The Brain



The vertebrate brain formed at the a anterior end of the spinal cord. The brain undergoes regional expansion during embryonic development. It developed from the hollow tube of nervous tissues. The brain and human heart are interconnected by neurons. This tube develops into the three basic parts of brain.

Types of brain



  1. Hind Brain

  2. Mid Brain

  3. Fore brain


The central canal of the spinal cord extends up into the brain.

Ventricles


Central canal of the spinal cord extends up unto the brain. Brain has divisions called ventricles. These ventricles of brain are filled with cerebrospinal fluid.

Types Of Brain


1. Hind Brain


In this type of brain, hind-brain is continuous with the spinal cord. Hind brain is further consists of three structures.

Medulla oblongata

It's an enlargement of the spinal cord. It contains reflex centers for breathing, swallowing, cardiovascular function, and gastric secretions. It is well developed in all jawed vertebrates. It oversight visceral functions. It screens for information that leaves or enters the brain.

Cerebellum

Cerebellum is the outgrowth of the medulla oblongata. It coordinates motor activity. This activity is relating with limb movement. It maintains posture and spatial orientation. The cerebellum in cartilaginous fishes has distinct anterior and posterior lobes. The cerebellum is large in actively swimming organisms like teleosts. It's very small in inactive fishes. Amphibians have a rudimentary cerebellum. It shows that they have simple locomotive patterns.  The cerebellum is expanded in tetra-pods. The cerebellum is much larger in birds and mammalian organisms.

Pons

It is a bridge of  transverse nerve tracts . It arises from the cerebrum  of the fore-brain. It also have tracts that joins the fore-brain and spinal cord.

2. Mid-Brain


Generally, mid-brain coordinates the visual input. It also took the functions of touch & hearing input. But its size remains constant

Optic tectum


The roof of the mid brain is called optic tectumIts a thicker region of grey matter. It integrates visual & auditory signals.

3. Fore-brain


It has two main parts

  1. Diencephlalons.

  2. Telencephlon or cerebrum.


1. Diencephlalon


It lies in front of the mid-brain. It contains thalamus, hypothalamus, pineal glans, and pituitary glands.

♦ Thalamus


It relays all sensory info to highest brain centers.

♦ Hypothalamus


It is present below the thalamus, It regulates many functions like sexual drive, hunger,  thirst, body temperature etc.

♦ Pineal glands


Its controls body rhythms.

♦ Pituitary glands


Pituitary glands are hormones secreting. It's a major endocrine gland. The most important part of the brain is corpus striatum in reptiles and birds.

3. Cerebrum


It present externally to the corpus striatum. It has large groove. This groove divides cerebrum into right and left cerebral hemisphere.

Cerebral cortex


The outermost part of the cerebrum is called cerebral cortex.

The layers of cerebrum fold back on itself many times.


Functions of cerebrum



  1. The cerebral cortex contains primary sensory areas and primary motor areas.

  2. Some areas of cortex controls the auditory signals of from environment.


This includes the ability to use language in written and spoken forms in living beings.

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