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
Acetyl Choline triggers
muscle contractions
How do poisons affect the body
it blocks acetyl choline so we become paralyzed
_______ is a stimulant of acetyl choline releasing neurons
Endorphins are
neurotransmitters released during pleasure or stress
