Respiratory System Overview

Respiratory System

• The primary function of the respiratory system is to supply the body with oxygen and remove carbon dioxide.

Processes Involved in Respiration

• Pulmonary Ventilation: Movement of air into and out of the lungs.
• External Respiration: Gas exchange between the alveoli (air sacs in the lungs) and the blood; oxygen enters the blood, and carbon dioxide leaves the blood.
• Transport of Gases: Oxygen and carbon dioxide are transported in the blood between the lungs and body tissues.
• Internal Respiration: Gas exchange between the blood in systemic capillaries and tissue cells; oxygen diffuses into tissues, and carbon dioxide diffuses into the blood.

Cellular Respiration's Role

• Cellular respiration is the process cells use oxygen to convert glucose into ATP (energy).
• Carbon dioxide is a waste product, removed by the respiratory system.

Respiratory and Conducting Zones

• The respiratory zone is where gas exchange occurs (alveoli).
• The conducting zone provides a pathway for air to reach the respiratory zone, conditioning the air through warming, humidifying, and filtering.

Nasal Cavity

• The nose provides an airway, filters and moistens the air, warms it, and houses olfactory receptors.
• The nasal cavity filters air by trapping particles and pathogens using mucus and cilia.

Pharynx

• The pharynx has three regions: nasopharynx, oropharynx, and laryngopharynx.
• These regions act as a passageway for air and food/liquid.

Larynx

• The larynx connects the pharynx to the trachea, conducts air, and houses vocal cords.
• The larynx plays a crucial role in speech production.

Trachea and Bronchi

• The trachea has cartilage rings to prevent collapse.
• The bronchi branch into smaller passages supported by cartilage plates that decrease in size as the airways get narrower.

Alveolar Ventilation

• Alveolar ventilation is the amount of air entering the alveoli per minute. This is essential for adequate gas exchange.

Intrapulmonary Pressure & Atmospheric Pressure

• During inhalation, intrapulmonary pressure drops below atmospheric pressure, causing air to enter the lungs.
• During exhalation, intrapulmonary pressure rises above atmospheric pressure, causing air to exit the lungs.

Intrapleural Pressure

• Intrapleural pressure is always negative relative to intrapulmonary pressure.
• This negative pressure keeps the lungs adhered to the thoracic wall, allowing them to expand and recoil.

Surfactant

• Surfactant reduces surface tension within alveoli, preventing lung collapse, especially during exhalation and when the lungs are at lower volumes.

Lung Volumes

• Tidal Volume (TV): Air moved into and out of the lungs with each normal breath.
• Inspiratory Reserve Volume (IRV): Extra air that can be inhaled beyond tidal volume.
• Expiratory Reserve Volume (ERV): Extra air that can be exhaled beyond tidal volume.
• Residual Volume (RV): Air remaining in the lungs after maximum exhalation.
• Vital Capacity: Tidal volume + inspiratory reserve volume + expiratory reserve volume. Represents the maximum amount of air a person can expel after a maximal inhalation.

Hypoventilation & Hyperventilation

• Hypoventilation: Insufficient alveolar ventilation leading to low oxygen (hypoxemia) and high carbon dioxide levels.
• Hyperventilation: Excessive alveolar ventilation leading to high oxygen and low carbon dioxide levels (respiratory alkalosis).

Partial Pressure Gradients

• Oxygen and carbon dioxide move across the respiratory membrane down their partial pressure gradients. Oxygen diffuses from high pressure in the alveoli to low pressure in the blood; carbon dioxide does the opposite.

Hemoglobin

• Hemoglobin carries most of the oxygen in the blood.
• Temperature and pH affect hemoglobin's affinity for oxygen (Bohr effect).

Medullary Respiratory Centre

• The medullary respiratory center in the brainstem controls the rhythmic breathing cycle.
• It responds to levels of oxygen, carbon dioxide, and pH, and input from peripheral and central chemoreceptors, to adjust breathing rate and depth.

This quiz covers the fundamental aspects of the respiratory system, including its primary functions, processes involved in respiration, and the role of cellular respiration. Test your knowledge on pulmonary ventilation, gas exchange, and the distinctions between respiratory and conducting zones.