The Respiratory System and Respiration

Study Notes

The respiratory system is a complex physiological process.
Its goal is to facilitate the exchange of gases between the atmosphere and the body's cells.
Objectives of respiratory system study include the process of respiration, the functional organization of the respiratory system, and identifying the functions of structures.
Asthma is listed as an example of a homeostatic imbalance.
Respiratory membrane components are identified.
The physical properties of the lungs (compliance and elasticity) are explained.
Breathing mechanics and modified breathing movements are included in the study.

Respiration encompasses several components.
Cellular respiration involves processes in the body's cells, producing energy.
External and internal respiration involve the exchange of gases between the lungs and blood.
Respiration is a complex process having four main components: gas exchange between the atmosphere and lungs, lung to blood exchange of oxygen and carbon dioxide, transport of gases in the blood, and blood to cell gas exchange.

The system has conducting and respiratory zones.
The conducting zone includes nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles.
The respiratory zone includes respiratory bronchioles, alveolar ducts, and alveoli.
These zones are integral to the overall gas exchange process.

The nose and nasal cavity warm, filter, and moisten incoming air.
The pharynx is a passageway for air and food, and also involves speech sound resonance. It is composed of the nasopharynx, oropharynx, and laryngopharynx.
The larynx, or voice box, is a passageway for air; it prevents ingested materials from the respiratory tract, and produces sound for speech.
The trachea, or windpipe, is a strong tube formed by cartilage rings. It links the larynx to the bronchi. It includes goblet cells that produce mucus, and cilia to remove foreign particles. The trachea also has a carina, with receptors linked to the cough reflex.
Bronchi are the branches of the trachea; one goes into each lung.
Bronchioles lead into tubes without cartilage, called bronchioles which can change the size to regulate the flow of air to the alveoli.

Alveoli are tiny air sacs in the lungs where gas exchange takes place.
The respiratory membrane comprises the alveolar epithelium, capillary endothelium, and their fused basement membranes.
Gas exchange occurs passively, facilitated by diffusion: oxygen from the alveoli moves to the blood, and carbon dioxide from the blood moves to the alveoli.

Type II alveolar cells secrete surfactant, a vital substance that prevents alveolar collapse.
Premature infants often lack sufficient surfactant production, leading to respiratory distress syndrome.

Compliance describes how easily the lungs expand.
Elasticity dictates the lungs' tendency to return to their initial size after distension.

Asthma is a chronic respiratory disease characterized by inflammation, edema of the airway, and bronchospasms.
Excessive mucus secretion often accompanies asthma.
Environmental factors such as allergens, respiratory infections, and exercise can trigger asthma attacks.
Immune cells such as eosinophils and mononuclear cells can infiltrate the airways in asthma.