Module 3 The Neuron

Structure of the Brain Genes –chains of chemicals that are arranged like rungs on a twisting ladder –there are about 100,000 genes that contain chemical instructions that equal about 1,000,000 pages of written instructions –genes program the development of individual parts into a complex & brain body

STRUCTURE OF THE BRAIN There are (2) types of cells that make up your brain. 1.Glial cells have many functions –guide the growth of developing neurons –wrap around neurons and form an insulation to prevent interference from other electrical signals –release chemicals that influence a neuron’s growth and function –help repair neurons when damaged –remove the carcasses of dead neurons

STRUCTURE OF THE BRAIN 2.Neurons –Transmit messages to other neurons as well as the rest of the body –Are responsible for all psychological activities either physical or mental: 1. physical: beating of heart, voluntary movement, sweating, pain etc. 2. mental: emotions, intelligence, language, etc. they have….

STRUCTURE OF THE BRAIN …… 2 specialized extensions –one extension is for receiving electrical signals –the other extension is for transmitting electrical signals

Types of Neurons

6 PARTS OF THE NEURON 1.Cell Body –large egg-shaped structure that provides fuel, manufactures chemicals, and maintains the entire neuron in working order 2.Dendrite –branchlike extensions that arise from the cell body –receive signals from other neurons, muscles, or sense organs –pass these signals onto the cell body

6 PARTS OF THE NEURON 3. Axon –a single threadlike structure that extends from and carries signals away from the cell body to the axon terminals. 4. Myelin Sheath - segments of fatty material that wrap around the axon insulating it from the electricity of other axons

6 PARTS OF THE NEURON 5. End/Terminal Bulbs - tiny bulbs at the end of the axon where neurotransmitters are stored and released to other neurons 6. Synapse - a “infinitely” small space (20-30 billionths of a meter) between the end bulb and a muscle, organ, or other neuron

Neuron Types

Next…..Functions of a Neuron Neurons function by creating small electrical currents. This currents make the neuron send signals in the form of chemicals to other neurons, organs, muscles.

Sending information –action potential is a tiny electrical current that is generated when the positive sodium ions rush inside the axon –the enormous increase of Na ions inside the axon causes the inside to reverse its charge –the inside becomes positive & the outside becomes negative FUNCTIONS: SENDING INFORMATION ACTION POTENTIAL SEQUENCE

….How?: SENDING INFORMATION ACTION POTENTIAL SEQUENCE –axon membrane has chemical gates that can open to allow electrically charged particles to enter or can close to keep out these particles –ions are chemical particles that have electrical charges –opposite charges attract and like charges repel

FUNCTIONS: SENDING INFORMATION ACTION POTENTIAL SEQUENCE Sending Information –the neural impulse refers to the series of separate action potentials that take place segment by segment as they move down the length of the axon (Like a Fuse) All-or-None law -if an action potential starts at the beginning of the axon, the action potential will continue at the same speed segment to segment to the very end of the axon

Resting state –the axon has a charge –the charge results from the axon membrane separating positive ions on the outside from negative ions on the inside FUNCTIONS: SENDING INFORMATION ACTION POTENTIAL SEQUENCE

Introduction to Psychology, 7th Edition, Rod Plotnik Module 3: Brain’s Building Blocks …To Review :Functions of a Neuron Electrical charges inside and outside of the neuron mix up to make the neuron fire called a NEURAL IMPULSE (Think of a gun firing) once you pull the trigger there is no stopping it

…..And Sending Information So, once these ions become charged they fire in what is called the _______ ________. Once again (Think of a gun firing) After it fires, the neuron releases a neurotransmitter into the synapse. and………..

To Review:Functions of a Neuron 1. Neurons do not actually touch each other 2. They are separated by the synapse. 3. Neural impulses force the neuron (terminal buttons) to release chemicals into this synapse. 4. The chemicals then attach to the dendrites from another neuron.

Synapse The synapse is a small gap separating neurons. This space is microscopic. This space is absolutely microscopic.

