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Brain (मस्तिष्क) – Biology For Competitive Exams

Brain (मस्तिष्क) – Biology for Competitive Exams

Biology topic – “Human Brain (मस्तिष्क)” is important for all competitive exams like SSC CGL, SSC CHSL, RRB NTPC, UPSC and other state civil services exams. In these exams, almost 4-5 questions are coming from Biology. Let’s start the topic: Human Brain (मस्तिष्क).

Human Brain (मस्तिष्क)

There are 2 Types of Nervous System in Human body:

  • Central Nervous system    ⇒    Brain + Spinal Cords
  • Peripheral Nervous System.

Central Nervous System consists two Major Parts- Brain and Spinal Cords. Here, we are discussing Human Brain. Let’s start:

                      Brain is the central organ of the human nervous system. It is located in the head and protected within the skull. It plays a role in every major body system. It is the most complex organ in a vertebrate’s body. It consists of the Cerebrum (Fore Brain), the Brain-stem and the Cerebellum.

                       The cerebrum is the largest part of the human brain. It is divided into two cerebral hemispheres. In a human, the cerebral cortex contains approximately 14–16 billion neurons. The cerebrum is connected by the brainstem to the spinal cord. The brainstem consists of the midbrain, the pons, and the medulla oblongata. The cerebellum is connected to the brainstem by pairs of tracts.

                        The part of a Skull (खोपड़ी) in Which Brain is protected, is called:  Cranium or Brain Box. Human Brain and spinal cord is protected with a membranes layer, known as Meninges Layer.

There are three layers of meninges:

  • Dura mater (closest to the bone),
  • Arachnoid loosely around the brain,
  • Pia mater is closely attached to the brain and spinal cord surface.

Brain is divided in main three parts:

  1. Fore Brain (अग्र मष्तिष्क),
  2. Mid Brain (मध्य मस्तिष्क),
  3. Hind Brain (पश्च मस्तिष्क),

biology- brain According to Size:        F.B > H.B >   M.B.

  1. Fore Brain (अग्र मष्तिष्क):

         The forebrain is the largest brain division. It includes the Thalamus,  Hypothalamus and Cerebrum. The olfactory and optic cranial nerves are found in the forebrain.  Three main part of Fore Brain are:

     1)  Thalamus,      2) Hypothalamus,     3) Cerebrum (प्रमस्तिष्क)

A) Thalamus:  Out of 5 sense organs, three – Nose, Tongue and Skin sensory organs are controlled by                                 the Thalamus of the fore Brain.

    • Nose: Sense of smelling is controlled by — Olfactory Nerve.
    • Tongue: To detect taste — Gustatory Receptor Nerve.
    • Skin: Largest Sensory Organ of human body.

B) Hypothalamus: Following Works are done by the Hypothalamus of Human Brain:

    • Sleep (नींद),
    • Hunger (भूख),
    • Thirst (प्यास),
    • Behaviour (व्यवहार),
    • Emotions & Feelings (भावनाए) – Anger, Love etc.
    • Control of Body Temperature (शरीर का तापमान): That’s why it is called Thermometer of Human body.

C) Cerebrum:  It is the largest part of Human Brain. Approximate 2/3 part of Human Brain mass covered by it. It is also called Intelligence mind.

        Working of Cerebrum:

    • Thinking,
    • Reasoning & Verbal,
    • Calculations & Mathematics,
    • Imagination (कल्पनाएँ).
  1. Mid Brain (मध्य मस्तिष्क):

         Out of 5 sense organs, functions of Two Organs à Ear (कान) and Eye (आँख) sensory organs are controlled by this. The midbrain helps control eye movement and processes visual and auditory information.

