Transcript Module_3vs9_Final - Doral Academy Preparatory

Module 3
Brain’s Building Blocks
INTRODUCTION
• Alzheimer’s disease
– 10% of cases start after age 50
– 90% of cases start after age 65
• Symptoms:
– _____________________________
– _____________________________
– _____________________________
– _____________________________
INTRODUCTION (CONT’D)
• Alzheimer’s disease
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Period of 5 to 10 years, symptoms worsen
Result is profound memory loss
Lack of recognition of family and friends
Deterioration in personality
Emotional outbursts
Widespread damage to the brain (hippocampus,
involved in memory)
• no cure; always fatal
INTRODUCTION (CONT’D)
• Alzheimer’s disease
• Diagnosis and causes
– Researchers are close to identifying cause
– Genetic
– Neurological
– Possible environmental factors
– Certain chemicals (____________) that occur
naturally in all brains seem to multiply and are
believed to cause Alzheimer’s (chemicals act like glue
and destroy brain cells)
DEVELOPMENT OF THE BRAIN
• Fact that your brain doesn’t develop into a nose is
because of instructions contained in your genes
• Genes
– Chains of chemicals arranged like rungs on a twisting
ladder
– You have about _______________genes that contain
chemical instructions equaling roughly ________
pages of written instructions
– Genes program the development of individual parts
into a complex body and brain
DEVELOPMENT OF THE BRAIN (CONT’D)
DEVELOPMENT OF THE BRAIN (CONT’D)
STRUCTURE OF THE BRAIN
• Human brain
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Shaped like a small, wrinkled melon
1,350 grams (less than three pounds)
Pinkish-white color
Consistency of firm Jell-O
Fueled by ______________________________
1 trillion cells divided into
• ____________________
• ____________________
STRUCTURE OF THE BRAIN (CONT’D)
• Glial cells
– ________________________________
– __________________________________
– __________________________________________
__________________________________________
______________
STRUCTURE OF THE BRAIN (CONT’D)
STRUCTURE OF THE BRAIN (CONT’D)
• Neuron
– Brain cell with two specialized extensions
– One extension is for ____________ electrical signals
– The other extension is for ______________ electrical
signals
STRUCTURE OF THE BRAIN (CONT’D)
GROWTH OF NEW NEURONS
• Can a brain grow new neurons?
– Canary brain
• can grow about 20,000 neurons a day during the
spring (learns new breeding song)
– Primate and human brain
• researchers conclude that adult monkey and
human brains are capable of growing relatively
limited numbers of neurons throughout adulthood
• some new neurons play important role in
continuing to learn and remember new things
(hippocampus)
GROWTH OF NEW NEURONS (CONT’D)
• Repairing the brain
– Advances in stem research suggest the human brain
may be able to grow more neurons
– Repair damages due to
• accident
• disease
• Alzheimer’s
BRAIN VERSUS MIND
• Mind-body question:
– How complex mental activities such as
• feeling
• thinking
• learning
– can be explained by the
• physical
• chemical
• electrical activities
– of the brain
ALZHEIMER’S DISEASE AND NEURONS
• Alzheimer’s disease
– Excessive buildup of glue-like substances
– _______________________________________
• Researchers can study a person’s mental activities by
taking brain scans of the neural activities going on inside
the living brain
ALZHEIMER’S DISEASE AND NEURONS
PARTS OF THE NEURON
• Cell body
– Large egg-shaped structure that provides ______,
_______________, and maintains the entire neuron
in working order
• Dendrite
– __________________that arise from the cell body
• ____________ signals from other ___________,
____________, or _________________
• ____________ these signals onto the cell body
PARTS OF THE NEURON (CONT’D)
• Axon
– A _________________that extends/carries signals
away from the cell body to neighboring neurons,
organs, or muscles
• Myelin sheath
– Looks like ____________________ composed of
fatty material that wraps around and insulates an
axon
– Prevents ______________ from
________________generated in adjacent axons
PARTS OF THE NEURON (CONT’D)
• End bulbs or terminal bulbs
– Located at _______________of the axon’s branches
– Miniature container that stores chemicals called
______________________(used to communicate
with neighboring cells)
• Synapse
– Infinitely small space (20-30 billionths of a meter)
– Exists between an end bulb and its adjacent body
organ, heart, muscles, or cell body
NERUONS VERSUS NERVES
• Reattaching limbs
– John Thomas
• lost arms in farming accident
• Transplanting a face
– Isabelle
• face severely disfigured by a dog
• received
– new nose
– lips
– chin
NERUONS VERSUS NERVES
PERIPHERAL & CENTRAL NERVOUS SYSTEM
• Peripheral nervous system
– Made up of nerves located throughout the body,
_________________ in the brain and spinal cord
• Nerves
– String-like bundles of axons and dendrites that come
from the ______________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
– Those in the ________________have the ability to
_______________ _____________________
PERIPHERAL & CENTRAL NERVOUS SYSTEM
(CONT’D)
• Central nervous system
– Made up of neurons located in the
______________________________
• Multiple sclerosis
– Disease that attacks the
________________________that wrap around
and insulate cells in
___________________________________
SENDING INFORMATION: ACTION POTENTIAL
SEQUENCE
