What is the Brain?
Table Of Content:
The brain is a complex organ that receives information through various senses such as vision, touch, smell, taste, etc. It interprets the information of the external world and facilitates the body to react in response. It is also responsible for controlling intelligence, creativity, memories, emotions, etc.
The brain consists of several parts that perform specific functions and the skull protects the brain. The nerves with the spinal cord along with the brain at the centre make up the nervous system. On an average, an adult human brain weighs about 1.2 – 1.4 Kgs.
Cells of the brain
Following are the two types of cells that make up the brain:
- Neurons: The neuron or nerve cells consist of dendrites, an axon and a cell body that are of different shapes and sizes. A neuron can transmit its energy to the neighbouring neurons. The gap between neurons which help to transfer the energy is a synapse and the arms of the cells that receive the messages and send it to the cell body are dendrites. The cell body analyses the signals and decides whether they must pass the message or not. Important messages move to the end of the axon to sac that contains neurotransmitters and opens into the synapse. The neurotransmitters travel in the form of molecules and fit into the receptors of the receiving nerve cells that stimulate the cell to pass the message.
- Glia cells: They provide nourishment, support and insulation to the neurons. Microglia digest dead neurons and pathogens, astroglia transport nutrients to neurons, hold them in place and digest parts of dead neurons along with maintaining the blood-brain barrier. Oligodendroglia provides insulation to the neurons.
Parts of the brain
- Skull: The skull is not a part of the brain or the nervous system. It is a part of the skeletal system present in the head and is a fusion of 8 cranial bones and 14 facial skeletal bones. It consists of three distinct areas: anterior fossa, middle fossa and posterior fossa.
- Cerebrum: It is the most significant part of the brain that performs the functions of interpreting vision, touch, hearing, speech, etc. It is divided into two sections i.e. the left and the right hemispheres which perform different functions. The cerebrum has many folds and wrinkles which increases the space and accommodates a higher number of neurons making it more efficient. A bundle of axons known as the corpus callosum connects the two hemispheres. The right hemisphere is responsible for creativity, while the left provides logical abilities. The outermost layer of the cerebrum is made up of grey matter known as the cerebral cortex. The grey matter is the area where all the interpretations take place while the white matter helps to transfer signals within the grey matter and from the grey matter to the various body parts.
- Cerebellum: Another name for the cerebellum is ‘little brain.’ It is also made up of two hemispheres and present at the top of the brain stem and spinal cord. Its cortex also has many folds like the cerebral cortex. However, this part of the brain is comparatively smaller. Its function is to receive information from the sensory organs and regulate voluntary motor movements and speech, along with maintaining balance and coordination. It is also responsible for smooth muscle movement.
- Brainstem: This region connects the spinal cord to the cerebrum and the cerebellum. It consists of the midbrain, pons and medulla. It helps in carrying out the involuntary tasks of the body such as breathing, temperature, heart rate, digestion, sneezing, vomiting, coughing, etc.The midbrain facilitates vision, eye movement, body movement, hearing, etc. Pons help in motor control, sensory analysis and maintaining a level of consciousness while sleeping. The medulla helps in controlling breathing and heart rate.
Important structures within the brain
- Thalamus: It is present above the brain stem, between the cerebral cortex and midbrain. Its primary function is to relay the motor and sensory signals to the cerebral cortex.
- Pituitary gland: It is known as the master gland of the body. It is present at the base of the brain and its size resembles that of a pea. It produces hormones that travel throughout the body and stimulate the glands to produce other hormones. It promotes bone and muscle growth, responds to stress and helps to fight diseases.
- Limbic system: It is a part of the cerebrum and is known as the ‘emotional brain.’ It contains the hypothalamus, thalamus, cingulate gyri, hippocampus and amygdala.
- Pineal gland: The gland releases melatonin which regulates the circadian rhythms and the body’s internal clock. It is found behind the third ventricle and also has a partial role in the sexual development.
- Hypothalamus: It is the central controlling organ of the autonomic system. It is located at the bottom of the third ventricle and controls hunger, sexual response, sleep, thirst, etc. while regulating blood pressure, body temperature, secretion of hormones, etc.
- Basal Ganglia: They work in coordination with the cerebellum to regulate fine movements such as those at the fingertips. They consist of caudate, putamen and globus pallidus.
Left and right brain
The left and right hemispheres are connected by the corpus callosum wherein each hemisphere controls the opposite side of the body. The two hemispheres also have certain functions that are exclusive to them. The left side of the brain controls arithmetic, speech, writing and comprehension, while the right side regulates spatial ability, creativity, music and artistic skills. Use of hand and language is under the control of the left hemisphere.
The hemispheres have fissures that divide the brain into the following lobes that are present in both the hemispheres:
- Frontal lobe controls body movement, personality, concentration, speech, writing, self-awareness, judgment, planning, self-awareness, behavior, emotions and planning.
- Parietal lobe interprets words, language, spatial and visual perception, sense of touch, pain, temperature, signals from vision, hearing, motor, sensory and memory.
