NEURONS, SYNAPSES &

NERVE IMPULSES

MARIO ANDRES CRUZNATALIA GONZALEZ

LUIS FERNANDO VELAZQUEZ

MEN 1

NEURONSA neuron is a nerve cell that is the basic building

block of the nervous system.

Neurons are similar to other cells in the human body in a number of ways, but neurons are specialized to transmit information throughout the body.

These highly specialized nerve cells are responsible for communicating information in: chemical electrical forms

There are several different types of neurons responsible for different tasks in the human body.

TYPES OF NEURONSTYPE OF NEURON FUNCTION

Sensory Neurons

Carry information from the sensory receptor cells throughout the body to the brain.

Motor NeuronsTransmit information from the brain to the muscles of the body.

Interneurons

Responsible for communicating information between different neurons in the body.

TYPES OF NEURONS

TYPES OF NEURONS

NEURON STRUCTUREDENDRITES

Treelike extensions at the beginning of a neuron that help increase the surface area of the cell body and are covered with synapses.

These tiny protrusions receive information from other neurons and transmit electrical stimulation to the soma.

NEURON STRUCTURESOMA

Where the signals from the dendrites are joined and passed on.

These two structures serve to maintain the cell and keep the neuron functional.

The support structures of the cell include: Mitochondria: provides energy for the cell. Golgi apparatus: packages products created by the

cell and secretes them outside the cell wall.

NEURON STRUCTUREAXON HILLOCK

It’s located at the end of the soma and controls the firing of the neuron.

If the total strength of the signal exceeds the threshold limit of the axon hillock, the structure will fire a signal (known as an action potential) down the axon.

NEURON STRUCTUREAXON

It’s the elongated fiber that extends from the cell body to the terminal endings and transmits the neural signal.

The larger the axon, the faster it transmits information.

Some axons are covered with a fatty substance called myelin that acts as an insulator. These myelinated axons transmit information much faster than other neurons.

NEURON STRUCTURETERMINAL BUTTONS

These are located at the end of the neuron and are responsible for sending the signal on to other neurons.

At the end of the terminal button is a gap known as a synapse. Neurotransmitters are used to carry the signal across the synapse to other neurons.

NEURON STRUCTURE

ACTION POTENTIAL In order for neurons to communicate, they

need to transmit information both: within the neuron from one neuron to the next.

This process utilizes electrical signals and chemical messengers.

The dendrites of neurons receive information from sensory receptors or other neurons. This information is then passed down to the cell body and on to the axon.

Once the information has arrived at the axon, it travels down the length of the axon in the form of an electrical signal known as an action potential.

NEUROTRANSMITTERSNEUROTRANSMITTER CHARACTERISTICS

Acetylcholine

Associated with memory, muscle contractions, and learning. A lack of acetylcholine in the brain is associated with Alzheimer’s disease.

Endorphins

Associated with emotions and pain perception. The body releases endorphins in response to fear or trauma. These chemical messengers are similar to opiate drugs such as morphine, but are significantly stronger.

Dopamine

Associated with thought and pleasurable feelings. Parkinson’s disease is one illness associated with deficits in dopamine, while schizophrenia is strongly linked to excessive amounts of this chemical messenger.

SYNAPSEOnce an electrical impulse has reached the end

of an axon, the information must be transmitted across the synaptic gap to the dendrites of the adjoining neuron. In some cases, the electrical signal can almost instantaneously bridge the gap between the neurons and continue along its path.

In other cases, neurotransmitters are needed to send the information from one neuron to the next. Neurotransmitters are chemical messengers that are released from the axon terminals to cross the synaptic gap and reach the receptor sites of other neurons. In a process known as reuptake, these neurotransmitters attach to the receptor site and are reabsorbed by the neuron to be reused.

MESSAGE TRANSMISSION

SOURCESWhat is a Neuron?

http://psychology.about.com/od/biopsychology/f/neuron01.htm

Structure of a Neuron.

http://psychology.about.com/od/biopsychology/ss/neuronanat_6.htm

Great Pacific Media. Neuron Synapse

http://www.youtube.com/watch?v=LT3VKAr4roo