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A Level Biology Paper 2 > Receptors > Flashcards

Receptors Flashcards

1
Q

Effect of iodopsin being more stable than rhodopsin

A

Greater light intensity to break it down and release neurotransmitter

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2
Q

Resting heart rate in typical adult

A

70 beats per minute

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3
Q

What is acuity

A

Ability to see something clearly

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4
Q

What neurotransmitter does opsin release

A

Glutamate

Excitatory NET

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5
Q

Function of the non conducting connective tissue layer between the atria and the ventricles

A

Prevents electrical impulses from SAN passing into the ventricles
Prevents electrical impulses from the AVN passing into the atria

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6
Q

Importance of the delay at the AVN

A

Allows the artia to empty
And ventricles to be filled
Before ventricles contract

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7
Q

Benefit of purkinje fibres running to base of ventricles

A

Ventricular contraction can start at the base

And push blood up into arteries

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8
Q

Functions of autonomic nervous system

A

Heart rate
Blood pressure
Respiration
Digestion

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9
Q

How do chemoreceptors detect changes in pH

A 
Changes in CO2 levels due to changes in respiration 
CO2 forms a weak acid in solution 
Decreasing the pH
More CO2 means lower pH (more acidic)
Chemoreceptors detect low pH
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10
Q

What is a receptor

A

Specialised cell
That detects a stimulus
Converting one form of energy into a generator potential (electrical)
Which may cause an action potential in the sensory neurone

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11
Q

What is the pacinian corpuscle

A

A pressure receptor
That responds to mechanical stimuli
Found deep in the skin (fingers, external genitalia, feet soles)
And in joints, tendons and ligaments

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12
Q

Where are pacinian corpuscles found

A

Deep under the skin
Of feet, external genitalia, soles of feet
And in joints, tendons and ligaments

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13
Q

Structure of the pacinian corpuscle

A

Many layers of connective tissue with a viscous gel between (lamellae)
Which surround the ending of a single sensory neurone
Sensory neurone ending has stretch mediated sodium ion channels
And a myelinated axon

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14
Q

How does the pacinian corpuscle work

A

Stimulus of pressure deforms viscous gel layers
Exposed axons stretch mediated sodium ion channel proteins open
Sodium ions diffuse in down a concentration gradient
More positive ions on inside of membrane
Causing depolarisation
Leading to an electrical potential difference called a generator potential
If generator potential reaches or exceed threshold value an action potential is generated and a nerve impulse propagated along the sensory neurone

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15
Q

How does an increased pressure affect the pacinian corpuscle

A

More stretch mediated sodium ion channel proteins open
So more sodium ions diffuse in
Leading to a larger generator potential

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16
Q

What is the eye

A

A sense organ
That has 2 types of receptor
That detect and respond to light intensity and wavelengths of light
Located in retina

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17
Q

Structures of the eye

A 
Cornea
Iris
Pupil
Lens
Vitreous gel
Retina
Macular
Fovea
Optical nerve

The macular in the retina contains the fovea

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18
Q

Features of rods

A

Evenly distributed throughout the macula
Low density in fovea
Sensitive to all wavelengths of light
Rhodopsin is the light sensitive pigment
High visual sensitivity to low light intensity
Low visual acuity so unclear image
Retinal convergence due to several rods sharing a single bipolar neurone and generator potentials combine to reach threshold

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19
Q

Where are rods found

A

Evenly distributed through the macula

Low density in fovea

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20
Q

Features of cones

A

Densely packed in the fovea
Small area in the macula
Each cone detects a specific wavelength of light
3 types of iodipsin (RGB)
Low visual acuity to low levels of light intensity (iodopsin is more stable so requires a higher light intensity of specific photons per second)
High visual acuity gives a sharp image because each cine synapses with a single bipolar neurone
So send a separate impulse to brain

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21
Q

Why aren’t bipolar neurone myelinated

A

They are very short (micrometers) in length
So pointless
Myelination more efficient for long neurones

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22
Q

Explain retinal convergence

A

Many rods synapse with one bipolar neurone
Stimulation of several rods results in enough neurotransmitter released to reach threshold value in bipolar neurone
Leading to spatial summation

23
Q

How does light lead to a generator potential in rods

A

Photons of light cause rhodopsin to break down
Into opsin
Altering its chemical structure
Causing it to act like an enzyme
And release the neurotransmitter glutamate
Generator potential reaches threshold value
Action potential produced in bipolar neurone
Opsin used to resynthesise rhodopsin

24
Q

How does light lead to a generator potential in cones

A

Photons of light cause iodopsin to break down
Altering its chemical structure
Causing it to act like an enzyme
And release neurotransmitter
Generator potential reaches threshold value
Action potential produced in bipolar neurone
Used to resynthesise iodopsin

3 different types of iodospin (RGB)

