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• First…
Thank You!
It’s been a pleasure!
• I’m going to post these slides!
Exam Format
Same as midterm
multiple choice & short answer
not nearly as many calculations
Formulas will be given
Calculators OK
How to contact me
• My Office Hours
– This week Tues 12-1, Wed 11-12
– Next week Tues 11-1, Wed 11-1
– By appointment
• Email: [email protected]
Study Tips
3. What if scenarios
2. Make associations between related material
1. Know the material and practice recalling it
Things you asked for:
1. Photoreceptor circuit
2. Cochlea / hair cells
3. Muscle spindle
Photoreceptor
With Light
In the Dark
Depolarized
Hyperpolarized
Steady release of
of
neurotransmitter
Inhibitory synapse
Hyperpolarized
Bipolar cell
 transmitter release
Neurotransmitter
release is reduced
Inhibition is relieved
Depolarizes
 transmitter release
Excitatory synapse
APs
Ganglion cell
APs
To Optic Nerve 
Light on
0 mV
Vm
1000 mV
Light off
Oval window
Basilar Membrane
Base
Round
Window
Apex
Cross section of the Cochlea
Scala vestibuli
Scala media
Endolymph – low Na+, high K+
Scala tympani
Perilymph – high Na+, low K+
cochlear nerve
Basilar membrane
Shear force generated
Tectorial membrane
Hair bundle
Outer
Hair Cell
Basilar membrane
Inner Hair Cell
Hinge Points
Vibrates in response
to sound
K+
Repolarization
K+
Endolymph
High K+, Low Na+
Voltage gated K channel
K+ K+
Ca++
Ca++
perily
Perilymph
Low K+, High Na+
Muscle Spindle
 Motor
neurons
 Motor
neurons
Group I and II
Sensory fibers
Extrafusal
Muscle fibers
Intrafusal
Muscle fibers
 Motor
neuron
stimulate
Ia sensory
neuron
APs in sensory -  Motor neuron only
shorter
record
Muscle
length
longer
 Motor
neuron
stimulate
Ia sensory
neuron
APs in sensory -  Motor neuron only
shorter
record
 Motor
neuron
Muscle
length
longer
APs in sensory -  and  Motor neurons
Spinal cord
Ia sensory
neuron
Inhibitory interneuron
 Motor neurons
Muscle spindle
Transmembrane proteins are essential for stimulating and inhibiting cellular
function. Provide evidence to support this statement by identifying the three
major groups of transmembrane proteins discussed in class. Indicate how they
function and give examples of how they act to stimulate and inhibit cellular
physiology.
1.
VOLTAGE-GATED ION CHANNELS
•
•
•
2.
Forms a pore that opens and closes in response to changes in membrane voltage
Stimulate – Na channel allows + charge to enter cell – depolarize-Action Pot
Inhibit – K channel allows + charge to leave – hyperpolarize repolarize
LIGAND-GATED ION CHANNELS
•
•
•
3.
Forms a pore that opens and closes in response to binding of a molecule with a receptor
Stimulate – Ach receptor responsible for Excitatory synaptic potentials by allowing Na+ to
enter cell
Inhibit – GABA receptor responsible for Inhibitory synaptic potentials by al;lowin Cl- into
cell
G-PROTEIN COUPLED RECEPTORS
•
•
•
Link molecules binding to receptor to intracellular signalling
Stimulate - 2 1 adrenoreceptor stimulate adenylate cyclase
Inhibit - 2 adrenoreceptor inhibit adenylate cyclase
Adrenal Medulla
• Catecholamine
Adrenal Cortex
• Steroid Hormones
– Epinephrine
– Norpinephrine
– Mineralocorticoids
• Stored in vesicles within
chromaffin cells
• Fight or flight
• Release controlled by
SNS activity
– Ach depolarizes chromaffin
cell, allows Ca+ to enter,
vesicles fuse and secrete
hormone into blood
• Effects – many
Heart
Smooth muscle
Metabolism
Neural
• Aldosterone
• Impt for Na channel
expression and water
reabsorption in kidney
– Glucocorticoids
• Cortisol
• Regulates liver enzymes
that produce glucose
• Controlled by:
– Neural input 
hypothalamic neurons 
release CRH  Ant
pituitary  release ACTH
Compare and contrast the role of membrane and
cytoplasmic receptors in the hormonal regulation
of cellular function.
• lipid soluble and insoluble hormones
• Cite examples (cortisol, epinephrine)
• Cytoplasmic receptors
– Go to nucleus
– effect transcription / translation
• Membrane receptors
– interact with G-proteins to initiate second messenger
production and signaling pathway
– Activate effector molecules (kinases) which modulate
many targets (ion channels, other enzymes)
– Identify specifics of cited examples
Excitation of the muscle spindle leads to muscle
contraction through a reflex arc. Identify role that
passive ionic currents play in this process.
• Spindle is a sensory organ – stretch will cause local
currents to flow and a depolarizing receptor potential to
be generated. If large enough this will lead to AP in the
sensory neuron
• At the synapse AP induces Ca++ mediated exocytosis,
resulting in the opening of ligand-gated ion channels in
the motor neuron.
• Local current flow through these receptors generates
EPSPs or IPSPs.
• If EPSP big enough AP generated in motor neuron
• At NMJ, neurotransmitter results in local current flow and
generation of EPP
– If twitch fiber  large enough EPP, muscle AP
– If non-twitch  graded potential