Respiratory System Quiz

Respiratory System: Anatomy

• The respiratory system's purpose is acquiring oxygen (O2) and removing carbon dioxide (CO2) from the blood.
• All body cells need O2 to produce ATP (adenosine triphosphate), a crucial energy source.
• CO2 is a byproduct of ATP production and must be removed from the bloodstream to maintain proper pH levels. Higher CO2 levels decrease blood pH.

Anatomy of the Respiratory System

• External nose: Encloses the chamber for air inhalation.
• Nasal cavity: Warms, cleanses, and humidifies inhaled air, acting as a filtration, warming, and humidifying chamber.
• Pharynx (throat): Shares a passageway for food and air, acting as a conduit for both.
• Larynx (voice box): Contains the vocal cords, essential for voice production.
• Trachea (windpipe): A tube that cleans and funnels inhaled air into each lung.
• Bronchi: Direct air into the lungs.
• Lungs: Contain intricate networks of air tubes and alveoli (air sacs), where gas exchange with the blood occurs.

Functions of the Respiratory System

• Upper respiratory tract: Structures from the nose to the larynx.
• Lower respiratory tract: Structures from the trachea to the alveoli in the lungs.
• Conducting zone: Structures that transport air, such as from the nose to the air tubes in the lungs.
• Respiratory zone: Structures, including alveoli, where gas exchange occurs.

Functions of the Respiratory System Details

• Ventilation: Breathing—the process of moving air into and out of the lungs.
• External respiration: Exchange of O2 and CO2 between the air in the lungs and the blood.
• Gas transport: Movement of O2 and CO2 in the blood to and from cells.
• Internal respiration: Exchange of O2 and CO2 between the blood and tissues.

Additional Functions of the Respiratory System

• Regulation of blood pH: The respiratory system adjusts blood pH by altering CO2 levels.
• Production of chemical mediators: The lungs produce an enzyme (ACE—angiotensin-converting enzyme) that regulates blood pressure.
• Voice production: Air moving past vocal folds produces sounds and speech.
• Olfaction (smell): Airborne molecules detected in the nasal cavity.
• Protection: Preventing some microorganisms from entering the body and removing them from respiratory surfaces.

Anatomy of the Nose

• External nose: Primarily composed of hyaline cartilage.
• Nasal cavity: Extends from nares (nostrils) to the choanae (openings to the pharynx). The hard palate forms its roof, and the nasal septum divides it into two halves.
• Paranasal sinuses: Air-filled spaces within bones that open into the nasal cavity.
• Conchae: Bony projections on the nasal cavity's lateral walls that increase surface area for warming, cleaning, and humidifying inspired air.
• Nasolacrimal ducts: Carry tears from the eyes into the nasal cavity.

Functions of the Nasal Cavity

• Serves as an air passageway, remaining open even when the mouth is full,
• Cleans the air: Lined with hairs to trap dust particles.
• Humidifies and warms inspired air.
• Contains the olfactory epithelium, the sensory organ for smell.
• Helps determine voice sounds as nasal cavities and paranasal sinuses act as resonating chambers.

Pharynx

• Pharynx: Passage for both air and food.
• Nasopharynx: Air passageway.
• Oropharynx: Passage for food and air.
• Laryngopharynx: Passage for food and air.
• Uvula: Extension of the soft palate, acting as a flap to prevent food from entering the nasal cavity.
• Pharyngeal tonsils: Part of the lymphatic system, assisting in defending against infections.

Larynx

• Located in the anterior throat.
• Composed of nine cartilages, the largest being the thyroid cartilage (Adam's apple).
• Epiglottis: Cartilage preventing swallowed material from entering the larynx.

Vestibular Folds and Vocal Folds

• Vestibular folds (false vocal cords): Folds of tissue within the larynx.
• Vocal folds (true vocal cords): Produce sound during speech, with the force of air determining loudness and tension pitch.

Lower Respiratory Tract

• Trachea: Windpipe; a tube with C-shaped cartilage rings to keep it open and support its shape.
• Bronchi: Two tubes that branch from the trachea and enter each lung.
• Tracheobronchial tree in lungs: Branched network of tubes bringing air deeper into the lungs.
• Alveoli: Tiny air sacs in the lungs where the gas exchange occurs.

Alveoli

• Small air sacs where gas exchange between air and blood takes place.
• Surrounded by capillaries and amount to approximately 300 million in the lungs.

Respiratory Membrane

• Formed by the walls of alveoli and capillaries.
• Important part of the gas exchange process due to its thin structure, allowing for the diffusion of gases.
• Also, a respiratory membrane is found in the alveolar ducts and respiratory bronchioles.

