INTRODUCTION TO THE NERVOUS SYSTEMJasmine OMike TuborasValerie Zuniga

A NEURON

ANATOMY & FUNCTION OF A NEURON1) Neurons recieve signals

I) The signal travels to the soma

II) signal leaves the soma and travels down the axon to the synapse.

ANATOMY AND FUNCTION OF NEURON CONT'D...

III) The signal leaves through the synapse to be passed along to the next nerve cell.

2)Neurons pass messages to each other using an electrical signal.

Synapse- it triggers the neuron to release a chemical neurotransmitter.

Neurotransmitters- brain chemicals that communicate information throughout our brain and body.

CLASSIFICATION OF NEURONSMultipolar neurons-* have one axon and many dendritic branches.* These carry signals from the central nervous system to other parts of your body such as your muscles and

glands*Found in brain and spinal cord

CLASSIFICATION OF NEURONS CONT’D…• Pyridimal Neuron-• shaped cell body (soma) and two distinct dendritic trees.• found in the spinal cord• Information process and behavior

Pseudo unipolar neuron- (Unipolar)• Sensory neuron• This neuron contains a long dendrite and a short axon that connects to the spinal cord• Can be found in retina of the eye

CLASSIFICATION CONT'D...

Bipolar neurons-• have one axon and only one dendrite branch.• They pass signals from one neuron to the next inside the central nervous system•Found in olfactory epithelium, retina of eye

CLASSIFICATION CONT’D

• Relex arc-• nerve pathway that connects certain muscle groups to others.• primarily control involuntary movements in response to some sort of

stimulus. Rapidly blinking the eyes in response to dust or dirt in the air 

CLASSIFICATION AND INTRODUCTION OF DIFFERENT NERVOUS SYSTEMS:

• 1) Peripheral –also known as PNS or Peripheral Nervous System

- is part of the nervous system that consists of nerves and ganglia outside of the brain and spinal cord.

- It provides links to and from the external environment.

- Has two different types of cells which are the sensory cells and the motor cells.

- Sensory cells carry messages to the central nervous system.

- The motor cells carry the signal from the central nervous system to the internal organs, muscles, and glands in the

outer edges of the body.

CLASSIFICATION OF NEUROGLIAL CELLSCNS:1) Astrocyte

2) Oligodendrocyte

3) microglia cells

4) ependymal cells

CLASSIFICATION OF NEUROGLIAL CELLS

• 1) astrocyte- provide both mechanical and metobalic support for neurons, regulating the environment where they function.

CLASSIFICATION OF NEUROGLIAL CELLS

• 2) oligodendrocyte- Oligodendrocytes are responsible for producing a fatty protein, called myelin, which insulates axons, the long extensions of nerve cells (neurons).

CLASSIFICATION OF NEUROGLIAL CELLS

• 3) microglia cell- provide protective function to nervous tissue in that they can become phagocytoic

CLASSIFICATION OF NEUROGLIAL CELLS

• 4) ependymal cells-Type of neuronal support cell (neuroglia) that forms the epithelial lining of the ventricles (cavities) in the brain and the central canal of the spinal cord.

NEUROGLIAL CELLS CONT'D

PNS:• schwann cells

• satellite cell

CLASSIFICATION NEUROGLIAL CELLS

• schwann cells-One of the most important functions of the Schwann cell is to myelinate the axons of the PNS. Myelin, which is a fatty layer that insulates the axon, helps to increase the saltatory conduction of the neuron.

CLASSIFICATION OF NEUROGLIAL CELLS

• satellite cell- Are small, flattened cells found in the ganglia of the peripheral nervous system. They help and regulate and stabilize the environment around ganglion cell bodies.

• 2) Autonomic- also known as ANS or Autonomic Nervous System

- Are divided into 3 separate into 3 separate divisions called the parasympathetic, the sympathetic, and

the entericdivisions.

- Control muscles but these muscles are involuntary.  

-  Preganglionic cell bodies for the parasympathetic outflow are in the brainstem and in the sacral spinal cord. The individual

functions as a whole.

CLASSIFICATION AND INTRODUCTION OF DIFFERENT NERVOUS SYSTEMS CONT’D:

ACTION POTENTIAL: RESTING

• The electrical potential across a nerve cell membrane before it is stimulated to release the charge.

• The potential for a neuron is between 50 and 100 mV• With an exception of an excess of negatively charged ions inside the

cell membrane • Created by a transport protein called the sodium-potassium pump• It moves large numbers of sodium ions (Na+) outside the cell, creating

the positive charge.• At the same time, the protein moves some potassium (K+) ions into the

cell’s cytoplasm.

ACTION POTENTIAL

• Sodium channels in the neuron’s membrane to open, allowing the Na+ ions that were outside the membrane to rush into the cell.

• Sodium channels are called gated ion channels because they can open and close in response to signals like electrical changes.

• More gated ion channels open, allowing more Na+ ions inside the cell, and the cell depolarizes so that the charges across the membrane completely reverse

• Potassium ions move outside the membrane, and sodium ions stay inside the membrane, repolarizing the cell.

• When the K+ gates finally close, the neuron has slightly more K+ ions on the outside than it has Na+ ions on the inside.

ACTION POTENTIAL: REFACTORY

• At the peak of the action potential , all Na+ become inactivated. • When inactivated, they cant be re opened immediately. • Is a time and voltage dependent process, and the full recovery usually

takes about 3-4 mins. • Na+ ions are moved outside of the cell and K+ ions to the inside,

returning the neuron to its normal polarized state.

ACTION POTENTIAL: NEUROTRANSMITTERS AND THEIR ROLE

• Several types of neurotransmitters, and each one of them is responsible for some specific functions.

• Usually classified as amino acids, peptides, and monoamines • The neurotransmitters that fall into the category of amino acids are: - Glutamate - Aspartate - Glycine - D-serine - Gamma- aminobutyric acid (GABA) - Acetylcholine (ACH)

ACTION POTENTIAL: NEUROTRANSMITTERS AND THEIR ROLE CONT’D

• A large number of neurotransmitters fall into he category of peptides, of which a few important ones are:

- Beta-endorphin - Opioid peptides - Somatostatin - Calcitonin - Vasopressin - Oxytocin - Glucagon

ACTION POTENTIAL: NEUROTRANSMITTERS AND THEIR ROLE CONT’D

• The most important monoamines or other biogenic amines that are considered as neurotransmitters are:

- Serotonin - Norepinephrone - Epinephrine - Histamine - Melatonin

RESOURCES

• http://vanat.cvm.umn.edu/neurLab1/neuron.html• http://medicine.academic.ru/144496/pseudounipolar_neuron• http://www.scholarpedia.org/article/Autonomic_nervous_system• http://study.com/academy/lesson/peripheral-nervous-system-definition-

function-parts.html• http://mason.gmu.edu/~cbeck/biol124/MARIEB7%20CH13.htm• http://www.dummies.com/how-to/content/action-potential-of-

neurons.html