Parts of the Brain and Their Functions


Parts of the Brain
The three main parts of the brain are the cerebrum, cerebellum, and brainstem, but these portions contain many key sections.

The human brain is the epicenter of our nervous system and plays a pivotal role in virtually every aspect of our lives. It’s a complex, highly organized organ responsible for thoughts, feelings, actions, and interactions with the world around us. Here is a look at the intricate anatomy of the brain, its functions, and the consequences of damage to different areas.

Introduction to the Brain and Its Functions

The brain is an organ of soft nervous tissue that is protected within the skull of vertebrates. It functions as the coordinating center of sensation and intellectual and nervous activity. The brain consists of billions of neurons (nerve cells) that communicate through intricate networks. The primary functions of the brain include processing sensory information, regulating bodily functions, forming thoughts and emotions, and storing memories.

Main Parts of the Brain – Anatomy

The three main parts of the brain are the cerebrum, cerebellum, and brainstem.

1. Cerebrum

  • Location: The cerebellum occupies the upper part of the cranial cavity and is the largest part of the human brain.
  • Functions: It’s responsible for higher brain functions, including thought, action, emotion, and interpretation of sensory data.
  • Effects of Damage: Depending on the area affected, damage leads to memory loss, impaired cognitive skills, changes in personality, and loss of motor control.

2. Cerebellum

  • Location: The cerebellum is at the back of the brain, below the cerebrum.
  • Functions: It coordinates voluntary movements such as posture, balance, coordination, and speech.
  • Effects of Damage: Damage causes problems with balance, movement, and muscle coordination (ataxia).

3. Brainstem

  • Location: The brainstem is lower extension of the brain, connecting to the spinal cord. It includes the midbrain, pons, and medulla oblongata.
  • Functions: This part of the brain controls many basic life-sustaining functions, including heart rate, breathing, sleeping, and eating.
  • Effects of Damage: Damage results in life-threatening conditions like breathing difficulties, heart problems, and loss of consciousness.

Lobes of the Brain

The four lobes of the brain are regions of the cerebrum:

  1. Frontal Lobe
    • Location: This is the anterior or front part of the brain.
    • Functions: Decision making, problem solving, control of purposeful behaviors, consciousness, and emotions.
  2. Parietal Lobe
    • Location: Sits behind the frontal lobe.
    • Functions: Processes sensory information it receives from the outside world, mainly relating to spatial sense and navigation (proprioception).
  3. Temporal Lobe
    • Location: Below the lateral fissure, on both cerebral hemispheres.
    • Functions: Mainly revolves around auditory perception and is also important for the processing of both speech and vision (reading).
  4. Occipital Lobe
    • Location: At the back of the brain.
    • Functions: Main center for visual processing.

Left vs. Right Brain Hemispheres

The cerebrum has two halves, called hemispheres. Each half controls functions on the opposite side of the body. So, the left hemisphere controls muscles on the right side of the body, and vice versa. But, the functions of the two hemispheres are not entirely identical:

  • Left Hemisphere: It’s dominant in language and speech and plays roles in logical thinking, analysis, and accuracy. .
  • Right Hemisphere: This hemisphere is more visual and intuitive and functions in creative and imaginative tasks.

The corpus callosum is a band of nerves that connect the two hemispheres and allow communication between them.

Detailed List of Parts of the Brain

While knowing the three key parts of the brain is a good start, the anatomy is quite a bit more complex. In addition to nervous tissues, the brain also contains key glands:

  • Cerebrum: The cerebrum is the largest part of the brain. Divided into lobes, it coordinates thought, movement, memory, senses, speech, and temperature.
  • Corpus Callosum: A broad band of nerve fibers joining the two hemispheres of the brain, facilitating interhemispheric communication.
  • Cerebellum: Coordinates movement and balance and aids in eye movement.
  • Pons: Controls voluntary actions, including swallowing, bladder function, facial expression, posture, and sleep.
  • Medulla oblongata: Regulates involuntary actions, including breathing, heart rhythm, as well as oxygen and carbon dioxide levels.
  • Limbic System: Includes the amygdala, hippocampus, and parts of the thalamus and hypothalamus.
  • Amygdala: Plays a key role in emotional responses, hormonal secretions, and memory formation.
  • Hippocampus: Plays a vital role in memory formation and spatial navigation.
  • Thalamus: Acts as the brain’s relay station, channeling sensory and motor signals to the cerebral cortex, and regulating consciousness, sleep, and alertness.
  • Basal Ganglia: A group of structures involved in processing information related to movement, emotions, and reward. Key structures include the striatum, globus pallidus, substantia nigra, and subthalamic nucleus.
  • Ventral Tegmental Area (VTA): Plays a role in the reward circuit of the brain, releasing dopamine in response to stimuli indicating a reward.
  • Optic tectum: Also known as the superior colliculus, it directs eye movements.
  • Substantia Nigra: Involved in motor control and contains a large concentration of dopamine-producing neurons.
  • Cingulate Gyrus: Plays a role in processing emotions and behavior regulation. It also helps regulate autonomic motor function.
  • Olfactory Bulb: Involved in the sense of smell and the integration of olfactory information.
  • Mammillary Bodies: Plays a role in recollective memory.
  • Function: Regulates emotions, memory, and arousal.

