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Your Amazing Brain

• Receives information – within a fraction of a second, too minuscule to measure

• Acts on the external universe – allows you to cry, walk, play a musical instrument

• Utilizes language – one of your most advanced functions

• Possesses emotions – creates your affective universe

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Your Amazing Brain

• Thinks –is responsible for your memory, intelligence, your thoughts

• Controls your autonomic functions – heart rate, breathing, homeostasis

• Controls your immune system – protects you from viruses

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Peripheral Nervous System

• Handles the CNS’s input and output.

• Contains all the portions of the NS outside of the brain and spinal cord.

• Contains sensory nerves and motor nerves

• Divided into autonomic nervous system and somatic nervous system.

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Peripheral Nervous System

• Sensory Nerves

(to the brain)

Carry messages from special reporters in the skin, muscles, and other internal and external sense organs to the spinal cord and then to the brain

• Motor Nerves

(from the brain)

Carry orders from CNS to muscles, glands to contract and produce chemical messengers

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Peripheral Nervous System

• Somatic NS

Consists of nerves connected to sensory receptors and skeletal muscles

Permits voluntary action (writing your name)

• Autonomic NS

Permits the involuntary functioning of blood vessels, glands, and internal organs such as the bladder, stomach and heart

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Autonomic Nervous System

• Sympathetic NS

Like the accelerator of your car

Mobilizes the body for action

Increases heart rate

Elevates blood pressure

• Parasympathetic NS

Like the brakes in your car

Slows the body down to keep its rhythm

Enables the body to conserve and store energy

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Sympathetic NSand Emotion

• You perceive the sensory stimulus.• The adrenal gland sends two hormones:

epinephrine and norepinephrine.• They activate the sympathetic nervous system. • That produces a state of arousal or alertness that

provides the body with the energy to act (the pupils dilate, the heart beats faster, and breathing speeds up).

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Central Nervous System

• The Spinal Cord

• The Brain

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The Spinal Cord

• Protected by a column of bones• Produces some behaviors of its own without

the help of the brain• These spinal reflexes are automatic,

requesting no conscious effort• Sometimes they are influenced by thought

and emotion• Example: touching a hot iron

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The Brain

• Areas of the Brain

• The Four Lobes of the Brain

• Lateralization

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The Hindbrain

• Medulla – breathing, heart rate

• Pons – sleeping, walking, dreaming

• Riticular Activating System – alertness, attention

• Cerebellum – balance, coordination for the muscles

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The Forebrain

• ThalamusDirect sensory messages to higher centers in

the brainThe sight of sunset is directed to a visual areaThe only sense that completely bypasses the

thalamus is the sense of smell, which has its private switching station, the olfactory bulb

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The ForebrainThe Limbic System

The AmygdalaResponsible for evaluating sensory informationIt determines its emotional importanceIt makes the decision to approach or to withdrawIts initial response may be overridden by the appraisal of the

cerebral cortex

The HippocampusThe gate way to memory

The HypothalamusIt is involved with drives associated with survival such as

hunger, thirst, emotion, sex, and reproduction

The ForebrainThe Limbic System

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The Endocrine

System

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The Endocrine System

• The body’s slow chemical communication system; a set of glands that secrete hormones into the blood stream.

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The Endocrine SystemA Set of Glands

Thyroid gland – affects metabolism

Pancreas – regulates the level of sugar in the blood

Parathyroids – help regulate the level of calcium in the blood

Ovary – secretes sex female hormones (estrogen)

Testes – secrete sex male hormone (Androgens)

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The Endocrine SystemA Set of Glands

The Adrenal Glands

A pair of endocrine glands just above the kidney

They secrete epinephrine and norepinephrine which help to arouse the body in times of stress.

The Endocrine SystemA Set of Glands

The Pineal Gland

Helps secrete melatonin which helps to regulate daily biological rhythms and promotes sleep.

