The Nervous System Nerve Cell Function History Galvani (1759) proposed that nerves work exactly the same way that the wiring in your house. That they.

Slides:

Advertisements

Similar presentations

Advertisements

Nerve Impulses and Reflex Arcs

Section 9.2 Assignment Electrochemical Impulse

Nerves, hormones and homeostasis

Chapter 48 Neurons, Synapses, and Signaling

6.5 (part 1)The nervous system

The Electrical Nature of Nerves

The Nervous System Part II. The electrochemical impulse In 1939, by placing tiny electrodes across the membrane of the giant axon of a squid the researchers.

9.2 Electrochemical Impulse

Questions 17-1 Q: What happens to a nerve impulse once it reaches the end of an axon? Q: How does one neuron communicate with another?

Neuroscience and Behavior Most information in this presentation is taken directly from UCCP content, unless otherwise noted.

The Neuron An everyday (every second!) use of active transport

Transmission of Nerve Impulses WALT Neurones transmit impulses as a series of electrical signals A neurone has a resting potential of – 70 mV Depolarisation.

Chapter 9.2: Electrochemical Impulse Pages

Chapter 48.  Short distance communication ◦ Synapses between cells  Neurotransmitters.

The Nervous System Neuron –Cell body; Dendrites; Axon Three general groups of neurons –Sensory neurons (afferent or receptor) Receive the initial stimulus.

9.2 Electrochemical Impulses. Nerves impulses are similar to electrical impulses but are slightly slower. They stay the same strength throughout the entire.

Copyright © 2009 Pearson Education, Inc. Neurons and Neurological Cells: The Cells of the Nervous System  The nervous system  Integrates and coordinates.

9.2 Electrochemical Impulse. Late 18 th Century: Luigi Galvani  leg muscle of dead frog could be made to twitch under electrical stimulation.

Unit 1B: Nerve Impulses and Synapses. Nerve Impulse A neuron’s job is to transmit a message to a muscle, gland, or another neuron The message travels.

How neurons communicate ACTION POTENTIALS Researchers have used the axons of squids to study action potentials The axons are large (~1mm) and extend the.

8.2 Structures and Processes of the Nervous System

The Neuron An everyday (every second!) use of active transport.

Structures and Processes of the Nervous System – Part 2

Myelin again Myelin speeds up the nerve impulse because nerve fibers have Schwann cells around them – Schwann cells restrict ion movement – So impulse.

How signals are sent through the nervous system. Synapse  Synapse = Junction between two connecting neurons Synaptic cleft-between the neurons, signal.

Chapter 17 The nervous system.

NEUROMUSCULAR JUNCTION & NERVE IMPULSES. Characteristics of Muscle Tissue 1)Irritability: ability to respond to a stimulus 2)Contractility: ability to.

Nerve Impulses.

2 Functional Properties of Neurons 1. Irritability Ability to respond to stimuli 2. Conductivity Ability to transmit an impulse.

Action Potential revisited When a stimulus reaches threshold level, Sodium channels open up and Sodium rushes into the axon along the concentration gradient.

Neuron Structure and Function. Nervous System  Nervous system is composed of specialized cells called neurons.  Neurons have long “arms” called axons.

The Electrochemical Impulse Action Potential Threshold Level All-or-None Response.

Section 9.2 Page 418 The Electrochemical Impulse.

THE NERVE IMPULSE. Cells and membrane potentials All animal cells generate a small voltage across their membranes This is because there is a large amount.

Chapter 35-2 Nervous System.

NERVE IMPULSE TRANSMISSION  nerve cells are like no other cell in the body because they possess an electrical charge  the axon of a neuron has a cell.

 When a neuron sends a signal down it’s axon to communicate with another neuron, this is called an action potential. When the action potential reaches.

17-1 Part I - The Nervous System Function: To coordinate the actions of your body To ensure effective behavior To maintain the internal environment within.

Chapter 49 Table of Contents Section 1 Neurons and Nerve Impulses.

Upload 9.06 Nerve Impulse Notes to eBackpack

Warm-Up What is an electrochemical gradient? In what organelles do we find these in a cell?

Do Now 1/9/15 1.Name 3 glial cells and describe their function and location. 2.Which neural pathway transmits a signal when the internal body temperature.

Neurons and Synapses 6.5. The Nervous System Composed of cells called neurons. These are typically elongated cells that can carry electrical impulses.

Synapses. C. Action potential reaches the end of a presynaptic neuron. F. Voltage gated calcium channels open D. Calcium ions flow into the presynaptic.

