🫁 Breathing and Exchange of Gases
| Category | NCERT Examples | Key Physiological Value / Feature |
|---|---|---|
| Respiratory Organs | • Skin/Cuticle: Earthworms, Amphibians • Tracheal Tubes: Insects • Gills (Branchial): Aquatic Arthropods, Fishes • Lungs (Pulmonary): Reptiles, Birds, Mammals | Mechanism depends on habitat and level of organization. |
| Respiratory Volumes | • Tidal Volume (TV): 500 mL • Inspiratory Reserve (IRV): 2500–3000 mL • Expiratory Reserve (ERV): 1000–1100 mL • Residual Volume (RV): 1100–1200 mL | RV cannot be measured by a standard spirometer. |
| Respiratory Capacities | • Vital Capacity (VC): ERV + TV + IRV • Total Lung Capacity (TLC): RV + ERV + TV + IRV | VC is the max volume a person can breathe in after a forced expiration. |
| Oxygen Transport | Oxyhaemoglobin | Each gram of Hb carries ~1.34 mL of O₂; 100 mL of oxygenated blood delivers 5 mL of O₂ to tissues under normal conditions. |
| Carbon Dioxide Transport | • Bicarbonate ions: 70% • Carbamino-haemoglobin: 20–25% • Dissolved state in plasma: 7% | 100 mL of deoxygenated blood delivers 4 mL of CO₂ to the alveoli. |
| Respiratory Disorders | • Asthma: Inflammation of bronchi and bronchioles. • Emphysema: Alveolar walls damaged (due to cigarette smoking). • Occupational Disorders: Silicosis, Asbestosis (fibrosis of upper lungs). | Emphysema drastically reduces the respiratory surface area. |
🩸 Body Fluids and Circulation
| Category | NCERT Examples / Components | Key Count / Feature / Value |
|---|---|---|
| Plasma Proteins | • Fibrinogen: Clotting / Coagulation • Globulins: Defense mechanisms • Albumins: Osmotic balance | Plasma without clotting factors is called Serum. |
| Formed Elements | • Erythrocytes (RBCs): 5 to 5.5 Million / mm³ • Leucocytes (WBCs): 6000–8000 / mm³ • Platelets (Thrombocytes): 1,500,00–3,500,00 / mm³ | RBC lifespan is 120 days; destroyed in the spleen (graveyard of RBCs). |
| Granulocytes | Neutrophils, Eosinophils, Basophils | Neutrophils are the most abundant (60–65%); phagocytic. |
| Agranulocytes | Lymphocytes (B and T cells), Monocytes | Monocytes (6–8%) are phagocytic; Lymphocytes (20–25%) handle immunity. |
| Heart Auto-excitable Nodes | SAN (Sinoatrial Node), AVN (Atrioventricular Node) | SAN is the Pacemaker; generates 70–75 action potentials per minute. |
| Cardiac Cycle Values | • Stroke Volume: 70 mL • Cardiac Output: ~5000 mL (5 Litres) | Cardiac Output = Stroke Volume × Heart Rate. |
| Circulatory Disorders | • Hypertension: BP ≥ 140/90 mmHg • CAD (Atherosclerosis): Calcium/fat deposition in coronary arteries. • Angina Pectoris: Acute chest pain due to low O₂ reaching heart muscles. | Heart Failure is not the same as Cardiac Arrest or Heart Attack. |
🦘 Excretory Products and Their Elimination
| Category | NCERT Examples | Key Mode / Mechanism |
|---|---|---|
| Ammonotelic | Aquatic amphibians, bony fishes, aquatic insects | Highly toxic; requires large amounts of water to eliminate. |
| Ureotelic | Mammals, terrestrial amphibians, marine fishes | Ammonia is converted to urea in the liver (Ornithine cycle). |
| Uricotelic | Reptiles, Birds, Land snails, Insects | Excreted as pellets/paste with minimum water loss. |
| Excretory Organs | • Protonephridia (Flame cells): Platyhelminthes, Rotifers, Amphioxus • Nephridia: Earthworms • Malpighian Tubules: Cockroaches • Antennal / Green Glands: Prawns | Protonephridia primarily control osmoregulation. |
| Glomerular Filtration Rate | GFR = 125 mL/min (or 180 Litres per day) | Only 1.5 Litres of urine is excreted daily (99% reabsorbed). |
| Counter-Current Mechanism | Henle's Loop and Vasa Recta | Maintains an osmolarity gradient from 300 mOsmol/L to 1200 mOsmol/L. |
| Excretory Disorders | • Uremia: Accumulation of urea in blood. • Renal Calculi: Stones of crystallized salts (oxalates) in the kidney. • Glomerulonephritis: Inflammation of glomeruli. | Uremia indicates kidney failure and requires hemodialysis. |
🦴 Locomotion and Movement
| Category | NCERT Examples / Counts | Specific Bone Names / High-Yield Features |
|---|---|---|
| Axial Skeleton (80 Bones) | Skull (22), Hyoid (1), Ear Ossicles (6), Vertebral Column (26), Sternum (1), Ribs (24) | Cranium has 8 bones; Facial structure has 14 bones. |
| Rib Types | • True Ribs: 1st to 7th pairs • Vertebrochondral (False): 8th, 9th, 10th pairs • Floating Ribs: 11th and 12th pairs | True ribs attach dorsally to vertebrae and ventrally to sternum via hyaline cartilage. |
| Appendicular Skeleton | Girdles (6 bones) and Limbs (30 × 4 = 120 bones) | Pectoral girdle has Clavicle and Scapula; Pelvic girdle has 2 Coxal bones. |
| Fibrous Joints | Sutures in flat skull bones | Synarthroses (Immovable joints). |
| Cartilaginous Joints | Between adjacent vertebrae, Pubic symphysis | Amphiarthroses (Permits limited movement). |
| Synovial Joints | • Ball and Socket: Shoulder, Hip joints • Hinge: Knee, Elbow joints • Pivot: Atlas and Axis • Gliding: Between Carpals • Saddle: Between Carpal and Metacarpal of thumb | Diarthroses (Freely movable joints characterized by synovial fluid). |
| Skeletal Disorders | • Myasthenia Gravis: Autoimmune; affects neuromuscular junction. • Muscular Dystrophy: Genetic; progressive degeneration of muscle. • Tetany: Rapid spasms due to low Ca²⁺ in body fluid. • Gout: Inflammation of joints due to accumulation of uric acid crystals. | Myasthenia gravis targets acetylcholine receptors. |
🧠 Neural Control and Coordination
| Category | NCERT Systems / Examples | Key Feature / Function |
|---|---|---|
| Neural Systems | • Hydra: Network of neurons • Insects: Brain, ganglia, and neural tissues • Vertebrates: Highly developed CNS and PNS | Nerve cells in Hydra are apolar (unpolarized). |
| Types of Neurons | • Apolar / Non-polar: Hydra • Unipolar: Embryonic stage • Bipolar: Retina of eye, olfactory epithelium • Multipolar: Cerebral cortex | Multipolar neurons have one axon and two or more dendrites. |
| Meninges | Dura mater (outer), Arachnoid (middle), Pia mater (inner) | Cranial meninges protect the brain structure. |
| Forebrain Structures | Cerebrum, Thalamus, Hypothalamus | Hypothalamus controls body temperature, urge for eating and drinking. |
| Hindbrain Structures | Pons, Cerebellum, Medulla oblongata | Medulla controls respiration, cardiovascular reflexes, and gastric secretions. |
🧪 Chemical Coordination and Integration
| Gland / Source | Secreted Hormone | High-Yield NCERT Disorders & Features |
|---|---|---|
| Hypothalamus | GnRH, Somatostatin, TRH | • GnRH: Stimulates pituitary gonadotropins. • Somatostatin: Inhibits GH release from pituitary. |
| Anterior Pituitary | GH, PRL, TSH, ACTH, LH, FSH | • Gigantism / Dwarfism: Excess/deficit of GH. • Acromegaly: Excess GH in adults (severe disfigurement). |
| Posterior Pituitary | Oxytocin, Vasopressin (ADH) | • Diabetes Insipidus: Deficit of ADH (water loss, diuresis). • Pituitary synthetically stores hormones made by the hypothalamus. |
| Thyroid Gland | T₃, T₄, Thyrocalcitonin (TCT) | • Goitre: Iodine deficiency. • Cretinism: Hypothyroidism during pregnancy (stunted growth). • Exophthalmic Goitre (Graves' Disease): Hyperthyroidism. |
| Parathyroid Gland | Parathyroid Hormone (PTH) | Hypercalcemic hormone (increases blood Ca²⁺ levels; counteracts TCT). |
| Adrenal Cortex | Glucocorticoids (Cortisol), Mineralocorticoids (Aldosterone) | • Addison's Disease: Hyposecretion of corticoids (altered carbohydrate metabolism, acute weakness). |
| Pancreas (Islets) | α-cells (Glucagon), β-cells (Insulin) | • Diabetes Mellitus: Prolonged hyperglycemia, ketoacidosis, glucose in urine. |
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NEET Biology Revision