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Biological Bases of Behavior

• Human thought and behavior are affected by the nervous system, endocrine system, brain, and genetics.
• Everything psychological is simultaneously biological.
• The link between biology and behavior belongs to biological psychology

Phrenology

• Franz Gall, a German physician, invented phrenology in the early 1800s.
• Phrenology was a theory that claimed the bumps on the skull could reveal mental abilities and character traits
• Parts of the brain control different aspects of behavior.

Biological Psychology

• A branch of psychology concerned with the links between biology and behavior.
• It is also called biopsychology
• Biological psychology deals with topics like sleep/dreams, depression, hunger and sex, stress and disease, etc.
• Biological Psychologists are also called behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, and biopsychologists

Nervous System Research

• Much research is done on animals, with similar neural systems between animals and humans.
• Squids and slugs can be studied to understand neural systems.
• Rats and mice have biological similarities to humans, making up 90-95% of mammals in bio-medical research.

The Nervous System

• The nervous system has two parts: the central nervous system (brain and spinal cord) and the peripheral nervous system (network of nerves connecting the brain and spinal cord to the body)
• The central nervous system contains 99% of all nerve cells.

The Central Nervous System

• Brain and spinal cord are part of the central nervous system
• Neurons network with nearby neurons for short, fast connections in neural networks.
• Learning occurs as feedback strengthens connections.
• The spinal cord is information highway connecting the peripheral nervous system to the brain.

Peripheral Nervous System

• The Peripheral Nervous System has two parts:
• 1. Somatic (Motor) Nervous System
• 2. Autonomic Nervous System

Somatic Nervous System

• Consists of neurons that communicate between the body and the brain.
• Motor Neurons carry messages from the spinal cord/brain to muscles and glands.

Autonomic Nervous System

• Coordinated by the hypothalamus
• Has two divisions:
• Sympathetic Division: Active when one is angry, afraid, or aroused that increases heart rate/breathing and stops digestion
• Parasympathetic division: Conserves energy resources and is calming

Neurons

• Neurons are nerve cells and the basic building blocks of the nervous system.
• Neurons contain:
• Dendrites (receive messages)
• Axon (passes messages away from the cell body)
• Myelin sheath (covers the axon to help speed neural impulses)

Types of Neurons

• Sensory neurons carry incoming information to the brain/spinal cord.
• Motor neurons carry outgoing information from the brain/spinal cord to the muscles/glands.
• Interneurons are located within the brain/spinal cord.
• Interneurons communicate internally between sensory inputs and motor outputs

Neural Communication

• Dendrites receive messages from other cells.
• The axon passes messages away from the cell body.

Simple Reflex

• A simple, automatic response to a sensory stimulus like a knee-jerk reaction
• Interneurons in the spinal cord process motor responses quickly to protect the body from harm.

Nodes of Ranvier

• These are the spaces in between the Myelin cells that encircle that axon.
• These spaces are important to keeping the charger going through the relatively Long axon.
• Without these spaces the charge might lose it's intensity before reaching the end of the cell.

Myelin Sheath

• A layer of tissues around the fibers around many of the neurons, made of glia cells that enable greater/faster transmission speed to neural impulses and up to age 25.
• Degeneration that occurs can affect MS (Multiple Sclerosis) which leads to the communication of muscles slowing and the eventual loss of muscle control
• Nutrients from breastmilk enhance brain growth by helping to manufacture the Myelin sheath, studies shown breastfed people average seven to ten points higher then those not breastfed.

Firing of a Neuron

• Neurons transmit massages when then are stimulated or fired by chemical of other neurons.
• When the excitatory minus the inhibitory signals reach the minimum intensity an Action Potential can occur.

Action Potential

• Fluid inside the Axon is negatively charged
• Fluids outside the Axon is positively charged
• "All-or-None" response meaning neurons either response or they don't

Process

• A neuron stimulation causes a very brief change in electrical change and if strong enough it will cause both depolarization and action potential
• The Action Potential continues down the Axon and the first section that had completely recharged.
• A short time called the Refractory Period will occur, a Resting-Pause where the Neurons will pump the positively sodium back outside but will fire each second.

Inside or Outside a axon

• Internal Fluid the neurons is considered to be negative from charged ions, a notable amount comes from Potassium Ions.
• In contrast the External Fluid outside the neuron has a selective permeable axon surface.
• Example, Resting Axons will have gates preventing positive sodium.

Sodium-Potassium Pump System

• This System allows any ions that are approved to pass through the membrane of the neural cell
• The system bring positive charged sodium ions to the cell which gets pumped back out once the action potential is over.

Communication Between Neurons

• Synapse: The junction/gap in between the sending Axon Neurons with the receiving.
• Synaptic gap/cleft: a very very tiny gap, almost a Millionth of an inch in width is at this junction.
• Once a Action Potential is released to the knowlike terminal that the axon end it will trigger chemical messengers, "Neurotransmission"
• During 1/10,000th of a second the Neurotransmitters will cross through the Synaptic gap while binding to their sites that receive to be locked.
• The sending neuron can then reabsorbs any extra Neurotransmitters in a process known as "reuptake".

Neurotransmitters Influence

• These include such chemicals such as: Acetylcholine, Dopamine, Serotonin, Norepinephrine, GABA, Glutamate and lastly Endorphins.

Altered Neurotransmitters

• Agonists versus antagonists molecules meaning
  • A "Agonist" mimics to bind a neurotransmitter
  • "Antagonist" instead blocks a neurotransmitter

Endocrine System

• The endocrine system is the body’s "slow" chemical communication system
• It is a set of glands that secrete hormones into the bloodstream.
• Hormones are chemical messengers manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues
• Controlled by the Hypothalamus gland

Glands Functions

• Pituitary – Master Gland, regulated by the hypothalamus and controls thirst, sexual behaviors among other activites.
• Thyroid Gland primary goal is to control the primary metabolism.
• The Parathyroid's in this case have control levels of calcium while the adrenal glands is the one releasing stress hormones
• Gonods (ovaris and testes) to secrete estrogen and testosterone
• Lastly Pineal Glands releases Melatonin which in this factor will be regulate any disturbing sleep-wake cycles.