The Central Nervous System

NERVOUS SYSTEM

Table Tennis is a very fast-paced sports that demands high agility and very quick response to a given stimuli. The moment you see the ball being hit by the racket, your eyes send signals for the brain to analyze so that you could respond properly to the ball: the proper timing, power, speed and the direction on where to land the ball.

In this lesson, we are going to learn about the Nervous System and try to explain how the brain gives commands or signals to different parts of the body and how the body process these signals to execute the command.

Major Divisions and Parts of the Nervous System

                                 (picture credit to Campbell Biology textbook Pearson Education)

1. The Central Nervous System (CNS)

             The CNS is like the Central Processing Unit (CPU) of a computer. It processes all of the stimuli it receives from the outside and commands the body to respond to it. Its main components are the Brain and the Spinal Cord

A.            Brain

It is the organ in the skull that processes all information that our senses receive and commands the body parts to respond to it. Here are some of the things that you need to know about the brain:

1.       It has an average mass of 3 pounds or 1.5 Kg.

2.       It has 10 billion neurons that process a person’s memory, emotions, movements, thoughts and senses.

         a.       Cerebrum – the large upper part of the brain that controls activity and thought

    - It has two sides: the left and right brain hemispheres

    - the outer part of the cerebrum is covered with a thin tissue called gray matter while the rest is made of white matter

    - the nerve fibers of the cerebrum pass down and cross through the brain and the spinal cord. Because of this, the right hemisphere of the brain controls the muscles of the left side of the body while the left hemisphere controls the muscles of the right side.

b.      Cerebellum – it is located at the lower back part of the cerebrum

     - it is the part of the brain that controls and coordinates movement, posture and balance

c.       Brain Stem – it is the part of the brain that connects the cerebrum  to the spinal cord

     - It controls automatic functions of the body such as breathing, heartbeat, digestion, and blood pressure

     - it is found at the base of the skull

   d.     Medulla – it controls breathing, swallowing and heat rate

   e.     Pons – It regulates breathing and helps control eye movement

   f.      Midbrain – linked to vision and controls movement of the eye

   g.     Thalamus – processes information coming from the senses

  h.     Hypothalamus – Regulates body temperature, use of water, blood pressure, and release of regulatory chemicals

(credits to Concepts in Biology, McGraw Hill)

B.   Spinal Cord -  is a long, thin, tubular bundle of nervous tissue and support cells that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. It is supported by the spinal (vertebral) column or backbone to keep it from damage. The brain and spinal cord together make up the central nervous system(CNS).

2.     2.   The Peripheral Nervous System (PNS)

               The Peripheral Nervous System (PNS) is a part of the nervous system that connects the Central Nervous System (CNS) to the limbs and to different organs of the body. It serves as the channel of commands coming from the brain to different parts of the body and messenger from the body parts to the brain. Unlike the brain and the spinal cord, the PNS is not protected by bones or fluid, making it prone to damage. The PNS is divided into two parts: the Somatic Nervous System and the Autonomic Nervous System.

A.            Somatic Nervous System - it is responsible for the voluntary muscle and skeletal control.                                                   The muscles and bones that you use to do a task are all controlled by the                                                Somatic Nervous System.

B.       Autonomic Nervous System - it is a division of the peripheral nervous system that responsible                                              for the involuntary movement of the internal parts of the body. The ANS controls bodily functions unconsciously such as digestion, sneezing, swallowing, vomiting, heart rate, respiration or breathing, pupil dilation, and sexual arousal. This involuntary function of the body is controlled by a certain part of the brain called the hypothalamus. The ANS has two branches: the Sympathetic and the Parasympathetic Nervous System.

a.    Sympathetic NS- tells us whether to "fight or flight", or face your opponents head on or run away from the fight.

b.   Parasympathetic NS - stimulates our "rest and digest" or "feed and breed" activities. This includes salivation, urination, defecation, digestion and sexual arousal.

Concept Map of the Nervous System

(credits to Concepts in Biology, McGraw Hill)