11.2 Nervous System Flashcards
Neurons use electrical signals called _________ to communicate with other neurons, muscles, or glands
nerve impulses
When microelectrodes are inserted in a resting neuron the electrical difference is _____ and called __________
-70 resting membrane potential
Resting membrane potential is stored in the form of ________
potential energy
When an appropriate stimulus comes along, the ______ provides energy for the generation of the impulse
resting membrane potential
Three things that generate polarization or -70 mV
- Large, negatively charged proteins that are present in the intracellular fluid
- Membrane containing ion specific membrane channels that allow the movement of K+ ions out of the cell
- Sodium potassium pump that pumps 3Na+ out and 2K+ in the cell
When a neuron conducts an electric impulse, there is an abrupt temporary change called _______
action potential
Phase 1 is
Stimulus and depolarization - stimulus disturbs plasma membrain on a dendrite causing sodium channels to open. Positive sodium ions flow in making it less negative until it reaches its threshold potential (-50 to -55 mV). More Na+ channels open
Phase 2 is
Above threshold - Na+ continues along its concentration gradient and then it increases sharply so that the plasma membrane becomes positive
Phase 3 is
action potential peak. +30mV or more. The sodium channels now close and the potassium ones open so that they can exit.
Phase 4 is
repolarization - the outward flow of K+ ions along its gradient makes the membrane potential fall.
Phase 5 is
hyperpolarization - the voltage gated potassium channels close slowly causing the membrane to undershoot its resting value
Phase 6
membrane potential stabilizes at resting value and is ready for new action potential
A synapse is
a site where a neuron makes a connection with another neuron or effector such as a muscle fibre or gland
Electrical Synapses are ______
quicker
Electrical Synapses have ______ _________ between pre and post synaptic cells
cytoplasmic continuity
Electrical synapse - pre and post synaptic cells are in _____ _______ meaning they are unbroken and rapid
direct contact
the communicating agent for electrical synapse is
ionic current
__________ allow ions to flow directly between two cells
gap junctions
Chemical Synapses are
slower, broken and more common
Chemical Synapses have no _______ _______ between pre and post synaptic cells
cytoplasmic continuity
chemical synapses are separated by a narrow gap called ___________ and it is ___ nm
synaptic cleft, 25
chemical synapse communicating agent is a
chemical transmitter also called neurotransmitter
Steps in chemical synapse.
1. action potential reaches ______ _____ of ___________ neuron
2. Voltage gated _______ ________ open and ___ enters _____ ______
3. ____________ are released by _________
4. _______________ binds to ____________ ____________
5. ___ channels open in _________ __________
axon terminal, pre-synaptic
calcium channels, Ca2, axon terminal
Neurotransmitters, exocytosis
Neurotransmitter binds to post synaptic receptor
ion, post synaptic membrane
Acetyl Choline is present in people with
alzheimers
