Week 3 121 124 Warm Up Tues 121

Week #3 (1/21 – 1/24) Warm Up – Tues, 1/21: - Review of Intro to NS Anatomy Fun Fact: Neurons, which are the largest cells in the human body, do not undergo the process of mitosis. - Why is this important to know? Agenda: 1. Begin Action Potential notes Pick up: ØAction Potential notes ØSyn. Pot. & NT Review wkst Have out: Ø? ? ? Homework: 1. Reflex Lab Abstract (5 I) – Fri, 1/24 2. Syn. Pot. & NT Review wkst – Fri, 1/24 3. Action Potential Quiz – Fri, 1/24

Warm-up: Intro to NS Review • What organs are included in the CNS? • What are the 3 main parts of a neuron? • What is the function of the dendrites? Cell body? Axon? • What does SNS stand for & what kind of tissue does it control? • Are reflexes controlled by the SNS monosynaptic or polysynaptic?

You may NOT write anything down! • Let’s play a game of “Telephone”! I’ll start by giving a message to…. • In a Reflex Arc, what role are you & I playing (hint: it’s a cell)? ▫ Neurons • In anatomy, what is the space between each communicator called? ▫ Synaptic cleft or synapse • Was the message sent successfully? ▫ If not, why not?

How many parts were there to communicating the message? 1 st: the person had to receive it (listening) – role of the dendrites of a neuron 2 nd: the listener had to process the information (understanding the context of the words) – role of the soma/cell Li ste ni ng body 3 rd: the person to send the (speaking/ it to the role of the axon Sending had Understanding message sending next person) –

• Information from one neuron flows to another neuron across a synapse/synaptic cleft… ▫ a small gap separating a presynaptic ending contains neurotransmitters other organelles, a postsynaptic ending receptor sites for NTs & a synaptic cleft or space & postsynaptic endings. neurons that consists of: (axon terminals) that (NTs), mitochondria & (dendrites) that contains between the presynaptic

BIOLOGY REVIEW: What is the process of Diffusion? • When it comes to understanding how neurons communicate (Action Potential or Nerve Impulse), you must understand how the process of diffusion works! ▫ Diffusion Animation ▫ Particles move down their concentration gradients (from high to low) • Is it an active or passive form of transporting dissolves nutrients? ▫ Passive – NO ATP REQUIRED!

• Also known as “Nerve Impulses” • Self-regenerating wave of electrochemical activity that allows neurons to carry a signal over a distance (“game of telephone”) • Pulse-like waves of voltage that travel along several types of cell membranes

• Analogy – assume students are POSITIVELYCHARGED Na & K IONS! • Initiation/Resting Stage: ▫ Outside the classrooms (neuron) vs. inside classrooms (neuron) ▫ At 7: 20 a. m. , more students are arriving to school than are sitting in a “ 0” hr class ▫ So the inside of the classrooms (neurons) have a “negative” polarity.

• Initiation/Resting Stage: ▫ Some K+ channels are open: K+ diffusion occurring (out) ▫ Initiated by stimulus above a certain intensity or threshold (~-70 m. V – resting potential) ▫ Could be a pin prick, light, heat, sound or an electrical disturbance in another part of the neuron (“telephone call”) ▫ Electrical signal rises from changes in permeability of the neuron’s axon membranes to specific ions (Na+ & K+)

• Analogy – assume students are POSITIVELYCHARGED Na & K IONS! § Depolarization (Rising Phase): ▫ Outside the classrooms vs. inside classrooms ▫ First bell rings & students move from the halls into the classrooms ▫ This gives the inside of the classroom (neuron) a more “positive” polarity.

§ Depolarization (Rising Phase) § K+ Channel gates are closed § Stimulus causes gate in the Na+ Channel to open § High concentration of Na+ outside, Na+ diffuses into neuron § Electrical potential changes to ~ +40 m. V

• Analogy – assume students are POSITIVELY-CHARGED Na & K IONS! § Repolarization (Falling Phase): ▫ Outside the classrooms vs. inside classrooms ▫ Dismissal bell rings & students leave the classroom & enter the halls ▫ This gives the inside of the classroom (neuron) a “negative” polarity again.