25
Explain how the active site of an enzyme causes a high rate of reaction
Lowers activation energy Induced fit cause active site of enzyme to change shape slightly so more complementary Enzyme-substrate complex causes bonds to form/break
26
Why is the visual cortex so large
Lots of complex information to process
27
What is a blind spot
Part of a visual field you can't see | Due to an absence of cones and rods/receptors in the area being stimulated by the light
28
Why do rods cause low visual acuity
Several rods are connected to one bipolar neurone So light falling on several rods only generate one impulse to the brain The brain can't distinguish between separate light sources that generate the impulses
29
Why do cones cause high visual acuity
Each cone synapses with an individual bipolar neurone They are so densely packed, meaning photons of light are likely to fall on 2 separate cone cells Generating 2 electrical impulses to the brain So it can distinguish between the light sources that generate them So the brain interprets this as 2 separate points of light
30
What is the SAN
Sino-Atrial Node A region of specialised muscle fibres Located in the right atrium wall of the heart That generates impulses and waves of depolarisation Which pass across the atria So the atrial muscles contract
31
Importance of being able to alter heart rate
In response to the needs of the body E.g during exercise or avoiding predation the heart rate must increase to supply more oxygen to muscles for more aerobic respiration to produce the ATP needed for muscle contractions and movement
32
Explain the resting heart rate
Sino-Atrial node generates an impulse So waves of depolarisation pass over the atria Atria contract (systole) Layer of connective, non conducting tissue between the atria and ventricles prevents electrical impulse reaching ventricles Delaying the impulse at the Atrio-Ventricular node So they atria can empty and ventricles can fill with blood before contracting Waves of depolarisation from the Atrio-Ventricular node pass down the purkinje fibres in the Bundle of His Causing the ventricles to contract from the apex upwards
33
What is the ANS
Autonomic Nervous System A branch of the Peripheral Nervous System With two of its own branches Called the parasympathetic and sympathetic nervous system
34
What is the sympathetic nervous system
``` Branch of the autonomic nervous system That stimulates effectors Speeds up heart rate Involved in fight or flight And uses the neurotransmitter noradrenaline ```
35
What is the parasympathetic nervous system
``` Branch of the autonomic system Inhibits effectors Controls activity at rest (&digest) Slows down the heart rate Uses neurotransmitter acetylcholine ```
36
What controls heart rate changes
The medulla oblongata in the brain stem | And it's cardio regulatory centre
37
Structure of the cardio regulatory centre
2 parts Acceleratory centre Inhibitory centre
38
What is the acceleratory centre
Found in the cardio regulatory centre in the medulla oblongata Links to the SAN node By the sympathetic nerve Of the sympathetic nervous system
39
What is the inhibitory centre
Part of the cardio regulatory centre on the medulla oblongata That links to the SAN by the parasympathetic nerve Of the parasympathetic nervous system
40
What are chemoreceptors
Receptors found in the aorta and carotid arteries Important in the control of the heart rate That respond to changes in pH
41
What are baroreceptors
Receptors found in the aorta and carotid arteries Important in controlling the heart rate That respond to changes in blood pressure
42
Increase in blood pressure
Detected by baroreceptors in the walls of the aorta and carotid arteries More frequent impulses sent to the medulla oblongata More frequent impulses from the inhibitory centre in the medulla to the Sino-Atrial node Via the parasympathetic nerve Decreased frequency of impulses from SAN across atria by acetylcholine Heart rate decreases So blood pressure decreases
43
Decrease in blood pressure
Detected by baroreceptors in the walls of the aorta and carotid arteries Less frequent impulses sent to the medulla oblongata More frequent impulses from the acceleratory centre in the medulla to the Sino-Atrial node Via the sympathetic nerve Increased frequency of impulses from the SAN across the atria By noradrenaline Heart rate increases So blood pressure increases
44
How do chemoreceptors work
Carbon dioxide levels rise (e.g from exercise and increased respiration) So blood pH decreases below normal level Detected by chemoreceptors in the walls of the aorta and carotid artery More frequent impulses sent to the medulla oblongata More frequent impulses sent from the acceleratory centre in the medulla to the Sino-Atrial node Via the sympathetic nerve More frequent impulses sent from the SAN across the atria Via noradrenaline Heart rate increases To supply more oxygen to respiration cells to produce the ATP needed for muscle contractions in exercise
45
Parasympathetic vs sympathetic nervous system
P: Inhibits effectors/S: Stimulates effectors P: Inhibitory centre to SAN via parasympathetic nerve/S: Acceleratory centre to SAN via sympathetic nerve P: Acetylcholine/S: Noradrenaline
46
How does dopamine stimulate the production of nerve impulses in the post synaptic neurone
``` Similar structure to acetylecholine Diffuses across the synapse Attaching to receptors on post synaptic membrane Opening sodium ion channel proteins Sodium ions can diffuse in Allowing for depolarisation And an action potential to be produced ```
47
How does morphine provide pain relief
Similar shape to endorphins So attatch to opioid receptors More dopamine released to provide pain reliefe
48
Advantage of the movement of mitochondria/ATP to the pre synaptic membrane
Mitochondria supply additional ATP To move vesicles/for active transport of ions To resynthesise and reabsorbed acetylcholine
49
How can damaged myelin sheath cause a slower response to stimuli
Less/no saltatory conduction | More depolarisation over length of membranes
50
Why does it take time for rods to recover sensitivity to light after moving into darkness
Rhodopsin is broken down by light | Required time for the resynthesis of rhodopsin
51
What causes vision in colour
3 different types of cone cells sensitive to different wavelengths of light
52
What causes vision to have high visual acuity
Each cone receptor connects to a separate neurone | Impulse sent along separate neurone from each bipolar neurone
53
How can a high rod density allow night vision
High visual sensitivity to the lower light intensities Several rods connect to a single bipolar neurone Spatial summation means enough neurotransmitter to overcome threshold
54
What is the AVN
Atrio-Ventricular Node A region of specialised muscle fibres In the atria above the non conducting connective tissue layer That sends electrical impulses that travel down Purkinje Fibres in the Bundle of His when stimulated by electrical impulses from the Sino-Atrial Node With a 0.1s delay

A Level Biology Paper 2 (16 decks)

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