Sympathetic nerve releases more neuro adrenaline 5. This stimulates the sino atrial node to increase impulses 6. Increases impulses to atrioventricular node

Question 28

Describe how a decrease in blood pressure results to an increase in rate of heartbeat?

Answer 28

1. Barorecptors in carotid arteries/ aorta detect a decrease in blood pressure 2. They send impulses to the medulla oblongata 3. Send more increased frequency impulses by the parasympathetic nerve to the sino atrial node 4. Releases acetylcholine neurotransmitters 5. Inhibiting sino atrial node to decreases impulses 6. Decreases impulses to atrial ventricular node

Question 29

Describe and explain how heart rate is increased in response to exercise?

Answer 29

1. More exercise means increased rate of aerobic respiration means increase in carbon dioxide concentration leading blood pH to fall. 2. This is detected by chemo receptors in carotid body 3. Send impulse to medulla oblongata 4. And more increase frequency of impulses by sympathetic nerve to sino atrial node 5. Releases neuro adrenaline 7. Stimulate signal to increase in sino atrial node 6. Increased impulses to atrial ventricular