1️⃣1️⃣ தரம் 11 · அலகு 6
மனித உடற் செயன்முறைகள்
★★★★★
சமிபாடுசுவாசம்குருதிச்சுற்று
நீங்கள் சாதம் சாப்பிட்டபின் — அந்த உணவு வயிற்றில் மறைய ஏன்? நீங்கள் நடக்கும்போது அதிகமாக மூச்சுவிடுவது ஏன்? இரண்டாயிரம் மைல் தூரம் வாழ்நாள் முழுவதும் ஓயாமல் இதயம் துடிப்பது எப்படி? கேள்வி கேட்டால் பதில் சொல்வது மூளையா — அல்லது நீளவே நீளவிருக்கும் நரம்புகளா? நம் உடல் ஒரே நேரத்தில் ஐந்து பெரும் தொகுதிகள் ஒத்திசைவாகச் செயல்படுத்தும் ஒரு மிக complex machine — உணவுச் சமிபாட்டுத் தொகுதி, சுவாசத் தொகுதி, கழிவகற்றும் தொகுதி, குருதிச் சுற்றோட்டத் தொகுதி, இயைபாக்கம் + ஒர்சீர்த்திட நிலையம் (homeostasis). இவ்வலகில் ஒவ்வொன்றையும் — structure + function + key disorders — ஆழமாக கற்போம்.
1. மனிதனின் உணவுச் சமிபாட்டுத் தொகுதி (Digestive system)
நாம் சாப்பிடும் உணவு — சாதம் (carbs), மீன்/பயறு (proteins), நெய் (fats) — செல்களுக்குப் பயனுள்ள எளிய molecules ஆக மாற்றப்பட்டு absorb ஆக வேண்டும். அந்த 2 stage process — (1) breakdown (digestion), (2) absorption — நிகழ்த்தும் organs-ன் கூட்டமே digestive system.
1.1 உணவு பாதையின் 6 பகுதிகள்
- வாய்க்குழி (Mouth): பல்லால் chewing (mechanical); உமிழ்நீர் (saliva — ptyalin enzyme) starch-ஐ maltose-ஆகச் சிதைக்க தொடங்கும்.
- களம் (Oesophagus): Peristalsis-ஆல் உணவை இரைப்பைக்கு push.
- இரைப்பை (Stomach): HCl + pepsin → protein-ஐ partially digest. Acidic killing of microbes.
- சிறுகுடல் (Small intestine): Pancreatic juice + bile + intestinal enzymes. முக்கிய absorption site — villi-ஆல் surface area அதிகம்.
- பெருங்குடல் (Large intestine): நீர் + minerals absorb. Bacteria-ஆல் vitamin K + some B synthesis.
- நேர்குடல் + குதம் (Rectum + anus): Faeces store + eliminate.
1.2 உதவி உறுப்புகள் (Accessory organs)
- ஈரல் (Liver): Bile production (fat emulsification); glucose store as glycogen; detox.
- பித்தப்பை (Gallbladder): Bile storage.
- சதையீரல் (Pancreas): Digestive enzymes (amylase, lipase, trypsin) + insulin/glucagon hormones.
- உமிழ்நீர் சுரப்பிகள் (Salivary glands): Saliva production.
1.3 மூன்று food groups + their enzymes
| உணவு | Enzyme | இறுதி பொருள் |
|---|---|---|
| Carbohydrate (starch) | Amylase, Maltase | Glucose |
| Protein | Pepsin, Trypsin | Amino acids |
| Fat (lipid) | Lipase | Fatty acids + Glycerol |
⭐ Quick rule Mouth = starch start; Stomach = protein start; Small intestine = all three complete + absorb.
2. சுவாசத் தொகுதி (Respiratory system)
Cells need O₂ to release energy from food (respiration: glucose + O₂ → CO₂ + H₂O + ATP). Respiratory system O₂-ஐ உடலுக்குள் கொண்டுவருகின்றது + waste CO₂-ஐ வெளியேற்றுகின்றது.
2.1 பாதை
நாசி → தொண்டை (pharynx) → குரல்வளை (larynx) → மூச்சுக்குழாய் (trachea) → branches mücülaris (bronchi) → bronchioles → நுரையீரல் (lungs) → alveoli (~300 million per lung, gas-exchange sacs).
2.2 Alveoli — gas exchange site
Alveoli surface = single-cell thick, capillary network surrounding. O₂ diffuses lung → blood (RBC haemoglobin-உடன் bind); CO₂ diffuses opposite. Total alveolar surface ~70 m² — அதிசயம்: ஒரு tennis court பரப்பளவு உள்ள கைப்பிடி தண்ணீர் mass-ல் !
2.3 Inhalation + Exhalation mechanism
- Inhalation: Diaphragm contract → flat → chest cavity expands. Intercostal muscles ribs உயர்த்தும். Volume up → pressure down → air rush in.
- Exhalation: Reverse — diaphragm relax → dome up. Volume down → pressure up → air pushed out.
Normal adult: 12-20 breaths/min. Each breath ~500 mL. Daily volume ~10,000 L air.
3. கழிவகற்றும் தொகுதி (Excretory system)
Metabolism-ஆல் கழிவுகள் (urea, uric acid, excess salts, water) உருவாகின்றன. கழிவகற்றும் தொகுதி — primarily kidneys — அவற்றை blood-இலிருந்து filter செய்து urine-ஆக வெளியேற்றுகின்றது.
3.1 சிறுநீரகங்கள் (Kidneys) — bean-shaped pair
- Each kidney has ~1 million nephrons (filtering units).
- Daily ~180 L blood filtered → ~1.5 L urine produced.
- Nephron 3 steps: glomerular filtration → tubular reabsorption → tubular secretion.
3.2 மற்ற excretory organs
- Lungs: CO₂ + small water vapour.
- Skin: Sweat (water + salts + minor urea).
- Liver: Bile pigments — bilirubin (RBC breakdown).
4. குருதிச் சுற்றோட்டத் தொகுதி (Circulatory system)
இதயம் pump as central engine; blood vessels as delivery network; blood as transport medium. Oxygen, nutrients, hormones-ஐ cells-க்கு கொண்டுசேர்த்து, CO₂ + waste-ஐ remove.
4.1 இதயம் — Four-chambered pump
- Right atrium — body-இலிருந்து deoxygenated blood receive.
- Right ventricle — அதை lungs-க்கு pump (pulmonary artery).
- Left atrium — lungs-இலிருந்து oxygenated blood receive (pulmonary vein).
- Left ventricle — body-முழுவதும் pump (aorta). Thickest muscle.
4.2 2 circuits
- Pulmonary (lungs): Right heart → lungs → left heart. Gas exchange.
- Systemic (body): Left heart → body → right heart. Nutrient + waste exchange.
4.3 Blood vessels
- Arteries: Thick walls, carry blood AWAY from heart (mostly oxygenated except pulmonary).
- Veins: Thin walls, valves, blood TO heart (mostly deoxygenated except pulmonary).
- Capillaries: One-cell thick, gas + nutrient exchange.
4.4 Blood components
- Plasma (55%): Liquid matrix, nutrients + hormones.
- RBC (45%): Haemoglobin → O₂ transport. ~5M/μL. No nucleus.
- WBC: Immunity. ~7K/μL. With nucleus.
- Platelets: Blood clotting.
Normal heart rate: 60-100 bpm at rest. Blood pressure: 120/80 mmHg.
5. இயைபாக்கம் + ஒர்சீர்த்திட நிலையம் (Coordination + Homeostasis)
5.1 நரம்புத் தொகுதி (Nervous system)
CNS (மூளை + முதுகுத்தண்டுவடம்) + PNS (peripheral nerves). Fast electrical signaling.
- Cerebrum (பெரு மூளை): Thinking, voluntary action, memory.
- Cerebellum (சிறு மூளை): Balance, coordination.
- Brain stem: Heart, breathing, BP — involuntary controls.
- Spinal cord: Reflex arc + signal highway.
5.2 சுரப்பித் தொகுதி (Endocrine system)
Slower chemical signaling via hormones. Key glands:
- Pituitary (உச்ச சுரப்பி): "Master gland." Growth hormone, others.
- Thyroid: Metabolism, thyroxine. (Deficiency → goitre.)
- Pancreas: Insulin (lowers blood sugar) + glucagon (raises). Diabetes = insulin issue.
- Adrenal: Adrenaline (flight/fight).
- Gonads (ovary/testis): Sex hormones.
