Nervous system
Unlocking the Secrets of How Your Body Thinks, Moves, and Reacts"
Nervous System
If you touch a hot stove, instantly, the message is conveyed to your brainand the brain orders you to jerk your hand away. This happens within a second. Similarly, when an insect sits on your arm, your brain receives the information and sends back a stimulus for you, to jerk your hand or to flick the insect away before it stings you. How do these actions happen? The organ system in the human body that carries messages from one part of the body to another and make us feel and react to things and situations is called the nervous system. The human nervous system consists of neurons and tissues that regulate stimuli and responses. The nervous system is a complex information processing system that consists mainly of the brain, spinal cord and nerves. Our nervous system is divided into two parts.
(1). The central nervous system (CNS).
(2). The peripheral nervous system (PNS).
Science TidBit The brain of an adult human weighs between 1300-1400 grams. The brain of a cat weighs about 30 grams and dog about 70 grams. The brain of an elephant is about 6000 grams.
The Central Nervous System (CNS)
The central nervous system acts as a control center of the whole nervous system. It comprises brain and spinal cord.
1. The Brain: The human brain is enclosed in a bony case called the cranium. An adult human brain weighs about three pounds and consists of billions of neurons. Three layers of connective tissues called meninges and the fluid present in these layers protect the brain. The brain can be divided into three main parts, called fore brain, mid brain and hind brain.
(a) Fore brain is the largest part of the brain. It consists of three main parts, i.e. cerebrum, thalamus and hypothalamus. Cerebrum is the top most and the largest part of the brain. It is divided into right and left cerebral hemispheres. The right cerebral hemisphere controls movement and activities of the left side of the body, while the left cerebral hemisphere controls the right side of the body. Cerebrum is the control centre of many sensory areas like sight, speech, smell, taste and hearing. It is also concerned with learning, thinking, intelligence, memory and voluntary movements. Inside the cerebrum, there is a small structure called thalamus. It acts as a processing centre between the body and the cerebrum by receiving sensory information like touch and sound and carrying them to the cerebrum. At the base of the thalamus is the Hypothalamus, which regulates body temperature, hunger and thirst.
(b) Mid brain It is the central part of the brain. Its basic function is to transfer information and impulses between the fore brain and the hind brain. This part of the brain is associated with vision, hearing, sleep/wake and temperature regulation. The mid brain also serves to control some reflexes such as changing size of the pupil to control the amount of light entering the eye.
(c) Hind brain
The hind brain of three parts, i.e. Cerebellum, Pons and Medulla oblongata. onsists Cerebellum is the second largest part of the brain. It is mainly concerned with posture, balance and locomotion of the body. Pons is a small oval structure present above the medulla oblongata. It serves as a bridge for the conduction of impulses between the cerebrum, medulla oblongata and the cerebellum. It is concerned with the rate of breathing, sleeping and also regulate eye movement and facial expressions. Medulla oblongata connects the brain to the spinal cord. It controls heart beat, swallowing, vomiting, coughing, sneezing, digestion and breathing etc. Medulla oblongata keeps on working when the rest of the brain does not work.
About the Creator
muhammad ilyas
My name is Muhammad Ilyas, and I completed my bachelor's degree in microbiology. I am sharing with you an article about biological science. I believe everyone can enjoy and understand the science behind our world.
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Excretory system
Cells produce nitrogenous materials, salts and carbon dioxide as by-products of metabolic breakdown of sugars, fats and proteins. If these toxic wastes accumulate in the body, they may cause damages. The process of removing the waste products from the body is called excretion. The organ system responsible for this excretion is known as excretory system. The excretory system removes non-solid wastes through sweat, urine and exhalation. The human excretory system consists of one pair of kidneys and associated structures, i.e. two ureters, a urinary bladder and urethra.
