Nervous+period+2

__**By Sean Kilcullen, Tanya Kolesnic, Jake Chaffee, Zarina Saynutdinova**__media type="custom" key="9643092" media type="youtube" key="xRkPNwqm0mM" height="349" width="425" ** The Nervous System ** The nervous system is split into two parts, the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). The CNS consists of the inter-neurons, neurons in the brain and inner spinal cord. The CNS coordinates all your body’s activities. Your Peripheral Nervous System consists of sensory neurons and motor neurons. The PNS controls motor-activities and the senses. The PNS is also split into two parts, Somatic system which controls the skeletal muscles, and the Autonomic system which controls the involuntary actions such as breathing. The Autonomic system is also split into two parts, the sympathetic system and parasympathetic. The Sympathetic system controls the body’s organs in times of stress while the parasympathetic controls them when at rest. The Nervous System works like this, your sensory neurons detect a smell, sight, sound or feeling. They transmit that data on to the PNS nerves in the spinal cord that then pass it on to the brain. The brain is part of the CNS. The CNS receives the data and then makes sense of it. If the CNS decides to react to data recieved for some reason, say you touch something hot, your CNS will send another signal down the spinal cord and to the PNS which will move your hand. These signals are very fast.

The nervous systems all rely on neurons. Neurons are cells that conduct impulses throughout the nervous system. Neurons fall into three categories: interneurons, sensory neurons and motor neurons. Interneurons receive impulses and send impulses to motor neurons; they are located in the brain and spinal cord. Motor neurons carry impulses sent from the interneurons to muscles and organs. Sensory neurons control the five senses. They collect data such as a tap on the shoulder, and then send it to the brain that then sends an impulse to motor neurons that move your neck to see what or who tapped you. Let us look at the structure of a neuron. A neuron consists of a soma or cell body, dendrites and an Axon. The soma is pretty much like a regular cell. It has all the normal organelles and functions like a cell. What makes a neuron unique is its branch like structures called dendrites and its long tail like structure called an axon. Dendrites receive impulses and the Axon sends impulses. On the end of the axon, where the soma isn’t, lies the axon terminal. The axon terminal is where an impulse is sent to other neurons. The axon has a protective layer called the myelin sheath. Like a plastic coating around an electrical wire, the myelin sheath insulates the axon making sure no ions are lost when sending an impulse. This structure of the neuron is helpful because with the long branches of the dendrites, the cell can connect too many neurons and increase the efficiency of transmitting data through the nervous system. How do your neurons send these impulses? Impulses are sent by depolarization. At rest a neuron is negatively charged and as a large stock of potassium ions. Outside the cell, there is a large amount of sodium ions and it is positively charged. When at rest a neuron’s membrane is said to be polarized, which means it has the potential to send an impulse. When a neuron is stimulated, sodium channels in the membrane open up and the cell quickly turns from negative to positive. This wave of depolarization moves down the axon. Eventually it reaches the axon terminals. Dendrites of another neuron are at the axon terminal. The two structures do not touch though. There is a tiny space called the synapse in between them. When the impulse reaches the axon terminal, it causes calcium channels to open up. The calcium causes vesicles, inside the neuron, filled with chemicals called neurotransmitters, too attach to the axon terminal’s membrane and release the neurotransmitters into the synapse. Then the neurotransmitters defuse across the synapse and bind to receptors on another neuron’s dendrite. When the neurotransmitter is in the other neuron, it is quickly broken down by enzymes to stop the continual firing of impulses. Impulses are how neurons speak to each other and are very important. media type="youtube" key="90cj4NX87Yk" height="349" width="425" ** Major parts of the Brain ** ** The BRAIN! **  The Brain is a vital part of the Central Nervous System. Everything from feelings to running, your brain controls it. In the brain there are lobes, Cerebellum, Medulla Oblongata, thalamus and hypothalamus. Here are some of the functions >> >>>>>>> ** CVA ** CVA stands for **__Cerebrovascular__** **__accident__** and it refers to the sudden death of some brain cells due to the lack of oxygen when the blood flow to the brain is damaged by a blockage or crack of an artery to the brain, in other words, it’s a stroke. The two main types of CVA are **__Ischemic__** and **__Hemorrhagic.__** result from arterial blockage, the plaque that blocks these can break or rupture (split open), causing a blood clot to form inside the artery and stopping blood flow to the brain. This type of stroke is very damaging to the brain; it causes certain parts of the brain to die. Imbalance and falling
 * The spinal cord is the messenger link between the PNS and the brain (like a highway)
 * It has an ascending and descending nerve tracts
 * 31 pairs of spinal nerves
 * During a reflex, the reflex impulse travels only to the spinal cord and travels back to the muscles. It doesn’t have to go all the way to the brain
 * Lobes
 * Frontal
 * motor functions
 * motivation
 * aggression
 * sense of smell
 * mood
 * Vision
 * Vision
 * Parietal
 * Evaluation of sensory details
 * Occipital
 * Temporal
 * Memory
 * Smell
 * Hearing
 * Parietal
 * Evaluation of sensory details
 * Occipital
 * Thalamus
 * Memory
 * Hypothalamus
 * Autonomic nervous system
 * Body temperature
 * Hunger
 * Thirst
 * Metabolism
 * Cerebellum
 * Balance
 * Posture
 * Coordinates muscle movements
 * Limbic System
 * Emotions
 * Medulla Oblongata
 * Heart rate
 * Blood vessel diameter
 * Respiratory rate
 * Vomiting
 * Coughing
 * **__Ischemic strokes__**
 * Loss of (or abnormal) sensations in an arm, leg or one side of the body
 * Weakness or paralysis of an arm or leg or one side of the body
 * Partial loss of vision or hearing
 * Double vision
 * Dizziness
 * Slurred speech
 * Problems thinking of or saying the right word
 * Inability to recognize parts of the body


