Chapter 4 - Week 3 Flashcards
What is the membrane potential?
The difference in electrical charge between the inside and outside of a cell.
What is a neuron’s resting potential?
Around -70 mV
What is the abbreviation for sodium ions?
Na+
What is the abbreviation for potassium ions?
K+
What do the plus signs indicate in the abbreviation of neurons?
That it carries a single, positive charge.
Describe the ions when the neurons are at resting potential.
There are more Na+ (sodium) ions outside the cell than inside and more K+ (potatssium) ions inside than outside.
At resting potential, describe what push Na+ ions to enter the neuron.
- Electrostatic pressure (because opposite charges attract, the negative 70 mV charge attracts the Na+ postitive charge) and
- pressure from random motion pressure for Na+ ions to move down their concentration gradient.
What are the two effects that neurotransmitter molecules have when they bind to postsynaptic receptors?
- Either depolarize (decrease the resting potential) or
2. Hyperpolarise it (increase the resting membrane potential from -70mV to -72 for example)
What is the threshold of excitation that causes an action potential to fire?
Around -65 mV.
How long does an action potential last?
1 millisecond
Before an action potential is fired, positive and negative neurons are added to the “membrane sum”. They might add together making a greater charge, or cancel each other out. What is this called
Integration.
Substance nigra produces a substance called what?
Dopamine
The difference in electrical charge between the inside and the outside of a cell is called the what?
Membrane potential.
When a neuron is in its resting state, there is a greater concentration of what ions outside the neuron?
Sodium.
The ‘what’ channels are open during a neurons resting potential?
Potassium
Ions pass through neural membranes via specialised pores called what?
ion channels
The firing of neurons releases chemicals at their button terminals called what?
neurotransmitters
Neurotransmitters typically have one of two effects on postsynaptic neurons. They either depolarise them or what?
hyperpolarise
What is the sum of the postsynaptic potentials produces in rapid succession at the same synapse to form a greater signal called?
temporal summation
An action potential is elicited when the depolarisation of the neuron reaches the what?
threshold of excitation
Neurons integrate postsynaptic potentials in two ways: through spatial summation and through what other summation?
temporal
What is the period called after the absolute refractory period, wherein it is possible to fire the neuron again but only in higher than normal levels of stimulation?
The relative refractory period.
What are the four steps of an action potential?
- Sodium channels open and sodium rushes in
- potassium channels open and potassium flows out
- At peak, sodium channels close
- At the end, potassium channels start to close.
In myelinated axons, where is the only place that ions can pass through?
At the nodes of ranvier
The Hodgkin- Huxley model gives a supposedly factual account of neural conduction and its mechanisms. What was the problem with this theory?
The neurons and mechanisms are not representative of the variety, complexity and plasticity of many of the neurons in the mammalian brain
What does exocytosis mean?
The process of neurotransmitter release.
What is reuptake?
Once released, the neurotransmitters are drawn back into the presynaptic buttons by transporter mechanisms.
What are the four most studied amino acid neurotransmitters called?
- glutamate
- GABA
- aspartate
- glycine
What is the most prevalent excitatory neurotransmitter in the mammalian central nervous system?
Glutamate
Which is the most prevalent inhibitory neurotransmitter?
GABA
What are the four monoamine neurotransmitters?
- dopamine
- epinephrine
- norepinephrine
- serotonin
What are the four groups of small-molecule neurotransmitters?
1, amino acids
- monoamines
- acetylcholine
- unconventional neurotransmitters
Drugs that facilitate the effects of a particular neurotransmitter are said to be what of that neurotransmitter?
agonists
What are the drugs that inhibit the effects of a particular neurotransmitter called?
antagonists
How does botox work?
It blocks the release of acetylcholine at neuromuscular junctions
