module 3 the neuron. structure of the brain genes –chains of chemicals that are arranged like...

Module 3The

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 NEURON1.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 NEURON3. 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


• 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


Introduction to Psychology, 7th Edition, Rod PlotnikModule 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.

SynapseSynapse

The synapse is a small gap separating The synapse is a small gap separating neurons. neurons.

This space is This space is absolutely microscopic. 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

NeurotransmittersNeurotransmittersChemicals released to other Chemicals released to other neurons or body organs.neurons or body organs.•Some are Some are excitatoryexcitatory

Ex: they speed up your heart Ex: they speed up your heart when you’re angry, prepare when you’re angry, prepare you for “fight or flight”you for “fight or flight”

NeurotransmittersNeurotransmitters

Some types of Some types of transmitters can be transmitters can be inhibitoryinhibitory::

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

Types of Types of NeurotransmittersNeurotransmitters

AcetylcholineAcetylcholine- Movement, memory- Movement, memory

-If these neurons are destroyed what -If these neurons are destroyed what can happen?can happen?

DopamineDopamine- dopamine is similar to - dopamine is similar to adrenaline, affects movement, adrenaline, affects movement, emotional response, and ability to emotional response, and ability to experience pleasure and pain. experience pleasure and pain.

*** Schizophrenia*** Schizophrenia

Types Of Types Of NeurotransmittersNeurotransmitters

Norepinephrine- this Norepinephrine- this chemical can effect chemical can effect your mood, arousal, your mood, arousal, memory etc.memory etc.

**Cocaine produces **Cocaine produces more of this chemical more of this chemical to drastically to drastically affecting your mood affecting your mood


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

Overlap of Specific Neurotransmitters

Lastly: EndorphinsLastly: Endorphins

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


GABA- relaxes, GABA- relaxes, controls your controls your movement. movement. Alcohol Alcohol

acts like GABA on acts like GABA on the brain and the brain and reduces tension reduces tension and also effects and also effects other other transmitters.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!

module 3 the neuron. structure of the brain genes –chains of chemicals that are arranged like...

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