Intracellular (within) signaling

Question 1

Neurons transmit info within the cell…

Answer 1

…in the form of electrochemical impulses (ie both electrical and chemical)

Question 2

Chemical propagation (4)

Answer 2

1) The neuronal membrane is ‘selectively permeable’, it allows through protein molecules embedded in the membrane passage for ‘ions’ to enter or exit the cell.
2) Ions - electrically charged cells
3) at resting potential there is a higher concentration of positively charged sodium ions outside the neuron, giving rise to the potential difference.. This is achieved through ‘pumping’ sodium ions out and potassium ions into the cell.
4) when the dendrites are excited the ion gates open and sodium ions rush into the cell, giving rise to a positive potential the positive potential.

Question 3

within neurons there are two main forms of electrical transmission…

Answer 3

1) dendrite to axon; 2) axion h to terminal

Question 4

Dendrite to axon (4)

Answer 4

1) At rest, there is a difference in the electrical potential between the inside and outside of the neuron (polarisation)
2) The inside of the neuron is -70mV compared to the outside
3) When activated, electrical and chemical processes are set in motion, reducing the electrical potential difference in proportion to the strength of the input signal
4) When a critical strength is reached (-55mV in humans, called the response threshold) and all-or-none response is triggered at the axon h.

Question 5

Axion to terminal

Answer 5

1) when triggered, a wave of electrical excitation travels down the axion through the excitation of each segment by its neighbour.
2) once the AP reaches the terminal the NT is released
3) The neuron then returns to its polarized state ready to fire again