Unit 5 Nervous Systems Part 1 AP Biology Unit 5 Nervous Systems Part 1

From what you already know… 1) The parts of the Signal Transduction Pathway: Reception, Transduction, Response. 2) Ligand is a term for a signal molecule. 3)Energy can in the form of charged particles, called ions.

Step 1: Reception

Step 2: Transduction

Step 3: Response

150 mM KCl 150 mM NaCl –92 mV +62 mV Inner chamber Outer chamber Inner Ions and Energy –92 mV +62 mV Inner chamber Outer chamber Inner chamber Outer chamber 150 mM KCl 5 mM KCl 15 mM NaCl 150 mM NaCl Cl– K+ Na+ Cl– Potassium channel Sodium channel Artificial membrane

Evolution of a Nervous system in Animals Starts with the evolution of an organism. Wide Nerve Net: In Cinidarias…Jelly Fish---to help control movement. Evolution of the Brain (Mass of Neurons) leads to greater control of the system. It uses the nerve cord to span the body. The evolution of other sensory organs in the head region (cephalization) allows for reception and response to various types of stimuli from the environment.

Overview of the Nervous System Sensory Input: Sending information into the brain or spinal cord neurons in the body. Sensory Receptors receive a stimulus from the environment. Stimulus is a form of energy such as electromagnetic (light), mechanical (pressure) or sound waves. Integration: This is the interpretation of the energy by the Central Nervous System (CNS)---basically thinking about the stimulus. Motor Output: Sending out impulses from the brain or spinal cord to glands or muscles to create a response Effectors are muscles or glands. The structures can effect your body. Peripheral Nervous System: Tis includes the Sensory receptors and Motor Nerves.

CNS vs. PNS

Neuron structure Cell Body: This takes the stimuli from different dendrites and compiles the energy into one signal, like a funnel for fluids. Dendrites: These collect and carry stimulus energy IN to the cell body. They cover a large area. Axon: This one arm carries the one compiled signal AWAY toward the next neuron or effector cell. Axon Hillock-This is the swelling around the connection between the cell body and the axon. Myelin Sheath: This is the lipid layer of insulation around the axon created by Schwann Cells. It prevents the electrical energy of the neuron form burning the overlying muscle tissue. Rubber covering of electrical wiring. Synaptic Terminal: At the end of the axon (terminal means “ends”) Synapse: This is the gap between neurons or between neuron and effector cell. Neurotransmitter: This is the chemical, produced by the neuron, used to transmit the signal across the gap. The neurotransmitter is released from the presynaptic cell and travels to post synaptic neuron.

Synapse and Neurotransmitter

Glial Cells (Like a house frame … but for a brain Ganglia-This term refers to a bundle of neurons in the PNS. Nuclei—The term refers to a bundle of neurons in the CNS, The brain is a collection of nuclei.

Schwann Cells OR Oligiodendrocytes Nodes of Ranvier Layers of myelin Axon Schwann cell Schwann cell Axon Nodes of Ranvier Nucleus of Schwann cell Myelin sheath Glial Cells: Supporting cells for neurons to hang onto. They are analogous to the frame fro a house.—Help maintain the integrity of the system. Olidgodendrocytes—The term refers to the schwann cells of the CNS. Same type of cells; just in a different location. Schwann Cells are insulation cells of PNS Insulatin around Neuron; Produce Mylein MS—disease in where the Schwann cells in the CNS and PNS begin to die. The electricity traveling through the nerves then burns the muscles. 0.1 µm