The Brain
What is a Brain?
The human body's most complex organ is the brain. This three-pound organ controls behaviour, causes bodily movement, processes sensory information, and stores intelligence. All of the characteristics that make us human originate in the brain, which is housed in its bony shell and cleaned by protective fluid. It is the diamond in the human body's crown. The average adult's brain weighs roughly 3 pounds and is composed of 60% fat. Water, protein, carbs, and salts make up the remaining 40%, therefore it is not a muscle. It has nerves, including neurones and glial cells, as well as blood vessels.
How does it work?
Chemical and electrical impulses are transmitted and received throughout the body through the brain. It then interprets the messages that control various processes differently. For instance, some cause you to feel exhausted, while others cause you to experience discomfort.
It has two parts (Hemispheres)
The Right Hemisphere:
- Insight
- Imagination
- Awareness
- Music Awareness
- 3D Forms
The Left Hemisphere:
- Written language
- Spoken language
- Number Skills
- Reasoning skills
- Logic skills
The Main Parts of the Brain
The Cerebrum
The cerebrum is made out of gray matter (the cerebral cortex) and white matter at its center. Initiating and directing movement and controlling body temperature, the cerebrum is the biggest portion of the brain. Its other regions enable expression, judgement, reasoning, problem-solving, emotions, and learning. Other senses such as hearing, touch, vision, and others—are also involved.
The Cerebral Cortex
There are two hemispheres, or halves, to the cerebral cortex. It is coated in folds (sulci) and ridges (gyri). The left half controls the right side of the body, while the right hemisphere controls the left. The corpus callosum, a sizable C-shaped structure of white matter located in the middle of the cerebrum and nerve connections, serves as a pathway for communication between the two parts.
The Brainstem
The Cerebellum
The cerebellum, also known as the "little brain," is a fist-sized section of the brain situated above the brainstem and under the temporal and occipital lobes. It has two hemispheres, similar to the cerebral cortex. The inner region interacts with the cerebral cortex, while the outside part is home to neurones. Its roles include maintaining posture, balance, and equilibrium as well as coordinating voluntary muscle movements.
The Lobes of the Brain. What are Their Functions?
- The frontal lobe, the biggest lobe of the brain, is found at the front of the head and has an essential function in movement, personality traits, and decision-making. A portion of the frontal lobe is typically involved in smell recognition. In the frontal, there is also Broca's area, which is linked to speech capacity.
- The parietal lobe, located in the middle of the brain, helps with object identification and spatial relationship interpretation (comparing one's body to objects around yourself). Interpreting touch and pain in the body is another function of the parietal lobe. Here lies Wernicke's region, which aids in the brain's comprehension of spoken language.
- The temporal lobe is in charge with speech, short-term memory, musical rhythm, and a certain amount of smell recognition. They are all influenced by the sides of the brain.
- The occipital lobe lies in the back part of the brain. It is responsible for vision.
Definitions:
Amygdala = Two almond-shaped structures located in the medial temporal lobes of the brain.
Hypothalamus = A brain structure located below the thalamus and above the brain stem.
Nucleus accumbens = A region of the basal forebrain located in front of the preoptic region.
Orbital frontal cortex = A region of the frontal lobes of the brain above the eye sockets.
Periaqueductal gray = The gray matter in the midbrain near the cerebral aqueduct.
Preoptic region = A part of the anterior hypothalamus.
Stria terminalis = A band of fibers that runs along the top surface of the thalamus.
Thalamus = A structure in the midline of the brain located between the midbrain and the cerebral cortex.
Visual cortex = The part of the brain that processes visual information, located in the back of the brain.
The Deeper Structures of the Brain
The Gray and White Matter
The central nervous system is divided into two separate parts: gray matter and white matter. The more vibrant, inner part of the brain is referred to as white matter, while the darker, outside part is called gray matter (it is responsible for metabolism, keeping the cell alive and synthesising proteins). The structure is reversed in the spinal cord, where the gray matter is located within and the white matter is on the outside.
White matter is mainly made up of axons, which are the long stems that connect neurons together and are covered in myelin, a protective substance, whereas gray matter is mainly made up of neuron somas, which are the circular core cell bodies. On some scans, the two appear as different shades due to the varied composition of the neuron sections.
The Neurons
All throughout your body, neurons—nerve cells—transmit messages that allow you to breathe, speak, eat, walk, and think. Most neuroscientists (scientists who study the brain) believed that we were born with all of our neurons until recently. The development of neural circuits, which serve as information highways connecting various parts of the brain, may involve the growth of some new neurons in children (in the human brain, there are about 100 billion neurons.).
They send signals:
- Excitatory (like pluses - positive)
- Inhibitory (like minuses - negative)
There are 3 types of neurons:
-
Sensory neurons (from the external world).
EX- When you touch something hot and feel pain.
-
Motor neurons (they go from the brain out to your motor control and keep your heart beating).
EX- When you reach for something or you rent back your hand.
-
Interneurons (they connect different neurons without making any contact with external world).
EX- Sensation
- An axon of one neuron will communicate with the dendrites of another neuron.
- Neurons don’t actually touch one another. There is a gap between the axon terminal of one neuron and the dendrite of another one.
- This gap is known as a synapse.
- When one neuron fires, the axon releases neurotransmitters, that shoot over the that gap, and affect dendrites and other neurons.
