Human Brain- Structure, Diagram, function, diagram, Facts, Functions, Anatomy

Human Brain: Structure, Diagram, function, diagram, Facts, Functions, Anatomy

Edited By Irshad Anwar | Updated on Jul 02, 2025 06:47 PM IST

The human brain is the most complex central nervous system component that performs the control functions of thoughts, emotions, and actions. It closely relates to the spinal cord but differs in both structure and function. While the brain acts as the major processing site of sensory input, voluntary behaviour, and decision, the spinal cord acts mainly as a passageway. This difference in the functioning of the brain and the spinal cord shows the complementary ways that these two could work as central organs to establish appropriate communication and coordination leading to life processes, survival, and adaptation toward environmental changes. This is a very important topic in the Chapter Neural Control and Coordination in Biology.

This Story also Contains

What is the Human Brain?
Location of the Brain
Parts of the Human Brain
Neurons and Synapses
Blood Supply
Functions of the Brain

Human Brain: Structure, Diagram, function, diagram, Facts, Functions, Anatomy

What is the Human Brain?

The human brain is the most exceptional organ in human beings. It governs each part of our body and minds, centring our thoughts, emotions, memory, and behaviours. The structure and functions of the brain are so compelling that when understood, we would get overwhelmed by the complexity and huge role it plays in our day-to-day living. Weighing about 1.0 to 1.5 kg, an adult human brain contains approximately 86 billion neurons. The brain, together with the spinal cord, forms part of the central nervous system that controls all activities in the human body, from mere thoughts and body movements to the interpretation of senses.

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Location of the Brain

The brain sits in the skull, composed of 22 bones. It is cushioned by CSF, which also provides some immunological protection and suspends the brain to reduce its effective weight.

Parts of the Human Brain

The different parts of the human brain are:

Forebrain

The parts of the forebrain are:

Cerebrum: The largest part responsible for thinking, intelligence, consciousness, memory, and sensory interpretation.
Hypothalamus: Body temperature, emotions, hunger, sleep, synthesises some essential hormones
Thalamus: Relaying sensory and motor information

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Midbrain

The parts of the midbrain are:

Tectum: Conducts sensory information from the ears and controls reflex movements
Tegmentum: Seems to be concerned with body movements, the process of sleep, arousal and attention

Hindbrain

The parts of the hindbrain are:

Cerebellum: Coordinates balance of the body and voluntary movements
Medulla Oblongata: Coordinates autonomic functions such as heartbeat and breathing
Pons: Acts as a bridge in conduction signals between different parts of the brain and controls sleep cycles and respiratory activities.

Diagram of Brain

Structure of the Brain

The human brain can be anatomically divided into three main parts: the forebrain, midbrain, and hindbrain.
Each part includes specific structures and functions essential in various physiological and psychological processes.

Structure of the Brain

Neurons and Synapses

Neurons are the simplest functional units of the brain, transmitting information through electrical and chemical signals.
Synapses are interconnections between neurons, facilitating communication within the brain.

Blood Supply

The carotid and vertebral arteries supply blood to the brain.
The skull, meninges, and cerebrospinal fluid offer protection to the brain.

Functions of the Brain

The functions of the brain have been discussed below:

Cognitive Functions

The brain controls sensory processing, motor functions, cognition, emotions, and autonomic activities.
Different regions of the brain have specified functions.

Neuroplasticity

The brain can reorganise itself by forming new neural connections.
Neuroplasticity enables learning, memory, and recovery from brain injuries.

Important Points to Remember

The human brain weighs approximately 1.4 kilograms and contains approximately 86 billion neurons.
It takes up about 20 per cent of the energy of the whole body while it makes up only 2 per cent of the human body weight.
The left hemisphere of the brain controls the right side of the human body, and vice versa.

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Lobes of Cerebrum	Receptors
Choroid plexus	Structure of the Human Eye
Mechanism of Vision	Neuron

Frequently Asked Questions (FAQs)

1. What are the main parts of the human brain?

The human brain is divided into the forebrain, midbrain, and hindbrain.

2. What is the function of neurons?

Neurons are the simplest functional units of the brain and are responsible for transmitting information through electrical and chemical signals.

3. How is the brain protected?

The skull, meninges, and cerebrospinal fluid protect the brain.

4. What is neuroplasticity?

Neuroplasticity is when the brain reorganises itself to form new neural links; it's important in learning and memory and the recovery of function following injuries to the brain.

5. What is the approximate amount of energy consumed by the brain?

Brain energy consumption accounts for quite a huge portion of the body's energy, about 20%.

6. What is the blood-brain barrier, and why is it significant?

The blood-brain barrier is a selective semipermeable border of endothelial cells that prevents many substances from entering the brain from the bloodstream. It's crucial for protecting the brain from harmful substances and maintaining a stable environment for proper neural function. However, it can also prevent beneficial drugs from reaching the brain, posing challenges in treating brain disorders.

