THE HUMAN BRAIN BRIEF NOTES

                THE HUMAN BRAIN                          

The Brain is the command centre for the nervous system. It receives input from the sensory organs and sends output to the muscles. Brain is enclosed in brain box (Cranium) and protected by a cerebrospinal fluid which acts as shock absorber. It has several layers called MENINGES..

Parts of the Human Brain

The human brain is composed of three major parts, namely:

1. Forebrain: It is the anterior part of the brain. It consists of –

• Cerebrum,
• Hypothalamus
• Thalamus
1. Midbrain: It is a small and central part of the brainstem. It consists of –
• Tectum
• Tegmentum
2. Hindbrain: It is the main region of the brain and is composed of –
• Cerebellum
• Medulla
• Pons

Cerebrum

The cerebrum is the largest part of the brain which consists of the cerebral cortex and other subcortical structures. The cerebrum includes:

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

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

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 relaying motor information for movement and coordination.

Hypothalamus

The hypothalamus is a small and important part of the brain, located exactly below the thalamus. It is considered the 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 body temperature, peristalsis, the 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.

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. 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.

Cerebellum

The cerebellum is the second largest part of the brain which is located in the posterior portion of the medulla and pons. 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 body balance and posture during walking, running, riding, swimming, etc.

Medulla Oblongata

The medulla oblongata is a small structure present in the lowest region of the brain.  It essentially controls the body’s autonomic functions such as heartbeat, breathing, digestion, etc. 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 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. Transferring information between the cerebellum and motor cortex.
2. Controlling the magnitude and frequency of the respiration.
3. It is also involved in controlling sleep cycles.
4. In addition, the pons is involved in sensations such as the sense of taste, hearing, and balance.

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