Respiratory System Quiz

Respiratory System Overview

• The respiratory system brings oxygen into the body and removes carbon dioxide.
• It consists of airways, lungs, and respiratory muscles.
• The system includes the epiglottis, which helps protect the airway during swallowing.

Anatomy of the Respiratory System

• Consists of the airways, lungs, and respiratory muscles.
• Airways include nasal cavity, oral cavity, larynx, pharynx, trachea, bronchi, bronchioles, and alveoli.
• The lungs are cone-shaped, spongy tissues with millions of alveoli.
• Alveoli are the small air sacs where gas exchange occurs.
• The trachea is the windpipe, supported by cartilage rings.

Breathing Cycle

• Inhalation (inspiration) brings oxygen-rich air into the lungs.
• Exhalation (expiration) removes oxygen-depleted air (rich in CO2) from the lungs.
• External respiration is the gas exchange between the atmosphere and blood.
• Internal respiration occurs between the blood and body cells.

Thoracic Cavity

• Also known as the chest cavity.
• Located above the diaphragm.
• Houses the lungs and heart.
• Protected by the thoracic cage (ribs, spine, and sternum).
• Contains internal and external intercostal muscles for respiration.

Lungs

• Two lungs, one on each side of the body.
• Located in the thoracic cavity.
• Right lung is divided into three lobes, left lung into two.
• Each lung is cone-shaped.
• Made up of thousands of alveoli; tiny air sacs for gas exchange.

Pleura and Pleural Cavity

• Pleura are thin membranes that enclose the lungs.
• Inner layer: visceral pleura, lines the lungs' surface.
• Outer layer: parietal pleura, lines the chest wall and diaphragm.
• Pleural cavity is the space between visceral and parietal pleura.

Conducting Zone

• Consists of the passages that carry air to the respiratory zone.
• Include the nose, nasal cavity, mouth, pharynx, larynx, trachea, bronchial tree, terminal bronchioles.
• Warms, humidifies, and filters inhaled air.
• Contains goblet cells that produce mucus which helps with filtration.

Trachea

• Also known as the windpipe.
• Semi-flexible tube supported by cartilage rings.
• About 2.5cm in diameter and 12cm long.
• Branches into right and left primary bronchi.
• Largest cartilage in the larynx: Thyroid cartilage.

Bronchial Tree

• A network of progressively branching airways beginning with the primary bronchi.
• