Respiratory system

Ventilation

The movement of air in and out of the lungs.

Gas exchange

The exchange of oxygen (O2) and carbon dioxide (CO2) between the lung tissue and the circulatory system.

Cell respiration

The process that creates a constant demand for oxygen and a need to remove carbon dioxide.

Upper respiratory system

Includes the mouth, nose, pharynx, etc.

Lower respiratory system

Includes the bronchi, lungs, etc.

Trachea

A tube that carries air to the bronchi and is held open by rings of cartilage.

Bronchi

The two major air passages from the trachea that lead to the left and right lungs.

Bronchioles

Smaller airways that divide from the bronchi and lead to the alveoli.

Alveoli

Clusters of air sacs where gas exchange with the bloodstream occurs.

Diaphragm

A large muscle under the lungs that assists with ventilation.

Ciliated epithelial cells

Mucus-secreting cells that trap and remove dust and pathogens.

Boyle’s Law

Pressure is inversely proportional to volume in the context of gas behavior.

Inspiration

The process of taking air into the lungs by decreasing pressure.

Expiration

The process of expelling air from the lungs by increasing pressure.

Pneumocyte Type I

Thin, flat cells that form 95% of alveoli surface, minimizing diffusion distance.

Pneumocyte Type II

Cells that secrete pulmonary surfactant to reduce surface tension in the alveoli.

Surfactant

A substance that reduces surface tension in the alveoli and prevents collapse.

Haemoglobin

A protein in red blood cells that transports oxygen.

Cooperative binding

The process where binding of one O2 molecule to haemoglobin facilitates binding of others.

Oxygen dissociation curve

A graph showing the relationship between oxygen saturation of haemoglobin and oxygen levels.

Foetal haemoglobin

A type of haemoglobin with a higher affinity for oxygen than adult haemoglobin.

Carbon dioxide transport

Methods of transporting carbon dioxide in the blood, including binding to haemoglobin.

Bohr effect

A decrease in pH that shifts the oxygen dissociation curve to the right, promoting oxygen release.

Erythrocyte

A red blood cell that carries oxygen and helps in carbon dioxide transport.

Capillaries

Small blood vessels where gas exchange occurs between the blood and alveoli.

Diffusion

The process by which gases exchange between alveoli and capillaries.

Surface area for diffusion

The large area provided by numerous alveoli that enhances gas exchange efficiency.

Deoxygenated blood

Blood with low oxygen concentration that arrives at the alveoli from the body.

Oxygen concentration gradient

The difference in oxygen levels that drives the movement of oxygen into the blood.

Carbonic anhydrase (CAH)

An enzyme that catalyzes the conversion of carbon dioxide into carbonic acid.

Hydrogen ions (H+)

Ions that increase acidity in the blood and promote oxygen release from haemoglobin.

Bicarbonate (HCO3–)

A result of carbonic acid dissociating, important in maintaining blood pH.

Thoracic cavity

The chest compartment that changes volume during breathing.

Elastic connective tissue

Tissue in the lungs that allows for expansion and recoil.

Respiratory muscles

Muscles involved in ventilation, including the diaphragm and intercostals.

Hypoxic tissues

Tissues that are deficient in oxygen, leading to oxygen being released from haemoglobin.

Alveolar surface tension

The tension in the alveoli that surfactant helps to reduce to prevent collapse.

Oxygen-rich tissues

Tissues where oxygen is abundant and haemoglobin binds more oxygen.

Mucus

A viscous fluid secreted by epithelial cells to trap pathogens and dust.

Tracheobronchial tree

The branching system of the trachea and bronchi leading to the lungs.

Pressure gradient

The difference in pressure that drives airflow into and out of the lungs.

Respiratory system

The organ system responsible for the inhalation and exhalation of air.

Intercostal muscles

Muscles located between the ribs that assist in the breathing process.

Alveolar-capillary membrane

The thin barrier between alveoli and capillaries for gas exchange.

Closed respiratory cycle

The cycle of air moving in and out of the lungs during ventilation.

Pulmonary arteries

Blood vessels that carry deoxygenated blood from the right ventricle to the lungs.

Alveolar fluid

Fluid in the alveoli that helps dissolve gases for more efficient diffusion.