The Human Brain

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The Human Brain

The Human Brain

The Human Brain

All you need to know about The Human Brain

The human brain is the command center for the human nervous system. It receives signals from the body’s sensory organs and outputs information to the muscles. The human brain has the same basic structure as other mammal brains but is larger in relation to body size than any other brains.

Facts about the human brain

  • The human brain is the largest brain of all vertebrates relative to body size.
  • It weighs about 3.3 lbs. (1.5 kilograms).
  • The average male has a brain volume of 1,274 cubic centimeters.
  • The average female brain has a volume of 1,131 cm3.
  • The brain makes up about 2 percent of a human’s body weight.
  • The cerebrum makes up 85 percent of the brain’s weight.
  • It contains about 86 billion nerve cells (neurons) — the “gray matter.”
  • It contains billions of nerve fibers (axons and dendrites) — the “white matter.”
  • These neurons are connected by trillions of connections, or synapses.

The Structure of the Human Brain

The developing brain goes through many stages. In the embryos of vertebrates, the predecessor to the brain and spinal cord is the neural tube. As the fetus develops, the grooves and folds in the neural tube deepen, giving rise to different layers of the brain. The human brain is split up into three major layers: the hindbrain, the midbrain, and the forebrain.

Parts of The Human Brain

Hindbrain

The hindbrain is the well-protected central core of the brain. It includes the cerebellum, reticular formation, and brain stem, which are responsible for some of the most basic autonomic functions of life, such as breathing and movement. The brain stem contains the pons and medulla oblongata. Evolutionarily speaking, the hindbrain contains the oldest parts of the brain, which all vertebrates possess, though they may look different from species to species.

Midbrain

The midbrain makes up part of the brain stem. It is located between the hindbrain and forebrain. All sensory and motor information that travels between the forebrain and the spinal cord passes through the midbrain, making it a relay station for the central nervous system.

Forebrain

The forebrain is the most anterior division of the developing vertebrate brain, containing the most complex networks in the central nervous system. The forebrain has two major divisions: the diencephalon and the telencephalon. The diencephalon is lower, containing the thalamus and hypothalamus (which together form the limbic system); the telencephalon is on top of the diencephalon and contains the cerebrum, the home of the highest-level cognitive processing in the brain. It is the large and complicated forebrain that distinguishes the human brain from other vertebrate brains.

Cerebrum

The cerebrum is the largest part of the brain. It 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 fibre called the corpus callosum. The cerebrum is further divided into four sections or lobes:

  • Frontal lobe: It is associated with parts of speech, planning, reasoning, problem-solving and movements.
  • Parietal lobe: Help in movements, the perception of stimuli and orientation.
  • Occipital lobe: It is related to visual processing.
  • Temporal lobe: This region is related to perception and recognition of memory, auditory stimuli, and speech.
  • The brain consists of two types of tissues: Grey matter and White matter.

Grey matter mainly consists of various types of cells, which make up the bulk of the brain.

White matter is primarily composed of axons, which connect various grey matter areas of the brain with each other.

The exterior portion of the cerebrum is called the cortex or the cerebral mantle. The cortex is extremely convoluted, due to which, it has a large surface area. The cerebrum also includes:

Sensory areas: To receive the messages.

Association areas: These areas integrate the incoming sensory information. It also forms a connection between sensory and motor areas.

Motor areas: This area is responsible for the action of the voluntary muscles.

Thalamus

The thalamus is a small structure, located right above the brain stem responsible for relaying sensory information from the sense organs. It is also responsible for transmitting motor information for movement and coordination. 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.

Hypothalamus

The hypothalamus is a small and essential part of the brain, located precisely below the thalamus. It is considered the primary region of the brain, as it is involved in the following functions:

  • Receives impulses
  • Regulates body temperature
  • Controls the mood and emotions
  • Controls the sense of taste and smell
  • Synthesizes the body’s essential hormones
  • Coordinates the messages from the autonomous nervous system
  • Controls appetite, peristalsis, the rate of heartbeat, and blood pressure
  • Forms an axis with the pituitary gland which is the main link between the nervous and the endocrine systems

Tectum

The tectum is a small portion of the brain, specifically the dorsal part of the midbrain. It serves as a relay centre 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.

Tegmentum

Tegmentum is a region within the brainstem. It is a complex structure with various components, which is mainly involved in body movements, sleep, arousal, attention, and different necessary reflexes. It forms the platform for the midbrain and connects with the thalamus, cerebral cortex, and the spinal cord.

Cerebellum

The cerebellum is the second largest part of the brain, located in the posterior portion of the medulla and pons. 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 the foila. Apart from this, the cerebellum has the cerebellar peduncles, cerebellar nuclei, anterior and posterior lobes. 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 precision control of the voluntary movements. The main functions of the cerebellum include:

  • It senses equilibrium.
  • Transfers information.
  • Coordinates eye movement.
  • It enables precision control of the voluntary body movements.
  • Predicts the future position of the body during a particular movement.
  • Both anterior and posterior lobes are concerned with the skeletal movements.
  • The cerebellum is also essential for making fine adjustments to motor actions.
  • Coordinates and maintains body balance and posture during walking, running, riding, swimming.
  • Explore: Differences between Cerebellum and Cerebrum

Medulla Oblongata

The medulla oblongata is a small structure present in the lowest region of the brain. It mainly controls the body’s autonomic functions such as heartbeat, breathing, and digestion. It plays a primary role in connecting the spinal cord, pons and the cerebral cortex. Also, it helps us in maintaining our posture and controlling our reflexes.

Pons

The pons is the primary 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:

  • Controlling sleep cycles.
  • Regulating the magnitude and frequency of the respiration.
  • Transfers information between the cerebellum and motor cortex.
  • Pons is also involved in sensations, such as the sense of taste, hearing, and balance.

Source: Wikipedia, Google

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