The Nervous System Miranda Schmidt

What is the nervous system?  The network of nerve cells and fibers that transmits nerve impulses between parts of the body.  The nervous system includes both the Central nervous system and Peripheral nervous system.

The Central Nervous System  Made up of the brain and spinal cord.  The meninges are three layers or membranes that cover the brain and the spinal cord. The outermost layer is the dura mater. The middle layer is the arachnoid, and the innermost layer is the pia mater. The meninges offer protection to the brain and the spinal cord by acting as a barrier against bacteria and other microorganisms.

The Peripheral Nervous System  made up of the Somatic and the Autonomic nervous systems.  The somatic nervous system consists of peripheral nerve fibers that pick up sensory information or sensations from the peripheral or distant organs and carry them to the central nervous system.  The autonomic nervous system has three parts: sympathetic nervous system, the parasympathetic nervous system, the enteric nervous system.

The Autonomic Nervous System  Regulates certain body processes, such as blood pressure and the rate of breathing, that workwithout conscious effort.

The Somatic Nervous System  Consists of nerves that connect the brain and spinal cord with muscles and sensory receptors in the skin.

Interaction Between Two Neurons

Simple Reflex Arc

 The path taken by the nerve impulses in a reflex is called a reflex arc. In higher animals, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord. This characteristic allows reflex actions to occur relatively quickly by activating spinal motor neurons without the delay of routing signals through the brain, although the brain will receive sensory input while the reflex action occurs.

Cerebral Hemisphere  The cerebral hemisphere is one half of the cerebrum, the part of the brain that controls muscle functions and also controls speech, thought, emotions, reading, writing, and learning.

Diencephalon  Diencephalon is made up of four distinct components: the thalamus, the subthalamus, the hypothalamus, and the epithalamus. The hypothalamus is an integral part of the endocrine system, with one of the most important functions being to link the nervous system to the endocrine system via the pituitary gland.

Brain Stem  The brain stem has many basic functions, including regulation of heart rate, breathing, sleeping, and eating. It includes the medulla oblongata (myelencephalon), pons (part of metencephalon), and midbrain (mesencephalon).

Cerebellum  The cerebellum receives information from the sensory systems, the spinal cord, and other parts of the brain and then regulates motor movements.

Neurotransmitters  a chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure.

IPSP  An inhibitory postsynaptic potential ( IPSP ) is a kind of synaptic potential that makes a postsynaptic neuron less likely to generate an action potential.

EPSP  In neuroscience, an excitatory postsynaptic potential ( EPSP ) is a postsynaptic potential that makes the neuron more likely to fire an action potential.

Stroke  Strokes happen when blood flow to your brain stops.  Symptoms of stroke are:  Sudden numbness or weakness of the face, arm or leg (especially on one side of the body)  Sudden confusion, trouble speaking or understanding speech  Sudden trouble seeing in one or both eyes  Sudden trouble walking, dizziness, loss of balance or coordination  Sudden severe headache with no known cause  Post-stroke rehabilitation helps individuals overcome disabilities that result from stroke damage.

Encephalitis  Encephalitis is an inflammation of the brain. Usually the cause is a viral infection, but bacteria can also cause it.  Symptoms of severe cases include:  Severe headache  Sudden fever  Drowsiness  Vomiting  Confusion  Seizures  Treatments include oral and intravenous medicines to reduce inflammation and treat infection.