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Neural and Hormonal Systems

Module 3

“…it has been calculated that the number of possible permutations and

combinations of brain activity,..exceeds the number of

elementary particles in the known universe.”

Ramachandran in A Brief Tour Of Human Consciousness

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Neuroscience and BehaviorOverview

Neural Communication Neurons

How Neurons Communicate

How Neurotransmitters Influence Us

The Nervous System The Peripheral Nervous System

The Central Nervous System

The Endocrine System

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History of Mind

In 1800, Franz Gall suggested that bumps

of the skull represented mental

abilities.

Phrenology

Bettm

an/ Corbis

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Neural Communication

Neurobiologists and other investigators understand that humans and animals operate

similarly when processing information.

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Neural CommunicationThe body’s information system is built from

billions of interconnected cells called neurons.

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The Neuron

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Myelin sheath“Practice makes Myelin, Myelin

makes perfect.”• Specialized Glial cells • Acts as an electrical

insulator • Not present on all

cells• Increases the speed

of neural signals down the axon.

Myelin Sheath

Parts of a Neuron link .50

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How neurons communicate

• Neurons communicate by means of an electrical signal called the Action Potential

• Action Potentials are based on movements of ions between the outside and inside of the cell

• ….. Resting potential -70mv

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Action Potential

Neural impulse: When an AP occurs a

molecular message is sent to neighboring

neurons

Sodium Na+, Potassium K+, Chlorine Cl-

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Threshold

Threshold: When the excitatory signals exceed a minimum intensity the neuron

fires an action potential.

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Action Potential Properties

All-or-None Response: A strong stimulus can trigger more neurons to fire, and to fire more often, but it does not affect the action potentials

strength or speed.

Intensity of an action potential remains the same throughout the

length of the axon.

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Synapse Synapse: a junction between the axon tip of the sending neuron and the dendrite or

cell body of the receiving neuron.

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Neurotransmitters

Neurotransmitters (chemicals)

released from the sending neuron travel across the synapse and bind to receptor sites on the receiving

neuron.

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Reuptake

Neurotransmitters in the synapse are reabsorbed

through the process of reuptake.

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The body’s Chemical Messengers

• Neurotransmitters

• Hormones

• Neurohormones

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Some Neurotransmitters• Acetylcholine• Serotonin• Norepinephrine• Dopamine• Endorphins• GABA • Glutamate Neurotransmitter

song

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Acetylcholine (ACh)

• Found in neuromuscular junction

• Involved in muscle movements

• My muscles AChe…get it…

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Disruption of Ach Functioning

• Curare - blocks ACh receptors– paralysis results

• Nerve gases and Black Widow spider venom - too much ACh leads to severe muscle spasms and possible death

• Nicotine works on ACh receptors– can artificially stimulate skeletal muscles,

leading to slight, trembling movements

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Alzheimer’s Disease• Deterioration of memory, reasoning,

and language skills

• Symptoms may be due to loss of ACh neurons

• A=A

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Serotonin

Serotonin is involved with

mood regulation.

Prozac works by keeping serotonin in the synapse

longer, giving it more time to exert an effect (blocking

reuptake)

LSD and Seratonin at Nat Geo 2:21

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DopamineImportant for

movement, rewards & pleasure.

Involved with diseases such as

schizophrenia and Parkinson’s disease.

Link dopamine flood at Nat Geo 3:44

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Norepinephrine

• Arousal• Sympathetic nervous system• “Fight or flight” response• Wakefulness, sleep• Learning• Mood regulation

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Endorphins• Control pain and pleasure• Released in response to

pain• Morphine and codeine

work on endorphin receptors

• Runner’s High…• Or End pain..

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Gamma-Aminobutyric Acid (GABA)

• Main inhibitory neurotransmitter of the CNS when you sleep

• Benzodiazepines (which include tranquilizers such as Valium) and alcohol work on GABA receptors

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Glutamate

• Major excitatory neurotransmitter• Too much glutamate (and too little

GABA) associated with epileptic seizures

• Involved w/memory

• Glutes are exciting…

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Neurotransmitter pathways

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Lock & Key Mechanism

Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism.

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Agonists

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Antagonists

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The Nervous SystemConsists of all the nerve cells. It is the body’s speedy, electrochemical communication system.

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Central Nervous System (CNS): the brain and spinal cord.

Peripheral Nervous System (PNS): the sensory and motor neurons that connect the central nervous system (CNS) to the rest of

the body.

