BIOLOGICAL BASES OF BEHAVIOR (8-10%)

• 8-10%

The Neuron

• Is the basic building block of the nervous system. It uses both chemical & electrical signals to communicate messages to other neurons.• Glial cells guide the growth, provide

support to the developing neurons.

Structures of a neuron

The Neuron

• Soma• Dendrites• Axon• Myelin Sheath• Axon Terminal

Button• Vesicle

Vesicles contain neurotransmitters

SYNAPSE

• the gap between nerve cells.

NEUROTRANSMITTERS

Types of Neurons

Sensory Motor Interneuron

HOW A NEURON FIRES

All your behavior begins with actions of your neurons. A neuron gets incoming information from its receptor sites spread around the dendrites. That information is sent to the cell body. Neural impulses are electrical in nature along the neuron. The neuron at rest is more negative inside the cell membrane relative to the outside of the cell membrane.

• The neuron’s resting potential is -70mV (inside the axon). When sufficiently stimulated outside the cell of about +10mV a net flow of sodium ions into the cell causes a change known as the action potential.

• If stimulation is not strong enough, the neuron does not fire.

• The strength of the action potential is constant. It either fires or doesn't –known as the “all or none principle.”

Neural communication refers to how the neurons relay messages to each other. It is referred to an electrochemical reaction.

Neurons are surrounded by fluid. The fluid inside a neuron contains negative charged atoms, called ions, ( - ) from the fluid located outside the neuron, which has positive charged ions (+).

• Positive ions will flow into the neuron if not stopped or pumped out by the membrane. This is called the electrical potential, which is measured in millivolts.

• The resting potential is the neuron’s usual charge, which is –70 millivolts.

• When the resting potential has changed enough, about +10mv, the membrane changes and a message is sent, which is referred to as the action potential

• The speed at which an action potential travels the axon ranges from 2 to 250 mph.

• Neurotransmitter are released into the synapse, where they attach to specific receptor sites on dendrites, like a key fitting into a lock.

• Some of the synapses are excitatory, where an action potential is generated and the message gets sent., and some are inhibitory, preventing neural impulses.

• The constant flow of these neuro-chemical impulses regulates your metabolism, temperature, respiration, as well as your behavior & thoughts, decisions and memory.

Refractory Period- a resting pause, when the neuron pumps the positively charged ions back outside…then it can fire again.

Excitatory-signal to send the message Inhibitory-signal to stop the message Threshold -the level of stimulation required to

trigger a neural impulse Agonist-excite by mimicking particular

neurotransmitters or block their reuptake. Antagonists-inhibit a neurotransmitter’s release

or block its effect.

The Nervous System

Central(brain and

spinal cord)

Nervoussystem

Autonomic (controlsself-regulated action of

internal organs and glands)

Somatic or Skeletal (controlsvoluntary movements of

skeletal muscles)

Sympathetic (arousing)

Parasympathetic (calming)

Peripheral

THE CENTRAL NERVOUS SYSTEMCNS

Consists of our brain & spinal cord.

PERIPHAL NERVOUS SYSTEMPNS

Divided into two major sub-divisions:• Somatic Nervous system –

Controls our voluntary muscle movements

• Autonomic nervous system

AUTONOMIC NERVOUS SYSTEM• This controls the automatic functions of

our body-our heart, lungs, internal organs, and glands. These nerves control our flight or flight response to perceived threat.

• The autonomic nervous system is divided into 2 categories: the sympathetic & the parasympathetic nervous system

Sympathetic nervous system

• Mobilizes our body to respond to stress. This part carries messages to the control systems of the organs, glands, & muscles. It is the alert system of the body. It activates our heart rate, blood pressure,& respiration rate.

PARASYMPATHETIC NERVOUS SYSTEM

• Is responsible for slowing our body down after a stress response.

WAYS OF STUDYING THE BRAIN1. Accidents (the case of Phineas Gage)2. Lesions (use electric current to burn area)3. EEG (Electroencephalogram (brain waves)4. CAT or CT(shows structure, stroke, tumor)5. PET Scan (shows activity)

positron emission tomography6. MRI (maps structure)7. fMRI (shows activity)

functional magnetic resonance imaging

BRAIN STRUCTURE & FUNCTION

CEREBRAL CORTEX

Frontal Lobes involved in speaking and muscle movements

and in making plans and judgments Parietal Lobes

includes the sensory cortex, registers body sensations

Occipital Lobes include the visual areasTemporal Lobes includes the auditory areas, processes

hearing & speech

Aphasia impairment of language, usually caused by

left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding)

Broca’s Area an area of the left frontal lobe that directs

the muscle movements involved in speech Wernicke’s Area

an area of the left temporal lobe involved in language comprehension and expression

LIMBIC SYSTEM

Cerebellum the “little brain”

attached to the rear of the brainstem

it helps coordinate voluntary movement and balance

SPLIT BRAINCORPUS CALLOSUM

BRAIN PLASTICITY

• Means the brain is somewhat flexible or plastic. Other parts of the brain can adapt themselves to perform other functions if needed.• Younger brains are more plastic and

more likely to compensate for damage.

ENDOCRINE SYSTEM

the body’s “slow” chemical communication systema set of glands that secrete hormones into the bloodstream