7. How does the brain change with aging?

As the brain ages, it undergoes various changes. These include a gradual decrease in brain volume, particularly in the prefrontal cortex and hippocampus, reduced blood flow, and changes in neurotransmitter systems. Synaptic connections may decrease, and white matter integrity can decline. However, the aging brain also shows plasticity, with some older adults developing new neural pathways to compensate for age-related changes.

8. What is the role of glymphatic system in brain health?

The glymphatic system is a waste clearance system in the brain that removes metabolic waste products and toxins. It's most active during sleep, when brain cells shrink slightly, allowing for increased flow of cerebrospinal fluid. This system is crucial for maintaining brain health, potentially playing a role in preventing neurodegenerative diseases by clearing harmful proteins like beta-amyloid, which is associated with Alzheimer's disease.

9. What is neuroinflammation, and how does it affect brain function?

Neuroinflammation is an immune response in the nervous system, often triggered by injury, infection, or neurodegenerative processes. While acute neuroinflammation can be protective, chronic neuroinflammation can damage neurons and disrupt normal brain function. It's associated with various neurological disorders, including Alzheimer's and Parkinson's diseases. Neuroinflammation can affect neurotransmitter systems, synaptic plasticity, and overall cognitive function.

10. What is the role of the cerebral cortex in higher cognitive functions?

The cerebral cortex, the outer layer of the cerebrum, is crucial for higher cognitive functions. Different areas specialize in various tasks: the frontal cortex is involved in planning and executive function, the parietal cortex in spatial processing and attention, the temporal cortex in memory and language, and the occipital cortex in visual processing. The integration of information across these areas enables complex cognitive abilities like abstract thinking, problem-solving, and consciousness.

11. What is the default mode network, and what is its significance?

The default mode network (DMN) is a set of interconnected brain regions that are active when a person is not focused on the external environment. It's associated with introspection, mind-wandering, and self-referential thinking. The DMN is important for consolidating memories, planning for the future, and understanding others' perspectives. Alterations in the DMN have been linked to various neurological and psychiatric disorders.

12. What is the role of the prefrontal cortex in executive function?

The prefrontal cortex is crucial for executive functions, which include complex cognitive processes like planning, decision-making, impulse control, and working memory. It helps in organizing thoughts and actions in accordance with internal goals, allowing for flexible and goal-directed behavior. The prefrontal cortex is one of the last brain regions to fully develop, continuing to mature into early adulthood.

13. How does the brain process language?

Language processing involves multiple brain regions, primarily in the left hemisphere for most people. Broca's area is involved in speech production, while Wernicke's area is crucial for language comprehension. The arcuate fasciculus connects these areas, allowing for integrated language processing. Other regions, including the temporal and parietal lobes, contribute to various aspects of language, such as semantics and phonology.

14. How does the brain process and regulate emotions?

Emotion processing involves multiple brain regions, including the amygdala, prefrontal cortex, hippocampus, and insula. The amygdala plays a key role in detecting and responding to emotional stimuli, particularly threats. The prefrontal cortex is involved in regulating emotional responses. The interaction between these and other regions allows for the complex experience and modulation of emotions. Neurotransmitters and hormones also play crucial roles in emotional processing and regulation.

15. How does the brain's structure relate to its function?

The brain's structure is closely tied to its function. Different regions specialize in various tasks: the frontal lobe handles decision-making and personality, the temporal lobe processes memories and language, the parietal lobe integrates sensory information, and the occipital lobe manages visual processing. This specialization allows for efficient information processing and complex behaviors.

16. What is neuroplasticity, and why is it important?

Neuroplasticity is the brain's ability to change and adapt throughout life by forming new neural connections. It's crucial for learning, memory, and recovery from brain injuries. This adaptability allows the brain to rewire itself, compensating for damaged areas and optimizing function based on experiences and environmental stimuli.

17. How does the brain consume energy compared to other organs?

Despite making up only about 2% of body weight, the brain consumes approximately 20% of the body's energy. This high energy demand is due to the constant electrical activity of neurons and the need to maintain ion gradients for proper signaling. The brain primarily uses glucose as its energy source, highlighting the importance of stable blood sugar levels for optimal brain function.

18. What is the role of glial cells in the brain?

Glial cells, once thought to be mere support cells, play crucial roles in brain function. They provide physical and nutritional support to neurons, help maintain the blood-brain barrier, remove dead neurons and pathogens, and even participate in signal transmission. Types of glial cells include astrocytes, oligodendrocytes, and microglia, each with specific functions in maintaining brain health and function.

