BREATHING AND EXCHANGE OF GASES | Hinglish NEET Notes | Class 11 Biology

1. Introduction To Breathing And Gaseous Exchange

• Oxygen (O₂) living organisms ke liye bahut important hai. Ye simple food molecules jaise glucose, amino acids, aur fatty acids ko todne me help karta hai. Ye breakdown body ko energy deta hai, jo saari activities ke liye zaroori hai.
• Jab oxygen energy release karne me help karta hai, to ye carbon dioxide (CO₂) bhi as a waste product create karta hai. Ye gas harmful hai aur body se regular remove karna zaroori hai.
• Kyuki oxygen continuously use hota hai aur carbon dioxide continuously produce hota hai, body ko oxygen lena aur carbon dioxide push karna zaroori hai. Ye constant exchange survival ke liye necessary hai.
• Air se oxygen lena aur body se carbon dioxide remove karne ke process ko breathing kehte hain. Simple words me, breathing ye hai ki kaise hamari body gases ko environment ke saath exchange karti hai.
• Agar aap apne haath chest par rakho, to aap feel kar sakte ho ki chest up aur down ho rahi hai. Ye movement breathing ki wajah se hoti hai. Ye show karta hai ki lungs me air ja rahi hai aur bahar aa rahi hai.
• Body me special parts hote hain jo respiratory organs kehlate hain aur ye breathing me help karte hain. Ye organs proper system ke saath milke oxygen lete hain aur carbon dioxide push karte hain. Is chapter ke next sections me explain kiya gaya hai ki breathing kaise kaam karti hai detail me.

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2. Organs Involved in Breathing

• Mechanisms of breathing alag-alag animals me different hote hain. Ye unke habitat (jahaan wo rehte hain) aur body ke structure par depend karta hai.
• Lower invertebrates jaise sponges, coelenterates, aur flatworms gases ko simple diffusion ke through exchange karte hain. Inke paas breathing ke liye special organs nahi hote. Iske instead, oxygen (O₂) aur carbon dioxide (CO₂) unke poore body surface ke across move karte hain.
• Earthworms apni moist skin (cuticle) ke through breathe karte hain. Ye skin O₂ aur CO₂ ko directly air ke saath exchange karne me help karti hai.
• Insects ke paas tracheal system hota hai. Ye tiny air tubes se bana hota hai jo atmospheric oxygen ko directly body cells tak le jata hai aur carbon dioxide ko remove karta hai.
• Bahut se aquatic arthropods aur molluscs gills ka use karke breathe karte hain. Ye vascularised structures hote hain, matlab inme blood vessels hote hain. Is process ko branchial respiration kehte hain.
• Terrestrial animals jaise reptiles, birds, aur mammals breathing ke liye lungs ka use karte hain. Lungs vascularised sacs hote hain jahan oxygen aur carbon dioxide exchange hoti hai. Is process ko pulmonary respiration kehte hain.
• Fishes, jo ki vertebrates bhi hain, gills ke through breathe karte hain. Ye gills specially water me life ke liye adapt kiye gaye hain.
• Amphibians, jaise frogs, apni lungs ke through breathe kar sakte hain, lekin ye apni moist skin ke through bhi gases exchange kar sakte hain. Is process ko cutaneous respiration kehte hain.

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3. Components of Human Respiratory Tract

