Question

explain the human brain completely

Answer 1

The human brain is the central organ of the human nervous system, and with the spinal cordmakes up the central nervous system. The brain consists of the cerebrum, the brainstem and thecerebellum. It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body. The brain is contained in, and protected by, the skull bones of the head.

The cerebrum is the largest part of the human brain. It is divided into two cerebral hemispheres. The cerebral cortex is an outer layer of grey matter, covering the core of white matter. The cortex is split into the neocortexand the much smaller allocortex. The neocortex is made up of six neuronal layers, while the allocortex has three or four. Each hemisphere is conventionally divided into fourlobes – the frontal, temporal, parietal, andoccipital lobes. The frontal lobe is associated with executive functions including self-control,planning, reasoning, and abstract thought, while the occipital lobe is dedicated to vision. Within each lobe, cortical areas are associated with specific functions, such as the sensory,motor and association regions. Although the left and right hemispheres are broadly similar in shape and function, some functions areassociated with one side, such as language in the left and visual-spatial ability in the right. The hemispheres are connected bycommissural nerve tracts, the largest being thecorpus callosum.

The cerebrum is connected by the brainstem to the spinal cord. The brainstem consists of the midbrain, the pons, and the medulla oblongata. The cerebellum is connected to the brainstem by pairs of tracts. Within the cerebrum is the ventricular system, consisting of four interconnected ventricles in whichcerebrospinal fluid is produced and circulated. Underneath the cerebral cortex are several important structures, including the thalamus, the epithalamus, the pineal gland, thehypothalamus, the pituitary gland, and thesubthalamus; the limbic structures, including the amygdala and the hippocampus; theclaustrum, the various nuclei of the basal ganglia; the basal forebrain structures, and the three circumventricular organs. The cells of the brain include neurons and supportive glial cells. There are more than 86 billion neurons in the brain, and a more or less equal number of other cells. Brain activity is made possible by the interconnections of neurons and their release of neurotransmitters in response tonerve impulses. Neurons connect to formneural pathways, neural circuits, and elaboratenetwork systems. The whole circuitry is driven by the process of neurotransmission.

Answer 2

The human brain is the command center for the human nervous system. It receives signals from the body's sensory organs and outputs information to the muscles. The human brain has the same basic structure as other mammal brains but is larger in relation to body size than any other brains.

Facts about the human brain

The human brain is the largest brain of all vertebrates relative to body size.

It weighs about 3.3 lbs. (1.5 kilograms).

The average male has a brain volume of 1,274 cubic centimeters (cm3).

The average female brain has a volume of 1,131 cm3.

The brain makes up about 2 percent of a human's body weight.

The cerebrum makes up 85 percent of the brain's weight.

It contains about 86 billion nerve cells (neurons) — the "gray matter."

It contains billions of nerve fibers (axons and dendrites) — the "white matter."

These neurons are connected by trillions of connections, or synapses.

Anatomy of the human brain

The largest part of the human brain is the cerebrum, which is divided into two hemispheres, according to the Mayfield Clinic. Underneath lies the brainstem, and behind that sits the cerebellum. The outermost layer of the cerebrum is the cerebral cortex, which consists of four lobes: the frontal, parietal, temporal and occipital. [Related: Nervous System: Facts, Functions & Diseases]

Like all vertebrate brains, the human brain develops from three sections known as the forebrain, midbrain and hindbrain. Each of these contains fluid-filled cavities called ventricles. The forebrain develops into the cerebrum and underlying structures; the midbrain becomes part of the brainstem; and the hindbrain gives rise to regions of the brainstem and the cerebellum.

The cerebral cortex is greatly enlarged in human brains and is considered the seat of complex thought. Visual processing takes place in the occipital lobe, near the back of the skull. The temporal lobe processes sound and language, and includes the hippocampus and amygdala, which play roles in memory and emotion, respectively. The parietal lobe integrates input from different senses and is important for spatial orientation and navigation.

The brainstem connects to the spinal cord and consists of the medulla oblongata, pons and midbrain. The primary functions of the brainstem include relaying information between the brain and the body; supplying some of the cranial nerves to the face and head; and performing critical functions in controlling the heart, breathing and consciousness.

Between the cerebrum and brainstem lie the thalamus and hypothalamus. The thalamus relays sensory and motor signals to the cortex and is involved in regulating consciousness, sleep and alertness. The hypothalamus connects the nervous system to the endocrine system — where hormones are produced — via the pituitary gland.