5.3 Homeostasis
Body temperature ~37°C; blood glucose ~5 mM; pH 7.4 — strict ranges maintained despite external variations. Negative feedback loops.
⚠ Disorders to know Diabetes (insulin failure), goitre (iodine deficiency → thyroid swelling), kidney failure (urea buildup), heart attack (coronary block), stroke (brain vessel block), hypertension.
✅ விரைவுச் சோதனை
முக்கியக் கருத்துக்களை உறுதிப்படுத்துங்கள். தவறான விடைகள் உங்கள் தவறுக் குறிப்பேட்டில் சேமிக்கப்படும்.
🖊 கட்டுரை வினாக்கள் (பகுதி II)
பரீட்சை வடிவில் கட்டமைப்பு வினாக்கள். முதலில் நீங்களே எழுதுங்கள்; பின்னர் மாதிரி விடையைத் திறந்து சரிபாருங்கள்.
1. மனிதனின் உணவுச் சமிபாட்டுத் தொகுதியில் (digestive system) — உணவு வாயிலிருந்து குதம் வரை எடுத்துச் செல்லப்படும் பாதையை விளக்கி, ஒவ்வொரு organ-ன் primary வேலையை சுட்டிக்காட்டுக. Accessory organs (liver, pancreas) பங்கையும் சேர்க்க. (10 புள்ளி)
விடைத் திட்டம் — சேர்க்க வேண்டிய புள்ளிகள்:
- 6 organs sequential: mouth, oesophagus, stomach, small intestine, large intestine, rectum.
- Liver — bile + storage + detox.
- Pancreas — enzymes + insulin.
- 3 macronutrient enzymes.
உணவுப் பாதை — 6 main organs:
(1) வாய்க்குழி (Mouth): பல்லால் mechanical chewing → bolus formation. Salivary amylase (ptyalin) starch-ஐ maltose-ஆகச் சிதைக்கத் தொடங்கும். Tongue உணவை mix + swallow பயிற்சி.
(2) களம் (Oesophagus): 25 cm long muscular tube. Peristaltic contractions (wave-like) உணவை இரைப்பைக்கு push (gravity-independent — astronauts space-ல் சாப்பிட முடியும்).
(3) இரைப்பை (Stomach): J-shape muscular pouch. HCl + pepsin + gastric juice. pH ~1.5-2: (a) microbes kill, (b) pepsinogen → pepsin → protein partial digestion, (c) chyme உருவாக்கும். ~2-4 hour residence.
(4) சிறுகுடல் (Small intestine, 6 m): Three sections — duodenum (digestion), jejunum (absorption start), ileum (absorption continue). Bile (liver) + pancreatic juice + intestinal enzymes complete digestion. Villi + microvilli surface area ~200 m². Most nutrient absorption HERE.
(5) பெருங்குடல் (Large intestine, 1.5 m): Water + electrolyte absorption. Gut bacteria K + B vitamins synthesise. Faeces formation.
(6) நேர்குடல் + குதம் (Rectum + anus): Faeces store + voluntary elimination.
Accessory organs (உதவி உறுப்புகள்):
• ஈரல் (Liver, ~1.5 kg): Bile produces (fat emulsification). Glycogen storage. Drug + toxin detoxification. Plasma proteins (albumin, clotting factors) synthesise. Vitamin A, D, B12 storage.
• பித்தப்பை (Gallbladder): Liver-உற்பத்தி bile-ஐ store + concentrate; meal time-ல் duodenum-உக்கு release.
• சதையீரல் (Pancreas): Exocrine portion — amylase, lipase, trypsin enzymes secrete. Endocrine — insulin (lowers glucose) + glucagon (raises) hormones. Dual functions.
• உமிழ்நீர் சுரப்பிகள் (Salivary glands): 3 pairs — parotid, submandibular, sublingual. Daily 1-1.5 L saliva. Amylase + lysozyme + mucin.
3 macronutrient enzymes — final products:
• Carbohydrate (starch) → amylase + maltase → glucose.
• Protein → pepsin + trypsin + peptidase → amino acids.
• Fat → lipase (bile-emulsified) → fatty acids + glycerol.
All three absorbed at villi small intestine, transported via blood to liver (portal vein) for processing.
(1) வாய்க்குழி (Mouth): பல்லால் mechanical chewing → bolus formation. Salivary amylase (ptyalin) starch-ஐ maltose-ஆகச் சிதைக்கத் தொடங்கும். Tongue உணவை mix + swallow பயிற்சி.
(2) களம் (Oesophagus): 25 cm long muscular tube. Peristaltic contractions (wave-like) உணவை இரைப்பைக்கு push (gravity-independent — astronauts space-ல் சாப்பிட முடியும்).
(3) இரைப்பை (Stomach): J-shape muscular pouch. HCl + pepsin + gastric juice. pH ~1.5-2: (a) microbes kill, (b) pepsinogen → pepsin → protein partial digestion, (c) chyme உருவாக்கும். ~2-4 hour residence.
(4) சிறுகுடல் (Small intestine, 6 m): Three sections — duodenum (digestion), jejunum (absorption start), ileum (absorption continue). Bile (liver) + pancreatic juice + intestinal enzymes complete digestion. Villi + microvilli surface area ~200 m². Most nutrient absorption HERE.
(5) பெருங்குடல் (Large intestine, 1.5 m): Water + electrolyte absorption. Gut bacteria K + B vitamins synthesise. Faeces formation.
(6) நேர்குடல் + குதம் (Rectum + anus): Faeces store + voluntary elimination.
Accessory organs (உதவி உறுப்புகள்):
• ஈரல் (Liver, ~1.5 kg): Bile produces (fat emulsification). Glycogen storage. Drug + toxin detoxification. Plasma proteins (albumin, clotting factors) synthesise. Vitamin A, D, B12 storage.
• பித்தப்பை (Gallbladder): Liver-உற்பத்தி bile-ஐ store + concentrate; meal time-ல் duodenum-உக்கு release.
• சதையீரல் (Pancreas): Exocrine portion — amylase, lipase, trypsin enzymes secrete. Endocrine — insulin (lowers glucose) + glucagon (raises) hormones. Dual functions.
• உமிழ்நீர் சுரப்பிகள் (Salivary glands): 3 pairs — parotid, submandibular, sublingual. Daily 1-1.5 L saliva. Amylase + lysozyme + mucin.
3 macronutrient enzymes — final products:
• Carbohydrate (starch) → amylase + maltase → glucose.
• Protein → pepsin + trypsin + peptidase → amino acids.
• Fat → lipase (bile-emulsified) → fatty acids + glycerol.
All three absorbed at villi small intestine, transported via blood to liver (portal vein) for processing.
2. மனித சுவாசத் தொகுதியின் (respiratory system) anatomy + physiology-ஐ விளக்குக. Alveoli-வில் gas exchange எவ்வாறு நடைபெறுகின்றது? Smoking-ன் effects குறிப்பிடுக. (10 புள்ளி)
விடைத் திட்டம் — சேர்க்க வேண்டிய புள்ளிகள்:
- Air path: nose → pharynx → larynx → trachea → bronchi → bronchioles → alveoli.
- Inhalation mechanism.
- Alveolar surface 70 m², 1-cell wall, capillary network.
- O₂ in, CO₂ out by diffusion.
- Smoking damages ciliae + alveolar walls.
Respiratory system anatomy:
Air pathway:
நாசி (nostrils + nasal cavity) → pharynx (throat) → larynx (voice box) → trachea (windpipe) → 2 bronchi (one per lung) → progressively smaller bronchioles → terminal alveolar sacs.
Lungs: Spongy tissue, right lung 3 lobes, left lung 2 lobes (heart takes left space). Each lung ~300M alveoli. Total alveolar surface ~70 m² (tennis court size in chest cavity).
Breathing mechanism (inhalation):
• Diaphragm (dome muscle) contracts → flattens.
• External intercostal muscles raise ribs.
• Thoracic cavity volume ↑ → pressure ↓ (Boyle's law).
• Atmospheric air rushes in via mouth/nose.
Exhalation: Reverse — diaphragm relaxes, ribs lower, volume ↓, pressure ↑, air pushed out. Mostly passive (elastic recoil).
Normal rate: 12-20 breaths/min adult. Each ~500 mL (tidal volume). Total ~7 L/min at rest. During exercise → 100+ L/min.
Alveolar gas exchange:
Each alveolus = thin-walled sac (single cell thick) surrounded by dense capillary network (also single cell thick).
Diffusion (passive transport):
• O₂: Inhaled air ~21% O₂ → high partial pressure in alveolus. Capillary deoxygenated blood low pO₂. → O₂ diffuses alveolus → blood → binds Hb in RBCs.
• CO₂: Capillary blood high pCO₂ (cellular respiration waste) → low pCO₂ alveolus. CO₂ diffuses blood → alveolus → exhaled.
No energy needed — gradient-driven diffusion. ~300 mL O₂ absorbed/min at rest; ~250 mL CO₂ released.
Cellular use:
O₂ transported to all cells. In mitochondria: glucose + O₂ → CO₂ + H₂O + 36 ATP. ATP = cellular energy currency.
Smoking effects (புகைப்பழக்கம்):
• Cilia damage: Trachea + bronchi cilia (hair-like) mucus + debris sweep out. Smoke paralyses cilia → mucus accumulates → chronic cough.
• Alveolar destruction (emphysema): Inflammation breaks alveolar walls → surface area drops → less gas exchange → shortness of breath.
• Carcinogens: ~70 cancer-causing chemicals in tobacco smoke. Lung cancer 15-30× higher risk smokers.
• Tar deposition: Brown sticky residue darkens lungs.
• Carbon monoxide: CO binds Hb 200× stronger than O₂ → reduced O₂ delivery.
• Long-term: COPD, chronic bronchitis, heart disease, stroke, multiple cancers.
• Secondhand smoke harms others — children especially.
Sri Lanka tobacco prevention programmes since 2006 (NATA Act). Public smoking ban + warning labels.
Air pathway:
நாசி (nostrils + nasal cavity) → pharynx (throat) → larynx (voice box) → trachea (windpipe) → 2 bronchi (one per lung) → progressively smaller bronchioles → terminal alveolar sacs.
Lungs: Spongy tissue, right lung 3 lobes, left lung 2 lobes (heart takes left space). Each lung ~300M alveoli. Total alveolar surface ~70 m² (tennis court size in chest cavity).
Breathing mechanism (inhalation):
• Diaphragm (dome muscle) contracts → flattens.
• External intercostal muscles raise ribs.
• Thoracic cavity volume ↑ → pressure ↓ (Boyle's law).
• Atmospheric air rushes in via mouth/nose.
Exhalation: Reverse — diaphragm relaxes, ribs lower, volume ↓, pressure ↑, air pushed out. Mostly passive (elastic recoil).
Normal rate: 12-20 breaths/min adult. Each ~500 mL (tidal volume). Total ~7 L/min at rest. During exercise → 100+ L/min.
Alveolar gas exchange:
Each alveolus = thin-walled sac (single cell thick) surrounded by dense capillary network (also single cell thick).
Diffusion (passive transport):
• O₂: Inhaled air ~21% O₂ → high partial pressure in alveolus. Capillary deoxygenated blood low pO₂. → O₂ diffuses alveolus → blood → binds Hb in RBCs.
• CO₂: Capillary blood high pCO₂ (cellular respiration waste) → low pCO₂ alveolus. CO₂ diffuses blood → alveolus → exhaled.
No energy needed — gradient-driven diffusion. ~300 mL O₂ absorbed/min at rest; ~250 mL CO₂ released.
Cellular use:
O₂ transported to all cells. In mitochondria: glucose + O₂ → CO₂ + H₂O + 36 ATP. ATP = cellular energy currency.
Smoking effects (புகைப்பழக்கம்):
• Cilia damage: Trachea + bronchi cilia (hair-like) mucus + debris sweep out. Smoke paralyses cilia → mucus accumulates → chronic cough.
• Alveolar destruction (emphysema): Inflammation breaks alveolar walls → surface area drops → less gas exchange → shortness of breath.
• Carcinogens: ~70 cancer-causing chemicals in tobacco smoke. Lung cancer 15-30× higher risk smokers.
• Tar deposition: Brown sticky residue darkens lungs.
• Carbon monoxide: CO binds Hb 200× stronger than O₂ → reduced O₂ delivery.
• Long-term: COPD, chronic bronchitis, heart disease, stroke, multiple cancers.
• Secondhand smoke harms others — children especially.
Sri Lanka tobacco prevention programmes since 2006 (NATA Act). Public smoking ban + warning labels.
3. மனித இதயம் (heart) — anatomy + 4 chambers + valves + 2 circulations விளக்குக. சிஸ்டாலிக் + டயாஸ்டாலிக் BP மற்றும் ECG concept. (10 புள்ளி)
விடைத் திட்டம் — சேர்க்க வேண்டிய புள்ளிகள்:
- 4 chambers: 2 atria + 2 ventricles.
- RA → RV → lungs (pulmonary).
- LA → LV → body (systemic).
- Valves prevent backflow.
- Systole + diastole.
- BP 120/80.
Heart anatomy — 4 chambers + valves:
Human heart fist-sized muscular organ. Located in mediastinum (between lungs), slightly left.
Chambers:
• Right atrium (RA): Receives deoxygenated blood from body via superior + inferior vena cavae.
• Right ventricle (RV): Pumps deoxygenated blood to lungs via pulmonary artery. Thin muscular wall (low pulmonary resistance).
• Left atrium (LA): Receives oxygenated blood from lungs via 4 pulmonary veins.
• Left ventricle (LV): Pumps oxygenated blood to entire body via aorta. Thickest chamber (high systemic resistance).
Valves (4):
• Tricuspid: RA → RV. Prevents backflow.
• Pulmonary semilunar: RV → pulmonary artery.
• Mitral (bicuspid): LA → LV.
• Aortic semilunar: LV → aorta.
Valve failure → "murmur" sound. Rheumatic heart disease damages valves (post-streptococcal).
2 circulations:
(1) Pulmonary circulation (small):
RV → pulmonary artery → lungs → gas exchange → pulmonary veins → LA.
Deoxy → oxy in lungs.
Pulmonary artery = only artery carrying deoxygenated blood.
Pulmonary veins = only veins carrying oxygenated blood.
(2) Systemic circulation (large):
LV → aorta → systemic arteries → arterioles → capillaries (organ exchange) → venules → veins → vena cavae → RA.
Oxy → deoxy at tissues.
Cardiac cycle:
• Systole = ventricular contraction (pumping). ~0.3 s.
• Diastole = relaxation (filling). ~0.5 s.
Total cycle ~0.8 s → 75 bpm rest.
Blood pressure (BP):
• Systolic 120 mmHg = peak pressure during ventricular contraction.
• Diastolic 80 mmHg = minimum pressure during relaxation.
• Written: 120/80.
• Sphygmomanometer cuff + stethoscope measurement at brachial artery.
• Hypertension: >140/90 sustained = silent killer. Stroke, heart attack, kidney failure risk.
• Hypotension: <90/60 = fainting, shock risk.
ECG (Electrocardiogram):
Heart's electrical activity recorded. Waves:
• P wave: Atrial depolarization (contraction).
• QRS complex: Ventricular depolarization (powerful contraction).
• T wave: Ventricular repolarization (relaxation).
Normal ECG → heart electrical conduction healthy. Abnormalities:
• Arrhythmias (irregular rhythm)
• ST elevation → heart attack (myocardial infarction)
• Atrial fibrillation
• AV blocks
Life-saving diagnostic — emergency rooms standard.
Human heart fist-sized muscular organ. Located in mediastinum (between lungs), slightly left.
Chambers:
• Right atrium (RA): Receives deoxygenated blood from body via superior + inferior vena cavae.
• Right ventricle (RV): Pumps deoxygenated blood to lungs via pulmonary artery. Thin muscular wall (low pulmonary resistance).
• Left atrium (LA): Receives oxygenated blood from lungs via 4 pulmonary veins.
• Left ventricle (LV): Pumps oxygenated blood to entire body via aorta. Thickest chamber (high systemic resistance).
Valves (4):
• Tricuspid: RA → RV. Prevents backflow.
• Pulmonary semilunar: RV → pulmonary artery.
• Mitral (bicuspid): LA → LV.
• Aortic semilunar: LV → aorta.
Valve failure → "murmur" sound. Rheumatic heart disease damages valves (post-streptococcal).
2 circulations:
(1) Pulmonary circulation (small):
RV → pulmonary artery → lungs → gas exchange → pulmonary veins → LA.
Deoxy → oxy in lungs.
Pulmonary artery = only artery carrying deoxygenated blood.
Pulmonary veins = only veins carrying oxygenated blood.
(2) Systemic circulation (large):
LV → aorta → systemic arteries → arterioles → capillaries (organ exchange) → venules → veins → vena cavae → RA.
Oxy → deoxy at tissues.
