Chapter Four

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Chapter Four

• Biology
• Of
• Behavior
• By Courtney Graul

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Now for the stuff we all know and love the
brains components and how they affect us.

• The brain has two primary
• responsibilities
• 1)control of behavior
• 2)regulation of our bodys physiological
  functions

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In order for us to understand how the brain
carries out these to main functions we need to
understand how the brain itself works.
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Two Important Divisions

• The Central Nervous System
• Brain and spinal cord

• The Peripheral Nervous System
• Cranial and spinal nerves

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Central Nervous System

• Three main structures of the brain
• Brain stem
• Cerebellum
• Cerebral hemispheres

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Cells of the Nervous System

• Neurons (nerve cells) - the parts of the nervous
  system that bring sensory information to the
  brain, store memories, reach decisions, and
  control the activities of muscles

• Glial cells found in the CNS and provide
  support for neurons and supplies them with needed
  chemicals

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Principal Parts of a Neuron

• Soma or cell body, contains mechanisms that
  controls metabolism and maintenance of the cell.
  The soma also receives messages from other
  neurons.

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Principal Parts of a Neuron

• Dendrites branch from the soma to receive
  messages from other neurons and transmit that
  information to the soma.
• Axon (nerve fiber) carries messages away from
  the soma toward the cells the neuron is
  communicating with action potential

• Terminal button rounded swelling at the end of
  the axon of a neuron releases transmitter
  substance

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The Action potential

• The message carried by the axon a quick
  reversal in the electrical charge of the axon,
  causing the release of transmitter substance.

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• The outside of the membrane is positively charged
  (and the inside is negatively charged) because
  the axon contains ions. When the axon is
  resting, its ion channels are closed, so ions
  cannot move in or out of the axon. An action
  potential is caused by the opening of some ion
  channels in the membrane at the end of the axon
  nearest the soma.

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• Ion a positively or negatively charged
  particle produced when many substances dissolve
  in water

• Ion channel a special protein molecule located
  in the membrane of a cell controls the entry or
  exit of particular ions.

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Communication

• Neurons can communicate with the help of
  synapses.
• Synapse the junction between the terminal
  button of one neuron and the membrane of a muscle
  fiber, a gland, or another neuron.

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Types of Neurons

• Presynaptic Neuron- a neuron whose terminal
  buttons form synapses with and excite or inhibit
  another neuron.

• Postsynaptic Neuron a neuron with which the
  terminal buttons of another neuron form synapses
  and that is excited or inhibited by that neuron.

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Types of Neurons

• Motor neurons a neuron whose terminal buttons
  form synapses with muscle fibers. When an action
  potential travels down its axon, the associated
  muscle fibers will twitch.

• Sensory neuron detects changes in the external
  or internal environment and sends information
  about these changes to the central nervous system.

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Regions of Primary Sensory and Motor Cortex

• Three areas of the cerebral cortex receive
  information from sensory organs
• 1)primary visual cortex receives visual
  information and is located in occipital lobes
• 2)primary auditory cortex receives auditory
  information and is located in the temporal lobes

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• Primary somatosensory cortex receives
  information directly from the somatosensory
  system (touch, pleasure, vibration, pain, and
  temperature) and is located in the front part of
  the parietal lobes

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• The three regions of primary sensory cortex in
  each hemisphere receive information from the
  opposite side of the body. These connections
  between the sensory organs and the cerebral
  cortex are said to be contralateral.

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Various areas of the brain

• Primary motor cortex directly controls the
  movements of the body, located in the back part
  of the frontal lobes.
• Frontal lobe The front portion of the cerebral
  cortex, including Brocas speech area and the
  motor cortex damage impairs movement, planning
  and flexibility in behavioral strategies.

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• Parietal lobe located in the cerebral cortex
  behind the frontal lobe and above the temporal
  lobe contains the somatosensory cortex is
  involved in spatial perception and memory.
• Temporal lobe the portion of the cerebral
  cortex below the frontal and parietal lobes and
  containing the auditory cortex.

