Respiration Overview

Study Notes

Respiration is the process of taking in oxygen and releasing carbon dioxide.
Normal respiratory rates differ by age group:
- Newborn: 30-60 breaths per minute
- Early childhood: 20-40 breaths per minute
- Late childhood: 15-25 breaths per minute
- Adult: 12-16 breaths per minute
Tachypnea: More than 16 breaths per minute
Bradypnea: Less than 12 breaths per minute

Respiration is categorized into two types:
- External respiration: Exchange of gases between lungs and blood.
- Internal respiration: Exchange of gases between blood and tissues.

Occurs in two phases:
- Inspiration: Air enters the lungs from the atmosphere.
- Expiration: Air leaves the lungs.

Includes the upper and lower respiratory tract.
Upper respiratory tract: Nasal cavity, pharynx, and larynx.
Lower respiratory tract: Trachea, bronchi, bronchioles, and lungs.
Key points about the nose: It's the first organ of the respiratory tract.
- Larynx is also known as the voice box.
Epiglottis: Flexible cartilage preventing food and drink from entering the windpipe
Trachea consists of 16-20 C-shaped rings of hyaline cartilage.
Carina: The point where the trachea divides into two bronchi.
- Right bronchus/ is wider, shorter, and more vertical than Left bronchus leading to an increased chance of blockage.
Alveoli: Smallest units of the respiratory tract, located in the lungs.
Lungs contain roughly 300 million alveoli, providing a large gas exchange surface area (approximately 70 square meters)
- Type 1 Alveolar Cells (95% of cells): Primarily involved in gas exchange.
- Type 2 Alveolar Cells (5% of cells): Produce surfactant, reducing surface tension and preventing alveolar collapse during exhalation.
Surfactant: Phospholipid that prevents alveolar collapse during expiration.

Static lung volumes: Volumes of air breathed by an individual.
- Tidal volume (TV): Volume of air inhaled and exhaled in a normal breath (approximately 500 mL).
- Inspiratory reserve volume (IRV): Maximum volume of air that can be inhaled after a normal breath (approximately 3,300 mL).
- Expiratory reserve volume (ERV): Maximum volume of air that can be exhaled after a normal breath ( approximately 1,000 mL).
- Residual volume (RV): Volume of air remaining in the lungs after a maximal exhalation (approximately 1,200 mL).
Lung capacities: Combinations of two or more lung volumes.
- Inspiratory capacity (IC)
- Vital capacity (VC)
- Functional residual capacity (FRC)
- Total lung capacity (TLC)
Surfactant production begins around weeks 24-28 of fetal life and is usually sufficient by week 35.
Antrum: Space within the alveoli sac.

Percentage of oxygen and carbon dioxide in inspired and expired air:
- Inspired Air: Oxygen 21%, Carbon Dioxide 0.04%, Nitrogen 78%
- Expired Air: Oxygen 16%, Carbon Dioxide 4%, Nitrogen 78%