Cardiac cycle:
• Systole = ventricular contraction (pumping). ~0.3 s.
• Diastole = relaxation (filling). ~0.5 s.
Total cycle ~0.8 s → 75 bpm rest.
Blood pressure (BP):
• Systolic 120 mmHg = peak pressure during ventricular contraction.
• Diastolic 80 mmHg = minimum pressure during relaxation.
• Written: 120/80.
• Sphygmomanometer cuff + stethoscope measurement at brachial artery.
• Hypertension: >140/90 sustained = silent killer. Stroke, heart attack, kidney failure risk.
• Hypotension: <90/60 = fainting, shock risk.
ECG (Electrocardiogram):
Heart's electrical activity recorded. Waves:
• P wave: Atrial depolarization (contraction).
• QRS complex: Ventricular depolarization (powerful contraction).
• T wave: Ventricular repolarization (relaxation).
Normal ECG → heart electrical conduction healthy. Abnormalities:
• Arrhythmias (irregular rhythm)
• ST elevation → heart attack (myocardial infarction)
• Atrial fibrillation
• AV blocks
Life-saving diagnostic — emergency rooms standard.
4. மனிதனின் சிறுநீரகங்கள் (kidneys) — anatomy + nephron function + urine production. Kidney failure-ஆல் என்ன நிகழும் + treatment options. (10 புள்ளி)
விடைத் திட்டம் — சேர்க்க வேண்டிய புள்ளிகள்:
- 2 bean-shaped kidneys.
- 1M nephrons each.
- Filtration + reabsorption + secretion.
- 180 L filtered → 1.5 L urine.
- Failure → urea buildup → dialysis or transplant.
Kidneys anatomy:
Two bean-shaped organs, ~12 cm each, retroperitoneal (behind peritoneum) at thoracolumbar level. Receive ~25% of cardiac output (~1.2 L/min blood) despite being only ~0.5% body weight.
3 layers:
• Cortex (மேற்படை): Outer layer, glomeruli located.
• Medulla (உள்படை): Inner pyramids, tubules.
• Renal pelvis: Collecting space draining into ureter.
Renal blood supply:
Abdominal aorta → renal artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries → renal vein → IVC.
Nephron — functional unit (~1 million per kidney):
(1) Bowman's capsule + glomerulus (filtration):
Glomerulus = ball of capillaries. High pressure → plasma pushed into Bowman's capsule. Cells + large proteins retained in blood; water + glucose + ions + small wastes (urea) pass through.
Filtration rate: ~125 mL/min = 180 L/day filtered.
(2) Tubular reabsorption (~99% recovery):
Filtrate flows through proximal convoluted tubule (PCT) → Loop of Henle → distal convoluted tubule (DCT) → collecting duct.
Useful substances actively/passively reabsorbed:
• Glucose 100% (PCT) — normally none in urine.
• Amino acids ~100%.
• Na+, K+, Cl-, HCO3- regulated.
• Water ~99% reabsorbed (controlled by ADH).
(3) Tubular secretion:
Blood → tubule: H+, K+, drugs, toxins actively secreted.
Final urine: ~1-2 L/day = 0.6% of filtered.
Urine composition (normal):
• 95% water
• Urea (main waste, ~2%)
• Salts (Na, K, Cl)
• Creatinine (muscle waste)
• NO glucose, NO proteins normally
Hormonal control:
• ADH (vasopressin): Pituitary, increases water reabsorption.
• Aldosterone: Adrenal, increases Na+ reabsorption.
• EPO (erythropoietin): Kidney-produced, stimulates RBC production.
Kidney failure (renal failure):
Causes:
• Diabetes (most common worldwide)
• Hypertension
• Chronic glomerulonephritis
• Polycystic kidney disease
• Drug toxicity (NSAIDs overuse, aminoglycosides)
• Sri Lanka specific: CKDu (Chronic Kidney Disease of unknown etiology) — agricultural communities particularly affected.
Consequences:
• Urea, creatinine, K+ buildup in blood (uraemia).
• Fluid overload → swelling, lung edema.
• Acidosis (H+ retention).
• Anaemia (no EPO).
• Bone disease (vitamin D activation failure).
Treatment options:
(1) Haemodialysis:
Artificial kidney machine. 3 sessions/week × 4 hr each typical. Blood pumped through dialyser (semipermeable membrane), waste diffuses into dialysate.
(2) Peritoneal dialysis:
Patient's peritoneal membrane used. Sterile fluid injected into abdomen, equilibrates with blood, then drained. Can be done at home.
(3) Kidney transplant:
Donor (living relative or deceased) kidney implanted. Best long-term outcome. Lifelong immunosuppression. Sri Lanka — National Hospital pioneers, NIROGI Lanka kidney foundation support.
Prevention:
Control diabetes + BP. Avoid NSAID overuse. Adequate hydration. Regular checkups (creatinine, urine analysis).
Two bean-shaped organs, ~12 cm each, retroperitoneal (behind peritoneum) at thoracolumbar level. Receive ~25% of cardiac output (~1.2 L/min blood) despite being only ~0.5% body weight.
3 layers:
• Cortex (மேற்படை): Outer layer, glomeruli located.
• Medulla (உள்படை): Inner pyramids, tubules.
• Renal pelvis: Collecting space draining into ureter.
Renal blood supply:
Abdominal aorta → renal artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries → renal vein → IVC.
Nephron — functional unit (~1 million per kidney):
(1) Bowman's capsule + glomerulus (filtration):
Glomerulus = ball of capillaries. High pressure → plasma pushed into Bowman's capsule. Cells + large proteins retained in blood; water + glucose + ions + small wastes (urea) pass through.
Filtration rate: ~125 mL/min = 180 L/day filtered.
(2) Tubular reabsorption (~99% recovery):
Filtrate flows through proximal convoluted tubule (PCT) → Loop of Henle → distal convoluted tubule (DCT) → collecting duct.
Useful substances actively/passively reabsorbed:
• Glucose 100% (PCT) — normally none in urine.
• Amino acids ~100%.
• Na+, K+, Cl-, HCO3- regulated.
• Water ~99% reabsorbed (controlled by ADH).
(3) Tubular secretion:
Blood → tubule: H+, K+, drugs, toxins actively secreted.
Final urine: ~1-2 L/day = 0.6% of filtered.
Urine composition (normal):
• 95% water
• Urea (main waste, ~2%)
• Salts (Na, K, Cl)
• Creatinine (muscle waste)
• NO glucose, NO proteins normally
Hormonal control:
• ADH (vasopressin): Pituitary, increases water reabsorption.
• Aldosterone: Adrenal, increases Na+ reabsorption.
• EPO (erythropoietin): Kidney-produced, stimulates RBC production.
Kidney failure (renal failure):
Causes:
• Diabetes (most common worldwide)
• Hypertension
• Chronic glomerulonephritis
• Polycystic kidney disease
• Drug toxicity (NSAIDs overuse, aminoglycosides)
• Sri Lanka specific: CKDu (Chronic Kidney Disease of unknown etiology) — agricultural communities particularly affected.
Consequences:
• Urea, creatinine, K+ buildup in blood (uraemia).
• Fluid overload → swelling, lung edema.
• Acidosis (H+ retention).
• Anaemia (no EPO).
• Bone disease (vitamin D activation failure).
Treatment options:
(1) Haemodialysis:
Artificial kidney machine. 3 sessions/week × 4 hr each typical. Blood pumped through dialyser (semipermeable membrane), waste diffuses into dialysate.
(2) Peritoneal dialysis:
Patient's peritoneal membrane used. Sterile fluid injected into abdomen, equilibrates with blood, then drained. Can be done at home.
(3) Kidney transplant:
Donor (living relative or deceased) kidney implanted. Best long-term outcome. Lifelong immunosuppression. Sri Lanka — National Hospital pioneers, NIROGI Lanka kidney foundation support.
Prevention:
Control diabetes + BP. Avoid NSAID overuse. Adequate hydration. Regular checkups (creatinine, urine analysis).
5. மனிதனின் நரம்புத் தொகுதியின் (nervous system) structure + function — மூளை, முதுகுத்தண்டுவடம், neurons — விளக்கி, reflex arc-ஐ உதாரணத்துடன் காட்டுக. (10 புள்ளி)
விடைத் திட்டம் — சேர்க்க வேண்டிய புள்ளிகள்:
- CNS = brain + spinal cord. PNS = nerves.
- Cerebrum, cerebellum, brain stem functions.
- Spinal cord reflex + signal.
- Neuron parts.
- Reflex arc: receptor → sensory → CNS → motor → effector.
