Nerves & Action Potential Flashcards
Where is the thermoreceptor found and what is it sensitive to?
Skin and changes in temperature.
Where is the Pacinian Corpuscle found and what is it sensitive to?
Skin and Pressure
Where are the chemoreceptors (taste buds) found and what are they sensitive to?
Tongue and soluble chemicals
Where are the rods and cones cells found and what are they sensitive to?
Eyes (retina) and sensitive to light intensity and range of different wavelengths
Where is the sound receptor found and what is it sensitive to?
Ears and vibrations/sound waves
Where are the olfactory cells found and what are they sensitive to?
Nose and volatile chemicals
What do muscles spindles do?
They detect the length of muscle fibres
What is the reflex arc?
Change in environment
⬇️
Stimulus
⬇️
Detected by Sensory Receptor
⬇️
Action Potential sent along sensory Neurone⤵️ (To Brain) ⬇️
⬇️ CNS➡️Brain +Spinal Cord◀️⬇️
Action Potential sent along Relay Neurone ⬇
⬇️ (Synapse) ⬇️
Action Potential arrives at Motor Neurone ↩️
⬇️
Signal passed to Effector (Muscle/Gland)
⬇️
Effector Responds
What do Sensory Neurones do?
- they are transducers and convert the stimulus into a nerve impulse
- they carry the action potential from the Sensory Receptor to the CNS
What do Motor Neurones do?
They carry the Action Potential from the CNS to the Effector
How are Neurones adapted?
The neurones are:
• Very Long
To transmit the Action Potential over a long distance
• Myelin Sheath
Insulates the neurone from the electrical activity in nearby cells
• Dendrites
Increase the surface area
Describe the structure of the motor neurone
- the motor neurone has a cell body at the end with a large nucleus and lots of RER and Golgi bodies
- it has a many short dendrites that carry imposes to the cell body
- a long axon which caries an impulse from the cell body to the effector
Describe the structure of the sensory neurone
- the sensory neurone has long processes on either side of the cell body
- a dendron carrying nerve impulses from a receptor to the cell body
- an axon carrying an impulse from the cell body to the effector
What is the difference between Sensory Neurones and Motor Neurones?
In the Sensory Neurone, the DENDRON is called the AXON after the Cell Body.
(It’s only called the AXON AFTER the Cell Body)
Cell Bodies of Motor Neurones are located in the CNS or Brain - (At the end of the Neurone)
Cell Bodies of Sensory Neurones are located around the body - (In the MIDDLE of the Sensory Neurone)
Describe and explain how the resting potential is established
- when not conducting an impulse the potential difference across the membrane is about -70 mv
- the outside of the membrane is positively charged compared to the inside so the membrane is polarised
- sodium-potassium pumps actively transport (need ATP) 3 Na+ ions out of the neurone for every 2K+ ions moved in
- the membrane is impermeable to sodium ions so they can’t diffuse back in which creates a sodium ion electrochemical gradient because there are more positive sodium ions outside the cell than inside
- the membrane is permeable to potassium ions so they diffuse back out through potassium ion channels using facilitated diffusion down their concentration gradient
- this makes the outside of the cell positively charged compared to the inside