neuronal communication Flashcards
what is a pacinian corpuscle
a pressure sensor found in the skin
what is a sensory receptor
specialised cell nerve endings that respond to a stimulus in the internal or external environment and can create action potentials
what is a transducer
a cell that converts one form of energy into another- electrical impulse
how are transducer adapted
there are multiple transducers, each are adapted to detect changes in particular forms of energy
e.g. change in pressure on skin
what is a stimulus
a change in the internal or external environment
what receptors detect changes in light intensity
and what is the energy change
light sensitive cells
light energy to electrical energy
what receptors detect changes in temperature
temp receptors on skin and hypothalamus
heat to electrical
what receptors detect changes in pressure on skin and what is the enrgy change
pacinian corpuscles
movement to electrical (action potential)
describe the structure of a pacinian corpuscle
oval shape
rings of connective tissue wrapped around end of nerve cell
what happens to the connective tissue rings when pressure is exerted
they deform, causing pressure on the nerve ending
nervous system cells have protein channels specific. What are the two main channels
sodium channels
potassium channels
channels are sensitive to small movements, what happens when memebrane is deformed
the sodium channels open allowing sodium ions to diffuse into the cell
producing a generator potential
membranes also contain a sodium potassium pump. What is the function of this
for every two potassium pumped in, 3 sodium are pumped out of cell with Atp
what happens when all channels are closed
sodium potassium pumps create a concentration gradient- sodium concentration increases outside the cell
potassium concentration increases on the inside
what ion is the membrane more permeable to
potassium ions, therefore when protein channels are closed some potassium ions can diffuse through
what is the outcome of the movement of the ions across the membrane
potential gradient is formed across the membrane and the inside of the cell is more negatively charged than the outside
when the cell is inactive, what is it described as
polarised
how are nerve impulses created
altering the permeability of the neurone membrane to sodium ions
how is the membrane altered to allow more movement of sodium into the cell
by allowing the opening of the sodium ion channels, allowing the sodium ions to diffuse into the cell down the conc grad
what does the movement of ions across a membrane create
change in potential difference (CHARGE), the inside of the cell becomes less negative compared to the outside
stimuli can be small or large, what happens when the stimulus is quite small
only a few sodium channels will open if the stimuli is small
more gated channels will open if the stimuli is large
when will action potential be created
if enough sodium ions enter the neurone cells and the potential difference changes significantly
what receptors respond to a light stimuli
photoreceptors
what receptors respnd to chemicals
chemoreceptors
what receptors respond to temperature
thermo receptor
what receptors respond to physical changes
mechanoreceptors
what receptor is a pacinian corpuscle
mechanoreceptor
where is the pacinian corpuscle found
in skin, at the end of a sensory neurone axon
the pacinian corpuscle is surrounded by several layers of membrane, what are these called
lamallae
what is special about the lamallae of the pacinian corpuscle
there are stretch- mediated channels
means when lamellae is deformed/stretched, the channels open, allowing sodium ions to diffuse in down their conc grad and create a generator potential
what is the difference between a generator potential and an action potential
generator potential- when ions accumulate in a receptor cell and cause potential difference
action potential- Potential difference in a neurone
why must the phospholipid bilayer have sodium and potassium protein gated channels channels
because the bilayer isnt permeable to charged particles so ions must pass through protein channels to cross the membrane