- Pain withdrawal example.
Nervous system overview:
2 divisions:
• CNS (Central Nervous System): மூளை + முதுகுத்தண்டுவடம் (Brain + spinal cord). Decision-making centre.
• PNS (Peripheral): Nerves connecting CNS to body. 12 cranial pairs + 31 spinal pairs.
Also functional divisions: Somatic (voluntary) + Autonomic (involuntary) → Sympathetic (fight/flight) + Parasympathetic (rest/digest).
Brain (3 main parts):
(1) Cerebrum (பெரு மூளை): 80% of brain mass. Folded surface (gyri + sulci) = extra area. 2 hemispheres (left + right) connected by corpus callosum.
4 lobes:
• Frontal: Planning, decision, personality, voluntary movement, speech (Broca's area).
• Parietal: Touch, temperature, pain sensation.
• Occipital: Vision processing.
• Temporal: Hearing, language understanding (Wernicke), memory (hippocampus).
(2) Cerebellum (சிறு மூளை): Below cerebrum, behind brain stem. Balance, coordination, fine motor skills, posture, motor learning. Damage = ataxia.
(3) Brain stem: Midbrain + pons + medulla. Autonomic vital functions — heart rate, breathing, BP, swallowing, vomiting reflexes. Damage often fatal.
Spinal cord:
Protected by vertebral column (33 vertebrae). 45 cm long. White matter (myelinated axons) outside, grey matter (cell bodies) inside (H-shape). Two functions:
• Carries signals up (sensory) + down (motor).
• Reflex centre (some don't need brain).
Neuron — functional unit:
• Cell body (soma): Nucleus + organelles.
• Dendrites: Receive signals from other neurons.
• Axon: Long extension, sends signal away. May be myelinated (faster) or unmyelinated.
• Synapse: Junction with next neuron. Neurotransmitter (acetylcholine, dopamine, etc.) chemical signaling.
3 functional types:
• Sensory (afferent): Receptor → CNS.
• Interneuron: Within CNS.
• Motor (efferent): CNS → effector (muscle/gland).
Reflex arc — uthaaranam:
Example: Pain withdrawal (சூடான பாத்திரம் தொட்டால்):
1. Stimulus: Hand touches hot vessel.
2. Receptor: Thermal/pain receptors in skin activated.
3. Sensory neuron: Carries signal via peripheral nerve to spinal cord.
4. Interneuron: Within spinal cord, processes + immediately relays to motor neuron (NO conscious brain processing).
5. Motor neuron: Sends signal back to arm muscles.
6. Effector: Biceps contracts → arm withdrawn.
7. Response: Hand pulled away — <0.1 seconds — even before pain felt!
Brain notification: Signal also ascends to brain via spinothalamic tract → conscious pain sensation + memory of "this is hot, avoid next time."
Why reflexes exist:
Speed = survival. Brain reaction ~0.3 s; reflex ~0.05 s. Protective.
Other reflex examples:
• Knee jerk (patellar): muscle spindle → spinal cord → quadriceps contract.
• Pupillary light reflex: bright light → pupil constrict.
• Blink reflex: corneal touch → eyelid closure.
• Salivation: food sight/smell.
Reflex testing: Doctors check spinal cord integrity. Absent/exaggerated reflexes signal neurological problems.
2 divisions:
• CNS (Central Nervous System): மூளை + முதுகுத்தண்டுவடம் (Brain + spinal cord). Decision-making centre.
• PNS (Peripheral): Nerves connecting CNS to body. 12 cranial pairs + 31 spinal pairs.
Also functional divisions: Somatic (voluntary) + Autonomic (involuntary) → Sympathetic (fight/flight) + Parasympathetic (rest/digest).
Brain (3 main parts):
(1) Cerebrum (பெரு மூளை): 80% of brain mass. Folded surface (gyri + sulci) = extra area. 2 hemispheres (left + right) connected by corpus callosum.
4 lobes:
• Frontal: Planning, decision, personality, voluntary movement, speech (Broca's area).
• Parietal: Touch, temperature, pain sensation.
• Occipital: Vision processing.
• Temporal: Hearing, language understanding (Wernicke), memory (hippocampus).
(2) Cerebellum (சிறு மூளை): Below cerebrum, behind brain stem. Balance, coordination, fine motor skills, posture, motor learning. Damage = ataxia.
(3) Brain stem: Midbrain + pons + medulla. Autonomic vital functions — heart rate, breathing, BP, swallowing, vomiting reflexes. Damage often fatal.
Spinal cord:
Protected by vertebral column (33 vertebrae). 45 cm long. White matter (myelinated axons) outside, grey matter (cell bodies) inside (H-shape). Two functions:
• Carries signals up (sensory) + down (motor).
• Reflex centre (some don't need brain).
Neuron — functional unit:
• Cell body (soma): Nucleus + organelles.
• Dendrites: Receive signals from other neurons.
• Axon: Long extension, sends signal away. May be myelinated (faster) or unmyelinated.
• Synapse: Junction with next neuron. Neurotransmitter (acetylcholine, dopamine, etc.) chemical signaling.
3 functional types:
• Sensory (afferent): Receptor → CNS.
• Interneuron: Within CNS.
• Motor (efferent): CNS → effector (muscle/gland).
Reflex arc — uthaaranam:
Example: Pain withdrawal (சூடான பாத்திரம் தொட்டால்):
1. Stimulus: Hand touches hot vessel.
2. Receptor: Thermal/pain receptors in skin activated.
3. Sensory neuron: Carries signal via peripheral nerve to spinal cord.
4. Interneuron: Within spinal cord, processes + immediately relays to motor neuron (NO conscious brain processing).
5. Motor neuron: Sends signal back to arm muscles.
6. Effector: Biceps contracts → arm withdrawn.
7. Response: Hand pulled away — <0.1 seconds — even before pain felt!
Brain notification: Signal also ascends to brain via spinothalamic tract → conscious pain sensation + memory of "this is hot, avoid next time."
Why reflexes exist:
Speed = survival. Brain reaction ~0.3 s; reflex ~0.05 s. Protective.
Other reflex examples:
• Knee jerk (patellar): muscle spindle → spinal cord → quadriceps contract.
• Pupillary light reflex: bright light → pupil constrict.
• Blink reflex: corneal touch → eyelid closure.
• Salivation: food sight/smell.
Reflex testing: Doctors check spinal cord integrity. Absent/exaggerated reflexes signal neurological problems.
6. சுரப்பித் தொகுதியின் (endocrine system) முக்கிய glands + hormones-ஐ விளக்கி, diabetes mellitus-ன் pathology + management விரிவாக காட்டுக. (10 புள்ளி)
விடைத் திட்டம் — சேர்க்க வேண்டிய புள்ளிகள்:
- Pituitary, thyroid, pancreas, adrenal, gonads.
- Each hormone + function.
- Diabetes: insulin failure → high BG.
- Type 1 vs Type 2.
- Symptoms + complications + treatment.
Endocrine system overview:
Ductless glands secrete hormones directly into blood. Slower than nervous system but longer-lasting effects. Coordinates growth, metabolism, reproduction, stress response.
Major glands + key hormones:
(1) Pituitary (உச்ச சுரப்பி) — "Master gland":
Under brain (hypothalamus control). Pea-sized.
• Growth hormone (GH) → growth, metabolism.
• TSH → stimulates thyroid.
• ACTH → stimulates adrenal cortex.
• ADH → kidney water retention.
• Oxytocin → labour contractions + milk ejection.
• Prolactin → milk production.
• FSH, LH → gonad stimulation.
(2) Thyroid:
Butterfly-shaped, neck front. Requires iodine.
• Thyroxine (T4) + T3 → basal metabolic rate, body temp.
• Calcitonin → lowers blood calcium.
Disorders:
• Hypothyroidism → cold intolerance, weight gain, fatigue (Hashimoto's).
• Hyperthyroidism → weight loss, anxiety, tremor (Graves' disease).
• Goitre → iodine deficiency enlargement.
(3) Parathyroid:
Behind thyroid.
• PTH → raises blood calcium (bone, kidney).
(4) Pancreas:
Dual exocrine + endocrine. Islets of Langerhans:
• β cells → insulin (lowers BG).
• α cells → glucagon (raises BG).
(5) Adrenal:
On top of kidneys. 2 parts:
• Cortex → cortisol (stress, anti-inflammatory), aldosterone (Na/K balance), sex hormones.
• Medulla → adrenaline (fight/flight).
(6) Gonads:
• Testes → testosterone.
• Ovaries → oestrogen + progesterone.
(7) Pineal gland:
Melatonin → sleep-wake cycle (circadian rhythm).
(8) Thymus:
T-cell maturation (immunity).
----
Diabetes Mellitus (DM) — Detailed:
Definition: Chronic metabolic disorder of elevated blood glucose due to insulin deficiency, resistance, or both.
Normal glucose regulation:
After meal → BG rises → β cells secrete insulin → cells take up glucose → BG normalises. Liver stores excess as glycogen.
Between meals → BG falls → α cells secrete glucagon → liver releases glucose → BG maintained ~5 mM.
Diabetes types:
Type 1 (insulin-dependent):
• Autoimmune destruction of β cells.
• Usually onset childhood/young adulthood.
• Complete insulin deficiency.
• Always needs insulin injections.
• ~10% of all DM.
Type 2 (insulin-resistant):
• Cells resist insulin action + later β cell exhaustion.
• Usually onset adulthood (>40), but younger now due to obesity epidemic.
• Lifestyle-related — obesity, sedentary, diet.
• ~90% of all DM.
• Sri Lanka prevalence ~10% adults.
Gestational diabetes: Pregnancy-related. Often resolves after delivery but increases future risk.
Symptoms (3 Ps):
• Polyuria: Excessive urination (glucose pulls water).
• Polydipsia: Excessive thirst.
• Polyphagia: Excessive hunger (cells starved despite high BG).
• Plus: weight loss, fatigue, blurred vision, slow wound healing, recurrent infections.
Diagnosis:
• Fasting glucose ≥126 mg/dL (7 mM).
• Random glucose ≥200 mg/dL with symptoms.
• HbA1c ≥6.5% (3-month average).
• OGTT 2-hr ≥200 mg/dL.
Long-term complications ("Micro + Macro"):
Microvascular (small vessels):
• Retinopathy → blindness (leading cause worldwide).
• Nephropathy → kidney failure.
• Neuropathy → loss of sensation feet, autonomic dysfunction.
Macrovascular:
• Coronary artery disease → heart attack.
• Stroke.
• Peripheral arterial disease → amputation.
Other:
• Infections (poor immune response).
• Diabetic ketoacidosis (DKA) — emergency in Type 1.
• Cataracts.
Management:
(1) Lifestyle (Type 2 cornerstone):
• Diet: ↓ refined carbs, ↑ fiber, portion control.
• Exercise: 150 min/week moderate.
• Weight loss 5-10% body weight major improvement.
(2) Medications:
• Metformin (first-line Type 2).
• Sulphonylureas (insulin secretagogues).
• SGLT2 inhibitors, GLP-1 agonists (newer, also cardio-renal benefit).
• Insulin — all Type 1 + some Type 2.
(3) Monitoring:
• Self glucose monitoring.
• HbA1c every 3 months (target <7%).
• Annual: eye exam, foot exam, kidney function, lipids.
(4) Education + support:
• Diabetes educators.
• Family awareness.
• Sri Lanka — Diabetes Association support groups.
Prevention (Type 2):
Maintain healthy weight + regular exercise + balanced diet + avoid smoking. Family history → earlier screening recommended.
Ductless glands secrete hormones directly into blood. Slower than nervous system but longer-lasting effects. Coordinates growth, metabolism, reproduction, stress response.
Major glands + key hormones:
(1) Pituitary (உச்ச சுரப்பி) — "Master gland":
Under brain (hypothalamus control). Pea-sized.
• Growth hormone (GH) → growth, metabolism.
• TSH → stimulates thyroid.
• ACTH → stimulates adrenal cortex.
• ADH → kidney water retention.
• Oxytocin → labour contractions + milk ejection.
• Prolactin → milk production.
• FSH, LH → gonad stimulation.
(2) Thyroid:
Butterfly-shaped, neck front. Requires iodine.
• Thyroxine (T4) + T3 → basal metabolic rate, body temp.
• Calcitonin → lowers blood calcium.
Disorders:
• Hypothyroidism → cold intolerance, weight gain, fatigue (Hashimoto's).
• Hyperthyroidism → weight loss, anxiety, tremor (Graves' disease).
• Goitre → iodine deficiency enlargement.
(3) Parathyroid:
Behind thyroid.
• PTH → raises blood calcium (bone, kidney).
(4) Pancreas:
Dual exocrine + endocrine. Islets of Langerhans:
• β cells → insulin (lowers BG).
• α cells → glucagon (raises BG).
(5) Adrenal:
On top of kidneys. 2 parts:
• Cortex → cortisol (stress, anti-inflammatory), aldosterone (Na/K balance), sex hormones.
• Medulla → adrenaline (fight/flight).
(6) Gonads:
• Testes → testosterone.
• Ovaries → oestrogen + progesterone.
(7) Pineal gland:
Melatonin → sleep-wake cycle (circadian rhythm).
(8) Thymus:
T-cell maturation (immunity).
----
Diabetes Mellitus (DM) — Detailed:
Definition: Chronic metabolic disorder of elevated blood glucose due to insulin deficiency, resistance, or both.
Normal glucose regulation:
After meal → BG rises → β cells secrete insulin → cells take up glucose → BG normalises. Liver stores excess as glycogen.
Between meals → BG falls → α cells secrete glucagon → liver releases glucose → BG maintained ~5 mM.
Diabetes types:
Type 1 (insulin-dependent):
• Autoimmune destruction of β cells.
• Usually onset childhood/young adulthood.
• Complete insulin deficiency.
• Always needs insulin injections.
• ~10% of all DM.
Type 2 (insulin-resistant):
• Cells resist insulin action + later β cell exhaustion.
• Usually onset adulthood (>40), but younger now due to obesity epidemic.
• Lifestyle-related — obesity, sedentary, diet.
• ~90% of all DM.
• Sri Lanka prevalence ~10% adults.
Gestational diabetes: Pregnancy-related. Often resolves after delivery but increases future risk.
Symptoms (3 Ps):
• Polyuria: Excessive urination (glucose pulls water).
• Polydipsia: Excessive thirst.
• Polyphagia: Excessive hunger (cells starved despite high BG).
• Plus: weight loss, fatigue, blurred vision, slow wound healing, recurrent infections.
Diagnosis:
• Fasting glucose ≥126 mg/dL (7 mM).
• Random glucose ≥200 mg/dL with symptoms.
• HbA1c ≥6.5% (3-month average).
• OGTT 2-hr ≥200 mg/dL.
Long-term complications ("Micro + Macro"):
Microvascular (small vessels):
• Retinopathy → blindness (leading cause worldwide).
• Nephropathy → kidney failure.
• Neuropathy → loss of sensation feet, autonomic dysfunction.
Macrovascular:
• Coronary artery disease → heart attack.
• Stroke.
• Peripheral arterial disease → amputation.
Other:
• Infections (poor immune response).
• Diabetic ketoacidosis (DKA) — emergency in Type 1.
• Cataracts.
Management:
(1) Lifestyle (Type 2 cornerstone):
• Diet: ↓ refined carbs, ↑ fiber, portion control.
• Exercise: 150 min/week moderate.
• Weight loss 5-10% body weight major improvement.
(2) Medications:
• Metformin (first-line Type 2).
• Sulphonylureas (insulin secretagogues).
• SGLT2 inhibitors, GLP-1 agonists (newer, also cardio-renal benefit).
• Insulin — all Type 1 + some Type 2.
(3) Monitoring:
• Self glucose monitoring.
• HbA1c every 3 months (target <7%).
• Annual: eye exam, foot exam, kidney function, lipids.
(4) Education + support:
• Diabetes educators.
• Family awareness.
• Sri Lanka — Diabetes Association support groups.
Prevention (Type 2):
Maintain healthy weight + regular exercise + balanced diet + avoid smoking. Family history → earlier screening recommended.
7. Homeostasis என்றால் என்ன? உடல் வெப்பநிலை regulation + blood glucose regulation — இரண்டையும் negative feedback loop framework-ல் விளக்குக. Failure-ஆல் என்ன ஆகும்? (10 புள்ளி)
விடைத் திட்டம் — சேர்க்க வேண்டிய புள்ளிகள்:
- Definition.
- Negative feedback principle.
- Thermoregulation hypothalamus + sweat/shiver.
- Glucose: insulin/glucagon.
- Failure → hypothermia/hyperthermia, hypoglycaemia/diabetes.
Homeostasis (ஒர்சீர்த்திட நிலையம்):
The ability of organisms to maintain stable internal physical + chemical conditions despite external environmental variations. Coined by Cannon (1929) based on Bernard's "milieu intérieur" concept.
Examples of regulated variables:
• Body temperature: 37 ± 0.5 °C.
• Blood glucose: 4-7 mM.
• Blood pH: 7.35-7.45.
• Plasma osmolality: 280-295 mOsm/kg.
• Calcium: 2.2-2.6 mM.
• Oxygen saturation: 95-100%.
Negative feedback loop — core mechanism:
Components:
1. Stimulus: Change in regulated variable.
2. Sensor (receptor): Detects change.
3. Control centre: Integrates + compares to set point.
4. Effector: Acts to oppose the change.
5. Response: Variable returns to set point.
"Negative" = response opposes (reduces) the stimulus.
----
Example 1 — Thermoregulation:
Set point: ~37°C. Hypothalamus = control centre.
When body temp ↑ (hot day, exercise, fever):
• Sensor: Hypothalamic thermosensitive neurons + peripheral skin receptors detect ↑.
• Effectors:
- Sweat glands: Eccrine glands secrete sweat → evaporation cools (each gram water = 580 cal heat loss).
- Skin blood vessels: Vasodilation → more blood to surface → radiation heat loss.
- Behaviour: Seek shade, remove clothes.
• Result: Body temp ↓ back to 37°C.
When body temp ↓ (cold day):
• Sensor: Hypothalamic + skin cold receptors detect ↓.
• Effectors:
- Shivering: Skeletal muscle rapid contractions → heat production.
- Vasoconstriction: Skin blood vessels narrow → reduced heat loss.
- Goose bumps: Hair erector muscles (vestigial in humans).
- Brown fat thermogenesis: Babies (less developed in adults).
- Thyroid: Long-term ↑ metabolism.
- Behaviour: Wear more, seek warmth.
• Result: Body temp ↑ back to 37°C.
Fever:
Not homeostasis failure — controlled set-point elevation. Pyrogens (e.g., bacterial lipopolysaccharide → IL-1, IL-6) reset hypothalamus to higher set point. Body "feels cold" at 37°C, shivers to reach new set point ~39°C. Useful for fighting infection (most pathogens prefer 37°C).
Failures of thermoregulation:
• Hypothermia (<35°C): Confusion, slow breathing, eventually death. Cold exposure, immersion, alcohol intoxication.
• Hyperthermia (>40°C): Heat stroke. Brain damage, multi-organ failure, death if not rapidly cooled. Tropical climate + dehydration + exertion.
• Heat exhaustion: Excessive sweating → dehydration + electrolyte loss. Cramps, dizziness.
----
Example 2 — Blood glucose regulation:
Set point: 4-7 mM (~80-126 mg/dL fasting).
After eating (BG ↑):
• Sensor: Pancreatic β cells detect ↑ glucose.
• Effector: β cells secrete insulin.
• Insulin actions:
- Cells (muscle, fat) take up glucose via GLUT4 transporter.
- Liver stores glucose as glycogen.
- Inhibits gluconeogenesis.
- Promotes fat + protein storage.
• Result: BG ↓ back to set point.
Between meals (BG ↓):
• Sensor: Pancreatic α cells detect ↓ glucose.
• Effector: α cells secrete glucagon.
• Glucagon actions:
- Liver breaks down glycogen → glucose (glycogenolysis).
- Liver produces new glucose from amino acids (gluconeogenesis).
- Adipose tissue releases fatty acids.
• Result: BG ↑ back to set point.
Cortisol + adrenaline: Stress hormones also ↑ BG (longer-term + emergency).
Failures:
• Hypoglycaemia (<3.5 mM): Brain depends on glucose. Symptoms: sweating, tremor, confusion, seizure, coma. Insulin overdose, starvation, severe liver disease.
• Hyperglycaemia (chronic): Diabetes mellitus (covered separately). Long-term tissue damage.
• DKA: Severe insulin deficiency → fat breakdown → ketone bodies → metabolic acidosis. Emergency.
----
Other homeostasis examples (brief):
• pH: Buffer systems (bicarbonate) + lung CO₂ excretion + kidney H+ excretion.
• Water balance: ADH (vasopressin) + thirst.
• Calcium: PTH + calcitonin + vitamin D + kidney + bone.
• Blood pressure: Baroreceptors + heart rate + vascular tone + RAAS.
Why homeostasis matters:
Enzymes work optimally at narrow conditions. Outside range → cells die. Humans evolved set points for survival/reproduction. Disease often = homeostatic disruption.
The ability of organisms to maintain stable internal physical + chemical conditions despite external environmental variations. Coined by Cannon (1929) based on Bernard's "milieu intérieur" concept.
Examples of regulated variables:
• Body temperature: 37 ± 0.5 °C.
• Blood glucose: 4-7 mM.
• Blood pH: 7.35-7.45.
• Plasma osmolality: 280-295 mOsm/kg.
• Calcium: 2.2-2.6 mM.
• Oxygen saturation: 95-100%.
Negative feedback loop — core mechanism:
Components:
1. Stimulus: Change in regulated variable.
2. Sensor (receptor): Detects change.
3. Control centre: Integrates + compares to set point.
4. Effector: Acts to oppose the change.
5. Response: Variable returns to set point.
"Negative" = response opposes (reduces) the stimulus.
----
Example 1 — Thermoregulation:
Set point: ~37°C. Hypothalamus = control centre.
When body temp ↑ (hot day, exercise, fever):
• Sensor: Hypothalamic thermosensitive neurons + peripheral skin receptors detect ↑.
• Effectors:
- Sweat glands: Eccrine glands secrete sweat → evaporation cools (each gram water = 580 cal heat loss).
- Skin blood vessels: Vasodilation → more blood to surface → radiation heat loss.
- Behaviour: Seek shade, remove clothes.
• Result: Body temp ↓ back to 37°C.
When body temp ↓ (cold day):
• Sensor: Hypothalamic + skin cold receptors detect ↓.
• Effectors:
- Shivering: Skeletal muscle rapid contractions → heat production.
- Vasoconstriction: Skin blood vessels narrow → reduced heat loss.
- Goose bumps: Hair erector muscles (vestigial in humans).
- Brown fat thermogenesis: Babies (less developed in adults).
- Thyroid: Long-term ↑ metabolism.
- Behaviour: Wear more, seek warmth.
• Result: Body temp ↑ back to 37°C.
Fever:
Not homeostasis failure — controlled set-point elevation. Pyrogens (e.g., bacterial lipopolysaccharide → IL-1, IL-6) reset hypothalamus to higher set point. Body "feels cold" at 37°C, shivers to reach new set point ~39°C. Useful for fighting infection (most pathogens prefer 37°C).
Failures of thermoregulation:
• Hypothermia (<35°C): Confusion, slow breathing, eventually death. Cold exposure, immersion, alcohol intoxication.
• Hyperthermia (>40°C): Heat stroke. Brain damage, multi-organ failure, death if not rapidly cooled. Tropical climate + dehydration + exertion.
• Heat exhaustion: Excessive sweating → dehydration + electrolyte loss. Cramps, dizziness.
----
Example 2 — Blood glucose regulation:
Set point: 4-7 mM (~80-126 mg/dL fasting).
After eating (BG ↑):
• Sensor: Pancreatic β cells detect ↑ glucose.
• Effector: β cells secrete insulin.
• Insulin actions:
- Cells (muscle, fat) take up glucose via GLUT4 transporter.
- Liver stores glucose as glycogen.
- Inhibits gluconeogenesis.
- Promotes fat + protein storage.
• Result: BG ↓ back to set point.
Between meals (BG ↓):
• Sensor: Pancreatic α cells detect ↓ glucose.
• Effector: α cells secrete glucagon.
• Glucagon actions:
- Liver breaks down glycogen → glucose (glycogenolysis).
- Liver produces new glucose from amino acids (gluconeogenesis).
- Adipose tissue releases fatty acids.
• Result: BG ↑ back to set point.
Cortisol + adrenaline: Stress hormones also ↑ BG (longer-term + emergency).
Failures:
• Hypoglycaemia (<3.5 mM): Brain depends on glucose. Symptoms: sweating, tremor, confusion, seizure, coma. Insulin overdose, starvation, severe liver disease.
• Hyperglycaemia (chronic): Diabetes mellitus (covered separately). Long-term tissue damage.
• DKA: Severe insulin deficiency → fat breakdown → ketone bodies → metabolic acidosis. Emergency.
----
Other homeostasis examples (brief):
• pH: Buffer systems (bicarbonate) + lung CO₂ excretion + kidney H+ excretion.