 * __ Hemorrhagic strokes __** occur when the blood vessels of the brain are weak, abnormal, or under unusual pressure, and intracerebral hemorrhage bleeding within the brain.
 * Intracerebral hemorrhage results from when chronic high blood pressure weakens a small artery causing it to burst
 * The first symptom is often a severe headache
 * Diagnosis is based on symptoms and results of a physical examination and imaging tests.
 * Diagnosis is based on symptoms and results of a physical examination and imaging tests.
 * Results: inability to move one or more limbs on one side of the body, inability to understand, or formulate speech.



For more information on cerebrovascular accident go to:

[] ** Trivia Questions **
 * (Use the Brain and Nervous system Diagram to answer the questions!) **
 * Q ** : **Which part of your brain makes up 85% of your brain’s weight?**


 * a) ** Cerebrum, **b)** Thalamus, **c)** Cerebellum


 * A: **


 * Q ** : **What does the Hypothalamus control in your brain?**


 * a) ** The release of growth hormones, **b)** Temperature, **c)** Emotions


 * A: **


 * Q: Which part of your brain keeps you breathing? **


 * a) ** The brain stem, **b)** the cerebellum, **c)** the pituitary gland
 * A: **


 * Q: How much does the brain weigh? **


 * a) 6 ** lbs**. b)** 3lbs**. c)** 1lbs.
 * A: **


 * Q: What is the second largest part of the brain? **


 * a) ** Cerebellum, **b)** Pituitary gland**, c)** Diencephalon
 * A: **


 * Q: Where is Diencephalon located at? **


 * a) Core of the brain b) beneath the brain c) around the spinal cord **


 * A: **


 * Q: How many neurons does the cerebral cortex of a human brain contain? **


 * a) 10 billion, b) 15-33 billion, c) 50 billion **


 * A: **
 * FUN FACTS! **
 * If all of the neurons in a person's body were lined up that line would stretch to a length of 600 miles.
 * 4% of all brain cells are used; the rest are “back up.”
 * The right side of the brain controls the left side of the body, and the left side of the brain controls the right side of the body.
 * The human brain weighs about 3 lbs.
 * A man’s spinal chord is about 17.7 inches, and a woman’s is around 16.9 inches.
 * The rate of neuron growth in a fetus is 250 000 neurons per minute