Respiratory System Flashcards
Why Respiration?
Purpose: Provides energy for life activities through complex metabolic processes.
Energy is derived from food or photosynthesis.
What is Respiration?
Definition: Exchange of gases or metabolic reactions to produce energy.
Types:
Organismic Respiration: Breathing (inhalation and exhalation) and gas exchange.
Cellular Respiration: Metabolic reactions to produce energy in the form of ATP.
Cellular Respiration
Aerobic Respiration:
Uses oxygen to produce energy.
Example: Electron transport chain in mitochondria.
Anaerobic Respiration:
Does not use oxygen, relies on other molecules to produce energy.
Example: Fermentation in some bacteria.
Organismic Respiration
Definition: Breathing or ventilation (inhalation and exhalation).
Gas exchange occurs in specialized organs (e.g., lungs in humans).
Difference Between Cellular and Organismic Respiration
Cellular Respiration: Metabolic reactions producing energy (ATP). Involves oxygen utilization or fermentation.
Organismic Respiration:
Coordinated movements for inhalation and exhalation. Involves gas exchange in lungs or organs.
Respiration in Air vs. Water
Air: Easier due to lower density and higher oxygen concentration.
Water: More difficult due to higher density and lower oxygen availability.
Respiration in Plants
Gas Exchange:
Occurs through stomata in mesophyll cells.
Guard cells regulate stomatal opening for transpiration.
Roots: Absorb oxygen from air in the soil.
Aquatic Plants: Extract oxygen dissolved in water.
Human Respiratory System Overview
Main Components:
Air Passageways:
Nostrils & Nasal Cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Lungs:
Pleural cavity
Body of lungs
Alveoli (smallest units for gas exchange)
Structure and Function of Air Passageways
Nose & Nasal Cavity:
Function: Inhalation and filtration.
Structure: Lined with ciliated epithelium and mucus to trap dirt and particles.
Air processed: Filtered, moistened, and warmed before entering lungs.
Pharynx (Throat):
Function: Muscular passage for air.
Structure: Lined with mucous membrane, air passes from pharynx to larynx.
Larynx (Voice Box):
Function: Voice production.
Structure: Cartilage structure with vocal cords that vibrate for sound. Mucous membranes line the larynx.
Trachea (Windpipe):
Function: Conducts air to lungs.
Structure: Tube with C-shaped cartilaginous rings to prevent collapse. Located ventrally to the esophagus. Divides into two bronchi.
Bronchi, Bronchioles, and Alveoli
Bronchi:
Function: Divide into smaller tubes, leading air into the lungs.
Structure: Have cartilage rings that become irregular as they divide further.
Bronchioles:
Function: Smaller tubes leading deeper into lungs.
Structure: Less than 1mm in diameter, branching from bronchi.
Alveoli (Air Sacs):
Function: Site of gas exchange.
Structure: Microscopic air sacs covered by capillary networks. Oxygen and carbon dioxide exchange occurs here.
Structure of the Lungs
Lungs:
Function: Main organs for respiration.
Structure: Two lungs (right and left) located in the chest cavity. Spongy texture due to alveoli. Protected by ribs and pleural cavity (fluid-filled membrane).
Diaphragm: A muscular floor beneath the lungs that aids in breathing.
Pleural Cavity:
Function: Protects lungs with a double membrane fluid-filled cavity.
Key Points to Remember for MCQs
Air passage: Nose → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli.
Alveoli: Functional unit of lungs where gas exchange happens.
Trachea: C-shaped cartilage for support; divides into bronchi.
Lungs: Protected by ribs, pleural cavity, and diaphragm.
Breathing Process
Definition: Inhalation and exhalation of air.
Role of Diaphragm:
Contracted diaphragm: Flattens, expanding the chest, leading to inhalation.
Relaxed diaphragm: Becomes dome-shaped, increasing chest pressure, leading to exhalation.
Rib Cage Movement:
Contracted intercostal muscles: Elevate ribs during inhalation.
Relaxed intercostal muscles: Ribs settle during exhalation.
Gas Exchange in Alveoli
Mechanism: Gas exchange occurs due to pressure differences between blood and alveolar air.
Structure: Blood capillaries surround alveoli for efficient gas exchange.
Hemoglobin (Hb) Role:
Hemoglobin binds with oxygen (O2) to form oxyhemoglobin (HbO2).
This process is reversible depending on gas pressure.
Transport of CO2
Carbon Dioxide in Blood:
20% as carboxyhemoglobin.
5% bound to plasma proteins.
70% as bicarbonate ions (HCO3-).
Reaction:
CO₂ + H₂O → H₂CO₃ (Carbonic acid) → H⁺ + HCO₃⁻.
Factors Affecting Gas Exchange
Carbon Dioxide (CO₂):
Increased CO₂ reduces oxygen (O₂) binding capacity of hemoglobin.
Temperature:
Higher temperatures reduce hemoglobin’s oxygen-carrying capacity.
pH:
Lower pH decreases oxygen binding (due to H⁺ ions).
Lung Capacity and Exercise
Normal Lung Capacity: 5 liters when fully inflated.
At rest: About 0.5 liters exchanged.
During exercise: Up to 3.5 liters exchanged.
Residual volume: 1.5 liters (air that cannot be expelled).
Breathing Rate:
At rest: 15-20 breaths per minute.
During exercise: Up to 30 breaths per minute.
Changes in Composition of Breathed Air
Oxygen (O₂): Inhaled air contains 21% oxygen, while exhaled air contains 16% oxygen.
Carbon Dioxide (CO₂): Inhaled air has 0.04% carbon dioxide, but exhaled air contains 4% carbon dioxide.
Nitrogen (N₂): The concentration of nitrogen remains constant at 79% in both inhaled and exhaled air.
Water Vapors: Inhaled air has variable amounts of water vapor, while exhaled air is always saturated with water vapor.
