Receptors, Eye, Pacinian Corpuscle & Chemo/Baro Receptors Flashcards
(36 cards)
What happens to the Pacinian corpuscle when pressure is applied?
Membrane/lamellae become deformed or stretched.
What does deformation of the lamellae cause?
Sodium ion channels in the membrane open.
What happens when sodium ion channels open?
Sodium ions move into the neurone.
What is the result of sodium ions entering the neurone?
Depolarisation leading to a generator potential.
How does increasing pressure affect the sodium channels?
More channels open, allowing more sodium ions to enter.
How does pressure affect lamellae in the Pacinian corpuscle?
Pressure deforms the lamellae.
What kind of sodium channels open due to pressure?
Stretch-mediated Na+ channel proteins.
How do sodium ions move into the neurone?
Sodium diffuses across the membrane into the neurone.
What does sodium ion entry cause in the neurone?
Depolarisation.
How does increased pressure influence the generator potential?
Opens more channels and increases sodium ion entry, increasing generator potential size.
What determines the frequency of action potentials?
The size of the generator potential.
How does the fovea increase image detail?
By providing high visual acuity.
How is each cone connected in the fovea?
Each single cone connects to a single bipolar neurone.
What is the significance of this one-to-one connection?
Each cone sends a separate impulse to the brain.
What happens when several rods connect to one bipolar cell?
Spatial summation occurs.
How does spatial summation affect visual acuity?
It decreases acuity because stimuli from different rods cannot be distinguished.
How does summation of sub-threshold stimuli affect sensitivity?
It produces threshold stimulation.
What is the effect on sensitivity?
Sensitivity is increased.
Why are people with red-green colour blindness unable to distinguish these colours?
Because green-sensitive pigment/cones are non-functional.
How many types of pigment/cones are there?
Three different types.
How are other colours perceived?
Due to stimulation of more than one type of cone/pigment.
Which brain area coordinates increased cardiac output?
The medulla (cardiac centre).
How are impulses sent to increase cardiac output?
Along the sympathetic nerve to the SAN.
What chemical is released at the SAN?
Noradrenaline.
