My College Class Notes

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How the Brain Governs Behavior

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How do the neurons work and what do they do?

The brain governs all physical and psychological functions through its connection with other parts of the body.

The brain contains many billions of neurons, or neural cells; each neuron receives messages, processes them, and transmits them to thousands of other neurons throughout the body.Some neurons act as glands and transmit into the bloodstream various hormones, which affect the bodily functioning in areas distant from the brain. The brain also contains even more billions of glia, which performs functions such as regulating the biochemical environment of the brain, helping sustain neurons, modulating neural transmissions, and helping guide early brain development and maturation. Each neuron in the nervous system is a fiberlike cell with receivers call dendrites at one end and senders call terminal braches at the other. Stimulation of the neurons at its dendrites—or receptor sites on its cell body—sets off an electrical impulse that travels the length of the axon to the terminal branches. There the stage is set for stimulation or inhibition of other neurons, as well as muscles or glands. Other important structures include the nucleus, myelin sheath, and nodes.

A neuron ordinarily fires in accord with the all-or-none principle. The key to the transmissions of nervous messages is the synapse, a junction where the sender of one neuron is separated by only a microscopic distance from the receiver of another neuron. When the neuron fires, it releases neurotransmitters, which flow across the synaptic cleft and act on receiving neurons.

What constitutes the central nervous system?

The central nervous system (CNS) is made up of the brain and the spinal cord. The neurons of CNS affect functions and behavior throughout the rest of the body through the peripheral nervous system (PNS). Afferent Neurons carry information from the sense organs to the brain; efferent neurons carry messages from the brain to the glands and muscles; and interneurons are the intermediaries between other neurons in the CNS.


Why do psychologist and other scientist place so much emphasis on understanding the functions of the brain’s outer surface?

The topmost and largest area of the brain is the cerebrum, which is covered by the cerebral cortex; each is divided down the middle into a left hemisphere and a right hemisphere.

The cerebral cortex, which is larger in relation to body size in human beings that in any other species, is the part of the brain primarily responsible for higher processes such as thinking, remembering, and planning. When damaged, it sometimes displays remarkable plasticity.


How the Brain Governs Behavior: Neuron Definitions


The Neural cell; the basic unit of the nervous system


The primary “receiving” parts of a neuron. 

Receptors Sites 

Spots on the cell body of a neuron that, like the dendrites, can be stimulated by other neurons. 

Cell Body 

The part of a neuron that converts oxygen, sugars and other nutrients into energy


The core of the cell body of a neuron or other cell, containing the genes. 


The fibrous body of a neuron that carries the neural impulse to the terminal branches. 

Myelin sheath

A whitish coating of fatty protective tissue that “insulates” the axons of neurons.


Constrictions of the myelin sheath of an axon that act as booster stations for neural impulses.

Terminal branches 

The parts of a neuron that send messages to other neurons or to muscles or glands. 


The connecting point where a terminal branch of one neuron is only a microscopic distance from a dendrite or receptor site of another neuron.


Biochemicals released at neuron synapses that aid or inhibit neural transmission. 


A biochemical that typically is released into the bloodstream to perform its function at locations distance form the brain, but that can also effect brain functioning itself.


Cells that perform a wide array of functions such as regulating the biochemical environment of the brain, helping sustain neurons, modulating neural transmissions, and aiding in the repair of neurons in case of injury. They are also important in early brain development.

All-or-none Principle

The general rule that a neuron either fires or doesn’t


How the Brain Governs Behavior: CNS Definitions

Functions of the Cerebral Cortex

Many motor and sensory functions have been “mapped” to specific areas of the cerebral cortex, some of which are indicated here. In general, these areas exist in both hemispheres of the cerebrum, each serving the opposite side of the body. Less well defined are the areas of association, located mainly in the frontal cortex, operative in functions of thought and emotion and responsible for linking input from different senses. The areas of language are an exception: both Wernicke’s area, concerned with the comprehension of spoken language, and Broca’s area, governing the production of speech, have been pinpointed on the cortex.

Spinal Cord 

The thick cable of neurons that mostly connects PNS neurons to the brain. 

Central Nervous System (CNS) 

The brain and the spinal cord 

Peripheral Nervous System (PNS)

The network of neurons outside of the CNS 


A CNS neuron that carries messages between neurons. 

Cerebral cortex 

Among its many other functions, the part of the brain responsible for thinking, remembering, and planning. 


The large brain mass that is covered by the cerebral cortex. 


The power of the brain to reorganize and shift functions. 


Written by Joseph Eulo

May 28, 2008 at 1:12 pm

2 Responses

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  1. Do I have permission to use one diagram: How the brain governs behaviour, for my dissertation?


    November 1, 2010 at 12:05 am

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