The human brain is a part of the nervous system and it is wrapped by a lining called the meninges. The top layer is called the duramater, and the fluid between the brain and the meninges is called the cerebrospinal. The fluid acts as a shock absorber, and the brain is covered by the skull to give more protection. The brain weighs about three pounds, and three main parts of the brain are: cerebrum, cerebellum, and the brain stem. Each section of the brain consists of neurons, and each neuron has dendrites to collect messages that are transmitted from other cells. Also, each neuron contains an axon to transmit information to other cells. Neurons secrete chemical substances called neurotransmitters that transmit nerve impulses to other neurons. Emotions and the Brain The brain and the emotions are interlinked, and neurotransmitters present in the brain plays the key role in the mood fluctuations. The chemical components that affect mood are serotonin, epinephrine, dopamine, endorphin, phenylethylamine, and melatonin. Serotonin helps in the smooth transmission of messages in the body and brain. Epinephrine helps the body to move during instant action. Dopamine transmits information to higher levels, and also regulates pleasure and pain. Endorphin is the natural pain killer and melatonin regulates the sleep and wake cycles. Phenyethylamine, a chemical is produced during the emotional infatuation or sexual attraction. What do People Feel When they Fall in Love? When a person falls in love, the brain releases certain chemicals or neurotransmitters that include oxytocin, dopamine, pheromones, serotonin, and norepinephrine. All the released neurotransmitters trigger the brain’s pleasure area that leads to numerous side effects such as loss of sleep, loss of appetite, increased heart beat, and an increased feeling of excitement. Brain Disorders Changes in the neurotransmitter systems lead to brain disorders or neurological problems. With respect to symptoms, brain disorders are classified into many divisions such as anxiety disorders, bipolar disorders, depression, migraine, panic disorder, sleep disorder, stroke, and dementia. Mood disorders are health conditions that are characterized by the disturbance of emotional states of an individual. People with this mood changes often suffer from sad feeling or depression. Common Brain Injuries A brain injury is a trauma that leads to injury of the skull, scalp, or brain, and the injuries can range from mild to severe. The brain injury is classified into: traumatic and acquired. The traumatic injury includes concussion, coup-contrecoup, diffuse axonal, contusion, and penetration. The acquired injuries are anoxia and hypoxic. The common type of brain injuries are: concussion and contusion. The concussion is the loss of awareness for a few minutes or few hours after the traumatic event. The contusion is the swelling or bleeding inside the brain itself. The severe injuries can lead to coma, paralysis, loss of sensation, chronic headaches, speech and language problems, and seizures.