Transcript With Light
• 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