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Renin Angiotensin Mechanism.

Human Brain: Brain Stem.

 

Brain Stem.

  • Lower part of the brain.

  • Located in front of the cerebellum and ends in the spinal cord.

  • It consists of,

    1. MidBrain

    2. Pons

    3. Medulla Oblongata.

  1. MidBrain:

  • Also called “Mesencephalon” in Greek Mesen means middle and cephalon means brain hence “The Middle Brain”.

  • Starts from diencephalon to pons.

  • Anterior part contains a pair of tracts called “Cerebral Peduncles”.

  • Posterior part, called “Tectum”, contains four elevations called “Cerebral Colliculus”.

  • Superior colliculi are responsible for ``Visual Activity”.

  • Inferior colliculi are responsible for “Auditory Activity”.

  • It also contains a dark pigmented area called “Substantia nigra” the degeneration of neurons in this area is the prime cause of “Parkinson's Disease.”

  • Midbrain contains two pairs of cranial nerves,

    • Oculomotor nerve. (III Cranial Nerve)

    • Trochlear nerve. (IV th Cranial Nerve)

  1. Pons:

  • Present above medulla oblongata and in front of the cerebellum.

  • It connects parts of the brain with one another.

  • It contains a “Respiratory center” which operates with the association of areas of Medulla Oblongata.

  • Contains four pairs of cranial nerves.

    • Trigeminal Nerve (V th cranial nerve).

    • Abducens Nerve (VI th cranial nerve).

    • Facial Nerve (VII th cranial nerve).

    • Vestibulocochlear Nerve (VIII th cranial nerve).

  1. Medulla Oblongata:

  • Lowermost part of the brain.

  • It ends in the spinal cord.

  • Important part as contains several regulatory centers like,

    • Cardiovascular Center: Deals with heart rate, regulation of blood pressure.

    • Rhythmicity Area: Deals with maintaining the rhythm of breathing.

    • Vasomotor area: Maintaining blood pressure.

    • Swallowing center.

    • Sneezing Center.

    • Cough Center.

    • Hiccuping Center.

  • Also contains four pairs of cranial nerves.

    • Vestibulocochlear nerve. (VIII th Cranial Nerve)

    • Glossopharyngeal nerve. (IX th Cranial Nerve).

    • Vagus Nerve. (Xth Cranial Nerve).

    • Accessory Nerve (XIth Cranial Nerve).

    • Hypoglossal Nerve (XII th Cranial Nerve).

Commonly Asked Questions.

  1. Write a short note on Brain Stem.

  2. Give functions of Medulla oblongata.
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