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The Endocrine SystemA Set of Glands

The Pituitary GlandA sort of master glandIt is cherry-sized endocrine glandThe hormones it secretes affect growth and the

secretion of other endocrine glandsThe real boss is the hypothalamus

Feedback System

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The Forebrain

• The CerebrumHigher forms of thinking take place in itIt is divided into two halves called the

cerebral hemispheres that are connected by a large band of fibers called the corpus callosum

They have different tasks (lateralization)

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The Forebrain

• The Cerebral CortexThe cerebrum is covered by several thin

layers of densely packed cells known as the cerebral cortex

On each cerebral hemisphere, deep fissures divide the cortex into 4 lobes

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The Four Lobes of theCerebral Cortex

Occipital Lobes

Parietal Lobe

Temporal Lobes

Frontal Lobes

-at the back of the head

-Visual cortex

-at the top of the brain

-Somato-

sensory cortex

-pressure, touch, pain

-at the sides of the brain

-Auditory cortex

-memory, perception, emotion, language

-toward the front of the brain

-Motor cortex

-voluntary movement of muscles

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Functions of the Cortex

Motor Cortex – an area of the frontal lobes that controls voluntary movements.

It sends messages out to the body.

When stimulating, specific parts of the region in the left or right hemisphere, specific body parts moved on the opposite side of the body.

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Functions of the Cortex

Sensory Cortex – the area at the front of the parietal lobes that receives, registers, and processes body sensations.

Association Functions – areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking.

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Functions of the Cortex

Language 1- Broca’s Area – an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech2- Wernicke’s Area – a brain area involved in language comprehension and expression; usually in the left temporal lobe.

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Specialization and Integration in Language

1- Visual cortex – receives written words as visual stimulation.

2- Angular gyrus – transforms visual representations into an auditory code.

3- Wernicke’s area – interprets auditory code.

4- Broca’s area – controls speech muscles via the motor cortex.

5- Motor cortex – word is pronounced.

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Lateralization

Left HemisphereVerbal competenceSpeaking, reading,

thinking & reasoningProcesses info in

sequenceOne piece of data at a

timelogical

Right HemisphereNonverbal areasComprehension, spatial

relationships, drawing, music, emotion

Processes info. As a whole

intuitive

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Emotion and Lateralization

Left Hemisphere

• Important for the expression of positive emotion

• Damage to the L.H. leads to loss of the capacity of joy.

• Activation in the L.H. leads to tendencies to approach other people.

Right Hemisphere

• Important for the expression of negative emotion

• Damage to the R.H. may make people euphoric.

• Activation in the R.H. leads to tendencies to withdraw from people.

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Neurons

• The NS is made up in part of neurons

• They are held in place by glial cells

• The Function of Glial Cells:– Provide neurons with nutrients– Insulate neurons– Remove cellular debris when neurons die

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The Structure of the Neuron

• 1- DendritesAct like antennas receiving messages• 2- The Cell BodyContains the biochemical machinery to keep

the neuron alive• 3- The AxonTransmits messages away from the cell body

to other neurons

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How Neurons Communicate

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Myelin Sheath

• Surrounds the axons

• A layer of fatty material, which is derived from glial cells

• There are 2 purposes of the myelin sheath:– To prevent signals from adjacent cells from

interfering with each other– To speed up the production of neural impulses

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Stop!

• Is the brain capable of reorganizing itself if damaged?

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Plasticity

• When one brain area is damaged, other areas may in time reorganize and take over some of its functions.

• If neurons are destroyed, nearby neurons may partly compensate for the damage by making new connections that replace the lost ones.

• Examples: How the sense of touch in blind men invades the visual part of the brain.

How the brain struggles to recover from a minor stroke.

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Stop!

• Could damaged neurons in the central nervous system multiply and grow back?

