receptors Flashcards
receptors are specific, what does this mean
they only detect one p articular stimulus, e.g. light, pressure or glucose concentration.
There are many different types of receptor that each detect _______
a different type of stimulus
what type of receptor is a photoreceptor
cells
what are the three types of receptors
cells, proteins, cell surface membranes
what are photoreceptors
photoreceptors are receptor cells that connect to the nervous system.
what are glucose receptors
glucose receptors are proteins
found in the cell membranes of some pancreatic cells.
what happens when a nervous system receptor is in its resting state
When a nervous system receptor is in its resting state (not being stimulated), there’s a difference in charge
between the inside and the outside of the cell — this is generated by ion pumps and ion channels
This means that there’s a voltage across the membrane. Voltage is also known as potential difference
what is the potential difference when the cell is at rest
its resting potential. When a stimulus
is detected, the cell membrane is excited and becomes more permeable, allowing more ions
to move in and out of the cell — altering the potential difference. The change in
potential difference due to a stimulus is called the generator potential.
what does a bigger stimulus do
A bigger stimulus excites the membrane more, causing a bigger movement of ions and a
bigger change in potential difference — so a bigger generator potential is produced
if a generator potential is big enough what will it trigger
If the generator potential is big enough it’ll trigger an action potential
what is an action potential
an electrical impulse along a
neurone
if the stimulus is too weak what will happen
If the stimulus is too weak the generator potential won’t re ach the threshold, so there’s no action potential.
what is the threshold level
the level the generator potential must meet to trigger an action potential
(the number of action potentials triggered during a certain time period)
why is the strength of stimulus measured by frequency of action potentials
Action potentials are all one size
what are pacinian corpuscles
Pressure Receptors in Your Skin
what type of receptors are pacinias corpuscles
Pacinian corpuscles are mechanoreceptors — they
detect mechanical stimuli, e.g. pressure and vibrations
They’re found in your skin
what do pacinian receptors contain
Pacinian corpuscles contain the end of a sensory
neurone, imaginatively called a sensory nerve ending.
The sensory nerve ending is wrapped in loads of layers
of connective tissue called lamellae.
what happens when a pacinians corpuscle is stimulated
W hen a Pacinian corpuscle is stimulated,
e.g. by a tap on the arm, the lamellae are
deformed and press on the sensory nerve ending.
what do the lamellae becoming deformed and pressing on the sensory nerve ending
This causes the sensory neurone’s cell membrane to
stretch, deforming the stretch-mediated sodium ion
channels. The channels open and sodium ions diffuse
into the cell, creating a generator potential.
what happens when the generator potential reaches the threshold
he generator potential reaches the threshold,
it triggers an action potential.
what are photo receptors
Photoreceptors are Light Receptors in Your Eye
how does light enter the eye
Light enters the eye through the pupil.
The amount of light that enters is controlled by the muscles of the iris
what are light rays focused by
Light rays are focused by the lens onto the retina, which lines the inside
of the eye. The retina contains photoreceptor cells — these detect light.
what is the fovea
The fovea is an area of the retina where there are lots of photoreceptors
how do nerve impulses reach the brain
Nerve impulses from the photoreceptor cells are carried from the retina
to the brain by the op tic nerve, which is a bundle of neurones.
W here the optic nerve leaves the eye is called the blind spot —
there aren’t any photoreceptor cells, so it’s not sensitive to light.
what are all the part of the eye
lens, pupil, iris, retina, fovea, blind spot, optic nerve.
