Year 13 - Receptors Flashcards
(13 cards)
State the stimuli that the Pacinian corpuscle is a receptor for and describe how a Pacinian corpuscle works
Pressure stimuli deforms lamellae of Pacinian corpuscle surrounding dendrites
Deforming stretch mediated Na+ channels
Causing channels to open and Na+ to diffuse in
Depolarising membrane leading to a generator potential
If stimuli big enough, builds to reach threshold potential at the start of an axon
Causing Na+ voltage gated channels to open and Na+ to diffuse in causing depolarisation
Triggering action potential with maximum response due to the all or nothing principle
Describe the interaction of muscles that cause the pupil to:
Constrict
Dilate
Constrict:
Circular muscles contract
Radial muscles relax
Dilate:
Circular muscles relax
Radial muscles contract.
Describe why vision using the fovea give high detailed images
- High density of cones only on the fovea
- Each cone is connected to a single separate bipolar neuron
- Temporal summation - impulse from each cone kept separate
- Cones pigment iodopsin breaks down when absorbing light leading to a generator potential so send separate impulses to the brain via optic nerve
- Giving high visual acuity
Describe how we see colour using cones
High density of only cones on the fovea
Colour detected by cones
Humans have three types of cones (red/blue/green) each sensitive to different wavelength of light due to different pigments (called Iodopsin).
Different colours can be seen due to stimulation of more than one cone.
Describe cone photoreceptor exhaustion
Staring at an image made up of wavelengths of blue light stimulate one specific type of cone receptor (blue cones).
Cones (red/green) that are not sensitive to that colour are not stimulated.
Iodopsin (pigments in cones) broken down (bleached) at high light intensities
Sensitive cones become exhausted
so stop working due to exhaustion of pigment, (exhaustion of) neurotransmitters and (exhaustion of) ATP.
After image = cones that are still working are stimulated giving their colour only.
Describe how an organisms vision can be adapted to live/hunt/find a mate in the dark
-high density of rods away from fovea in the retina
-contain rhodopsin pigment making rod cells very sensitive to all wavelengths of light. (help see in dark)
-Light breaks down rhodopsin leading to generator potential
-several rods connected to a single bipolar neuron
-meaning if enough light detected by any of the rod cells, spatial summation gives enough neurotransmitter to reach and pass threshold
-to send single nerve impulse to optic nerve/brain (via bipolar neuron)
-giving high visual sensitivity
Rod cell recovery
Rhodopsin pigment absorbs light
Sensitive to all wavelengths of light
Absorbs certain wavelengths more readily as more sensitive
Light breaks down (bleaches) rhodopsin in rod cells at low light intensities stimulating the bipolar neuron through spatial summation
In dark it will be resynthesised
The more sensitive to one colour rhodopsin is, the more time that rod will need
Describe co-ordination of a heartbeat
SAN (pacemaker) initiates heart beats by sending wave of electrical activity across atria causing atrial contraction.
Non-conducting tissue, between atria and ventricles, prevents immediate contraction of ventricles as impulses can’t reach ventricles.
AVN delays impulse so atria empty and ventricles fill with blood before their contraction.
Electrical activity only through AVN that sends impulse down Bundle of His (to apex).
Wave of electrical activity (depolarisation) passes over both ventricles at the same time.
Causing ventricles to contract from apex/base upwards
Describe how heart rate is controlled by the sympathetic branch of the autonomic nervous system
The medulla oblongata co-ordinates heart rate
By sending nerve impulses along sympathetic nerve
Releasing noradrenaline
To SAN, increasing impulses from SAN, so increasing heart rate
Describe how heart rate is controlled by the parasympathetic branch of the autonomic nervous system
The medulla oblongata co-ordinates heart rate by
Sends nerve impulses along parasympathetic nerve
Releasing acetylcholine
To SAN, so decreasing impulse from SAN, decreasing heart rate
Describe how a rise in blood pressure results in a decrease in the rate of heartbeat
Baroreceptors in carotid sinus/aorta (aortic arch) detect an increase in blood pressure
Parasympathetic flashcard
Describe how a decrease in blood pressure results in an increase in the rate of heartbeat
Baroreceptors in carotid sinus/aorta (aortic arch) detect an decrease in blood pressure
Sympathetic flashcard
Describe and explain how heart rate is increased in response to exercise
More exercise means increased rate of aerobic in muscles cells
Causes increase in CO2 concentration causing blood pH to fall
Detected by periphery chemoreceptors in carotid bodies
Sympathetic flashcard