• Water balance: ADH (vasopressin) + thirst.
• Calcium: PTH + calcitonin + vitamin D + kidney + bone.
• Blood pressure: Baroreceptors + heart rate + vascular tone + RAAS.
Why homeostasis matters:
Enzymes work optimally at narrow conditions. Outside range → cells die. Humans evolved set points for survival/reproduction. Disease often = homeostatic disruption.
🔥 மீட்டல் மையம்
பரீட்சைக்கு முன் இறுதி ஒரு நிமிடம் — மறக்கக்கூடாதவை மட்டும்.
- 5 body systems: Digestive · Respiratory · Excretory · Circulatory · Nervous/Endocrine (coordination).
- Digestion path: வாய் → களம் → இரைப்பை → சிறுகுடல் → பெருங்குடல் → குதம்.
- 3 macros: Carb → amylase → glucose. Protein → pepsin/trypsin → amino acid. Fat → lipase → fatty acid+glycerol.
- Accessory organs: ஈரல் (bile, store), பித்தப்பை (bile store), பாக்கிரியாஸ் (enzymes + insulin), salivary glands.
- Absorption: சிறுகுடல் villi-ல் primary.
- Respiration: நாசி → trachea → bronchi → bronchioles → alveoli (gas exchange).
- Inhalation: diaphragm ↓ contract, chest expand. Exhalation: reverse.
- Alveoli: 300M/lung, 70 m² surface, single-cell wall.
- Kidneys: 1M nephrons each, 180 L filtered → 1.5 L urine/day.
- Nephron 3 steps: filtration → reabsorption → secretion.
- Heart: 4 chambers (2 atria + 2 ventricles), 4 valves. BP 120/80.
- 2 circuits: Pulmonary (heart-lungs) + systemic (heart-body).
- Blood: Plasma 55% + RBC 45% + WBC + platelets.
- Brain: Cerebrum (thinking) + cerebellum (balance) + brain stem (vitals).
- Hormones: Insulin (pancreas, ↓BG), Adrenaline (stress), Thyroxine (metabolism), Growth hormone (pituitary).
- Homeostasis: Temp 37°C, BG 5 mM, pH 7.4 — negative feedback.
அலகின் முதுகெலும்பு — கருத்துக்களும் தொடர்புகளும்.
- 1. Digestive — mouth: Mastication + salivary amylase starch→maltose.
- 2. Stomach: HCl pH 2 (microbes kill) + pepsin protein digestion.
- 3. Small intestine (6m): Bile (liver, fat emulsify) + pancreatic enzymes + intestinal enzymes complete digestion. Villi+microvilli 200 m² absorption.
- 4. Large intestine: Water+mineral absorb. Bacterial vitamin K+B synthesis.
- 5. Liver: Bile, glycogen storage, detox, plasma proteins.
- 6. Pancreas: Exocrine (amylase, lipase, trypsin) + endocrine (insulin, glucagon).
- 7. Respiratory path: Nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli.
- 8. Breathing: Diaphragm contraction → volume↑ pressure↓ → inhale. Relaxation → exhale.
- 9. Gas exchange: O₂ alveolus→blood (Hb-bind in RBC). CO₂ blood→alveolus. Diffusion-driven.
- 10. Cellular respiration: Glucose + O₂ → CO₂ + H₂O + 36 ATP (mitochondria).
- 11. Kidney anatomy: Cortex + medulla + renal pelvis. ~1.2 L/min blood flow.
- 12. Nephron: Glomerular filtration (180 L/day) → tubular reabsorption (99%) → secretion. Final 1.5 L urine.
- 13. Urine: 95% water + urea + salts. NO glucose normally (Glycosuria = diabetes sign).
- 14. Other excretion: Lungs (CO₂), skin (sweat), liver (bile pigments).
- 15. Heart chambers: RA→RV→lungs (pulmonary); LA→LV→body (systemic). LV thickest.
- 16. Valves: Tricuspid, pulmonary, mitral, aortic. Prevent backflow.
- 17. Blood vessels: Arteries thick (high pressure) + Veins thin+valves (low return) + Capillaries 1-cell exchange.
- 18. Blood components: Plasma (yellowish liquid 92% water), RBC (Hb O₂ transport), WBC (immunity 5 types), Platelets (clotting).
- 19. Heart rate: 60-100 bpm rest. BP 120/80. Athletes 40-60.
- 20. CNS: Brain + spinal cord. PNS: peripheral nerves.
- 21. Cerebrum: 4 lobes (frontal-planning, parietal-touch, occipital-vision, temporal-hearing). Consciousness + memory.
- 22. Cerebellum: Balance, coordination, fine motor.
- 23. Brain stem: Vitals — heart, breathing, BP.
- 24. Spinal cord: Reflex centre + signal highway.
- 25. Neuron: Cell body + dendrites (input) + axon (output) + synapse. 3 types: sensory, inter, motor.
- 26. Reflex arc: Stimulus → receptor → sensory neuron → CNS interneuron → motor neuron → effector → response. <0.1 s.
- 27. Endocrine: Pituitary (master), thyroid (metabolism), pancreas (insulin), adrenal (stress), gonads (sex).
- 28. Diabetes: Insulin failure → high BG. Type 1 = β-cell destruction. Type 2 = insulin resistance.
- 29. Goitre: Iodine deficiency → thyroid enlargement.
- 30. Homeostasis: Negative feedback — stimulus→sensor→control→effector→opposite response.
பரீட்சைக்கு முந்தின இரவு முழு அலகையும் ஓட்டிப் பார்.
- Digestion: Mouth (amylase starch) → Stomach (HCl+pepsin protein) → Small intestine (complete + absorb) → Large intestine (water) → Rectum.
- Enzymes: Amylase=starch; Pepsin/trypsin=protein; Lipase=fat. End products glucose, amino acids, fatty acids.
- Accessory: Liver=bile+glycogen, Pancreas=enzymes+insulin, Gallbladder=bile store.
- Respiratory path: Nose→trachea→bronchi→bronchioles→alveoli (gas exchange).
- Inhale = diaphragm contracts ↓ + chest expands. 12-20 breaths/min, ~500 mL each.
- Alveoli: 300M/lung × 2, ~70 m² total surface, single-cell wall, capillary-rich.
- O₂ transport: RBC haemoglobin binds O₂ → tissues. CO₂ back to lungs.
- Cellular resp: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 36 ATP in mitochondria.
- Kidneys: Filter 180 L blood/day → 1.5 L urine. ~1M nephrons each.
- Nephron: Glomerular filtration → tubular reabsorption (99%) → secretion.
- Glucose in urine = diabetes. Protein in urine = kidney damage.
- Heart: 4 chambers (RA, RV, LA, LV). LV thickest = pumps body.
- RA→RV→lungs→LA→LV→body→RA. Pulmonary artery only artery with deoxy blood; pulmonary vein only vein with oxy.
- Vessels: Arteries thick away; veins thin+valves to heart; capillaries single-cell exchange.
- Blood: Plasma (55%) + RBC (O₂) + WBC (immune) + platelets (clot).
- BP normal: 120/80. Hypertension >140/90.
- Brain: Cerebrum (thinking, voluntary) + Cerebellum (balance) + Brain stem (heart, breathing).
- Spinal reflex: Pain → receptor → sensory → spinal interneuron → motor → muscle. Brain bypassed for speed.
- Hormones: Insulin lowers BG, Glucagon raises. Thyroxine ↑metabolism (iodine needed). Adrenaline = stress.
- Diabetes: ↑BG, polyuria, polydipsia, polyphagia. Long-term: retinopathy, nephropathy, neuropathy, CVD.
- Homeostasis: Temp 37°C, BG 5 mM, pH 7.4. Negative feedback maintains.
- ⚠ Common traps: Pancreas has BOTH digestion + hormones. Pulmonary artery carries deoxy blood. Reflex bypasses brain.
- ⭐ Numerical anchors: 4 chambers + 4 valves + 6 m small intestine + 300M alveoli + 70 m² alveolar surface + 180 L blood filtered + 1M nephrons + 5 L blood total + 5M RBC/μL.
- 📋 Tamil glossary: சமிபாடு=digestion; சுவாசம்=respiration; குருதி=blood; இதயம்=heart; சிறுநீரகம்=kidney; ஈரல்=liver; சதையீரல்=pancreas; நரம்பு=nerve; சுரப்பி=gland; ஹார்மோன்=hormone; மூளை=brain; ஒர்சீர்த்திட நிலையம்=homeostasis.