Ach receptors heart are metabotropic and inhibitory

• Chemical synapses: release of transmitter which binds to postsynaptic receptor
– Slow but __________; postsynaptic cells add up signals from many presynaptic inputs
• Fast EPSPs & Fast IPSPs + ‘modulatory’ postsynaptic effects – Type of response depends on receptor _____ionotropic & metabotropic.

e.g. ACh receptors on heart are metabotropic and inhibitory, but ACh receptors on skeletal muscle are ionotropic & excitatory

2. Action potential depolarizes terminal causing opening of voltage-gated

________ channels

Snare Complex & Vesicle Fusion Fig. 5.14B

Receptors for chemical messengers

	Chemical messengers ____to protein ‘receptors’
	–

	Activation of G-protein → slower changes in excitability of target cells: ‘slow ______’ Changes in behavioral _____

Acetylcholine receptor structure and other
transmitter-gated ion channel receptors similar

Transmitter-gated ACh receptor

Excitatory postsynaptic potential: EPSP

• Neurotransmitter-gated ion channels permeable to both Na+& K+ bring Vm toward __________
Result is an ‘excitatory postsynaptic
potential’: ‘EPSP’
– ACh- and __________gated ion channels result in EPSPs

ECl- = _______
– Result is an IPSP

– _____-gated ion channel receptors

• ACh cleared from neuromuscular junction by acetylcholinesterase: Nerve gases inhibit this enzyme

• After reuptake, monoamine oxidase (MAO) metabolizes the amines serotonin, norepinephrine and dopamine. MAO inhibitors are used to treat Parkinson s disease and also as antidepressants

– EPSP is greatly diminished at a distance from the synapse • _________ of many EPSPs is necessary to reach threshold for an action potential at axon hillock

at same synapse

G-protein coupled receptors GPCRs)• Single protein with _ membrane spanning domains


	•	examples: β-adrenergic (NE) and muscarinic (ACh) on_______
	Sequence of events
	1.
	2.
	3.

receptor __________

Acetylcholine (ACh)

	• Somatic motor system – Motor neuron soma: brainstem & spinal cord – release ACh onto skeletal muscle • Autonomic nervous system (ANS) – Sympathetic branch • Preganglionic soma in spinal cord: cholinergic • Postganglionic: adrenergic – Parasympathetic branch • Preganglionic soma in brainstem & spinal cord: cholinergic • Postganglionic: cholinergic

Glutamate

–

	• ‘Sedatives’ & ‘Anxiolytics’: Benzodiazepines, Barbiturates, & ethanol enhance GABA induced opening of the Cl- channel

• On Sakai
– Quiz 2
– Submission deadline: Friday, Sept 24 at 10 PM