• Hamare paas external nostrils ka ek pair hota hai jo upper lips ke upar located hai. Ye nostrils ek nasal passage me open hote hain, jo ek nasal chamber tak jata hai.
• Nasal chamber pharynx me open hota hai, jo ek aisa region hai jo dono food aur air ke liye common path serve karta hai.
• Pharynx larynx se connect hota hai, jo trachea me lead karta hai. Larynx ek cartilaginous box hai jo sound produce karne me help karta hai, isliye ise sound box bhi kehte hain.
• Swallowing ke dauran, ek thin elastic cartilage jo epiglottis kehlata hai, glottis ko cover karta hai. Ye food ko larynx me enter karne se prevent karta hai.
• Trachea ek straight tube hai jo chest ke middle (thoracic cavity) tak jata hai. 5th thoracic vertebra ke level par, ye right aur left primary bronchi me divide hota hai.
• Har primary bronchus further divide hota hai aur secondary bronchi, tertiary bronchi, aur phir chhoti tubes jo bronchioles kehlati hain banata hai, jo finally terminal bronchioles me end hoti hain.
• Trachea, bronchi, aur initial bronchioles incomplete rings of cartilage se supported hote hain, jo airways ko open rakhte hain.
• Har terminal bronchiole se chhoti, thin-walled, aur vascularised structures alveoli banti hain, jahan gas exchange hota hai.
• Bronchi, bronchioles, aur alveoli ka network milkar lungs banata hai.
• Do lungs hote hain, aur har ek double-layered pleura se covered hota hai. In layers ke beech pleural fluid hota hai, jo lungs ke move karte waqt friction reduce karta hai.
• Outer pleural membrane chest wall (thoracic lining) se attached hoti hai, jabki inner pleural membrane lung surface se attached hoti hai.
• Respiratory system ka part jo nostrils se terminal bronchioles tak hai, usse conducting part kehte hain. Ye air transport karta hai, foreign particles ko filter karta hai, moisture add karta hai, aur air ko warm karta hai.
• Alveoli aur unke ducts respiratory ya exchange part banate hain, jahan actual gas exchange hota hai oxygen (O₂) aur carbon dioxide (CO₂) ke beech air aur blood me.
• Lungs thoracic cavity me located hain, jo ek completely closed, air-tight space hai.
• Thoracic cavity piche vertebral column, front me sternum, sides me ribs, aur bottom me dome-shaped diaphragm se banta hai.
• Thoracic cavity ke size me koi bhi change lung volume me change lead karta hai. Ye link chest cavity aur lung cavity ke beech essential hai, kyuki hum directly lung size control nahi kar sakte.

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Respiration includes the following important steps:-

• Breathing or pulmonary ventilation– Bahar ka air lungs me enter karta hai, aur CO₂-rich air push out hoti hai.
• Gas diffusion across alveolar membrane– Oxygen blood me enter karta hai, aur CO₂ blood se alveoli ke through leave karta hai.
• Transport of gases through blood– Blood oxygen aur carbon dioxide ko tissues tak aur tissues se carry karta hai.
• Diffusion of gases between blood and body tissues– Oxygen tissues me jata hai aur carbon dioxide wapas blood me aata hai.
• Cellular respiration– ChatGPT said:
• Oxygen cells dwara nutrients ko break down karne ke liye use hota hai (catabolic reactions), aur carbon dioxide waste product ke roop me release hoti hai.

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4. Process of Inhalation and Exhalation

• Breathing ke do main steps hote hain: inspiration aur expiration. Inspiration me, atmosphere se air lungs me enter karta hai. Expiration me, lungs se air push out hoti hai.
• Air lungs me in aur out move karta hai lungs aur bahar ke atmosphere ke beech pressure difference ki wajah se.
• Inspiration tab hoti hai jab lungs ke andar ka pressure (intra-pulmonary pressure) atmospheric pressure se lower hota hai. Ye negative pressure air ko lungs me kheenchta hai.
• Expiration tab hoti hai jab intra-pulmonary pressure atmospheric pressure se higher ho jata hai, jo air ko lungs se bahar force karta hai.
• Ye pressure difference diaphragm aur intercostal muscles (ribs ke beech ke muscles) ke dwara create hota hai, jo chest cavity ko expand aur shrink karne me help karte hain.
• Inspiration tab start hoti hai jab diaphragm contract karta hai, jo chest cavity ko front-to-back (antero-posterior) direction me larger banata hai.
• Saath hi, external intercostal muscles contract karte hain aur ribs aur sternum ko lift karte hain, jo chest size ko top se bottom (dorso-ventral direction) me increase karta hai.
• Chest volume me increase lung (pulmonary) volume me increase lead karta hai.
• Jaise hi lung volume increase hota hai, intra-pulmonary pressure atmospheric pressure se neeche gir jata hai, aur air lungs me flow karta hai. Ye inspiration hai.
• Jab diaphragm aur intercostal muscles relax karte hain, chest cavity shrink hoti hai, aur lung volume decrease hota hai.
• Ye pulmonary volume me decrease intra-pulmonary pressure ko thoda atmospheric pressure se upar le jata hai, aur air push out hoti hai. Ye expiration hai.
• Hum zarurat padne par zyada strongly breathe kar sakte hain, abdomen ke extra muscles ka use karke inhalation aur exhalation ki force increase karte hain.
• A healthy person usually breathes 12 to 16 times per minute under normal conditions.
• Breathing ke dauran move hone wale air ka amount ek device ke through measure kiya ja sakta hai, jise spirometer kehte hain. Ye lung health aur respiratory function check karne me medical tests me useful hai.

