Adaptive Immunity

Neural Structure and Function

Lesson

Topic

Essential Idea and Objective(s)

IB Curriculum Connections

Activities

1	Neuron Structure	Most animals have nervous systems, which consist of cells called neurons and transmit electrical impulses. State the function of the nervous system. State that Porifera do not have nervous systems whereas cnidarians, molluscs and arthropods do. The structure of a typical neuron includes a cell body, an axon and dendrites. Draw the structure of a typical neuron. State the function of the following cell parts: dendrites, axon and cell body. Identify the cell body, axon and dendrites in typical sensory and motor neurons.	Neurons transmit electrical impulses (6.5.U1).	Initial Knowledge Audit Intro slides (includes neuron model building) Animal nervous systems diagram Sheep brain dissection Types of neurons handwritten Idea for giant neuron posters why the first drawings of neurons were defaced (A&B) Neurons: Beyond the Textbook Based on this source Neural models A&B: unlocking ALS For students For teachers
2	Ions and Membrane Proteins	Nerve impulses depend on the movement of ions through specific membrane bound channels and pumps. Define ion, cation and anion. Contrast the function of channels and pumps. Outline the specificity of membrane channels and pumps. List the types of “gated” channels.		Reading link for “electrically active cell membranes” Handwritten annotations of the page
3	Resting Potential	Neurons generate and maintain a resting potential. Define resting potential. Explain three mechanisms that together create the resting potential in a neuron. State the voltage of the resting potential. Describe the structure of the sodium-potassium pump. Describe the role of the sodium-potassium pump in maintaining neuronal resting potential. Outline the six steps of sodium-potassium pump action.	Structure and function of the sodium-potassium pumps for active transport and potassium channels for facilitated diffusion in axons (1.4.A1). Neurons pump sodium and potassium ions across their membranes to generate a resting potential (6.5.U3).	Reading link for “the membrane potential” Handwritten annotations of the page Na-K Pump video clip Na-K pump animation Resting potential video clip Handwritten annotations of the page Membrane Potential Check for Understanding For students For teachers Review slides Modeling Resting potential whiteboards
4	Action Potential	When a neuron receives a stimulus that causes the membrane to depolarize, an action potential is generated. Define action potential. State that an action potential is only initiated if the threshold potential is reached. Outline the mechanism of neuron depolarization. Outline the mechanism of neuron repolarization. Outline the cause and consequence of the refractory period after depolarization. Oscilloscope traces show resting potentials and action potentials. Outline the use of oscilloscopes in measuring membrane potential. Annotate an oscilloscope trace to show the resting potential, action potential (depolarization and repolarization), threshold potential and refractory period.	An action potential consists of depolarization and repolarization of the neuron (6.5.U4). Nerve impulses are action potentials propagated along the axons of neurons (6.5.U5). A nerve impulse is only initiated if the threshold potential is reached (6.5.U9). Analysis of oscilloscope traces showing resting potentials and action potentials (6.5.S1).	Modeling the action potential Action Potential Handwritten Action potential review slides Phet interactive simulation AP Puzzle (print and cut cards for sorting and grouping; prints 11X17) Transport Proteins involved in Action potential (prints 11X17; key) AP Check for Understanding For students For teachers AP Review games Kahoot Quizizz Reading: Feel no pain (A&B) For students For teachers Never Quite Now (A&B) For students For teachers
5	Propagation of the Impulse	Nerve impulses are action potentials that travel along neurons due to sodium and potassium ions moving down electro-chemical gradients to create local currents. Define nerve impulse. Describe how nerve impulses are propagated along the neuron axon. Explain how the movement of sodium ions propagates an action potential along an axon. Explain movement of sodium ions in a local current. State that local currents cause each successive part of the axon to reach the threshold potential.	Propagation of nerve impulses is the result of local currents that cause each successive part of the axon to reach the threshold potential (6.5.U6).	Propagation notes (slides) Propagation notes (handwritten) Action potential propagation video Domino model of impulse propagation TEDEd: how do nerves work? (propogration)
6	Myelination	Increased diameter of axons in some animals and the myelination of nerve fibers in others allows for quicker transmission of nerve impulses. Compare the speed of transmission in giant axons (e.g. earthworm or squid) to other neurons. Compare the speed of transmission of myelinated axons to unmyelinated ones. Outline how the myelination of neurons allows for saltatory conduction, in which the differences in the distribution of electrically charged ions across the membrane can effectively jump from node to node. State that in myelinated neurons, the gated and non-gated Na+ and K+ ion channels are clustered down the axon at nodes of Ranvier.	The myelination of nerve fibers allows for saltatory conduction (6.5.U2).	Scitable: Myelin Saltatory conduction slides Modeling saltatory conduction Multiple Sclerosis A&B Radiolab “Falling” (50:15 - 53:50) For students For teachers
7	Synaptic Transmission	Synapses are junctions between neurons and between neurons and receptor or effector cells. Define synapse, synaptic cleft and effector. When an action potential reaches the presynaptic end of a neuron, a neurotransmitter is released into the synapse, which diffuses to the postsynaptic neuron. State the role of neurotransmitters. State that neurotransmitters can either be excitatory or inhibitory. Outline the mechanism of synaptic transmission, including the role of depolarization, calcium ions, diffusion, exocytosis, neurotransmitters, receptors, sodium ions, sodium channels, threshold potential and action potential. Initiation or inhibition of an action potential in a postsynaptic neuron is the result of the summation of all excitatory and inhibitory neurotransmitters received from a presynaptic neuron. Interpret graphical representations of the summation of combinations of excitatory and inhibitory neurotransmitters. State that synapses that involve the secretion and reabsorption of acetylcholine are known as cholinergic synapses. Define cholinergic synapse. State that acetylcholine is one of the most common neurotransmitters in both invertebrates and vertebrates and is used as the neurotransmitter in many synapses including between neurons and muscle fibers. Outline the secretion, action, reabsorption and formation of acetylcholine.	Synapses are junctions between neurons and between neurons and receptors or effector cells (6.5.U7). When presynaptic neurons are depolarized they release a neurotransmitter into the synapse (6.5.U8). Secretion and reabsorption of acetylcholine by neurons at synapses (6.5.A1).	Synaptic transmission notes handwritten Synaptic transmission slides Neurotransmitters and summation notes Neurotransmitters Synapses crash course ScitC: neuronal synapses Chemical weapons Neonicotinoids Reading: pesticides messing with bees For students For teachers
8	Drugs	Synaptic transmission in insects can be blocked by the binding of neonicotinoid pesticides to acetylcholine receptors. Outline the mechanism of action of neonicotinoids used as insecticides. State why neonicotinoids insecticides are not highly toxic to humans. Psychoactive drugs affect the brain by either increasing or decreasing post synaptic transmission. State the stimulant drugs increase postsynaptic transmission while depressant drugs decrease post-synaptic transmission. Outline the effects of nicotine and alcohol on the brain.	Blocking of synaptic transmission at cholinergic synapses in insects by binding of neonicotinoid pesticides to acetylcholine receptors (6.5.A2).	Neonic handwritten Chemical weapons Neonicotinoids slides Reading: pesticides messing with bees
9	Wrap Up and Review	Not applicable	Not applicable	Final Knowledge Audit For students For teachers Kahoot review (ICTD) Quizizz Review (OCI) 1 page-summary (OCI) General directions Specifics for this unit Final Knowledge Audit (ICI)
10	Assessment	Not applicable	Not applicable