8b. Action Potentials and reflexes Flashcards
(15 cards)
what causes excitability in cells?
Ions move across membrane
Differences in ionic concentrations across the membrane
NA+K pump
describe a resting cell membrane
Higher concentration of Na and Cl outside of the membrane
Higher concentration of K, proteins and PO4 inside the cell
describe the RMP and its value
the difference in charge across the cell membrane in a resting cell
-70mV
what is the RMP caused by?
leak channels and the Na/K pump
what happens during depolarisation?
Na voltage gated channels open and Na moves into the cell and the inside of the cell becomes more positively charged than the outside of the cell
what happens during repolarisation?
Na voltage channels close
K voltage channels open, and K moves out of the cell and the intracellular side becomes more negative
how is the RMP re-established?
RMP is reestablished by NA/K Pump which redistributes ions as all Na and K gated channels are closed
what is a saltatory conduction?
when action potentials jump from one Node of Ranvier to the next
how does calcium enter a pre-synaptic terminal?
action potential stimulates voltage-gated calcium channels
what is calcium’s effect when it enters the pre-synaptic terminal?
Calcium diffuses into the cell and stimulates exocytosis of the synaptic vesicles, which release neurotransmitter molecules
how is an action potential passed to an adjacent neuron
Neurotransmitter molecules combine with their receptor sites and cause ligand gated Sodium channels to open. Sodium diffuses into the cell and causes depolarisation
describe meninges
connective tissue membrane surrounding the brain and spinal cord
what is the anatomical pathway of a reflex arc?
Sensory receptor
Sensory neuron
Interneuron
Motor neuron
Effector organ
what does an autononmic reflex involve?
Involves smooth muscles, cardiac muscles or viscera (pupillary reflex)
