5.3 Neuronal Communications Flashcards
Receptors
Detect a change
Sensory receptors examples
Light sensitive, pressure sensitive, heat sensitive, chemoreceptors
Light sensitive cells
in the retina receptors detect change in light intensity + convert it to an electrical signal
Pressure sensitive cells
- Change in pressure on skin = by pacinian corpuscles in the skin (receptor) converts movement to electrical
Temperature sensitive cells
Receptors in the skin are peripheral receptors
chemoreceptors
detect change in chemicals + ions
Transducer
Anything that converts one type of signal to another
Sensory neurone
detects the change = passes it from receptor to CNS
Motor neurone
passes info from CNS to the effector = part of body that performs the response + can be a muscle or a gland
Relay neurone
connects sensory and motor neurone
Dendrite
part of neurone that receives information (not in sensory neurones).
Difference between dendron and axon
Towards cell body = dendron, away from cell body = axon
Cell body
where organelles are found (end of motor neurone, not on end of sensory neurone)
Labelled motor neurone diagram
Labelled sensory neurone diagram
Labelled relay neurone diagram
Pacinian corpuscle stages
- when pacinian corpuscle’s stimulated, lamellae deformed + press on sensory ending
- causes stretch mediated sodium ion channels in sensory neurone’s membrane to become deformed
- sodium ion channels open, ions diffuse into cell, creating generator potential
- when the generator potential reaches the threshold it triggers an action potential
Action potential diagram
Stage 1
At rest, sodium + potassium pumps can pump sodium out + potassium in. 3 sodium’s out for every 2 potassium (requires ATP). Going to be negative inside compared to outside bc less protons come in for the amount that come out. Membrane quite permeable to potassium ions so they tend to leak out = very negative = -60 mV. Also have anions inside that contribute to this.
Neurone membrane charge at rest
- polarised (negatively charged)
- resting potential = -60mV
Stage 2
the membrane becomes depolarised (becomes less negative). Becomes less negative become sodium channels open so sodium enters so the membrane charge becomes less negative. This creates a generator potential (opening of sodium ion channels)
Stage 3
- Reached threshold. Some sodium ion channels are voltage gated (open at specific voltages)
Stage 4/5
eventually enough sodium ions enter to reach +40 mV. (2-5 = depolarisation) once you reach max point +40 mV the sodium ion channels close. (Positive feedback)
Stage 6
- Potassium ion channels open and potassium leaves so the membrane potential decreases. (Repolarised)