§ Repolarization (Falling Phase) § Depolarization causes K+ Channel gates to immediately open & Na+ Channels close § K+ diffuses out of neuron § Reestablishment of initial electrical potential of ~-60 m. V

§ Refractory Period (Recovery Phase) § Na+ & K+ Channels cannot be opened by a stimulus § Na+/K+ Pump actively (ATP required) pumps Na+ out of & K+ into neuron (against/up their concentration gradients) § Reestablishment of ion distribution of resting neuron § This AP acts as stimulus to neighboring proteins within neuron membrane & initiates AP in another part of neuron § Wave of APs travel from dendrites to axon terminals § At axon terminal, electrical impulse is converted to a chemical signal (neurotransmitter)

Week #3 (1/21 – 1/24) Warm Up – Wed, 1/22 & Thurs, 1/23: - Analyzing the Change in Impulse Anatomy Fun Fact: The sciatic nerve is the largest in the human body, about as thick as a pencil (~0. 78 in). It is composed of nerve fibers (collection of neurons) that run from the spinal cord to & down the back of each leg. Agenda: 1. Getting the Message across the Synapse 2. Neuron/Action Potential Model-building OR Pushing the Limits: Brain Power Have out: ØReflex Lab handout Pick up: ØAnalyzing the Change in Impulse wkst Homework: 1. Reflex Lab Abstract (5 I) – Fri, 1/24 2. Syn. Pot. & NT Review wkst – Fri, 1/24 3. Action Potential Quiz – Fri, 1/24

Action Potential animation

• Getting the message across (the synapse)? ▫ At axon terminal, chemical signal (NT) crosses synapse between adjacent neurons Starts AP on this neuron ▫ This activates Ca 2+ channel to open Ca 2+ diffuses into neuron Causes NT vesicles to move to end & fuse with cell membrane Through exocytosis, NTs are released into synapse ▫ NTs diffuse across synapse & bind to NT receptors on another neuron Causes Na+ channels to open & AP is initiated in next neuron

Let’s Review… How do neurons communicate? • Action potential animation (~3 mins) • What is another name for the nerve impulse that travels from the cell body down the axon to the axon terminal? • What happens in the Rising Phase/ Depolarization? ▫ Falling Phase/Repolarization? ▫ Recovery Phase/Refractory Phase? • Once the AP has reached the axon terminal, what ion entering the neuron instigates the movement of synaptic vesicles to the cell membrane? • What do the vesicles release into the synapse?

Action Potential/Neuron Model • You will be divided into 4 groups to create 4 different Neuron models! • You will be presented with various materials you may choose to use for your model. • Each group will develop a model of a neuron, including: ▫ Dendrites ▫ Axon - Cell body (soma) - Synaptic terminal (axon terminal) • Your neuron will also demonstrate the transmission of: ▫ Action potential - Neurotransmitters • You will be demonstrating your model to the class on Fri, 1/24 (before Quiz on Action Potentials)! • Return any unused materials to where you found them! • Do NOT waste materials…all materials were bought by me!

Action Potential/Neuron Model • Each model of a neuron has to include: ▫ ▫ Dendrites Cell body (soma) Axon Synaptic terminal (axon terminal) • Your neuron will also demonstrate the transmission of: ▫ Action potential ▫ Neurotransmitters

Pushing the Limits – Brain Power • Title your paper “Pushing the Limits: Brain Power Facts” paper & have out a pen/pencil. ▫ Identify & explain at least 5 new concepts/ideas/facts you learn about the human brain/mind from the video. Add these to your paper!

Week #3 (1/21 – 1/24) Warm Up – Fri, 1/24: - Neuron Models Demo/Syn. Pot. & NT Review wkst Anatomy Fun Fact: An action potential (nerve impulse) is very quick & has the ability of transmitting impulses at the speed of 100 meters/second. The speed of message transmission to the brain can be as high as 180 mph. Agenda: 1. Action Potential Quiz 2. Ch. 14 Tour (Brain) Turn in: ØReflex Lab Abstract (5 I) Have out: ØNeuron models? ØSyn. Pot. & NT Review wkst Homework: 1. Ch. 14 Tour – Wed, 1/29 & Thurs, 1/30