Human Brain

Human Brain

A human brain is the largest, the developed structure in the anatomy of human beings and other well-organized organisms. The brain is made up of about 100 billion neurons and it weighs about 1300g or 3lbs.

The brain is called the Central Nervous System as it performs our body’s decision and is the communication center for organs and activities. The  Peripheral Nervous System and the spinal cord is composed of nerves. The daily activities starting from breathing, blinking of our eyes to reflex action and to memorize the facts are altogether controlled by these two systems –

  1. The central nervous system – CNS
  2. The Peripheral Nervous System – PNS.

The brain is the part of the central nervous system present in the head and is protected by the skull, both laterally and dorsally. Cranium,  a bony structure is called as the house for the brain which is located within the skull. It is also known as the centralized command for the nervous system, as brain receives information from the sensory organs and sends output through the muscles.

The brain is made up of different chambers and compartments for various functions. A human brain works continuously day and night by sending instructions to different organs of our body and function as per the requirements.

Isn’t this amazing? Let’s find out more in detail about the human brain along with its part.

The Main Parts of the Brain

A human brain is composed of three main parts- the forebrain, the midbrain and the hindbrain. These three parts have specific functions.

  1. Forebrain: This consists of the cerebrum, hypothalamus, and thalamus.
  2. Midbrain: Consists of the tectum and tegmentum.
  3. Hindbrain: Is made of the cerebellum, medulla, and pons.

Three main parts of brain

Forebrain – The cerebrum

The cerebrum is the largest part of the brain which consists of the cerebral cortex and other subcortical structures.It is composed of two cerebral hemispheres that are joined together by heavy dense bands of fiber called the corpus callosum. It is further divided into four sections or lobes :

  1. Frontal lobe: It is associated with parts of speech, planning, reasoning, problem-solving and movement.
  2. Parietal lobe: Helps in movement, the perception of stimuli and orientation.
  3. Occipital lobe: Related to visual processing.
  4. Temporal lobe: Related to perception and recognition of memory, auditory stimuli, and speech.

The cerebrum

The exterior portion of the cerebrum is the cortex, it consists of the neurons cells which are grey in color, hence are also referred as the grey matter. The internal part of the cerebrum is the medulla, it comprises of the neurons cells which are white in color. The cortex is extremely convoluted that increase its surface area.The cerebrum also includes

  1. Sensory areas: It is to receive the messages.
  2. Association areas: It is to associate the information with the previous and other sensory information.
  3. Motor areas: It is responsible for the action of the voluntary muscles.

The cerebrum is also responsible for the thinking, intelligence,  consciousness, memory,  and willpower.

Forebrain -Thalamus

An area which coordinates the sensory impulses receiving from the various sense organs including eyes, ears, skin, etc. and then transmits it to the cerebrum. Thalamus is found in the limbic system within the cerebrum. This limbic system is mainly responsible for the formation of new memories and storing past experiences.

Forebrain -Hypothalamus

The hypothalamus is a small and important part of the brain, located exactly below the thalamus of the limbic system within the cerebrum. It is considered as a most important region of the brain as it is involved in :

  1. Controlling the mood and emotions.
  2. Receiving the impulses, sense of taste and smell.
  3. Coordinating the messages from the autonomous nervous system.
  4. Synthesizing of body’s essential hormones.
  5. Controlling the body temperature, peristalsis, rate of heartbeat, and blood pressure.
  6. Forming an axis with the pituitary which is the main link between the nervous and the endocrine systems.

Midbrain- Tectum

The tectum is a small portion of the brain, specifically the dorsal part of the midbrain. It serves as a relay center for the sensory information from the ears to the cerebrum. It also controls the reflex movements of the head, eye and neck muscles. It provides a passage for the different neurons moving in and out of the cerebrum.

Midbrain- Tegmentum

Tegmentum is a region found in the brainstem. It is the largest complex structure with the ninety nuclei present under the rectum. It forms the platform for the midbrain and connects with the thalamus, cerebral cortex, and the spinal cord.It is mainly involved in the movements,  sleep, arousal, attention,  and various basic reflexes.

Hindbrain- The Cerebellum

The cerebellum is the second largest part of the brain which is located in the posterior portion of the medulla and pons. Both, the cerebellum and cerebrum are separated by tentorium cerebelli and transverse fissure. Cortex is the outer surface of the cerebellum and its parallel ridges are called as the foila. Apart from this, the cerebellum has the cerebellar peduncles, cerebellar nuclei, anterior and posterior lobes, etc. The cerebellum consists of two hemispheres the outer grey cortex and the inner white medulla.  It is mainly responsible for coordinating and maintaining the body balance during walking, running, riding, swimming, and fine control of the voluntary movements. The main functions of the cerebellum include:

  1. It senses equilibrium.
  2. Transfer of information.
  3. Fine control of the voluntary body movements.
  4. The cerebellum is responsible for coordinating eye movements.
  5. It predicts the future position of the body during a particular movement.
  6. The cerebellum is also essential for making fine adjustments to motor actions.
  7. Both anterior and posterior lobes are concerned with skeletal movements.
  8. Coordinating and maintaining the body balance and posture during walking, running, riding, swimming, etc.

Hindbrain- The Medulla oblongata

The medulla oblongata is a small and the lowest region of the brain that is enclosed and well protected. It comprises of the cardiovascular center and the respiratory center. We cannot live without the medulla as it plays a primary role in connecting the spinal cord and the skull henceforth helping us in maintaining our posture and controlling our reflexes. The main functions of the medulla oblongata include:

  1. It helps in controlling the involuntary functions of both respiratory and cardiovascular centers.
  2. It is involved in regulating life-sustaining functions such as coughing, sneezing, swallowing, vomiting,  salvation, hiccups, etc.

Hindbrain- The Pons

The pons is the major structure of the brain stem present between the midbrain and medulla oblongata. It serves as a relay signals between the lower cerebellum, spinal cord, the midbrain, cerebrum and other higher parts of the brain.The main functions of the pons include:

  1. It is involved in transferring information between the cerebellum and motor cortex.
  2. It controls the magnitude and frequency of the respiration.
  3. It is also involved in controlling the sleep cycles.
  4. In addition, the pons is involved in sensations such as the sense of taste, hearing, and balance.

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Practise This Question

Chemical messengers responsible for control and coordination in plants and animals are: