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  Centrosome and Centrioles NEET Notes: 9×3 Arrangement Explained  Structure of centrosome and centriole showing the characteristic 9×3+0 microtubule arrangement and cartwheel organization. - Dr.Sanjaykumar Pawar  Centrosome and Centrioles  Centrosome Centrosome is a cell organelle present mainly in animal cells . It is located near the nucleus . A centrosome usually contains two centrioles . The two centrioles are surrounded by a protein-rich material called pericentriolar material (PCM) . The centrosome acts as the microtubule-organizing centre (MTOC) of the cell. It helps in the formation of spindle fibres during cell division. Structure of Centrioles Centrioles are cylindrical structures . The two centrioles in a centrosome are arranged perpendicular (90°) to each other . Each centriole shows a cartwheel-like arrangement . A centriole is made up of nine peripheral fibrils . These fibrils are composed of tubulin protein . Each peripheral fibri...

  Endocrine System Summary Notes (NEET Biology – Easy Line by Line Explanation)  - Dr.Sanjaykumar pawar 1. Hormones and Their Functions Hormones are special chemical messengers produced by endocrine glands. They help in: Coordination of body activities Regulation of body functions Integration between organs Hormones control: Metabolism Growth Development Reproduction Homeostasis 2. Endocrine System Organs The human endocrine system includes: Hypothalamus Pituitary gland Pineal gland Thyroid gland Adrenal gland Pancreas Parathyroid gland Thymus Gonads: Testis (male) Ovary (female) Other organs also producing hormones: Gastrointestinal tract Kidney Heart 3. Pituitary Gland (Master Gland) Divisions of Pituitary The pituitary gland has 3 parts: (i) Pars distalis (Anterior pituitary) Produces 6 trophic hormones. Trophic hormones regulate other endocrine glands. (ii) Pars intermedia Secretes only one hormone: MSH (Melanocyte Sti...

  Mechanism of Hormone Action – Easy NEET Notes Introduction Hormones regulate different physiological activities of the body. Based on their chemical nature, hormones are divided into four groups. Types of Hormones 1. Peptide / Polypeptide / Protein Hormones Examples Insulin Glucagon Pituitary hormones Hypothalamic hormones Important Features Made up of amino acids. Water soluble. Cannot pass through cell membrane. Act through membrane-bound receptors. NEET Point These hormones use second messengers like: cAMP IP₃ Ca²⁺ 2. Steroid Hormones Examples Cortisol Testosterone Estradiol Progesterone Important Features Lipid soluble. Can easily pass through plasma membrane. Receptors are inside the cell. NEET Point They directly influence: Gene expression Protein synthesis 3. Iodothyronines (Thyroid Hormones) Examples T₃ (Triiodothyronine) T₄ (Thyroxine) Important Features Derived from amino acid tyrosine. Regulate metabolism and ...

  19.3 Hormones of Heart, Kidney and Gastrointestinal Tract Easy NEET Notes (Line-by-Line Explanation) Introduction Original Idea: Some tissues other than endocrine glands also secrete hormones. Easy Explanation: We usually study hormones secreted by endocrine glands like pituitary, thyroid, adrenal etc. But some other organs and tissues also produce hormones. These hormones help in regulating important body functions. Hormones of Heart Atrial Natriuretic Factor (ANF) Line: “The atrial wall of our heart secretes a peptide hormone called atrial natriuretic factor (ANF).” Explanation: The atria are the upper chambers of the heart. Their walls produce a hormone called ANF . ANF is a peptide hormone (made of amino acids). Function of ANF Line: “ANF decreases blood pressure.” Explanation: ANF helps to lower high blood pressure. It maintains normal blood circulation. Line: “When blood pressure is increased, ANF is secreted which causes dilation of blo...

  NEET-Level MCQs (Hard) Chapter: Neural Control and Coordination  By- Dr.Sanjaykumar pawar 1. Homeostasis is best defined as: A. Coordination between muscles and bones B. Maintenance of constant internal environment C. Production of hormones by glands D. Transmission of impulses through neurons ✅ Answer: B Explanation: Homeostasis means maintaining stable internal body conditions like temperature, pH, oxygen level, etc. 2. Which of the following systems provides point-to-point rapid coordination? A. Endocrine system B. Circulatory system C. Neural system D. Excretory system ✅ Answer: C Explanation: Neural system uses electrical impulses for fast and precise communication. 3. During physical exercise, increased oxygen demand directly causes: A. Decrease in heartbeat B. Reduced respiration rate C. Increase in respiration rate D. Kidney failure ✅ Answer: C Explanation: More oxygen is needed during exercise, so breathing rate increases. 4. Which s...