Introduction to Respiration and Anatomy

The gas exchange between the atmosphere and lung tissues.

Gas exchange between lung tissues and blood.

Gas exchange between blood and body tissues.

Exchanges gases, regulates blood pH, and allows for voice production and smell.

The parts of the body involved in gas exchange, e.g. alveoli.

Interior and anterior space of the nose, bounded by the nasal bones and oral cavity, kept unobstructed by bone and cartilage.

Structure dividing the nasal cavity into left and right halves.

Cavities within the bones surrounding the nasal cavity, lined with mucus membranes, involved in speech and singing.

Structures within the nasal cavity that swirl inhaled air.

Part of nasal cavity, contains sensory receptors for smell, ciliated but without goblet cells.

Muscular tube lined with mucous membrane, a passageway for air and food, extending from nasal passages to the cricoid cartilage.

Tube of cartilage, involved in voice production and preventing food from entering the airway, containing vocal folds and vestibular folds.

Structures in the larynx that vibrate to produce sound, made of stratified squamous epithelium, and elastic ligaments.

Tube connecting the larynx to the bronchi, reinforced with cartilage rings to keep it open.

Branches of the trachea leading to the lungs and ending in terminal bronchioles. Include the carina.

A double-layered membrane that surrounds the lungs, reducing friction and providing surface tension during breathing.

The space between the two layers of the pleural membrane, filled with pleural fluid.

The inferior portion of the lung, resting on the diaphragm.

The superior portion of the lung, extending just above the clavicle.

A region on the medial surface of the lung where the bronchi, blood vessels, nerves, and lymphatic vessels enter and exit.

A concave indentation on the left lung that accommodates the heart.

Grooves that divide the lungs into lobes.

A diagonal fissure that separates the superior and inferior lobes of the lungs.

Branches of the bronchi that supply each lobe of the lung.

A section of lung tissue supplied by a segmental bronchus, arteriole, venule, lymphatic vessel, and wrapped in elastic connective tissue.

Small compartments within bronchopulmonary segments, containing a terminal bronchiole, arteriole, venule, lymphatic vessel, and elastic connective tissue.

Microscopic branches of the bronchial tree lined with simple cuboidal epithelium, leading to alveolar ducts for gas exchange.

Tiny air sacs at the end of the respiratory bronchioles, responsible for gas exchange.

Clusters of alveoli at the end of alveolar ducts, resembling a bunch of grapes.

Thin, squamous epithelial cells lining the alveoli, facilitating gas diffusion.

When the blood is too acidic, the body responds by increasing the rate and depth of breathing to release more carbon dioxide (CO2), which is acidic. This lowers the acidity, bringing blood pH back to normal.

Rapid and deep breathing, often caused by anxiety or low blood pH. This increases the amount of CO2 expelled, making the blood less acidic.

A lower than normal level of carbon dioxide (CO2) in the blood, often caused by hyperventilation.

A deficiency of oxygen in the blood or tissues, which can result from hyperventilation.

A protective mechanism that prevents over-inflation of the lungs during strenuous exercise. Stretch receptors in the lung tissue signal the brain to stop breathing.

Sensory receptors located in the bronchi and bronchioles that detect stretching of the lungs. They send signals to the brain to control breathing.

A major nerve that carries signals from the baroreceptors in the lungs to the brain, helping to regulate breathing.

The blood flow through the lungs, which is increased during exercise to support the increased oxygen demands of the body.

During inhalation, the diaphragm contracts, flattening and moving downwards. This increases the volume of the thoracic cavity, decreasing pressure inside and drawing air into the lungs.

The external intercostal muscles contract during inhalation, pulling the ribs upwards and outwards. This further increases the volume of the thoracic cavity, aiding in air intake.

The intrapleural pressure is lower than atmospheric pressure, creating negative pressure within the pleural cavity. This pressure keeps the lungs adhered to the thoracic cavity wall, ensuring they expand during inhalation.

Exhalation is normally a passive process. When the diaphragm and intercostal muscles relax, the elastic recoil of the lungs forces air back out, reducing thoracic cavity volume and increasing pressure inside the lungs.

During strenuous activities like exercise or playing wind instruments, active exhalation occurs. The abdominal and internal intercostal muscles contract, forcing more air out of the lungs.

Surfactant is a fluid that reduces surface tension in the alveoli. This makes it easier for the lungs to expand and contract, ensuring efficient breathing.

An accumulation of fluid in the pleural cavity. This fluid buildup can compress the lungs, limiting their expansion and leading to difficulty breathing.

Lung compliance refers to the ease with which the lungs can be stretched. Healthy lungs have high compliance, meaning less effort is required to breathe. Low compliance means more effort is needed.

Airway resistance is the opposition to airflow through the respiratory system. Factors affecting resistance include airway diameter and obstruction.

Gases move from areas of high partial pressure to areas of low partial pressure. This gradient is crucial for efficient gas exchange.

The solubility of a gas in a liquid (like blood) affects its diffusion rate. CO2 is more soluble in water than O2, meaning it diffuses faster in the blood.

During exercise, the partial pressure of oxygen (PO2) in the alveoli is lower than at rest. This is because the body increases the delivery of deoxygenated blood to the lungs to meet increased demands. To compensate, the movement of oxygen across the alveolar membrane speeds up.

Tissues constantly produce CO2 as a byproduct of cellular respiration. This raises the partial pressure of CO2 outside systemic capillaries, driving its movement into the blood.

Most of the oxygen in the blood is transported bound to hemoglobin in red blood cells. Only a small percentage remains dissolved in plasma.

During exercise, the partial pressure of oxygen (PO2) in the alveoli is lower than at rest. This is due to increased delivery of deoxygenated blood to the lungs, requiring faster oxygen transfer to meet the body's demands.

Hemoglobin (Hb) is a protein in red blood cells that binds oxygen reversibly, allowing for efficient oxygen transport throughout the body.

Hemoglobin saturation refers to the percentage of Hb molecules carrying oxygen. It indicates how much oxygen is bound to Hb.

Various factors influence Hb's affinity for oxygen, including: partial pressure of oxygen (PO2), blood pH, partial pressure of carbon dioxide (PCO2), temperature, 2,3-bisphosphoglycerate (BPG), and type of hemoglobin.

Higher partial pressure of oxygen (PO2) increases Hb saturation, meaning more oxygen binds to Hb. Conversely, lower PO2 decreases saturation.

Increased acidity (lower pH) decreases Hb's affinity for oxygen. This means Hb releases oxygen more readily in acidic environments.

High PCO2 lowers blood pH, indirectly decreasing Hb's affinity for oxygen.

Increased temperature, like during exercise, decreases Hb's affinity for oxygen, promoting oxygen delivery to working muscles.

2,3-bisphosphoglycerate (BPG) is a byproduct of glycolysis and binds to Hb, decreasing its affinity for oxygen.

Fetal hemoglobin (Hb-F) has a higher affinity for oxygen than adult hemoglobin (Hb-A), allowing the fetus to extract oxygen from the mother's blood.

A small percentage of CO2 is transported dissolved directly in blood plasma.

About 23% of CO2 binds to Hb, forming carbaminohemoglobin.

The majority (70%) of CO2 is transported as bicarbonate (HCO3-) in the blood.

At the systemic capillaries, HCO3- diffuses out of red blood cells, causing Cl- ions to move in, maintaining electrical balance.

The respiratory centre in the brain, specifically in the medulla oblongata and pons, controls the rate and depth of breathing.

The DRG in the medulla oblongata controls normal, rhythmic breathing.

The VRG in the medulla oblongata controls forceful breathing, often during exercise or exertion.