Respiratory System

ATP = universal energy currency in respiration.
Crebs cycle in mitochondria produces maximum number of ATP.
Lungs covered by pleural membranes.
Oxygen transport: carried by haemoglobin.
Carbon monoxide poisoning: CO forms carboxyhaemoglobin (toxic).
Respiration: Process of gas exchange (oxygen intake, carbon dioxide removal).
Ventilation: Movement of air into and out of lungs (breathing).
Alveoli: Tiny air sacs in lungs where gas exchange occurs; surrounded by capillaries.
Diaphragm: Muscle aiding lung expansion/contraction during breathing.
Trachea: Windpipe channeling air to lungs; Reinforced by cartilage, conducts air to bronchi.
Bronchi/Bronchioles: Airway branches leading to alveoli; Distribute air to alveoli.
Gas Exchange: simple diffusion; Diffusion of oxygen and carbon dioxide across alveolar membranes.
Larynx: Voice box aiding sound production and air passage.
- Epiglottis: Covers larynx when something is swallowed.
Nasal Cavity: Filters, warms, moistens incoming air.
Pharynx: Common passage for air and food; directs air to larynx.
Lungs: Contain alveoli; right lung (3 lobes, longer), left lung (2 lobes, smaller & flattened).
Diaphragm and Intercostal Muscles: Facilitate ventilation by expanding/contracting chest cavity.
Inhalation: Diaphragm contracts, chest expands, air enters lungs.
Exhalation: Diaphragm relaxes, air is expelled.
Transport: Oxygen binds to haemoglobin in red blood cells; carbon dioxide is transported as bicarbonate or dissolved gas.
Medulla Oblongata: Controls breathing rate based on Carbon dioxide levels.
Chemoreceptors: Detect changes in blood pH, Carbon dioxide, and Oxygen.
Olfactory receptor: Nose (Not well developed in humans), well developed in dogs, cats.
Photoreceptor: Eyes.
Importance:
- Supplies oxygen for cellular respiration
- Removes carbon dioxide, maintaining pH balance
- Supports metabolic energy production and homeostasis
Clome in fish, prawns
Pulmonary skin in Lizard, bird
Trachea in Grasshopper, cockroach

Introduction

The respiratory system is the biological system responsible for intake of oxygen and removal of carbon dioxide through the process of breathing and cellular respiration.
In Bihar, issues like air pollution, tuberculosis, and asthma make this topic socially and medically significant.

Major Organs of the Human Respiratory System

Nasal Cavity: Filters, moistens, and warms air
Pharynx: Passage for air and food
Larynx: Voice box
Trachea: Windpipe; lined with mucus and cilia
Bronchi & Bronchioles: Airways into lungs
Lungs: Site of gas exchange
Alveoli: Air sacs in lungs where oxygen enters blood and CO₂ exits
Diaphragm: Dome-shaped muscle; helps in breathing

📝 PYQ (BPSC): Exchange of gases occurs in which part of lungs? → Alveoli

Types of Respiration

External Respiration: Exchange of gases between lungs and blood
Internal Respiration: Exchange between blood and body tissues
Cellular Respiration: In mitochondria → Glucose + O₂ → ATP + CO₂ + H₂O

Breathing Process

Inhalation: Diaphragm contracts → chest expands → air enters lungs
Exhalation: Diaphragm relaxes → chest contracts → CO₂ expelled
Rate: ~12–20 breaths per minute in adults

📝 Expected MCQ: Which muscle helps in breathing? → Diaphragm
📝 Expected MCQ: During inhalation, what happens to diaphragm? → Contracts and flattens

Transport of Gases

Oxygen:
- 97% carried by hemoglobin in RBCs
- 3% dissolved in plasma
Carbon Dioxide:
- 70% as bicarbonates
- 23% with hemoglobin
- 7% in plasma

📝 Expected MCQ: Most CO₂ is carried in which form? → Bicarbonates

Diseases Related to Respiratory System

Asthma: Narrowing of airways, breathing difficulty
Bronchitis: Inflammation of bronchial tubes
Pneumonia: Infection in alveoli (often by bacteria/virus)
Tuberculosis (TB): Caused by Mycobacterium tuberculosis
Lung Cancer: Often due to smoking or air pollution

Bihar-Specific Relevance

Air pollution in urban areas (e.g., Patna) → rise in asthma, bronchitis
High burden of tuberculosis, especially in rural Bihar
Indoor smoke from biomass fuel → affects women and children
Government programs:
- Nikshay Portal for TB monitoring
- Ujjwala Yojana to reduce smoke exposure
- National Tuberculosis Elimination Program (NTEP)

📝 Expected MCQ: Which scheme provides free LPG to reduce indoor pollution? → Ujjwala Yojana

PYQs + Expected MCQs

📝 PYQ (BPSC): Exchange of gases occurs in? → Alveoli
📝 Expected MCQ: Voice box is also known as? → Larynx
📝 Expected MCQ: TB affects which organ? → Lungs
📝 Expected MCQ: Name the muscle involved in breathing. → Diaphragm
📝 Expected MCQ: What carries most oxygen in blood? → Hemoglobin

Quick Revision Points

Respiration = Inhalation + Exhalation + Cellular ATP production
Gas exchange occurs in alveoli
O₂ → carried by hemoglobin; CO₂ → as bicarbonate
TB, asthma, pollution-related diseases affect Bihar severely
Diaphragm helps in breathing
Govt schemes: NTEP, Ujjwala, Nikshay

Sources Used

NCERT Class 10 Science – Life Processes
Lucent GK – Biology Section
Drishti Science Quick Book
Ghatna Chakra PYQs – BPSC, Teacher
Ministry of Health – Nikshay Dashboard
State Health Society Bihar – TB & Air Pollution Reports