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• Occipital lobe the rearmost portion of the
  cerebral cortex contains the primary visual
  cortex.
• Sensory association cortex receives information
  from the primary sensory areas.
• Motor association cortex those regions of the
  cerebral cortex that control the primary motor
  cortex involved in planning and executing
  behaviors.

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More vocabulary

• Corpus callosum a large bundle of axons that
  connects the cortex of the two cerebral
  hemispheres.
• Homeostasis the process by which important
  physiological characteristics are regulated so
  they remain at their optimum level.

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The Brain Stem

• The brain is made up of three main structures
  including
• 1)medulla closest to the spinal cord controls
  vital functions such as heart rate and blood
  pressure.
• 2)Pons just anterior to the medulla involved
  in the control of sleep.

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The Brain Stem

• Midbrain just anterior to the pons involved in
  control of fighting and sexual behavior (and
  decreased sensitivity to pain during these
  behaviors).

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Cerebellum

• Plays an important role in the control of
  movement.
• Monitors information concerning posture and
  balance and produces eye movements that correlate
  with changes in the position of the head.
• Damage to the cerebellum could result in jerky,
  uncoordinated movements. May also have
  difficulty speaking because control of speech
  muscles muscles may have been affected.

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Structures within the Cerebral Hemispheres

• Thalamus all sensory information except
  olfactory information is sent here and then
  relayed to the cerebral cortex.
• Hypothalamus located just above the pituitary
  gland controls the autonomic nervous system and
  many behaviors related to regulation and
  survival, such as eating, drinking, fighting,
  shivering, and sweating.

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• Autonomic Nervous System the portion of the
  peripheral nervous system that controls the
  functions of the glands and internal organs.
• Sympathetic branch portion of the ANS that
  activates functions that accompany arousal and
  expenditure of energy.

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• Parasympathetic Nervous System The portion of
  the ANS that activates functions that occur
  during a relaxed state (such as digestion of
  food).
• Limbic system a set of interconnected
  structures of the brain important in emotional
  and species-typical behavior includes the
  amygdala, hippocampus, and limbic cortex.

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• Amygdala part of the limbic system of the brain
  located deep in the temporal lobe damage causes
  changes in emotional and aggressive behavior.
• Hippocampus also a part of the limbic system,
  located in the temporal lobe plays important
  role in learning.

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DRUGS

• Drugs can affect the release or production of
  transmitters substances.
• Drugs can mimic the effects of transmitter
  substances on receptor molecules, block these
  effects, or interfere with the reuptake of a
  transmitter substance once it has been released.
  These changes can alter perceptions, thoughts,
  and behaviors controlled by certain transmitters
  substances.

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Barbiturates

• This is a drug that causes sedation by depressing
  the brains activity by stimulating a certain
  category of neuromodulator receptors.
• In low doses can have a calming effect, but as
  the dose increases may produce difficulty in
  walking, talking, may lead to unconsciousness,
  coma, and death.

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• Abused by people searching for something to calm
  them.
• Sometimes prescribed as sleep medications, but
  they have serious downfalls such as
• -inhibit or suppress dreaming
• -produce unrefreshing sleep
• -a dose prescribed to allow sleep is not much
  lower than one causing death not very safe.

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Benzodiazepine

• Many antianxiety drugs belong to the
  benzodiazepine family of drugs
• Includes Valium and Librium
• Are very effective at reducing anxiety and are
  sometimes used to treat people who are afflicted
  by periodic attacks of severe anxiety

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Cocaine and Amphetamine

• Both inhibit the reuptake of dopamine therefore
  strengthen the effectiveness of synapses that use
  this transmitter substance.
• The drugs mimic the effects of reinforcing
  stimuli and cause many to abuse them

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• If these drugs are taken over a period of several
  days in large enough doses the result could be
  symptoms of paranoid schizophrenia.
• Those using the drugs regularly may suffer from
  hallucinations and their thoughts may be confused
  and difficult to control.

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The End
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