NERVOUS
SYSTEM
KNOW YOURSELF
NERVOUS TISSUE
• Nervous System is made of nervous tissue.
• And nervous tissue is made up of:
1.
NEURONS: the cells that are able to transmit the
nervous impulse (electricity).
2.
GLIAL CELLS: cells of different kinds with specific
functions.
3.
EXTRACELLULAR MEDIUM: mixture of
substances that contain nutrients and waste
products and surround the cells.
NEURONS
• The main parts are:
1.
Dendrites: numerous and small
prolongations that have the
function of receiving stimuli.
2.
Soma: the central part of the
neuron that processes the
information.
3.
Axon: usually 1 single
prolongation that transmits the
nervous impulse to the next
neuron.
4.
Axon Terminals: ends of the
axon to communicate with
other neurons.
SYNAPSES
• Is the way neurons communicate by 2 ways: electricity and
chemical substances (neurotransmitters).
• Is formed by:
1. The end of the first neuron (presynaptic terminal).
2. A gap between neurons (synaptic cleft).
3. The beginning of the second neuron (postsynaptic terminal).
• To jump the synaptic cleft, neurotransmitters are needed, that are
going to join to specific receptors in the next neuron.
SYNAPSES
GLIAL CELLS
• There are 4 kinds:
1. Astrocytes--> essential cells for the nervous tissue because they perform
several functions:
a.
Support for the tissue
b.
Provide glucose to the neurons
c.
Eliminate neurotransmitters from the synaptic cleft
2. Microglia--> small cells that kill pathogens, so they defend the tissue.
3. Oligodendrocytes--> cells that surround axons in the central nervous
system.
4. Schwann cells--> cells that surround axons in the peripheral nervous
system.
PARTS OF THE NERVOUS SYSTEM
CENTRAL (CNS)
PERIPHERAL (PNS)
• Brain
• Nerves
• Spinal Cord
• Ganglions
BRAIN
• Is the most complex organ of the body and sends
orders to other elements.
• Is surrounded by a fluid with nutrients called
cerebrospinal fluid, produced in the cerebral
ventricles.
• Is protected by 3 membranous layers called
meninges and by the skull, because is very
valuable.
PARTS OF THE BRAIN
1. CEREBRAL CORTEX:
• Is the biggest and most evolved part of the brain. It has many
foldings, that can host millions of neurons.
• Receives information from many other parts of the brain and
sends information to them. When it reaches the cerebral cortex,
become conscious.
• Perform voluntary movements and sensations become conscious
when they reach this part.
PARTS OF THE BRAIN
1. CEREBRAL CORTEX:
• Is responsible of superior mental abilities: reasoning, association,
memory, learning, planification...
• There are specialized areas for certain functions, that activate
when neccesary. Also, they interchange information with other
areas.
• Therefore, there are sensitive areas, motor areas, associative
areas, reasoning areas, etc.
PARTS OF THE BRAIN
1. CEREBRAL CORTEX:
PARTS OF THE BRAIN
LIMBIC SYSTEM:
• Formed by several areas in the brain: amigdala, hippocampus, basal
ganglions, etc.
2.
•
Related to emotions, feelings and linked responses.
•
Primary emotions and more elaborated ones are developed here.
•
Connects with the cerebral cortex and other parts of the brain.
PARTS OF THE BRAIN
3. CEREBELLUM:
•
Is a complex structure at
the back of the brain that
looks like a mini brain.
•
It has many foldings, similar
to the ones of the cerebral
cortex.
•
In charge of complex
movements, like driving,
riding a bicycle, swimming,
playing sports...
•
Also related to body
balance and spacial
orientation.
PARTS OF THE BRAIN
4. BRAIN STEM
•
Is the rest of the brain, and is formed by
the next parts:
I.
Thalamus (Tálamo o Diencéfalo)
II.
Mesencephalus (Mesencéfalo)
III.
Pons (Puente)
IV. Medulla Oblongata (Bulbo Raquídeo)
•
Thalamus receives information from the 5
senses and transmits a part to the cerebral
cortex (is a filter).
•
The other parts control basic functions as
breathing, heart rythm, sleeping...
•
Cranial nerves start here.
SPINAL CORD
• Is under the brain stem.
• It coordinates movements of
different levels of the body.
• Also receives sensations.
• Sometimes the information
passes to the brain, others not
(reflexes).
• Spinal nerves start here.
SOMATIC NERVOUS SYSTEM
• Is formed by motor and sensory nerves and ganglions.
• Sensory nerves receive information from the receptors of the 5
senses.
• Motor nerves transmit orders from the brain to the muscles.
• There are also mixed nerves that transmit both sensorial and
motor information.
AUTONOMIC NERVOUS
SYSTEM
• Formed by nerves and ganglions related to the
organs of the body.
• There are 2 parts:
1.
Sympathetic NS it stimulates organs (lungs,
heart, digestive system, etc) to work.
2.
Parasympathetic NS it inhibits organs (lungs,
heart, digestive system, etc) to stop working.
RESPONSES
• They can be voluntary or involuntary (reflexes).
• In voluntary responses cerebral cortex is involved, so the individual
realizes about what is happening.
• It works like this:
Receptors Spinal Cord Brain Muscle/s
REFLEXES
• They are involuntary.
• Spinal Cord is responsible of performing them thanks to sensory
neurons, interneurons and motor neurons.
• It works like this:
Receptors Sensory neuron Interneuron Motor neuron Muscle/s
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