Types of electrical potential recorded by intracellular
electrodes in neurons
The resting potential.
The potential difference across the cell membrane of an
un-stimulated neuron is usually 60 to 70 mV (inside
potential minus outside potential)
10.1 Anatomy of the human eye.
Section see over
10.4 Structure of the retina.
10.8 Structural differences between rods and cones.
10.5 An intracellular recording from a single cone (or rod ) stimulated with different amounts of light.
The photoreceptors h
Is a sensory modality that is related to, but separately
perceived from mechanoreception.
The perception of pain does not simply arise from
saturation of the response of mechanoreceptor or
thermoreceptor neurons by intense stimuli.
The Neuromuscular junction was the classic preparation for
understanding the basis for synaptic transmission in experiments in
the 1960s by Katz, Miledi and collaborators.
Generates a.p in
Nerve muscle preparation
EPP is a graded potentia
Ion pumps and transporters
Pumps and transporters move ions hundreds of times more
slowly across the membrane than do channels.
Consequently, they have only a minor role in generating
ion currents and determining membrane potential.
But they operate co
Classification of channel types.
In general, channels can be described by:
What ion the channel is selective to?
Some channels are selective to more than one ion or are non-selective for
all cations (but never both cations and anions why?) .
3.12 Action potential conduction requires both active and passive current flow.
When a.p.reaches Point A, passive current flow ahead of the a.p.
depolarizes the next patch of axon at point B to threshold.and so on
3.12 Action potential conduction
Box A Voltage Clamp Method
3.1 Current flow across an axon membrane during a voltage clamp
experiment. Depolarization elicits a large transient inward followed by a
large delayed outward current
What happens to the membrane current s when different steps
Vm =(RT/F) ln(Pk[K]o+PNa[Na]o+PCl[Cl]i)/( Pk[K]i+PNa[Na]i+PCl[Cl]o)
Membrane potential depends on the relative permeabilities
(P) for potassium, sodium, chloride ions as well as the
concentrations of those ions inside an
Typical animal cell (4)
110 mM anions
(e.g. amino acid, ATP 4-, phosphate
100 mM K+
10 mM K+
negative resting membrane potential
An equilibrium will soon be established for pot
A neural circuit the basic unit of function
1.7 A simple reflex circuit, the knee-jerk response. (Part 2)
Information is carried long distances encoded by the rate
of all-or nothing action potentials
Stretch of dendrites of sensory neuron
Synaptic (axon) terminal
The cell body is the site of protein synthesis
Dendrites receive information from other neurons
Synapses, usually onto dendrites and cell bodies, are sites of
information transfer between neurons
Axons can be covered in myelin, or
Understand the cellular and molecular basis
Understand how signals are generated and
Understand how the nervous system may be
modified by experience
Turn lecture into an active-learning