BSC 1010 - General Biology I

Neurons and Nervous Systems

Reading Assignment: POHS pp. 903 - 926

Self Quiz: 1-10

Applying Concepts: 1-3, 5

Additional Thought Question:

Lecture outline:


Definitions
	nervous system
		3 basic components
	neuron
	nerve impulse

Diversity of nervous systems
	nerve nets
	ganglia
	vertebrate nervous system
		central nervous system (CNS)
		peripheral nervous system (PNS)
		enteric nervous system
	
Neurons - functional unit of the nervous system
	- electrically excitable membrane
	- typically possess 4 regions:  cell body, dendrite,
		axon and axon terminal
	- synapse

Glia - support cells of the nervous system
	function
	types
		myelinating:  Schwann (PNS) and oligodendrocytes (CNS)
		astrocytes

Electrical concepts
	membrane potential
	resting potential
	action potential (nerve impulse)
	voltage (potential)
	current
	major ions

Ion pumps and channels
	membrane pumps
		Na-K
	ion channels
		voltage-gated
		stimulus-gated
			receptor
		non-gated ("leak")

Establishment of the resting potential
	resting potential established when electrical and gradient forces
		of K+ ions are in equillibrium
	significance

Changes in membrane potential
	hyperpolarization
	depolarization
	action potential
		defining characteristics
			reversal of membrane polarity
			all-or-none event
		generation
			role of voltage-gated Na+ and K+ channels
		refraction	
		propagation


Conduction velocity
	axon diameter
	myelination

Synapses
	definition
	types
		electric
		chemical
			gated ion 
				excitatory - EPSP
				inhibitory - IPSP
			secondary messenger

	fundamental theorem:  Outcome (depoarization, hyperpolarization, 
		etc.)of a synaptic event is determined by the 
		post-synaptic cell
	decision making by the neuron
		spatial summation
		temporal summation
	
The neuromuscular junction as an example of an excitatory chemical synapse
	neurotransmitter
	structure
		presynaptic
		synaptic cleft
		postsynaptic
			AChE
		mechanism of transmission

Neurotransmitter diversity

Neurons in circuits
	reflexes as the simples form of behavior
		monosynaptic reflex
		role of interneurons

Topics not covered in lecture for which you will be responsible:

	patch clamping							pp. 912-914
	presynaptic excitation and inhibition				p. 919
	neurotransmitter clearing mechanisms				p. 922
	Aplysia as a model system for learning and memory		p. 922