Topic 3: Nervous System 1 Flashcards
What are electrochemical gradients?
Differences in the concentration of ions and molecules between ICF and ECF which can signal nerve and muscle cells
Are non-gated channels more permeable to K+ or Na+ at rest?
K+: there are more K+ channels than Na+
What 4 types of stimuli cause gated channels to open?
Membrane voltage changes (voltage gates)
Chemicals (chemical gates)
Temperature (thermal gates)
Mechanical deformation (mechanical gates)
The difference in electrical charge between inside and outside of the cell is called the…
Membrane potential
What are some factors that establish the resting membrane potential?
Na+/K+ pump
pumps 3 Na+ out, 2 K+ in
Large negatively charged organic ions
Membrane is more permeable to K+ than Na+
K+ is the major determinant of RMP
What are the ONLY electrically excitable types of cells?
Muscle and nerve cells
When a neuron is stimulated…
______ ion channels open
MP produces a(n) ______ potential
If the ______ potential is met, it triggers a(n)______ potential
Gated
graded
threshold, action
What are the meanings of “depolarized” and “hyperpolarized”?
Depolarized: more + than resting
Hyperpolarized: more - than resting
When can NO action potential be generated in a neuron?
Absolute refractory period
What is the relative refractory period?
When an action potential can be generated, but only by a greater-than-normal stimulus
What does the rate of action potential propagation depend on?
Fibre (axon) diameter
larger = faster
Myelination
myelinated = faster
Why are myelinated fibres quicker than non-myelinated?
Action potential only occurs at the nodes of Ranvier (saltatory (leaping) conduction)
AS COMPARED TO
Continuous conduction, which is when the AP runs along the whole, unmyelinated fibre
What are the steps during synaptic transmission?
-AP arrives at axon terminal
-Ca++ voltage gates open to release into synapse
-Triggers exocytosis of neurotransmitters
-NT diffuse across synaptic cleft, then bind to postsynaptic membrane
What are the types of postsynaptic potentials (PSPs)
Excitatory PSPs: due to opening of Na+ (or Ca++) channels or closed K+
often acetylcholine (ACh) or glutamate
Inhibitory PSPs: due to opening of K+ or Cl- channels
often glycine or GABA
What is the junction between the axon terminal of a neuron & an individual muscle fibre?
Neuromuscular junction
What are the steps to synaptic transmission at a neuromuscular junction?
-Neurotransmitter released (ALWAYS ACh)
-Na+ chemical gates on muscle motor end plate (sarcolemma) open
-End plate potential (EPP) triggers AP on sarcolemma