19. How does sleep affect brain function and health?

Sleep is essential for brain health and function. During sleep, the brain consolidates memories, clears out toxins, and replenishes energy stores. Lack of sleep can impair cognitive function, mood regulation, and long-term brain health. Different sleep stages, particularly deep sleep and REM sleep, play unique roles in brain restoration and cognitive processes.

20. How does the brain regulate circadian rhythms?

The suprachiasmatic nucleus (SCN) in the hypothalamus acts as the brain's "master clock," regulating circadian rhythms. The SCN receives light information from the eyes, which helps synchronize internal rhythms with the external day-night cycle. It then coordinates various physiological processes, including sleep-wake cycles, hormone release, and body temperature fluctuations, through neural and hormonal signals.

21. How do neurons communicate with each other?

Neurons communicate through electrochemical signals. When a neuron is stimulated, it generates an electrical impulse (action potential) that travels along its axon. At the synapse, this electrical signal triggers the release of chemical neurotransmitters, which bind to receptors on the receiving neuron, potentially causing it to fire its own action potential.

22. What is the difference between gray and white matter in the brain?

Gray matter primarily consists of neuronal cell bodies, dendrites, and unmyelinated axons. It's responsible for processing and computing information. White matter, on the other hand, is composed mainly of myelinated axons, which form the brain's communication network. The myelin sheath gives white matter its characteristic color and allows for faster signal transmission between different brain regions.

23. What is the role of neurotransmitters in brain function?

Neurotransmitters are chemical messengers that transmit signals across synapses. Different neurotransmitters have various effects: for example, dopamine is involved in reward and motivation, serotonin affects mood and sleep, and glutamate is the primary excitatory neurotransmitter. Imbalances in neurotransmitter levels or function can lead to various neurological and psychiatric disorders.

24. How does the brain change during adolescence?

During adolescence, the brain undergoes significant changes, including synaptic pruning (elimination of unnecessary neural connections) and increased myelination of axons. The prefrontal cortex, responsible for decision-making and impulse control, is one of the last areas to fully develop. These changes contribute to improvements in cognitive abilities but can also lead to increased risk-taking behaviors characteristic of adolescence.

25. How does the brain process and store memories?

Memory processing and storage involve multiple brain regions and stages. Short-term memories are initially processed in the hippocampus. Through a process called consolidation, these memories can become long-term, involving structural changes in neurons and their connections. Different types of memories (e.g., procedural, semantic, episodic) are stored in various brain regions and retrieved through complex neural networks.

26. What is the function of the hippocampus?

The hippocampus plays a crucial role in forming, organizing, and storing new memories. It's particularly important for episodic and spatial memory. The hippocampus helps consolidate short-term memories into long-term memories and is involved in spatial navigation. Damage to the hippocampus can result in the inability to form new memories, as seen in certain types of amnesia.

27. How does the brain maintain homeostasis in the body?

The brain, particularly the hypothalamus, plays a crucial role in maintaining homeostasis. It regulates body temperature, blood pressure, fluid balance, and hunger/thirst sensations. The hypothalamus receives input from various body systems and coordinates responses through the autonomic nervous system and endocrine system to keep the body's internal environment stable.

28. How does the brain process visual information?

Visual processing begins in the retina, where light is converted into electrical signals. These signals travel through the optic nerve to the visual cortex in the occipital lobe. Different aspects of visual information (color, motion, form) are processed in specialized areas. The brain then integrates this information to create a coherent visual perception, often filling in gaps based on past experiences and expectations.

29. What is neurogenesis, and does it occur in the adult brain?

Neurogenesis is the process of forming new neurons. While most neurons are formed during embryonic development, neurogenesis does occur in specific regions of the adult brain, particularly the hippocampus and olfactory bulb. This process is important for learning, memory formation, and potentially for brain repair. Factors like exercise, diet, and stress can influence adult neurogenesis.

30. How does the brain process pain?

Pain processing involves multiple brain regions and is more complex than a simple stimulus-response mechanism. Nociceptors (pain receptors) send signals to the spinal cord and then to the brain. The thalamus acts as a relay station, and various brain regions, including the somatosensory cortex, insula, and anterior cingulate cortex, process different aspects of pain (location, intensity, emotional response). The brain can also modulate pain perception through descending pathways.

31. What is the basic structure of the human brain?

The human brain consists of three main parts: the cerebrum (largest part, divided into two hemispheres), the cerebellum (located at the back of the brain), and the brainstem (connecting the brain to the spinal cord). Each part has specific functions and works together to control our body and mind.

32. What is the function of the corpus callosum?

The corpus callosum is a large bundle of nerve fibers that connects the left and right cerebral hemispheres. Its primary function is to facilitate communication between the two hemispheres, allowing for the integration of sensory, motor, and cognitive information. This integration is crucial for complex tasks that require coordination between both sides of the brain.