Neuron Poster; Cockroach Flow Chart w/ Rubric Attached Due Today

Upload 9.06 Nerve Impulse Notes to eBackpack

Nerve Signals 11.2 (Image from:

Nerve cell membrane Electrochemical message is created by the movement of ions across the nerve cell membrane The resting nerve membrane has a electrical.

Electrochemical Impulse

Nerve Impulse Conduction

Neuron Function.

The Nerve Impulse.

Action Potential 6.5.

6.5 Nerves, Hormones, and Homeostasis

Chapter 49 Table of Contents Section 1 Neurons and Nerve Impulses.

2 Functional Properties of Neurons

Nerve Impulses.

2 primary cell types in nervous system

Cell Communication: Neuron.

Structures & Processes of the Nervous System

Today you will: Describe a resting membrane

Electrochemical Gradient Causing an Action Potential

ELECTROCHEMICAL IMPULSE

Notes Ch. 10c Nervous System 1

Gates + Potentials.

Today you will: Define threshold and use it to explain the all-or-none response Describe a synapse Explain how chemical transmitters aid in transmission.

Transmission of Nerve Signals

Presentation transcript:

The Nervous System Nerve Cell Function

History Galvani (1759) proposed that nerves work exactly the same way that the wiring in your house. That they carry electrical impulses. But in 1900 J. Bernstein demonstrated that nerve impulses were to slow to be electrical singles, so they must be an electrochemical impulse

History and the giant squid Bernstein’s theory was supported almost 40 years later by Curtis and Cole. They were able to use a Giant Squid’s nerve and measure the electrical difference across its membrane. Why did they use the nerves of the illusive G. Squid?

Experimental Evidence The Squids axons are large enough that they were able to place a tiny probes on the inside and the outside of the membrane and measure the potential difference. They found that a resting membrane there is about a -70mV difference between out and in. -70mV

E.E. Cont... They then stimulated the nerves and found that the potential difference changed as the nerve impulse traveled down the axon. The difference only lasted a few milliseconds. -70mV +40mV-70mV

Terms Resting potential (membrane) –The electrical potential that nerves have a rest -70mV Action potential –The reversal of charges as the membrane becomes excited +40mV Polarized –The resting membrane is said to be polarized because of the charge differential Depolarized –It then becomes Depolarized as the charge reverses –Through the action of an ion pump the nerve becomes repolarized

Terms Cont... Refractory period –The nerve takes a certain period of time to recharge The charge across the nerve membrane is caused by different concentrations of ions on each side (don’t forget ions have charges )

In-depth Look When the nerve is at rest there is a high concentration of Na+ on the out side and K+ on the inside. This creates the -70mV difference. As the nerve becomes depolarized Na flows in through specialized doors and K+ runs out. They are then re-pumped back into their resting positions. Let’s take a look

All or None and Threshold Levels Nerves need a minimum stimulus to fire. Anything below this value and the nerve will do nothing. Also the nerve will fire with the same intensity once that threshold is reached So it will either fire completely or not at all this is “All or None”

Things to think about If this is the case how do we know How hot something is or if we are being gently poked or stabbed?

The Synapses Contrary to popular belief there is not a direct connection between neurons. In fact there is a small space called a synapses. Synapses can also occur between neurons and effectors. Small vesicles containing transmitter chemicals are located at the end of axons terminus.

When the impulse reaches the end plate calcium rushes in and causes these vesicles to pop and release their neurotransmitters into the synaptic cleft (the space between axon and next nerve.) The space between neurons is really small ~20nm, but it still takes time for the transmitter to move across. This could be considered the weak link (wrt speed) in nerves.

Terms... Presynaptic neuron: PRN –The Neuron which release the transmitter Postsynaptic neuron PON –the neuron which dendrites receives the transmitter. NB the greater the number of synapses the longer it takes for a neural transmission.

Neural transmitters Acetylcholine –is one of the most common transmitters –when it is released from the PRN it diffuses across the synaptic cleft where it bonds to specialized receptors in the PON.

–These receptors open the sodium ion channels and cause the wave of transmission to flow down the next neuron. –What would happen to the PON if Acetylcholine was constantly attached to the PON? –The PON would be in a constant state of depolarization and never have a chance to recover.

How do we get rid of it then? The PRN released an enzyme called cholinesterase soon after the acetylcholine is released Cholinesterase destroys acetylcholine and allows the sodium ion channels to close which allows the PRN to recover and get ready for the next wave of excitement.