Neuron Structure (including Synapse)

NEUROTRANSMITTER Neurotransmitters –dozens of different chemicals that are made by neurons and then used for communication between neurons during the performance of mental or physical activities

NEUROTRANSMITTER Excitatory transmitters –open receptor locks and turn on neurons therefore “exciting” organs, muscles,other neurons Inhibitory transmitters –close locks and turn off neurons therefore “slowing” down organs, muscles, other neurons

Neurotransmitters Chemicals released to other neurons or body organs. Some are excitatory Some are excitatory Ex: they speed up your heart when you’re angry, prepare you for “fight or flight”

Neurotransmitters Some types of transmitters can be inhibitory: Some types of transmitters can be inhibitory: ***That is they relax, depress, or slow you down. Ex:Slow your heart while you sleep, slow down the feelings of pain to your brain (alcohol, painkillers)

Types of Neurotransmitters Acetylcholine- Movement, memory Acetylcholine- Movement, memory -If these neurons are destroyed what can happen? Dopamine- dopamine is similar to adrenaline, affects movement, emotional response, and ability to experience pleasure and pain. *** Schizophrenia

Types Of Neurotransmitters Norepinephrine- this chemical can effect your mood, arousal, memory etc. Norepinephrine- this chemical can effect your mood, arousal, memory etc. **Cocaine produces more of this chemical to drastically affecting your mood

Types of Neurotransmitters Serotonin- low levels in the brain to abnormal behaviors, such as: depression, suicide, alcoholism, and explosive rage. High levels: obsessive compulsion, fearfulness, lack of self-confidence, and shyness. Serotonin- low levels in the brain to abnormal behaviors, such as: depression, suicide, alcoholism, and explosive rage. High levels: obsessive compulsion, fearfulness, lack of self-confidence, and shyness.

Overlap of Specific Neurotransmitters

Lastly: Endorphins Endorphins- relieve pain, control your well-being. Cocaine, Heroin, Alcohol create these feelings and sometimes leads to addiction. Endorphins- relieve pain, control your well-being. Cocaine, Heroin, Alcohol create these feelings and sometimes leads to addiction.

Types of Neurotransmitters GABA- relaxes, controls your movement. Alcohol GABA- relaxes, controls your movement. Alcohol acts like GABA on the brain and reduces tension and also effects other transmitters. acts like GABA on the brain and reduces tension and also effects other transmitters.

WHAT DOES ALCOHOL DO? GABA Neurons –GABA neurons have chemical locks that can be opened by chemical keys in the form of the neurotransmitter GABA GABA Keys –alcohol molecules so closely resemble those of the GABA neurotransmitter that alcohol can function like GABA keys and open GABA receptors –when GABA neurons are excited, they decrease neural activity

PERIPHERAL & CENTRAL NERVOUS SYSTEM Peripheral Nervous System –made up of nerves that are located throughout the body, except in the brain & spinal cord Central Nervous System –made up of neurons located in the brain & spinal cord

PERIPHERAL & CENTRAL NERVOUS SYSTEM Nerves (Very different from neurons!) –string-like bundles of axons and dendrites that come from the spinal cord and are held together by connective tissue –carry information from the senses, skin, muscles, and the body’s organs to and from the spinal cord –nerves in the peripheral nervous system have the ability to grow or reattach if severed or damaged

… Did You Know? REFLEX Reflex –unlearned, involuntary reaction to some stimulus –neural connections underlying a reflex are pre-wired by genetic instructions

REFLEX (CONT.) Reflex sequence –sensors sensors trigger neurons that start the withdrawal effect –afferent neurons carry information from the senses to the spinal cord

REFLEX (CONT.) –Interneuron relatively short neuron whose primary task is making connections between other neurons –Efferent neuron carry information away from the spinal cord to produce responses in various muscles and organs throughout the body (Basically…. the point is, reflexes are involuntary and sometimes don’t involve any connections to your brain!