33. What is the role of the cerebellum in motor control?

The cerebellum, often called the "little brain," plays a crucial role in motor control. It coordinates voluntary movements, maintains balance and posture, and helps in motor learning. The cerebellum receives input from sensory systems and the cerebral cortex, integrates this information, and uses it to fine-tune motor activities, ensuring smooth and accurate movements.

34. What is the role of the amygdala in emotion processing?

The amygdala is a key structure in emotion processing, particularly for fear and anxiety. It helps evaluate emotional significance of stimuli and is involved in emotional learning and memory. The amygdala can trigger rapid responses to potential threats and influences the formation of emotional memories. Its connections with other brain regions allow it to modulate various aspects of cognition and behavior based on emotional context.

35. How does chronic stress affect brain structure and function?

Chronic stress can have detrimental effects on the brain. It can lead to atrophy of neurons in the hippocampus, affecting memory and learning. Stress also impacts the prefrontal cortex, potentially impairing decision-making and emotional regulation. Additionally, chronic stress can alter neurotransmitter systems, potentially contributing to mood disorders and cognitive decline.

36. What is the role of neurotrophic factors in brain health and function?

Neurotrophic factors, such as Brain-Derived Neurotrophic Factor (BDNF), are proteins that promote the growth, survival, and plasticity of neurons. They play crucial roles in brain development, learning, and memory formation. Neurotrophic factors support synaptic plasticity, enhance neuronal resilience, and can even promote neurogenesis in certain brain regions. Levels of these factors can be influenced by lifestyle factors like exercise and diet, impacting overall brain health.

37. How does the brain change in response to learning and experience?

The brain constantly changes in response to learning and experience through a process called neuroplasticity. This involves strengthening or weakening of synaptic connections, formation of new synapses, and even the growth of new neurons in certain brain regions. Repeated experiences or practice can lead to structural changes, such as increased gray matter volume in relevant brain areas. This plasticity allows the brain to adapt to new information and optimize its function based on environmental demands.

38. How does the brain process reward and motivation?

The brain's reward system, centered around the mesolimbic dopamine pathway, plays a key role in processing reward and motivation. When we experience something rewarding, dopamine neurons in the ventral tegmental area (VTA) are activated, releasing dopamine in the nucleus accumbens and other regions. This system reinforces behaviors, drives motivation, and is involved in learning and decision-making. Dysfunction in this system is implicated in addiction and mood disorders.

39. How does the brain process time and duration?

Time perception involves multiple brain regions and is not localized to a single "clock" in the brain. The basal ganglia and cerebellum are involved in processing short time intervals, while the prefrontal and parietal cortices play roles in perceiving longer durations. Dopamine levels can influence time perception, and factors like attention and arousal can affect how we experience the passage of time.

40. What is the role of the insula in brain function?

The insula, or insular cortex, is involved in a wide range of functions, including interoception (awareness of internal bodily states), emotion processing, empathy, and decision-making. It plays a crucial role in integrating sensory, emotional, and cognitive information, contributing to self-awareness and social cognition. The insula is also involved in pain perception and is implicated in various neuropsychiatric disorders.

41. How does the brain process and integrate sensory information?

Sensory processing involves multiple steps and brain regions. Primary sensory areas receive input from sensory organs, processing basic features of stimuli. This information is then integrated in association areas, which combine inputs from different senses and previous experiences. The parietal lobe plays a key role in sensory integration, while the prefrontal cortex is involved in interpreting and responding to sensory information in the context of goals and expectations.

42. What is the role of the thalamus in brain function?

The thalamus acts as a relay station for sensory and motor signals to the cerebral cortex. It plays a crucial role in regulating consciousness, sleep, and alertness. The thalamus filters and processes incoming sensory information before sending it to appropriate cortical areas. It's also involved in motor control, emotional processing, and memory functions. The thalamus's extensive connections make it a key hub in various brain networks.

43. How does the brain process social information?

Social information processing involves multiple brain regions, collectively known as the "social brain." This includes the medial prefrontal cortex (involved in understanding others' mental states), the temporoparietal junction (crucial for perspective-taking), the superior temporal sulcus (important for perceiving biological motion and facial expressions), and the amygdala (involved in emotional processing and social judgments). These regions work together to enable complex social cognition, including empathy, theory of mind, and social decision-making.

44. What is the role of the basal ganglia in motor control and learning?

The basal ganglia are a group of subcortical nuclei involved in motor control, learning, and executive functions. They play a crucial role in initiating and smoothing movements, as well as in motor learning and habit formation. The basal ganglia work in conjunction with the cortex and thalamus to select and inhibit motor programs. Dysfunction in the basal ganglia is associated with movement disorders like Parkinson's disease and Huntington's disease.