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5. Types of Pulmonary Volumes and Capacities

Some Important Terms Are Below There🥰-

• Tidal Volume (TV) wo amount of air hai jo ek person normal breathing ke dauran inhale ya exhale karta hai. Ye lagbhag 500 mL hota hai. Isliye, ek minute me ek healthy person 6000 to 8000 mL air inhale aur exhale karta hai.
• Expiratory Reserve Volume (ERV) wo extra amount of air hai jo ek person normal exhalation ke baad effort ke saath breathe out kar sakta hai. Ye lagbhag 1000 to 1100 mL hota hai.
• Inspiratory Reserve Volume (IRV) wo extra amount of air hai jo ek person normal inhalation ke baad effort ke saath breathe in kar sakta hai. Ye lagbhag 2500 to 3000 mL hota hai.
• Residual Volume (RV) wo amount of air hai jo lungs me hamesha rehta hai, even ek strong aur forceful exhalation ke baad bhi. Ye lagbhag 1100 to 1200 mL hota hai.

In basic respiratory volumes ko combine karke alag-alag lung capacities milti hain, jo medical diagnosis me useful hoti hain.

• Expiratory Capacity (EC) wo total air hai jo ek person normal inhalation ke baad breathe out kar sakta hai. Isme tidal volume (TV) aur expiratory reserve volume (ERV) include hote hain.
  • So, EC = TV + ERV.
• Inspiratory Capacity (IC) wo total air hai jo ek person normal exhalation ke baad breathe in kar sakta hai. Isme tidal volume (TV) aur inspiratory reserve volume (IRV) include hote hain.
  • So, IC = TV + IRV.
• ChatGPT said:
• Vital Capacity (VC) wo maximum amount of air hai jo ek person forceful exhalation ke baad inhale kar sakta hai, ya forceful inhalation ke baad exhale kar sakta hai.
  • It includes ERV, TV, and IRV.
• ChatGPT said:
• Functional Residual Capacity (FRC) wo amount of air hai jo lungs me normal exhalation ke baad bacha rehta hai. Isme expiratory reserve volume (ERV) aur residual volume (RV) include hote hain.
  • So, FRC = ERV + RV.
• Total Lung Capacity (TLC) wo maximum volume of air hai jo lungs ek strong inhalation ke baad hold kar sakte hain.
  • Isme RV, ERV, TV, aur IRV include hote hain, ya aap keh sakte ho TLC = VC + RV.

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6. Mechanism of Oxygen and Carbon Dioxide Exchange

