L8

Question 1

Jak się nazywa inaczej synapsa?

Answer 1

A contact between 2 neurons is called a synapse (Sherrington)

Question 2

Synapses can be of different types (2):

Answer 2

excitatory (depolarising),
inhibitory (hyperpolarising)

Some are depolarizing (EPSP): some are hyperpolarizing (IPSP):

Question 3

Opisz chemical synapses

Answer 3

•Chemical: most usual type, associated with the secretion of a small amount of chemical (neurotransmitter) from the nerve terminal, and is a one-way signalling mechanism. These are complex because the pre- and post-synaptic membranes are separated by a minute space called the synaptic cleft, hence the need for a chemical neurotransmitter from the pre-synaptic fibre.

Question 4

Opisz electrical synapses

Answer 4

•Electrical: the electrical current generated by the AP is transmitted directly to the post synaptic cell by electrical coupling because the two cells are in tight contact with each other (gap junctions). This is fast and reliable. This type of transmission occurs in some retinal cells and in cardiac cells. Also occurs between some glial cells e.g. astrocytes.

Question 5

Inhibitory synaptic transmission: hyperpolarisation

Answer 5

–IPSPs are graded 
–Neurotransmitter binds to receptor 
–Channels for either K+ or Cl- open 
–If K+ channels open 
•K+ moves out IPSP 
–If Cl- channels open, 
•Cl- moves in IPSP

Question 6

Przypomnienie: Action potential

inna nazwa na axon terminal
rozwiń skrót epsp

Answer 6

AP cannot cross the synaptic cleft: the synapse provides the solution.

End of nerve enlarges into axon terminal (synaptic bouton) containing vesicles which store transmitter

If sufficient Excitatory Post Synaptic Potentials (EPSPs) to depolarise the membrane an AP will be generated and the signal will travel along