Neuronal Communication Flashcards
What are sensory receptors?
Specialised cells that can detect changes to the environment.
What are transducers?
A cell that converts one energy into another. - eg- electrical to chemical
What is a nerve impulse?
How the sensory receptors respond to a stimulus by creating a signal in the form of electrical energy.
What detects the change in light intensity?
Rods and cones in the retina- light to electrical
What do temperature detectors in the skin and hypothalamus detects.
Temperature change- heat to electrical
What is a pacinan corpuscle?
A pressure sensor to detect change in pressure on the skin
Describe the Pacinian corpuscle?
Oval shaped
Concentric rings of connective tissue wrapped around the end of a nerve cell
How does the Pacinian Corpuscle work?
When pressure is applied the rings of connective tissue are deformed which push against the nerve endings
What causes the Pacinian Corpuscle to stop responding?
When pressure is constant
What can’t pass through the lipid bilayer?
Charged particles
Describe resting potential?
The sodium ion channels are kept closed
Some potassium gates are kept open
Potassium ions diffuse out the cell
The cell cytoplasm contains negatively charged ions
The inside is more negative that the outside- therefore is polarised
How is a nerve impulse created?
By altering the permeability of the nerve cell to sodium ions- by opening the sodium ion channels
What happens when the sodium ion channels open?
Sodium ions can move across the membrane down their concentration gradient.
What is the potential difference and how is it changed?
It’s the charge which is changed by the movement of ions across the membrane.
What change in potential difference is caused when creating a nerve impulse?
The inside of the cell becomes less negative compared to the outside- depolarisation
What is a generator potential?
The change in potential across a receptor menbrane
What is the relationship between the stimulus and the Sodium ion gates?
The larger the stimulus the more gated channels will open.
When will an action potential be initiated?
When enough Sodium ion gates are open and enough sodium ions enter the cell to change the potential difference across the membrane significantly
What is the initiation of an impulse?
An action potential
What is the ratio between sodium ions and potassium ions?
3 sodium ions are pumped out for every 2 potassium ions pumped in
What is the permeability of the cell membrane to NA/K ions?
More permeable to K ions so are able to leak out
Less permeable to NA ions- not able to leak in
What are motor neurones?
To carry an action potential from the CNS to an effector
Function of relay neurones?
To connect sensory and motor neurones
Give 2 features of neurones?
Very long to transmit the action potential over a long distance
Cell surface has many gated ion channels
