ORGAN: Brain

The human brain is one of the largest and most complex organs in the human body.It is made up of more than 100 billion nerves that communicate in trillions of connections called synapses.Each distinct part of the brain plays a different role in allowing humans to have thoughts and memories, move their arms and legs, sense smell, sight, hearing, touch, and taste, as well as maintain the functions of many organs within the body.

TISSUES THAT BUILT BRAIN

The brain is made up of many specialized areas that work together:

The cortex is the outermost layer of brain cells and it is wholely responsible for our Thinking and voluntary movements
The brain stem is between the spinal cord and the rest of the brain. Basic functions like breathing and sleep are controlled here.
The basal ganglia are a cluster of structures in the center of the brain. The basal ganglia coordinate messages between multiple other brain areas.
The cerebellum is at the base and the back of the brain. The cerebellum is responsible for coordination and balance
The brain is surrounded by a layer of tissue called the meninges. The skull (cranium) helps protect the brain from injury.

The human brain can be divided into three distinct parts, which include the cerebrum, the cerebellum, and the brainstem.

The cerebrum

The major portion of the brain is the cerebrum, which divides the left and right cerebral hemispheres, both of which have numerous folds and convolutions present on their surface. Between these convolutions are ridges known as gyri. Small grooves that are present between the gyri are known as the plural of sulcus or sulci, whereas larger grooves are referred to as fissures.

The right and left cerebral hemispheres, both of which are covered in the cerebral cortex that is otherwise known as gray matter, are joined together by the corpus callosum. Whereas the left hemisphere controls speech and abstract thinking, the right hemisphere controls spatial thinking.

The frontal, parietal, temporal, and occipital lobes are the four lobes that make up the cerebrum. The frontal lobes, which are present directly behind the forehead, are the largest lobes of the human brain. The frontal lobes are primarily responsible for controlling language, motor function, and various cognitive processes including self-awareness, mood, affect, memory, attention, as well as both social and moral reasoning.

Within the frontal lobe is Broca’s area, which is responsible for speech production. The parietal lobes, who can be found near the center of the brain between the frontal and occipital lobes, are responsible for interpreting different sensory and memory functions.

The temporal lobes, which is commonly referred to as the neocortex, is located close to the base of the skull. Within the temporal lobe is the Wernicke area, which allows individuals to understand both spoken and written language. In addition to processing speech, the temporal lobe also processes sensory information that contributes to the retention of memories, languages, and emotions.

The fourth and final lobe of the cerebrum is the occipital lobe, which is the smallest lobe of the cerebrum and forms the caudal part of the brain. The primary function of the occipital lobe is the interpretation of visual information.

The cerebellum

The largest of the hindbrain is the cerebellum. Upon reception of motor information from both the cerebral cortex and the musculoskeletal structures of the body, the cerebellum coordinates these signals to maintain the gait and posture of humans in motion. Although the cerebellum itself does not initiate muscle contraction, it aids in the refinement and accuracy of motor activity by controlling muscle tone. In addition to its role in controlling balance and regulating motor movement, the cerebellum also plays a role in the regulation of fear and other cognitive functions such as attention, language, and the human response to pleasure.

The brainstem

The cerebellum and spinal cord are connected to the cerebral hemispheres by the brainstem. The brain stem can be classified into four distinct sections that include the diencephalon, midbrain, pons, and medulla oblongata. The diencephalon, which is the most superior portion of the brainstem, is further subdivided into four portions that include the epithalamus, subthalamus, hypothalamus, and thalamus.

The thalamus, which is the largest portion of the diencephalon, serves as a relay point for all sensory information that enters the cortex and eventually gets transmitted to the cerebrum for processing. The hypothalamus also processes incoming sensory information; however, all of the information processed by the hypothalamus is derived from the autonomic nervous system (ANS). As a result, the hypothalamus maintains eating habits, sexual behavior, and sleep patterns in addition to maintaining an individual’s body temperature. Additionally, the secretions of the pituitary gland, which develops from a downward extension of the hypothalamus, is controlled by the hypothalamus.

The midbrain, which connects the diencephalon to the pons, controls ocular motion, whereas the pons is involved in the regulation of eye and facial movements, hearing and balance, as well as all sensory information processed by the facial nerves.

The medulla oblongata, which is located between the pons and the spinal cord and is therefore the most inferior portion of the brainstem, controls autonomic functions such as breathing, blood pressure, cardiac rhythms, and swallowing. Notably, brain death of patients in a clinical setting is declared when there is significant destruction of the medulla oblongata.

FUNCTIONS

Functions of cerebrum:

The cerebrum directs the body’s conscious or voluntary motor functions.
Inside the primary motor cortex and other frontal lobe motor areas where actions are scheduled, these functions originate.
Upper motor neurons in the primary motor cortex transmit their axons to the lower motor neurons, which innervate the muscles, to synapse into the brain stem and spinal cord.
In some forms of motor neuron disease, damage to motor areas of the cortex can result.
Instead of complete paralysis, this sort of harm results in loss of muscle strength and accuracy.
The olfactory sensory system is unusual in that its axons are sent directly to the olfactory cortex by neurons in the olfactory bulb, rather than to the thalamus first.
A deterioration of the sense of smell results in damage to the olfactory bulb.
From such brain areas as the amygdala, neocortex, hippocampus, locus coeruleus, and substantia nigra, the olfactory bulb also receives ‘top-down’ knowledge.
Its’ possible functions can be classified into four non-exclusive categories: 1. Distinguishing between odors 2.Improving odor detection sensitivity 3.Filtering out background odors 4.Allowing higher areas of the brain involved in arousal and attention to alter odor detection or discrimination.
Sections of the cerebral cortex are largely attributed to speech and language.
In the frontal lobe, motor portions of language are attributed to Broca’s field.
Wernicke’s area, at the temporal-parietal lobe junction, is due to speech comprehension.

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Functions of cerebellum:

Balance and posture management: t
- In order to maintain equilibrium, the cerebellum is essential for making postural changes.
- It modulates commands to motor neurons through its feedback from vestibular receptors and proprioceptors to compensate for changes in body position or changes in load on muscles.
- Balance problems are suffered by patients with cerebellar injury, and they frequently develop stereotyped postural strategies to compensate for this issue (e.g. a broad-based stance).
Voluntary movement synchronization: t
- Most movements consist of a variety of distinct muscle groups behaving in a temporarily organized manner together.
- One of the cerebellum’s key functions is to coordinate the timing and force to produce fluid limb or body movements of these various muscle groups.
Motor learning: t
- In adjusting and fine-tuning motor programs to make precise movements in a trial-and-error process e.g. learning to hit a baseball), the cerebellum plays a major role.
Cognitive roles: t
- Though the cerebellum is most commonly understood in terms of its contribution to motor regulation, some cognitive functions, such as language, are also involved.
- The cerebellum is therefore regarded historically as part of the motor system, like the basal ganglia, but its functions extend beyond motor control in ways that are not yet well understood.

Functions of brain stem:

The brainstem has three essential functions:
To act as a conduit for pathways to and from the brain to ascend and descend
To house the nuclei of cranial nerves
To merge the roles of many critical systems with each other

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