• Exchange of gases human physiology me ek vital process hai jahan oxygen (O₂) aur carbon dioxide (CO₂) lungs, blood, aur tissues ke beech transfer hote hain. Alveoli, jo lungs me tiny sac-like structures hain, primary site hain jahan ye exchange hota hai. Lekin, gas exchange sirf alveoli tak limited nahi hai; ye blood aur tissues ke beech poore body me bhi hota hai. Ye pura process simple diffusion ke through kaam karta hai, jahan gases higher concentration ya partial pressure wale regions se lower concentration wale regions me move karte hain. Ye movement passive hai aur iske liye koi energy ki zarurat nahi hoti.
• Gas exchange me ek important concept hai partial pressure, jo ek gas ke mixture me exert kiye gaye pressure ko refer karta hai. Is context me, pO₂ oxygen ka partial pressure represent karta hai aur pCO₂ carbon dioxide ka. Gas diffusion ki direction partial pressure gradient se determine hoti hai, jahan har gas high partial pressure wale region se low partial pressure wale region me move karti hai.
• Oxygen ke case me, partial pressure alveoli me sabse high hota hai (104 mm Hg), oxygenated blood me lower hota hai (95 mm Hg), aur tissues me lowest hota hai (40 mm Hg). Ye ek clear gradient create karta hai oxygen ke liye alveoli → blood → tissues move karne ke liye.
• Carbon dioxide me reverse hota hai. Iska partial pressure tissues me sabse high hota hai (45 mm Hg), thoda lower deoxygenated blood me hota hai (45 mm Hg), aur alveolar air me lowest hota hai (40 mm Hg). Ye allow karta hai CO₂ ko tissues → blood → alveoli move karne ke liye, jahan se ye exhalation ke through expel hoti hai.
• Partial pressure table ke according, atmospheric air me lagbhag 159 mm Hg O₂ aur sirf 0.3 mm Hg CO₂ hoti hai, jabki alveolar air me 104 mm Hg O₂ aur 40 mm Hg CO₂ hoti hai. Deoxygenated blood jo lungs me aata hai, usme sirf 40 mm Hg O₂ aur 45 mm Hg CO₂ hoti hai. Oxygenation ke baad, ye blood lungs se 95 mm Hg O₂ aur 40 mm Hg CO₂ ke saath nikalta hai, ready to deliver oxygen to tissues aur carbon dioxide pick up karne ke liye. Ye pressure differences body ke different parts me continuous aur effective gas exchange ko support karte hain.
• Gas exchange me ek aur critical factor hai solubility of gases. Carbon dioxide plasma me oxygen ke comparison me lagbhag 20–25 times zyada soluble hai. Is wajah se, chhota sa partial pressure difference bhi CO₂ ka large amount diffuse karne ke liye kaafi hota hai, jo uske removal ko zyada efficient banata hai. Contrast me, oxygen, kam soluble hone ki wajah se, effective diffusion ke liye steeper pressure gradient require karta hai. Gas exchange ki rate diffusion membrane ki thickness par bhi depend karti hai. Humans me, diffusion membrane teen extremely thin layers se bani hoti hai – squamous epithelium of alveoli, endothelium of alveolar capillaries, aur unke beech ek thin basement membrane. Teen layers hone ke bawajood, is membrane ki overall thickness 1 millimetre se kam hai, jo quick gas exchange ke liye ideal hai.
• In summary, exchange of gases ek highly efficient process hai, jo structural aur functional adaptations jaise thin membranes, partial pressure gradients, aur CO₂ ki high solubility se support hoti hai. Ye conditions ensure karti hain ki oxygen tissues tak effectively deliver ho aur carbon dioxide rapidly lungs ke through body se remove ho.

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7. Transport Mechanism of O₂ and CO₂

Blood gases, specifically oxygen (O₂) aur carbon dioxide (CO₂) ke transport ka medium ka kaam karta hai. Oxygen ka zyada tar, lagbhag 97%, red blood cells (RBCs) ke through transport hota hai. Ye RBCs oxygen ko hemoglobin ke saath bind karke carry karte hain. Baaki ka 3% oxygen dissolved form me blood plasma me transport hota hai, jo blood ka fluid component hai. Carbon dioxide ke case me, lagbhag 20–25% RBCs dwara carry hota hai, jabki majority, nearly 70%, bicarbonate ions ke form me plasma me transport hota hai. Sirf lagbhag 7% CO₂ dissolved state me plasma ke through transport hota hai. Ye show karta hai ki dono gases blood ke through transport hoti hain, lekin unke movement ke liye alag mechanisms aur proportions use hote hain.

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7.1 Oxygen Transport Mechanism

Haemoglobin ek red-coloured pigment hai jisme iron hota hai aur ye red blood cells (RBCs) me paya jata hai. Oxygen (O₂) haemoglobin ke saath reversible way me bind karta hai, jisse ek compound oxyhaemoglobin banta hai. Har haemoglobin molecule maximum four oxygen molecules carry kar sakta hai.

