Sourav Pan

Academic Writer, Microbiology Specialist | M.Sc. Microbiology, Calcutta University, Founder of Biologynotesonline.com

Sourav is the founder and sole author of Biology Notes Online. He holds a Master’s degree in Microbiology from Calcutta University and has over 5 years of experience in academic writing, life science content creation. His content reflects hands-on lab expertise, deep subject knowledge, and a strong passion for simplifying biology for students. Whether it’s genetics, microscopy, or metabolic pathways — Sourav explains it in a way that’s accurate, exam-focused, and easy to remember. He regularly updates and fact-checks all the material published on this site, ensuring students get trustworthy and updated biology notes with references to real scientific sources.

Classification of Fish (pisces) – Systematic Classification and Based on feeding habit, habitat and manner of reproduction

• Last Updated October 1, 2024 • 0 revisions • 22 min readby Sourav Pan

What is Fish? General description of fish Fish are fascinating aquatic vertebrates characterized by their unique adaptations for life in water. They are distinguished by the absence of limbs with digits, opting instead for fins that facilitate swimming. As anamniotes, fish embryos develop without an amniotic membrane, a trait that differentiates them from tetrapods such … Read more

5 Best Books for Endocrinology

• Last Updated November 29, 2024 • 0 revisions • 1 min readby Sourav Pan

Endocrinology is a branch of medicine that focuses on the study of the endocrine system, which comprises glands that secrete hormones directly into the bloodstream. These hormones regulate various bodily functions, including metabolism, growth and development, tissue function, sleep, mood, and sexual function. Key glands in the endocrine system include: Endocrinologists diagnose and treat conditions … Read more

Mechanism of Hormone Action by Extracellular and Intracellular receptors

• Published on September 27, 2024 • 10 min readby Sourav Pan

Hormones are biochemical messengers produced by glands in the endocrine system and secreted into the bloodstream to regulate various physiological processes in the body. They play a crucial role in maintaining homeostasis and influencing a wide range of functions, including: Hormones exert their effects by binding to specific receptors on target cells, initiating a cascade … Read more

Testis – Definition, Structure, Hormones, Functions

• Published on September 27, 2024 • 13 min readby Sourav Pan

What is Testicle (Testis)? Definition of Testicle (Testis) A testicle, or testis, is a male reproductive gland responsible for producing sperm and the hormone testosterone. Located in the scrotum, the testicles are essential for male fertility and the regulation of male secondary sexual characteristics. Structure of Testes The structure of the testes is integral to … Read more

Ovaries – Definition, Structure, Hormones, Functions

• Published on September 27, 2024 • 12 min readby Sourav Pan

What is Ovary? Definition of Ovary The ovary is a reproductive organ in females that produces eggs and secretes hormones like estrogen and progesterone, essential for regulating the menstrual cycle and fertility. Anatomy of the Ovary The ovary is a crucial organ in the female reproductive system, responsible for producing eggs and secreting hormones essential … Read more

Epidemiology Crossword Puzzle

• Last Updated October 13, 2024 • 0 revisions • 1 min readby Sourav Pan

Epidemiology is the branch of public health that studies the distribution, patterns, and causes of diseases and health conditions in populations. It aims to identify risk factors for diseases, understand how they spread, and develop strategies to prevent or control health problems. Epidemiologists use data and research to track health trends and inform public health … Read more

Gonads (Ovaries and Testes)- Structure, Hormones, Regulation, Disorders, Functions

• Published on September 27, 2024 • 13 min readby Sourav Pan

What are Gonads? Definition of Gonads Gonads are reproductive glands in organisms that produce gametes (sperm in males and eggs in females) and secrete sex hormones (such as testosterone, estrogen, and progesterone) essential for sexual development and reproduction. In males, they are called testes, while in females, they are referred to as ovaries. Structure of … Read more

Pancreas – Diagram, Structure, Hormones, Functions, Disorders

• Published on September 27, 2024 • 16 min readby Sourav Pan

What is Pancreas? Definition of Pancreas The pancreas is a vital organ in the human body that serves dual functions: it acts as an endocrine gland by producing hormones such as insulin and glucagon to regulate blood sugar levels, and as an exocrine gland by secreting digestive enzymes and bicarbonate into the small intestine to … Read more

Adrenal Gland – Location, Structure, Hormones, Functions, Diseases

• Published on September 27, 2024 • 16 min readby Sourav Pan

Adrenal Gland Structure and Hormones Production

What is Adrenal Gland? Definition of Adrenal Gland The adrenal glands, or suprarenal glands, are small, triangular-shaped endocrine glands located on top of each kidney. They consist of two main parts: the adrenal cortex, which produces steroid hormones such as cortisol and aldosterone, and the adrenal medulla, which produces catecholamines like adrenaline. These hormones play … Read more

Parathyroid Gland – Structure, Hormones, Functions, Disorders

• Published on September 27, 2024 • 12 min readby Sourav Pan

What is Parathyroid Gland? Definition of Parathyroid Gland The parathyroid glands are small endocrine glands located behind the thyroid gland that regulate calcium levels in the blood by secreting parathyroid hormone (PTH). This hormone helps maintain calcium balance by influencing the bones, kidneys, and intestines. Anatomical Location of Parathyroid Gland The parathyroid glands are small, flattened, … Read more