Finals Sem.1 / Respiration
Respiration
Overview of Respiration
Respiration involves the process of inhalation and exhalation as the shape of the respiratory system builds and alters.
Oxygen Production on Earth
Oxygen Contribution from Oceans:
- Estimates indicate that 50-80% of Earth's oxygen is produced by the oceans.
- Key contributor: Oceanic plankton - includes drifting plants, algae, and photosynthesizing bacteria.
- Notable Species: Prochlorococcus - the smallest photosynthetic organism on Earth, responsible for up to 20% of the total oxygen in the biosphere.
Comparative Atmospheric Composition
Mars and Earth
Mars:
- Atmospheric composition by volume:
- Carbon Dioxide: 96%
- Argon: 1.9%
- Nitrogen: 1.9%
- Trace Gases include Acetylene, Carbon Monoxide, Krypton, Methane, Neon, Nitrogen Oxide.Earth:
- Atmospheric composition by volume:
- Oxygen: 20.9%
- Nitrogen: 78.1%
- Trace Gases include Argon (0.93%), Carbon Dioxide, Helium, Hydrogen, Krypton, Nitrogen, Methane, Neon, Nitrous Oxide, Ozone, Water Vapour, Xenon.
- Note: Mars’ atmosphere is less than 1% of Earth’s.
Evolution of Earth’s Atmosphere
Prebiotic Atmosphere:
- Dominated by: H₂, NH₃, CO₂, CO, N₂.
- Characterized as a weakly reducing atmosphere.Modern Atmosphere:
- Composed of: Ar, N₂, H₂O, CH₄, CO₂.
- Classified as an oxidizing atmosphere.
Biological Contributions
Oxygen Accumulation in Earth’s History
Major contributors to O₂ build-up:
- Cyanobacteria (prokaryotes)
- Developments leading to the evolution of angiosperms, terrestrial animals, and complex land plant life.
Anatomy of the Respiratory System
Key Structures
Tonsils, Epiglottis, Vocal Cords: crucial components in breathing and sound production.
Trachea
Structural Features:
- Remains open due to 15–20 C-shaped bands of cartilage.
- Allows for expansion due to the absence of cartilage on the posterior wall - enabling esophageal expansion during swallowing.
Oxygen as an Electron Acceptor
Oxygen functions as an acceptor of de-energized electrons, crucial in biological and chemical processes.
Types of Energy in Respiration
Definitions
Total Energy: The sum of two forms:
- Potential Energy - stored energy, available for work.
- Kinetic Energy - energy of motion; associated with any moving object.
Measurement Units
Calories (cal): The energy needed to raise the temperature of 1 gram of water by 1°C (from 14.5°C to 15.5°C).
- Example: Typical energy bars contain approximately 240 kcal of potential energy.
Cellular Energy: ATP
Role of ATP in Cellular Processes
Adenosine Triphosphate (ATP) is termed the cellular energy currency.
ATP Formation Reaction:
-
- Reaction occurs during metabolism.
ATP Structure
Composition:
- Adenosine = adenine + ribose.
- Triphosphate = three phosphate groups.Reaction releasing ATP:
Cellular Respiration Mechanism
Overview of the Process
Cellular Respiration Equation:
-External Respiration Stages:
1. Pulmonary Ventilation: Movement of air in and out of the lungs (inspiration and expiration).
2. Gas Exchange: Diffusion of oxygen and carbon dioxide between lung air spaces and blood.
3. Transport: Oxygen and carbon dioxide transport via blood between lungs and body tissues.
4. Tissue Exchange: Diffusion of gases between blood and tissues.
Blood Circulation During Respiration
Circulatory System Functionality:
- Key to identifying oxygen-rich (O₂-rich) and oxygen-poor (O₂-poor) blood flows in the body.
- Major pathways include:
- Pulmonary Veins: Carry oxygen-rich blood from the lungs to the heart.
- Pulmonary Artery: Transports oxygen-poor blood from the heart to the lungs for oxygenation.
- Aorta: Distributes oxygen-rich blood to the rest of the body.
Mechanics of Breathing
Role of the Diaphragm:
- Inspiration: Diaphragm contracts; chest expands, allowing intake of air.
- Expiration: Diaphragm relaxes; chest contracts, forcing air out of lungs.
Lungs Anatomy and Functionality
Structure Overview
Lobes and Composition:
- Right lung has 3 lobes; left lung has 2 lobes (due to space occupied by the heart).
- Alveoli: Primary structures for gas exchange, organized into alveolar sacs resembling grape clusters.
Bronchi and Branching
Bronchial Structure:
- The bronchi divide into secondary and tertiary bronchi with C-shaped cartilage functioning for air passage.
- Bronchioles: Smaller branches without cartilage; equipped with elastic fibers to prevent collapse.
Importance of Alveoli in Gas Exchange
Gas Exchange Mechanism:
- Walls consist of Type I pneumocytes (for gas exchange) and Type II pneumocytes (produce surfactant).
- Air/Blood Barrier: Gas exchange occurs across the barrier formed by Type I pneumocytes and capillary endothelium.
Bronchodilation and Bronchoconstriction
Control of Airflow:
- Contraction and relaxation of smooth muscle lining bronchioles regulate airflow, impacting gas exchange efficiency.
Nervous System and Breathing
Control Centers in the Brain:
- Specialized neurons in the respiratory control centers (e.g. preBötzinger complex) regulate the autonomic nervous system's response influencing arousal states.
Physiological Impact of Breathing Techniques
Pranayama in Yoga:
- Meditation through breath control, influencing both physiological and emotional states (e.g., decreased oxygen consumption, heart rate, and increased calmness).