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Precursor Cells(Immature Cells)

• Precursor cells can give birth to new neurons when immersed in a growth-promotion protein

• Physical and mental exercise promote the survival and the production of new precursor cells

• Stress can prohibit the production of new cells• Nicotine can kill precursor cells

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Chemical Messengers in the NS

• Neurotransmitters

• Endorphins

• Hormones

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Neurotransmitters

• Neurotransmitters travel from one neuron to another. Changes occur in the receiving neuron’s membrane,

• The ultimate effect is either:– Excitatory: the probability that the receiving

neuron will fire increases– Inhibitory: the probability that the receiving

neuron will fire decreases

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Neurotransmitters

SerotoninSleep, appetite, sensory perception, temperature

regulation, pain suppression, and moodDopamineVoluntary movement, learning, memory, and

emotionAcetylcholineMuscle action, cognitive functioning, memory, and

emotion

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Neurotransmitters

Norepinephrine

Increased heart rate and the slowing of intestinal activity during stress, learning, memory, dreaming, waking from sleep, and emotion

GABA

(gama-aminobutyic acid)

The major inhibitory neurotransmitter in the brain

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Why Not Flood the Brain with Artificial Opiates?

• The brain may stop producing its own natural opiates.

• For a drug addict, the result is agony until the brain resumes production of its natural opiates or receives more artificial opiates.

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Is Designing a Drug Easy?

• Dopamine as a drug doesn’t help because dopamine doesn’t cross the blood-brain barrier by which the brain fences out unwanted chemicals circulating in the blood.

• L-dopa, a raw material the brain can convert to dopamine, can sneak through the fence.

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How Drugs and Other Chemicals Alter Neurotransmitters

The agonist molecule excites. It mimics the effects of a neurotransmitter on the receiving neuron.

Morphine mimics the action of neurotransmitters by stimulating receptors in the brain involved in mood and pain sensation.

The antagonist molecule inhibits by blocking the neurotransmitters or by diminishing their release.

Botulin poison causes paralysis by blocking receptors for acetylcholine (a neurotransmitter that produces muscle movement)

Endorphins

They have an effect similar to that of opiates.

They reduce pain and promote pleasure.

They play a role in appetite, sexual activity, blood pressure, mood, learning, and memory.

Some endorphins function as neurotransmitters.

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EndorphinsNeuromodulators

Most endorphins act as neuromodulators, which alter the effect of neurotransmitters by limiting or prolonging their effects.

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Hormones

InsulinProduced by the pancreasRegulates the body’s use of glucose & affects

appetite

MelatoninSecreted by the pineal glandHelps to regulate daily biological rhythms and

promotes sleep.

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Hormones

Adrenal HormonesProduced by the adrenal glands are involved in

emotion and stress. They rise in response to nonemotional conditions, such as cold, heat, pin injury, and physical exercise, and in response to some drugs such as caffeine and nicotine.

The Outer PartCortisolThe Inner PartEpinephrine (adrenalin) & Norepinephrine

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Hormones

Sex Hormones

Are secreted by the gonads and by the adrenal glands

Androgens

Masculinizing Hormones

Estrogens

Feminizing Hormones

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Neurotransmitters & Hormones

Acetylcholine

Shortage in acetylcholine may be associated with Alzheimer’s disease

Dopamine

The degeneration of brain cells that produce and use another neurotransmitter, dopamine, appears to cause symptoms of Parkinson’s disease.

Low levels of dopamine may cause ADHD

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Neurotransmitters & Hormones

Serotonin

Decrease in norepinephrine and serotonin is associated with depression. Elevated levels along with other biochemical and brain abnormalities have been implicated in childhood autism.

Norepinephrine

Norepinephrine, epinephrine, and adrenaline are associated with excitement and stress.

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Neurotransmitters & Hormones

CortisolCortisol is associated with stress. Increase in cortisol

damages the brain and may be associated with posttraumatic stress.

GABAAbnormal GABA levels have between implicated in sleep

and eating disorders and in compulsive disorders. GlutamateGlutamate, serotonin, and high levels of dopamine have been

associated with schizophrenia