Chapter 8 Flashcards
What does electrical signals in neuron entail?
Nerves and muscles are excitable, they can propagate signals into action potential to respond to stimuli, and this is all due to RMP and selective permeability of ion channels
What charge does the inside of a neuron have at rest?
Negative
What does RMP provide?
Chemical and electrical potential energy
What is another word for membrane potential?
Equilibrium potential
What is membrane potential influenced by?
Uneven distribution of charged ions across a cell
and
Differing membrane permeability to those ions
What is hyperpolarization or repolarization?
What is depolarization?
Where is sodium, chloride, and calcium are more concentrated?
Extracellular fluid
Where is potassium more concentrated?
Cytosol
What is RMP primarily determined by?
Potassium
Goldman-Hodgkin-Katz equation means what?
It predicts the membrane potential due to effects of all ions across the membrane
Depolarization
An increase in Na+ permeability will drive Na+ into the cell, down concentration gradient, making the inside more positive
Hyperpolarization
An increase in K+ permeability will drive K+ out of the cell, down concentration gradient, making the inside more negative
When do gated channels open and close?
As response to stimuli
What makes mechanically gated channels open?
In response to physical forces, such as pressure and stretch
What makes chemically gated channels respond?
To a variety of neurotransmitters, neuromodulators, or intracellular signals
What are the two main cells of the nervous system?
Neurons - the basic signalling unit
Glial cells - support cells
What part of the neuron receives signals?
Dendrites
What part of the neuron carries outgoing signals?
Axons
What is the site of communication in the neuron?
Synapse
Do neurons make up majority of the nervous system?
No
What is the cell body the site for?
Integration of electrical signals and protein synthesis
What happens at the axon hillock?
Where axon begins and where action potential is produced
What are the two basic electrical signals?
Graded potentials and action potentials
Graded potentials
waves of depolarization that travel over short distances in the dendrites and cell body and lose strength; always the first signal
Action Potential
Brief, large depolarizations that travel for long distances along an axon without losing strength
Do graded potentials lose strength as they move through the cell?
Yes
What does EPSP and IPSP
Excitatory post-synaptic potential
Inhibitory post-synaptic potential
Does stronger stimuli produce larger graded potential?
Yes
If stimulus is large enough at axon hillock, it will hit the threshold to open what?
Na+ channels, meaning graded potential will produce action potentials
How far do action potentials travel?
The length of an axon
What are the steps of K+ and Na+ moving across membrane in action potential?
- RMP
- Depolarizing stimulis
- Mem dep to threshold and gates open
- Rapid Na+ dep the cell
- Na+ chan close and slow and K+ open
- K+ moves cell to ECF
- K+ chan remain and open and additional K+ leaves hyperpolarizing the cell
- K+ chan close
- Cell returns to normal
Axonial Na+ channels have how many gates?
2
Activation gates - open quick
Inactivation gates - close slow
What do action potentials conduct away from?
The soma
What influences conduction of velocity?
Axon diameter and the resistance of the membrane ion leakage (larger diameter of axon, more leakage resistant)
Is conduction water in myelinated neutrons or non myelinated axons?
Myelinated, increases resistance
Saltatory Conduction
The rapid method by which nerve impulses move down a myelinated axon with excitation occurring only at nodes
Are most synapses chemical?
Yes
What are the two types of neurocrine receptors?
inotropic and Metabotropic
Ionotropic receptors
Open when ligand binds, is fast movement and changes movement of ions
Metabotropic receptors
Secondary, with amplification and cascades, transducer through g-coupled proteins
What is Acetylcholine?
A chemical that carries messages from your brain to your body through nerve cells
What does it mean to be Cholinergic?
Neurons that secrete ACh and receptors that bind ACh
What type of action does Ach have?
Excitatory reaction on nicotinic receptors on skeletal muscles
What is the main excitatory neurotransmitter of CNS?
Glutamate
What is the main inhibitory neurotransmitter in the brain?
Gamma-aminobutyric acid
Is the first part of graded potential nicotinic?
Yes
Where are neurotransmitters stored?
Axon terminal in synaptic vessels
What is the purpose of a synapse?
To send a message
How do you recycle ACh
Broken down in synaptic cleft by acetylcholinesterase, choline then moved to axon terminal with Na+ to make more ACh
What does the frequency of action potential firing indicate?
The more stimuli the more neurotransmitters released
Convergence (integration of neural info)
Many presynaptic neurons provide input to influence a smaller number of postsynaptic neurons (peripheral)
Divergence (integration of neural info)
one presynaptic neuron branches to effect a large number of post synaptic neurons
Apparent vs Epparent
Fast Synaptic Potentials
Involve opening of ion channels
Slow synaptic potentials
Involve G-protein coupled receptors and secondary messengers
What is Temporal Summation?
Between excitatory and inhibitory GP when multiple impulses arise at a single synapse
What is Spatial Summation
When multiple impulses arrive at more than one site
What does integration mean?
When excitatory and inhibitory GP determine if a cell fires action potential based on threshold
What is the difference between global and selective presynaptic inhibition?
Global targets everything, where inhibitory only targets one thing
What are the sensory afferent types
Bipolar nuerons, and pseudounipolar
What is an efferent effector?
A multipolar neuron, has many dendrites, and a single long axon
What is anterograde transport?
From the cell body to axon terminal
What is retrograde transport?
from axon terminal to cell body
What are the three main glial cells?
Oligodendrocytes (CNS) and Schwann (PNS) cells which have myelin sheaths and satellite cells (PNS)