CentralNervousSystem(CNS)

PeripheralNervousSystem(PNS)

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Kinds of Neurons

Sensory Neurons carry incoming

information from the sense receptors to the

CNS. Motor Neurons carry outgoing information

from the CNS to muscles and glands. Interneurons connect

the two neurons.

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Central Nervous System

The Spinal Cord and Reflexes

Simple Reflex

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The Nerves

Nerves consist of neural “cables” containing many axons. They are part of the peripheral

nervous system and connect muscles, glands, and sense organs to the central nervous

system.

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Peripheral Nervous System (PNS)

Somatic Nervous System: The division of the peripheral nervous system that controls the body’s skeletal muscles.

Autonomic Nervous System: Part of the PNS that controls the glands and other muscles.

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Autonomic Nervous System (ANS)

Sympathetic Nervous System: Division of the ANS that arouses the body, mobilizing its energy in stressful situations.

Parasympathetic Nervous System: Division of the ANS that calms the body, conserving its energy….HOMEOSTASIS

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Central Nervous SystemThe Brain and Neural Networks

Complex Neural Network

Interconnected neurons form networks in the brain.

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The Endocrine System

Endocrine System:

Communication is carried out by hormones

synthesized by a variety of

glands.

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Hormones

Hormones are chemicals synthesized by the endocrine glands that are

secreted in the bloodstream.

For example, epinephrine (adrenaline) increases heart rate, blood pressure, blood sugar, and feelings of excitement during

emergency situations.

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Hormones vs. Neurotransmitters

• Distance traveled between release and target sites

• Speed of communication

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Pituitary Gland – “the Master gland”

Regulates other glands and governs water and salt

balance.

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The effects of the pituitary are clearly shown here. Entertainer David Frost stands between the

world’s tallest and smallest man.

The tallest man in history was 8 feet 11 inches tall. He died at the age of 22, partly as a result of this defect. The shortest known person was 23 inches tall when she died at the age of 19. Today’s medicines can handle most of these problems if caught earlier enough, but these cases show what happen if the pituitary gland goes awry.

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• Tallest man• http://www.youtube.com/watch?

v=zL_nklbytbY• Smallest man• http://www.youtube.com/watch?

v=UyJOOS6raQw• Tallest woman• http://www.youtube.com/watch?

v=F0V_8ZXZyzM• Gigantism at National Geographic 44:55

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Adrenal GlandsAdrenal glands secrete adrenaline

(epinephrine and norepinephrine) during stressful and emotional situations, and

regulate salt and carbohydrate metabolism.

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Endocrine Glands

• Thyroid gland – metabolism, calcium

• Pineal gland - sleep and wakefulness

• Pancreas - regulates blood sugar level

• Ovaries and testes - secrete sex hormones such as testosterone and estrogen

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EXPLORING PSYCHOLOGY(7th Edition in Modules)

David MyersPowerPoint Slides

Aneeq AhmadHenderson State

University

Worth Publishers, © 2008

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• Slides removed from ppt pending deletion.

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• Altering neurons with light at ted talks 18:24

• Recording neuronal activity at ted talks 17:35

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The cell body

– Round, centrally located structure

– Directs metabolism

– No role in neural signaling

• Contains the cell’s Nucleus

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Dendrites

• Information collectors

• Receive inputs from neighboring neurons

• If threshold is reached the AXON will generate an output

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Dendritic Growth

• Dendrites can form new connections

• Provides room for more connections to other neurons

• New connections are basis for learning!

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Axon

• The cell’s output structure

• One axon per cell, 2 distinct parts– tubelike structure,

terminal branches at end that connect to dendrites of other cells

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Parkinson’s Disease

• Results from loss of dopamine-producing neurons

• Symptoms include– difficulty starting and stopping voluntary movements– tremors at rest– stooped posture– rigidity– poor balance

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Parkinson’s Disease

• Treatments– L-dopa– transplants of fetal dopamine-producing

substantia nigra cells– adrenal gland transplants– electrical stimulation of the thalamus has

been used to stop tremors

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Oliver Sacks: “Awakenings”

• Patients had suffered from encephalitis lethargica decades earlier

• Patients were in a frozen or semi-frozen state• Encephalitis lethargica causes the symptoms of

Parkinson’s disease

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Sacks: Results

• Patients “awoke” from their frozen states

L-Dopa

Sacks administered the experimental drug L-Dopa

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Sacks: Results & Legacy

• L-Dopa lost its effectiveness, and patients returned to their frozen state

• The experiment showed the relationship between encephalitis lethargica and dopamine and between encephalitis lethargica and Parkinson’s disease

• Showed how medicine can affect behavior