The Nervous System

By Ben & Josh

Drawings:

drawings continued:

• Your spine consists of 33 vertebrae:• 7 cervical vertebrae – neck (C1 to C7)• 12 thoracic vertebrae (T1 to T12)• 5 lumbar vertebrae – lower back (L1 to L5)• 5 sacral vertebrae (S1 to S5)• 4 fused vertebrae that form the coccyx• • The vertebrae are attached and held together by ligaments on both

sides of the spine. The Vertebrae are separated from each other by a disk made of cartilaginous material. When we move, these disks absorb and reduce the pressure between the vertebrae.

• • The spine may be compared to a flexible tube. The holes in the center

of each vertebrae form the spinal canal. Through the interior passes a ‘cord’ of nervous tissue called the ‘spinal cord’. The spine’s principal function is to protect the spinal cord.

Your spinal cord•  

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• The spinal cord which is made of nerve cells and nerve fibers, resembles a cable about the size of your little finger.

• • Approximately 21 inches (52.5cm) in length, it begins at

the base of your brain and passes through the interior of each of your cervical and thoracic vertebrae. It ends at the upper level of your lumbar vertebrae (the superior border of L2), where it branches into a collection on nerves that extend down to the region of the coccyx.

• • Simply put, the spinal cord works like a two-way

telephone line. Via this communication pathway, the brain sends and receives messages to and from different parts of your body. This is how it can ensure the proper functioning of the vital organs as well as muscle movement. Commands from your brain and sensations from

The Brain• Making sense of the brain's complexity isn't easy. What we

do know is that it's the organ that makes us human, giving people the capacity for art, language, judgments, and rational thought. It's also responsible for each individual's personality, memories, movements, and how we sense the world.

• All this comes from a jellylike mass of fat and protein weighing about 3 pounds (1.4 kilograms). It is, nevertheless, one of the body's biggest organs, consisting of some 100 billion nerve cells that not only put together thoughts and highly coordinated physical actions but regulate our unconscious body processes, such as digestion and breathing.

• The brain's nerve cells are known as neurons, which make up the organ's so-called "gray matter." The neurons transmit and gather electrochemical signals that are communicated via a network of millions of nerve fibers called dendrite and axons.

• The brain is an organ located inside your head. The brain and the spinal cord form the central nervous system. This complex system controls everything we do. Each part of the brain has a different job. Here are some examples of functions that the brain controls:

• movement such as walking or stretching• seeing, smelling, touching, tasting, and hearing (the 5 senses)• emotions, thoughts, and memory• breathing and heartbeat• digesting food• talking and understanding• The brain is like a busy city. Each part has different functions and

is made up of different types of cells. To work, different parts of the brain need to send messages to each other, and to other parts of the body.

• Read further to find out the different parts of the brain and what they do, how the brain is organized, and what the brain is made of.

1)What are the sense organs? What function do they serve?

• 1) Eyes, ears, nose, skin, tongue• The function of the Eyes is to see• The function of the ears is to hear• The function of the nose is to smell• The function of the skin is to act as

a cushion against insult to the body• The function of the tongue is to

taste

• Sensory nerves are designed to act as transistors and send sensations to the brain that differentiate between the many feelings a person is capable of experiencing. Motor nerves send sensations to the brain that tell various muscles how to work.

2)What is the difference between sensory nerves and motor nerves?

What is the function of the brain, nerves, and spinal cord? • Forebrain•

• The forebrain plays a critical role in helping the body carry out a number of vital functions, such as thinking, analyzing, learning and reproducing languages, processing information received from sensory organs, and regulating and coordinating movement and motor functions. The brain processes most of the information received in the cerebral cortex. The thalamus and hypothalamus are also found in the forebrain, which are involved in transmitting information received from sensory organs, motor control and regulating and overseeing autonomic functions.

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What is the difference between the central nervous system and the peripheral nervous system?

• There are two main parts of the peripheral nervous system: the somatic and autonomic systems. The somatic nervous system controls all the functions of the body that are voluntary, like sticking out a tongue or scratching an itch. The central nervous system controls all the functions that are involuntary, like breathing and heart rate. Digestion is also part of the central nervous system and is called the enteric system.

• The autonomic system of the body is broken down further into the parasympathetic and sympathetic systems. The parasympathetic system controls all the functions of the body while it is at rest, like salivation and urination. The sympathetic system controls all the functions of the body while it is under the effects of stress. It includes such “fight or flight” responses as shutting down digestion