What Is the Structure of the Human Brain? How Does the Human Brain Work?

The human brain is part of the central nervous system and has a complex structure. In adults, it weighs approximately 1.4 kg and consists of blood vessels, neurons, and supporting glial cells. From the early stages of life to adulthood, the weight and structure of the brain continuously change and develop. Both genetic and environmental factors can directly or indirectly affect brain development.

What Is the Structure of the Human Brain?

The brain is not a muscle-based organ; rather, it is a complex structure composed of numerous neurons and neuroglial cells. Neurons (nerve cells) connect with each other through synapses, allowing chemical and electrical signals to be transmitted to other parts of the brain or body. Neuroglial cells are essential support structures for neurons, providing nourishment to the nerve cells. Additionally, they form myelin, which facilitates signal transmission. This contributes to the maintenance of homeostasis (the body’s internal balance).

Support cells, known as glial cells, are more numerous than neurons. The neurons that make up the brain extend through the spinal cord, distribute throughout the body, produce responses in targeted regions, and bring information back to the brain. The brain receives incoming information, processes and uses it, interprets it, and generates responses. This enables the primary functions of the brain, such as the formation of emotions and feelings, cognitive activities like learning and memory, the operation of tissues and organs, hormone production, voluntary muscle movements like walking and talking, and involuntary muscle movements.

The brain consists of the right and left hemispheres and is divided into four distinct lobes. However, its overall structure can be divided into three main sections: the brain, cerebellum, and brainstem. All parts of the brain are organized structures interconnected with one another. Together with the spinal cord, it forms the central nervous system and connects to the peripheral nervous system. The peripheral nervous system includes the network of nerves that extends throughout the body, excluding the brain and spinal cord. The nerve networks circulating between the peripheral and central nervous systems transport signals in cycles (1, 2, 3, 4).

What Are the Parts of the Human Brain?

The brain receives signals from receptors in the sensory organs and transmits the resulting messages to muscles and various glands. Multiple areas of the brain may function together to carry out these processes. Although the human brain has a complex structure, it can generally be divided into three main parts:

Brainstem

Located at the base of the brain, the brainstem connects other parts of the brain to the spinal cord. The brainstem is made up of three main parts: the midbrain, pons, and medulla. The midbrain controls pupil dilation, eye movements, and reflexes of the head and body. The pons, acting as a bridge between the midbrain and the medulla, is responsible for facial sensations and movements, chewing, salivation, taste, tear production, blinking, certain eye movements, hearing, and balance coordination. Located at the lowest part of the brainstem, the medulla is the primary passage for neural connections entering and exiting the brain. It also regulates functions such as blood flow, respiration, heart rate, salivation, taste, shoulder and head movements, and balance. Additionally, it coordinates reflexes like vomiting, swallowing, coughing, and sneezing.

Cerebellum

The cerebellum, located at the lower back part of the brain, is separated from the brain by a tough fold. It primarily manages automatic movements, including muscle tone adjustments, limb positioning, posture maintenance, and balance. Recent studies suggest that the cerebellum may also have the ability to store information about frequently performed actions and learned skills.

Cerebrum

The cerebrum, also known as the brain, consists of gray matter (the cerebral cortex) and white matter. The gray matter, or cortex, covers the outer surface of the brain and features ridges and grooves called “gyri.” The white matter lies beneath the cortex and is connected to it by fibers. The cerebrum is divided into two hemispheres, the right controlling the left side of the body and the left controlling the right. The cerebrum is responsible for functions such as thinking, coordination, memory, learning, language, emotions, judgment and problem-solving, as well as sensory processes like vision, hearing, touch, and taste.

The brain can be divided into four different lobes based on function: the temporal, frontal, parietal, and occipital lobes. Additionally, deeper within the brain’s structure are structures such as the hypothalamus, pituitary and pineal glands, amygdala, and hippocampus.

How Does the Human Brain Work?

Information transfer between the human brain and other parts of the body occurs with the help of neurons that pass through the spinal cord. All sensory organs, muscles, endocrine glands, and other organs are surrounded by an extensive nerve network. The nerve network outside the brain and spinal cord is called the “peripheral nervous system.” When receptor cells in a sensory organ are stimulated by an effect, they generate electrical and chemical impulses. These impulses enable nerve cells to transfer information to other nerve cells. The chemicals that play a vital role in nerve transmission are called neurotransmitters.

Neurotransmitters are released from the axon of a nerve cell into the synaptic space, where they are received by another nerve cell. The neurotransmitters captured by receptors generate a signal in the new nerve cell. This process repeats sequentially between neurons, rapidly transmitting the signal to the brain. The brain hemispheres are connected by a thick nerve network known as the corpus callosum. The signal transmitted to the brain reaches the relevant area through these nerve networks. The right hemisphere is responsible for spatial information, while the left hemisphere manages language and speech functions. Additionally, the thalamus in the inner brain processes sensory information, while the hypothalamus regulates vital functions such as sleep, hunger, thirst, and blood pressure adjustment. The pituitary gland works with the hypothalamus to supply various hormones to the body.

The processed information in the brain is sent to the brain stem and spinal cord to be transmitted to muscles or glands. Neurons in the muscles and glands that help translate signals from the brain into action are called “motor neurons.” In reflex movements, nerve signals can generate responses without reaching the brain, with the spinal cord instead regulating these reflex actions.

How to Maintain Brain Health

Maintaining brain health is influenced by factors such as lifestyle, physical activity, nutrition, and managing stress and anxiety. Preserving brain health is essential throughout life, from early stages to old age. Deterioration in brain health can lead to issues in nerve transmission, hormonal production disorders, functional problems in muscles and glands, and disruptions in organ activities. Additionally, age-related changes in the brain, combined with external factors, may lead to certain illnesses. Within this scope, some recommended actions help maintain brain health:

• Regular physical activity can be effective in reducing depression risk, enhancing sleep quality, increasing blood flow to the brain and organs, and improving both physical and mental functions. Moreover, regular exercise may be associated with reduced risks of dementia and Alzheimer’s disease.
• Adequate and quality sleep can aid in the consolidation and storage of information acquired throughout the day, allowing the body to rest and reducing stress. Poor sleep may lead to memory difficulties, mood-related issues, and reduced concentration.
• Maintaining normal blood pressure is important for health. High blood pressure can damage blood vessels, potentially harming brain health.
• Balanced nutrition is recommended to maintain ideal weight and health. For brain functions to operate efficiently and maintain its healthy structure, it’s important to include whole grains, meats, poultry and fish, fresh fruits and vegetables, healthy fats, and dairy products in adequate amounts in the diet.

In addition to these, you can protect your brain health by reducing unnecessary medication use, managing stress and depression, and regularly following up on conditions like diabetes if applicable.