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An Overview of a Human Cell
What is a Cell?
A cell is the smallest fundamental unit of life and is responsible for the survival of the living being. Cells are known as the building blocks of human life.
Cell Discovery
Robert Hooke was the first biologist who discovered the cell in 1665. When he observed a piece of bottle cork under a microscope, he noticed minuscule structures and named them cells. Cells differ but share common organelles such as the nucleus, mitochondria, cytoplasm, lysosome, plasma membrane, Golgi apparatus, vesicle, smooth and rough endoplasmic reticulum, ribosomes, and cytoskeleton.
Types of Cells Based on Structure
Prokaryotic cells do not have a nucleus and have a nucleoid region where genetic material is freely suspended. These cells range from 0.1 to 0.5 µm in size and reproduce asexually, typically by binary fission.
Eukaryotic cells have a nucleus and range between 10–100 µm in diameter. Their plasma membrane manages nutrient transport and communication between cells. They reproduce both sexually and asexually. Plants, fungi, protozoans, and animals are examples. Plant cells contain chloroplasts and other plastids.
11 Types of Cells
Stem cells, found in embryos and adult tissues like bone marrow, start as unspecialised and can develop into specialised cells. They also serve as building blocks for organs and tissues and assist in tissue repair.
Endothelial cells form a single layer lining all blood vessels and regulate exchanges between the bloodstream and surrounding tissues. They influence the growth and development of connective tissues.
Bone cells are classified into osteoclasts, which break down bone; osteoblasts, which form new bone; and osteocytes, which help maintain bone structure and calcium balance.
Blood cells are formed in the bone marrow and include red blood cells for oxygen transport, white blood cells for immune defense, and platelets to aid in clotting and blood loss prevention.
Muscle cells include skeletal muscles for voluntary movement, cardiac muscles for involuntary heartbeat function, and smooth muscles lining internal organs such as the intestines and kidneys.
Fat cells, also known as adipocytes, are storage units for triglycerides, which are used for energy. These cells swell when storing fat and shrink when used for energy. They regulate blood pressure, clotting, and signal transmission.
Skin cells or epithelial cells form the outer protective barrier of the body. They prevent dehydration, store fat, and produce essential vitamins and hormones, while shielding the body from environmental threats.
Nerve cells, or neurons, are the brain’s messengers. They communicate between the brain, spinal cord, and other body parts using axons and dendrites to transmit electrical impulses.
Pancreatic cells function both as endocrine and exocrine units. Found in the islets of Langerhans, they regulate blood sugar and help digest carbohydrates, fats, and proteins. They produce hormones such as insulin, glucagon, and gastrin.
Cancer cells result from mutations, often caused by radiation or ultraviolet light. These cells resist normal growth signals and harm the body instead of supporting it.
Reproductive cells consist of male sperm, which have tails for mobility, and female ova, which are larger and stationary. These cells are formed through meiosis, unlike body cells that divide through mitosis.
Human Body Difference
The human body’s appearance varies due to skeletal size, muscle shape, and fat thickness. Males typically have broader shoulders, more body hair, and less evenly distributed fat compared to females.
Brain Function
The brain and spinal cord form the central nervous system. The brain functions like a train conductor, constantly processing thoughts that arrive like passengers. Monitoring and directing these thoughts is key to mental well-being.
Thoughts and Waves Similarity
Thoughts resemble ocean waves—continuous and difficult to trace to their origin. Brain waves are measured by EEG (electroencephalograph), which uses electrodes to capture electrical activity displayed as wavy lines.
Importance of Food Quality
Food acts as the body’s fuel. Light, nutritious food provides energy, while junk food leads to sluggishness. The heart circulates fresh, oxygenated blood to organs and removes old blood for purification.
Heart Function
The heart’s electrical signals are recorded by ECG (electrocardiograph). This test helps diagnose conditions like heart attacks and arrhythmias and is commonly used in clinics, hospitals, and ambulances.
Thought Management
Thoughts continuously arise in the human mind. Letting go of unnecessary thoughts leads to mental clarity, lightness, and overall happiness.
Structure of the Cell
Cells are the building blocks of the human body, forming tissues, muscles, nerves, blood, and bones. The outer membrane encloses cytoplasm containing organelles. The nucleus, which stores DNA, is the most vital component and plays a key role in determining genetic identity.
Brain Principle
The brain controls bodily functions via neurons, which transmit messages through dendrites and axons. Motor neurons can be multi-polar, bi-polar, or uni-polar, and they convert chemical signals into electrical impulses.
Central Nervous System (CNS)
The CNS controls and coordinates body functions through billions of neurons. It sends motor impulses to direct actions and electrical impulses that maintain internal readiness. The brain decides whether to fight or flee in a crisis. Emotions like anxiety and anger initiate these responses. The nucleus activates these functions by using nourishment from food, reinforcing that food is the fuel for better cellular function.
Note: The writer is not a doctor. The content is for general awareness only. The journal bears no responsibility for the accuracy of the views expressed.