– Stimulus (tack or nail)
– Skin has sensors that pick up mechanical pressure
and transform it into electrical signals
– Signals are sent by the neuron’s axon to various
areas in the spinal cord and brain
– Brain interprets electrical signals as “pain”
• 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: ACTION POTENTIAL
SEQUENCE (CONT’D)
• Resting state
– Axon has a charge
– Charge results from the
__________________positive ions on the outside
from negative ions on the inside
• Sodium pump
– Transport process that picks up any sodium ions that
enter the axon’s chemical gates and returns them
back outside
– Results in keeping axon charged by keeping sodium
ions outside the axon membrane
SENDING INFORMATION: ACTION POTENTIAL
SEQUENCE (CONT’D)
• Action potential
– Tiny electric current generated when _____________
sodium ions rush inside the axon
– Enormous increase of sodium ions inside the axon
causes the inside of the axon to _____________ its
charge
– Inside becomes ____________ and outside becomes
________________
SENDING INFORMATION: NERVE IMPULSE
(CONT’D)
• Nerve impulse
– Nerve impulse is made up of ____________ action
potentials, with the ___________ occurring at the
_________________ of the axon
• All-or-none law
– If an action potential starts at the beginning of the
axon, the action potential will continue at the
_________________ segment to segment to the very
end of the axon
SENDING INFORMATION: NERVE IMPULSE
(CONT’D)
TRANSMITTERS
• A _____________ is a chemical messenger that
transmits information between nerves and body organs,
such as muscles and heart
• Excitatory and inhibitory
– Excitatory transmitters
• _______________________________________
– Inhibitory transmitters
• _______________________________________
NEUROTRANSMITTERS
• Neurotransmitters
– Dozens of different chemicals made by neurons and
then used for communication between neurons during
the performance of mental or physical activities
NEUROTRANSMITTERS (CONT’D)
ALCOHOL
• Alcohol (ethyl alcohol)
– A psychoactive drug classified as a
__________________, which means that it
depresses the activity of the central nervous system
WHAT DOES ALCOHOL DO?
• Alcohol affects the brain by imitating a naturally
occurring neurotransmitter, ____________
• 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 ___________, they
_____________ neural activity
WHAT DOES ALCOHOL DO? (CONT’D)
• Many people drink alcohol to feel ______________ and
more ________________
• Appears to be a _____________ link between
______________ and __________________
• Deficiency in a specific brain protein is associated with
high anxiety and excessive alcohol use
NEW TRANSMITTERS
• Number of well-known neurotransmitters, such as
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Norepinephrine
GABA
Dopamine
Serotonin
NEW TRANSMITTERS (CONT’D)
– Endorphins (1970s)
• painkiller similar to morphine
• decreases effects of pain during great bodily stress
– Anandamide (1990s)
• similar to THC (active ingredient in marijuana)
– involved with
» memory
» motor coordination
» emotions
NEW TRANSMITTERS (CONT’D)
• Anandamide may help people regulate emotions, which
would help them to better deal with anxiety and stress
– Nitric oxide (mid-1990s)
• may be involved in regulating aggressive and
impulsive behaviors
NEW TRANSMITTERS (CONT’D)
– Orexin (hypocretin)
• late 1990s
• involved in the brain’s ____________ and
_______________
• high levels: __________________
• low levels: _____________________
• involved in sleep and wakefulness
– ______________________________
REFLEX
• Reflex
– _____________, ____________ reaction to some
________________
– Neural connections underlying a reflex are prewired
by genetic instructions
REFLEX (CONT’D)
• Reflex sequence
– Sensors
• sensors trigger neurons that start the withdrawal
effect
– Afferent neurons (sensory neurons)
• ________________________________________
________________________________________
REFLEX (CONT’D)
– Interneuron
• relatively short neuron whose primary task is
making connections between other neurons
– Efferent neuron
• ________________________________________
________________________________________
________________________________________
REFLEX (CONT’D)
PARKINSON’S DISEASE
• Parkinson’s disease
– Includes symptoms of tremors and shakes in the
limbs, a slowing of voluntary movements, muscle
stiffness, problems with balance and coordination,
and feelings of depression
– As the disease progresses, patients develop a
shuffling walk and may suddenly freeze in space for
minutes or hours at a time
– Michael J. Fox
PARKINSON’S DISEASE (CONT’D)
• Parkinson’s disease
– Caused by destruction of neurons that produce
dopamine
– L-dopa is a medication that boosts the levels of
dopamine in the brain
– Eventually, the drug causes involuntary jerky
movements
– After prolonged use, L-dopa’s beneficial effect may be
replaced by unwanted jerky movements
EXPERIMENTAL TREATMENTS
• Sterotaxic procedure
– Fixing a patient’s head in a holder and drilling a small
hole through the skull
– The holder has a syringe that can be precisely guided
into a predetermined location in the brain
EXPERIMENTAL TREATMENTS (CONT’D)
EXPERIMENTAL TREATMENTS (CONT’D)
EXPERIMENTAL TREATMENTS (CONT’D)
• Removing part of the brain
– Thalamotomy (Michael J. Fox)
• Brain stimulation
– Electrodes placed into thalamus
– Patient controls amount of stimulus
– Helps reduce tremors
EXPERIMENTAL TREATMENTS (CONT’D)