Thoracic Wall and Muscles of Respiration

• Thoracic wall: Thoracic vertebrae, ribs, costal cartilages, sternum, and associated muscles.
• Thoracic cavity: Space enclosed by the thoracic wall and diaphragm.
• Diaphragm: Sheet of skeletal muscle separating the thoracic cavity from the abdominal cavity.
• During ventilation, the actions of the diaphragm and skeletal muscles alter thoracic volume, aiding the movement of air in and out of the lungs.

Inspiration

• Diaphragm contracts and descends.
• Rib cage expands.
• Thoracic cavity volume increases.
• Air pressure in the thoracic cavity decreases.
• Air flows into the lungs.

Expiration

• Diaphragm relaxes and moves up.
• Rib cage recoils.
• Thoracic cavity volume decreases.
• Air pressure in the thoracic cavity increases.
• Air flows out of the lungs.

Pulmonary Volumes and Capacities

• Spirometer: Measures pulmonary volumes.
• Tidal volume: Volume of air inspired or expired during quiet breathing.
• Inspiratory reserve volume: Volume that can be inhaled after a normal inhalation.
• Expiratory reserve volume: Volume that can be exhaled after a normal exhalation.
• Residual volume: Volume of air remaining in the lungs after maximum exhalation.
• Inspiratory capacity: Total volume inhalable after a normal exhalation.
• Functional residual capacity: Amount of gas remaining in the lungs after a normal exhalation.
• Vital capacity: Total amount of air that can be exhaled after a maximum inhalation.
• Total lung capacity: Total volume of gas that the lungs can hold.

Alveolar Ventilation

• Measures the volume of air available for gas exchange per minute.
• Only some inhaled air reaches the alveoli for gas exchange, with the rest considered dead space.

Anatomical and Physiological Dead Space

• Anatomical dead space: Areas of the upper and lower respiratory tracts where no gas exchange takes place.
• Physiological dead space: Anatomical dead space plus the volume of alveoli not effectively involved in gas exchange.

Alveolar Pressure Changes

• Inspiration: Decrease in alveolar pressure.
• Expiration: Increase in alveolar pressure.

Factors Affecting Ventilation

• Gender
• Age
• Body size
• Physical fitness

Partial Pressure

• Partial pressure: Pressure exerted by a gas in a mixture of gases.
• Based on the amount of a gas and its total pressure.
• Atmosphere contains 21% O2.
• The partial pressure of O2 at sea level is 160 mm Hg.

Lung Recoil

• Expanded lungs tend to return to their original size, a process aided by the elastic fibers and fluid lining the alveoli.

Surfactant

• Mixture of lipoproteins produced by alveolar secretory cells.
• Reduces surface tension.
• Prevents lung collapse.

Pleural Pressure

• The pressure within the pleural cavity, always less than alveolar pressure.
• Helps prevent lung collapse.
• Pneumothorax: Piercing of the thoracic wall or lung causes lung collapse.

Diffusion Through Respiratory Membrane

• Partial pressure gradients for O2 and CO2 influence diffusion rates.

Gas Exchange- Lungs

• O2 moves from the alveoli into blood vessels (capillaries).
• CO2 moves from the blood into the alveoli.

Gas Exchange- Tissues

• O2 moves from blood vessels into tissues.
• CO2 moves from tissues into blood vessels.

Respiratory Membrane Thickness and Surface Area

• Increased membrane thickness slows gas diffusion.
• Lung edema can result in decreased gas exchange.
• Reduced membrane surface area diminishes gas exchange.

O2 and CO2 Transport in Blood

• O2 carried primarily by hemoglobin.
• O2 dissolves slightly in the plasma.
• CO2 transported in three ways: dissolved in plasma, bound to hemoglobin, and as bicarbonate ions.

Hemoglobin

• Protein within red blood cells that binds O2.

Oxygen Transport in Blood

• Hemoglobin carries most oxygen—98.5%.
• A small amount dissolves in the plasma—1.5%.

Carbon Dioxide Transport and Blood pH

• CO2 diffuses from cells into blood and is carried in three ways: dissolved in plasma, bound to hemoglobin, and as bicarbonate ions.
• Bicarbonate conversion impacts blood pH, crucial for normal physiological function.

Regulation of Ventilation

• Respiratory rate is regulated to maintain proper blood gas levels (O2 and CO2), influencing blood pH.
• Chemoreceptors respond to changes in CO2, O2, and pH to adjust the ventilation rate.
• Stretch receptors in the lungs (Hering-Breuer reflex) help to prevent over-expansion during inhalation.

Medullary and Pontine Respiratory Centers

• The medullary respiratory centers (DRG and VRG) establish the basic rhythm of breathing.
• Pontine respiratory group modifies breathing rate.

Generation of Rhythmic Ventilation

• The medullary respiratory center generates the basic rhythm of respiration, influenced by receptors and adjusting to changes in blood gas levels, temperature, muscle/joint movements, and emotional status.