- Occipital lobe interprets vision pertaining to light, movement and color.
- Temporal lobe helps to understand languages, controls memory and hearing and helps in sequencing and organization.
- Headache: This is the most common condition that occurs at one point of time or another. In most cases, treating a headache with analgesics or painkillers is sufficient, unless it has a serious underlying medical cause.
- Brain aneurysm: It refers to the weakening of an area in the artery in the brain that causes it to swell. There is a risk that the swelling may rupture leading to a stroke.
- Stroke: Sudden interruption of blood and oxygen flow to an area of the brain tissue may result in its death due to stroke. Strokes may also occur when there is a blood clot or bleeding in the brain.
- Concussion: Accidents or injuries that cause trauma to the brain may result in a concussion. It causes temporary disturbances in the functioning of the brain.
- Brain abscess: Often, bacteria may cause an infection in a particular area of the brain. Treatment of such a condition may include surgical drainage and consumption of antibiotics.
- Dementia: Malfunctioning or death of nerve cells in the brain may cause deterioration of cognitive functions. Alcohol abuse and other conditions that trigger strokes can also result in dementia.
- Intracerebral hemorrhage: It refers to bleeding inside the brain that may cause problems in its functioning.
- Subdural hematoma: The lining of the skull is the dura, bleeding under or within this area may cause a subdural hematoma. Neurological problems may emerge when the hematoma exerts pressure on the brain.
- Epidural hematoma: Bleeding between the dura and the skull may occur after a head injury. In case of incorrect treatment, the symptoms may progress rapidly and lead to unconsciousness and eventually, death.
- Brain tumor: Any abnormal tissue growth inside the brain is a tumor. It may be benign or malignant, but both are capable of causing problems by exerting pressure on the brain.
- Traumatic brain injury: Mental impairment, personality changes and mood swings are possible after a traumatic head injury. Such incidents are capable of causing permanent damage to the mental health of an individual.
- Glioblastoma: It is a type of tumor which is very difficult to treat because of its rapid development. Moreover, the tumor is malignant and aggressive.
- Cerebral edema: An individual may experience injuries or electrolyte imbalances. As a response to such conditions, the brain tissues may swell, this is known as cerebral edema.
- Epilepsy: The causes of epilepsy are commonly unknown. However, they may be a result of strokes or head injuries. It is a tendency to have seizures.
- Meningitis: Infection may cause inflammation of the lining around the spinal cord of the brain. Symptoms of meningitis include neck pain, fever, headache, sleepiness, stiff neck, etc.
- Encephalitis: Infection due to the virus may cause swelling in the brain tissue. Common symptoms include confusion, fever and headache.
- Hydrocephalus: The brain and spinal cord contain cerebrospinal fluids. When this fluid does not circulate properly, there can be an increase in its amount in the skull, this is known as hydrocephalus.
- Normal pressure hydrocephalus – Such a condition occurs when the pressure in the brain remains normal, despite an increase in the cerebrospinal fluid in the skull. It causes problems in walking, urinary incontinence and dementia.
- Huntington’s disease: It is a nervous disorder that affects the brain. It is hereditary and has dementia and chorea as its symptoms.
- Parkinson’s diseas: Degeneration of the nerves in the central area of the brain can cause problems in movement and coordination. Early signs of the disease include a tremor of the hands.
- Alzheimer’s disease: Nerves in some regions of the brain degenerate and cause dementia. It is the most common cause of dementia. However, the reason for the condition is unknown.
- CT Scan
- MRI Scan
- MRI (Magnetic Resonance Angiogram)
- Lumbar puncture/ Spinal tap
- Neurocognitive testing
- Brain biopsy
- Antibiotics: When there is an infection in the brain due to bacteria, consumption of antibiotics can help to treat the condition. The medicines will fight the disease-causing organism and cure the infection.
- Levodopa: It is a medication which helps to control the symptoms of Parkinson’s disease. It increases the level of dopamine in the brain which helps to reduce the symptoms.
- Thrombolytics: The doctor injects this medicine into the veins. It has clot-busting properties which can cure and improve strokes if it is given to the patient within a few hours after the symptoms start.
- Cholinesterase inhibitors: The medicine can help to improve brain function in case of mild or moderate Alzheimer’s disease. However, it does not prevent or slow the progression of the disease.
- Antiplatelet agents: Some prescribed medicines such as clopidogrel and aspirin prevent the formation of blood clots reduce the chances of strokes.
- Radiation therapy: The treatment is useful in cases where cancer affects the brain. Radiation therapy may help to reduce the symptoms and slow the growth of cancer.
- Craniotomy: Drilling of a hole at the side of the skull to relieve high pressure in the brain.
- Brain surgery: Increase in pressure may threaten to damage brain tissues. Performing this operation may help to relieve pressure or cure some brain tumors.
- Lumbar drain: It involves placing a drain into the fluid around the spinal cord to reduce pressure.
- Ventriculostomy: Placing a drain in the ventricles or natural spaces of the brain, this is also another way to reduce pressure.