Oxygen ka haemoglobin ke saath binding mainly partial pressure of oxygen (pO₂) par depend karta hai. Lekin, dusre factors jaise partial pressure of carbon dioxide (pCO₂), hydrogen ions (H⁺) ka concentration, aur temperature bhi is binding process ko affect karte hain.

Jab haemoglobin ki oxygen ke saath percentage saturation ko pO₂ ke against plot karte hain, to ek sigmoid-shaped curve milti hai. Is curve ko oxygen dissociation curve kehte hain, aur ye samajhne me useful hai ki kaise factors jaise pCO₂ aur H⁺ concentration oxygen-haemoglobin binding ko affect karte hain.

Lungs ke alveoli me, pO₂ high, pCO₂ low, H⁺ concentration low, aur temperature lower hota hai – ye sab conditions oxyhaemoglobin formation ko support karti hain. Contrast me, body tissues me pO₂ low, pCO₂ high, H⁺ concentration high, aur temperature higher hota hai, jo oxygen ko oxyhaemoglobin se separate hone ke liye suitable banata hai.

Iska matlab hai ki oxygen lungs me haemoglobin ke saath bind hota hai aur tissues me release hota hai. Normal physiological conditions me, har 100 ml oxygenated blood lagbhag 5 ml oxygen tissues tak deliver karta hai.

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7.2 Carbon Dioxide Transport Mechanism

Lagbhag 20–25% carbon dioxide (CO₂) body me haemoglobin dwara carbamino-haemoglobin ke form me carry hoti hai. Ye binding partial pressure of CO₂ (pCO₂) aur oxygen (pO₂) par depend karti hai.

• Tissues me (jahaan pCO₂ high aur pO₂ low hota hai), zyada CO₂ haemoglobin ke saath bind karta hai.
• Alveoli me (jahaan pCO₂ low aur pO₂ high hota hai), CO₂ haemoglobin se release hoti hai.

Red Blood Cells (RBCs) me ek enzyme carbonic anhydrase kaafi hota hai, jo help karta hai convert karne me:
CO₂ + H₂O ⇌ H₂CO₃ ⇌ HCO₃⁻ + H⁺
This reaction goes:

• Forward in tissues (CO₂ bicarbonate HCO₃⁻ me convert hoti hai transport ke liye).
• Backward in alveoli (HCO₃⁻ wapas CO₂ me convert hoti hai aur exhalation ke dauran release hoti hai).

Isliye, CO₂ blood me bicarbonate ke form me tissues se lungs tak carry hoti hai, aur har 100 ml deoxygenated blood se lagbhag 4 ml CO₂ alveoli me release hoti hai.

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8. How Respiration Is Regulated ?

• Human beings apni breathing rate ko body tissues ki needs ke hisaab se control aur adjust kar sakte hain. Ye control nervous system dwara manage hota hai. Brain ka ek special part, jo medulla me located hai, respiratory rhythm centre kehlata hai aur mainly is process ko control karta hai. Brain ka ek aur part pons region me, pneumotaxic centre ke naam se, respiratory rhythm centre ke actions ko influence kar sakta hai. Pneumotaxic centre se signals inspiration ki length reduce kar sakte hain aur is tarah breathing rate ko change karte hain.
• Rhythm centre ke paas ek chemosensitive area bhi hota hai jo carbon dioxide (CO₂) aur hydrogen ions (H⁺) ke liye bahut sensitive hai. Jab in substances ka level badhta hai, ye area activate hota hai. Ye phir rhythm centre ko signal deta hai taaki breathing process ko adjust kiya ja sake aur extra CO₂ aur H⁺ body se remove ho sake.
• Iske alawa, aortic arch aur carotid artery me receptors CO₂ aur H⁺ concentrations me changes detect kar sakte hain aur signals rhythm centre ko bhejte hain taaki corrective action liya ja sake. Interesting baat ye hai ki oxygen breathing rate control me major role nahi play karta.

