Transcript Introduction to the nervous system

INTRODUCTION TO THE
NERVOUS SYSTEM
Jasmine O
Mike Tuboras
Valerie Zuniga
A NEURON
ANATOMY & FUNCTION OF A NEURON
1) 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 NEURONS
Multipolar 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…
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Pyridimal Neuronshaped 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 CELLS
CNS:
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.
CLASSIFICATION AND INTRODUCTION OF
DIFFERENT NERVOUS SYSTEMS CONT’D:
• 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.
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-definitionfunction-parts.html
• http://mason.gmu.edu/~cbeck/biol124/MARIEB7%20CH13.htm
• http://www.dummies.com/how-to/content/action-potential-ofneurons.html
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