By muhammad ilyas10 months ago in Education
The Bridge He Never Crossed
The river had always divided the town into two halves. On one side lay the old neighborhoods — narrow streets, familiar faces, small shops where owners still remembered names and stories. On the other side rose the new city — glass buildings, bright lights, offices, opportunities, and futures that promised more than memory. Between them stood a narrow iron bridge. People crossed it every day without thinking. Buses rattled over it. Motorcycles rushed across it. Students walked laughing, lovers paused to take photographs, workers hurried with phones pressed to their ears. Only one man rarely crossed it. His name was Saad. Saad lived his entire life on the old side of town. He taught mathematics at a small school, returned home before sunset, drank tea on his veranda, and spent evenings reading while the world beyond the river glittered in the distance. His life was calm, predictable, and quietly safe. Too safe. Years ago, after finishing university with excellent grades, Saad had received an offer from a large firm in the new city. The salary was generous, the future promising, the path clear. But it required crossing the bridge. Not physically — he had crossed it many times before. But emotionally. It meant leaving familiar streets, aging parents, comfortable routines, and the quiet certainty of knowing where every road led. It meant risking failure, loneliness, and change. So Saad declined. He told himself he valued simplicity. He told others he preferred teaching. He convinced everyone — except himself — that he had chosen wisely. Yet every evening, as the sun dipped behind the glass towers across the river, a strange restlessness stirred inside him. One autumn afternoon, while walking home from school, Saad noticed an old painter standing near the bridge. The man had placed a small wooden stool by the railing and was painting the river with slow, deliberate strokes. His canvas showed neither the old town nor the new city — only the bridge itself, stretching quietly between them. Saad stopped to watch. “You paint only the bridge?” he asked. “Yes,” the painter replied without looking up. “It is the most honest subject here.” “How so?” “Because it belongs to neither side,” the man said. “Yet it connects both.” Saad visited the bridge more often after that. Sometimes the painter was there, sometimes not. When present, he spoke little, but his words lingered. One day, Saad confessed, “I have spent my life avoiding this bridge.” The painter smiled faintly. “Many people live beside their destiny without ever touching it.” Saad frowned. “Is crossing always destiny?” “No,” the painter said. “But refusing to cross is always a decision.” Those words followed Saad home. Memories returned — the ambition he once carried, the excitement he felt when imagining life in the new city, the disappointment he quietly buried when he chose safety instead. Weeks passed. One morning, Saad found a letter waiting on his desk at school. It was from an old university professor. A new training institute across the river was opening. They needed an experienced educator to design curriculum and mentor young teachers. The position was temporary — six months. The pay was modest. The risk, however, was real. Saad folded the letter carefully and placed it in his bag. All day, numbers blurred before his eyes. That evening, he stood at the bridge as traffic rushed past. Lights flickered on across the river, reflections trembling in the water like uncertain thoughts. The painter was there again. “I received an invitation today,” Saad said slowly. “From the other side.” “And?” “I am afraid.” The painter nodded. “Good. Fear means the road matters.” Saad laughed bitterly. “What if I fail?” “Then you return wiser,” the painter said. “But what if you never go?” Saad did not answer. That night, he could not sleep. He imagined two futures. In one, he remained — respected, comfortable, quietly wondering what might have been. In the other, he crossed — uncertain, challenged, but alive with possibility. At dawn, he rose, dressed carefully, and walked toward the bridge. The river whispered below, patient and indifferent. For the first time in years, Saad placed his foot on the iron surface. Halfway across, doubt struck fiercely. He stopped. The old town lay behind him, warm and familiar. The new city waited ahead, bright and unknown. He closed his eyes. And stepped forward. The months that followed were not easy. The institute demanded long hours, new methods, constant learning. Younger colleagues questioned his ideas. Administrators pressured results. Twice, Saad considered quitting. But slowly, something changed. He rediscovered the joy of growth. His lessons improved. His confidence returned. His mind awakened. Students respected him not only for knowledge, but for patience. Teachers sought his guidance. Ideas he had buried for years found voice again. Six months ended. The institute offered him a permanent position. Saad accepted without hesitation. One evening, long after settling into his new life, he returned to the bridge. The painter was gone. In his place, a small unfinished canvas leaned against the railing. It showed a man standing midway across a bridge — paused between worlds — eyes closed, heart steady. On the back, written simply: “Courage is not crossing without fear. Courage is crossing despite it.” Saad smiled. For the first time, the bridge no longer divided his life. It had united it.
By Muhammad yaseena day ago in Education
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