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9. Diseases Related to Breathing System

1. Emphysema:
   Ye ek chronic (long-term) disease hai jisme alveoli (lungs ke air sacs) ki walls damage ho jati hain. Isse gas exchange ke liye surface area reduce ho jata hai. Cigarette smoking emphysema ka ek major cause hai.
2. Asthma:
   Ye ek breathing problem hai jahan person ko difficulty in breathing hoti hai saath me wheezing sound bhi aata hai. Ye bronchi aur bronchioles (airways) me inflammation ki wajah se hota hai.
3. Occupational Respiratory Disorders:
   Aise jobs me jaise grinding ya stone-breaking, workers bohot dust inhale karte hain. Body ka defense system itna dust handle nahi kar pata, jisse inflammation aur fibrosis (extra fibrous tissues ka formation) hota hai. Isse serious lung damage hota hai. Isse bachne ke liye, workers ko protective masks use karne chahiye.

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10. Chapter Overview

• Oxygen is needed for energy:– Cells oxygen ka use metabolism ke liye karte hain, jo unhe energy produce karne me help karta hai. Lekin is process ke dauran, carbon dioxide (CO₂) bhi produce hoti hai, jo body ke liye harmful hai.
• Oxygen and carbon dioxide transport system:- Animals ne alag-alag methods develop kiye hain taaki oxygen sabhi body cells tak deliver ho aur carbon dioxide unse remove ho sake.
• Human respiratory system:– Humans me respiratory system well-developed hai. Isme do lungs aur airways jaise nose, trachea, bronchi, etc., shamil hain, jo breathing me help karte hain.
• Breathing is the first step of respiration:- Breathing ka matlab hai air ko lena (inspiration) aur air ko bahar release karna (expiration). Ye respiration ka pehla basic step hai.
• Respiration ke other steps:- :-
  • Oxygen aur carbon dioxide ka exchange alveoli (lungs) aur blood ke beech.
  • In gases ka blood ke through poore body me transport.
  • Gases ka exchange blood aur body tissues ke beech.
  • Cells oxygen ka use karke energy produce karte hain. Isse cellular respiration kehte hain.
• Breathing kaise hoti hai:- Breathing me outside air aur alveoli ke beech pressure differences create karna shamil hai. Ye intercostal muscles (ribs ke beech) aur diaphragm (lungs ke neeche ek muscle) ki help se hota hai.
• Breathing ke dauran air ko measure karna:- Breathing me involve air ka amount ek device ke through measure kiya ja sakta hai, jise spirometer kehte hain. Ye measurements medical diagnosis me helpful hain.
• Lungs aur tissues me gases ka exchange kaise hota hai:-
  • Gases (oxygen aur carbon dioxide) diffusion process ke through move karte hain. Ye movement depend karta hai on:-
    • Partial pressure of oxygen (pO₂) aur carbon dioxide (pCO₂),
    • Gases ki solubility,
    • Jis membrane par exchange hota hai uski thickness.
• Gas diffusion ki direction:-–
  • Oxygen alveoli se blood me aur blood se tissues me move karti hai.
  • Carbon dioxide tissues se blood me aur phir alveoli me move karti hai (opposite direction).
• Oxygen ka transport body me:-
  • Zyada tar oxygen red blood cells me haemoglobin ke through carry hoti hai. Is combination ko oxyhaemoglobin kehte hain.
    • Lungs me, jahaan pO₂ high hota hai, oxygen haemoglobin ke saath bind karta hai.
    • Tissues me, jahaan pO₂ low aur pCO₂ high hota hai, oxygen release hoti hai.
• Carbon dioxide transport body me:-
  • Lagbhag 70% CO₂ bicarbonate ions (HCO₃⁻) ke form me transport hoti hai, ek enzyme carbonic anhydrase ki help se.
  • 20–25% CO₂ haemoglobin ke saath bind karke carbamino-haemoglobin banata hai.
  • Tissues me (jahaan CO₂ high hota hai), ye blood me enter karta hai; alveoli me (jahaan CO₂ low hota hai), ye blood se bahar aata hai.
• Brain humari breathing rhythm control karta hai:-
  • Medulla part of brain me respiratory centre hota hai jo breathing ke rhythm ko control karta hai.
    • Pons region of brain me pneumotaxic centre hota hai jo breathing rate ko modify kar sakta hai.
    • Medulla me ek chemosensitive area bhi hota hai jo breathing ko adjust karne me help karta hai chemical signals jaise CO₂ levels ke based.

Thank You🥰

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