Glands in the Brain

The hypothalamus, pineal gland, and pituitary gland are the three endocrine glands within the brain:

  • Hypothalamus: The hypothalamus links the nervous and endocrine systems. It contains many small nuclei. In addition to participating in eating and drinking, sleeping and waking, it regulates the endocrine system via the pituitary gland. It maintains the body’s homeostasis, regulating hunger, thirst, response to pain, levels of pleasure, sexual satisfaction, anger, and aggressive behavior.
  • Pituitary Gland: Known as the “master gland,” it controls various other hormone glands in the body, such as the thyroid and adrenals, as well as regulating growth, metabolism, and reproductive processes.
  • Pineal Gland: The pineal gland produces and regulates some hormones, including melatonin, which is crucial in regulating sleep patterns and circadian rhythms.

Gray Matter vs. White Matter

The brain and spinal cord consist of gray matter (substantia grisea) and white matter (substantia alba).

  • White Matter: Consists mainly of axons and myelin sheaths that send signals between different brain regions and between the brain and spinal cord.
  • Gray Matter: Consists of neuronal cell bodies, dendrites, and axon terminals. Gray matter processes information and directs stimuli for muscle control, sensory perception, decision making, and self-control.

Frequently Asked Questions (FAQs) About the Human Brain

  1. How many cells are in the human brain?
    • The human brain contains approximately 86 billion neurons. Additionally, it has a similar or slightly higher number of non-neuronal cells (glial cells), making the total number of cells in the brain close to 170 billion.
  2. How many neurons are in the human brain?
    • There are about 86 billion neurons in the human brain. These neurons are connected by trillions of synapses, forming a complex networks.
  3. How much does the human brain weigh?
    • The average adult human brain weighs about 1.3 to 1.4 kilograms (about 3 pounds). This weight represents about 2% of the total body weight.
  4. What percentage of the brain is water?
    • The brain is about 73% water.
  5. How much of our brain do we use?
  6. What is the size of the human brain?
    • The average size of the adult human brain is about 15 centimeters (6 inches) in length, 14 centimeters (5.5 inches) in width, and 9 centimeters (3.5 inches) in height.
  7. How fast do brain signals travel?
    • Brain signal speeds vary depending on the type of neuron and the nature of the signal. They travel anywhere from 1 meter per second to over 100 meters per second in the fastest neurons.
  8. How does the brain change with age?
    • With age, the brain’s volume and/or weight decrease, synaptic connections reduce, and there can be a decline in cognitive functions. However, the brain to continues adapting and forming new connections throughout life.
  9. Can the brain repair itself after being injured?
    • The brain has a limited ability to repair itself. Neuroplasticity aids recovery by allowing other parts of the brain to take over functions of the damaged areas.
  10. What is the energy consumption of the brain?
    • The brain consumes about 20% of the body’s total energy, despite only making up about 2% of the body’s total weight. It requires a constant supply of glucose and oxygen.
  11. How does sleep affect the brain?
    • Sleep is crucial for brain health. It aids in memory consolidation, learning, brain detoxification, and the regulation of mood and cognitive functions.

References

  • Douglas Fields, R. (2008). “White Matter Matters”. Scientific American. 298 (3): 54–61. doi:10.1038/scientificamerican0308-54
  • Kandel, Eric R.; Schwartz, James Harris; Jessell, Thomas M. (2000). Principles of Neural Science (4th ed.). New York: McGraw-Hill. ISBN 978-0-8385-7701-1.
  • Kolb, B.; Whishaw, I.Q. (2003). Fundamentals of Human Neuropsychology (5th ed.). New York: Worth Publishing. ISBN 978-0-7167-5300-1.
  • Rajmohan, V.; Mohandas, E. (2007). “The limbic system”. Indian Journal of Psychiatry. 49 (2): 132–139. doi:10.4103/0019-5545.33264
  • Shepherd, G.M. (1994). Neurobiology. Oxford University Press. ISBN 978-0-19-508843-4.