  1. Hind Brain (पश्च मस्तिष्क):

          It is the lower part of the brainstem that bridges the brain with the spinal cord. It comprise mainly three parts:

             1) Pons/Pons Varolii,                 2) Medulla-Oblongata,                     3) Cerebellum (अनुमस्तिष्क)

A) Pons-Varolii/Pons (पोन्स वैरोलाई):   It control respiratory System of Human Body. Amount of Oxygen required in human body is decided by Pons-Varolii.

B) Medulla- Oblongata (मेडुला-ओब्लोगाटा): Following reactions of human body are controlled by Medulla-oblongata of hind brain:

    1. Vital Reaction (जैविक क्रियाए): Blood Circulation (रुधिर परिसंरचना), Breathing (श्वशन) (Respiration), Heartbeat (हृदय धड़कन), Digestion (पाचन), Excretion (उत्सर्जन)
    2. Accessory Reaction (सहायक अभिक्रियां): Hiccups (हिचकी), Sneezing (छिकना), Brap (डकार), Salivation (लार बनाना), Vomiting (उल्टी आना), Snoring (खराटें), Yawn (उबाशी लेना), Blinking of eyes (आखों का झपकना)

C) Cerebellum (सेरीबेलम):  The cerebellum is also called Little Brain &Tree of Life (जीवन का पेड़), because it provides balance to body. It receives information from the sensory systems, the spinal cord, and other parts of the brain and then regulates motor movements.

 Working of Cerebellum:     

  •  The cerebellum coordinates voluntary movements such as: Body posture, Body Balancing (शारीरिक संतुलन), Walking (चलना), Speaking (बोलना), Learning (सीखना) and Muscular Movement (मासपेशीय हलचल).

      Note:      After Drinking of Alcohol, this part of brain is effected, Hence Drinking and Driving is Prohibited.


Nerve Cell (तंत्रिका कोशिका):

                        Nerve Cell is structural and functional Unit of Brain/Nerve system. Nerve cell has Minimum power of regeneration, because it has less cell division (कोशिका विभाजन), In short we can say that in Human body, Neurons (तंत्रिका)/ Nerve Cell (तंत्रिका कोशिका) is only tissue in which no cell division takes place after birth.

   Note:    Maximum cell division power in human body contains by Liver Cell called  ⇒  Hepatic Cell.

Neurons contain Acetylcholine which is also called ⇒ Neuro transmitter, where electrical impulses are carried on.

                    Acetylcholine is an organic chemical that functions in the brain and body of many types of animals (and humans) as a Neurotransmitter—a chemical message released by nerve cells to send signals to other cells.


Important Facts about Human Brain for Competitive Exams:

  • Highest developed brain in animal kingdom is of     ⇒    Human Brain.
  • Study of Brain     ⇒    Neurology.
  • Doctor for Brain is called    ⇒    Neurologist.
  • The part of a Skull (खोपड़ी) in Which Brain is protected, called   ⇒   Cranium or Brain Box.
  • Human Brain and spinal cord is protected with a membranes layer, known as  ⇒  Meninges Layer.
  • After Accidental death of a Person, His brain remains active for    ⇒   7 Minutes.
  • Mineral: maximum Sodium is consumed by Brain.
  • Water:   75 % of water  in Human Body is consumed by Brain.
  • Oxygen: Our brains consume approx. 20 percent of the body’s oxygen supply.
  • Weight of Human Brain: Child   ⇒  300 – 400 Gram.
  • Average Weight of Adult Human Brain   ⇒  1400 gm
    • (Female = 1350 gram, Male = 1450 gram. It is according to their body Weight.                             
    • Weight of Brain is Approx. 2% of Human Body)
  • Post mortem is also known as Autopsy in which Examination of Brain takes place.

          Note:   (Death of Brain is the Death of Man).

  • Due to infection in it, Inflammation in Human Brain is called  ⇒  Meningitis.
  • Unit of Brain Cell is called   ⇒   Neurons (तंत्रिका)/ Nerve Cell (तंत्रिका कोशिका).

          Note:  It is the largest and the longest cell of the Human Body.

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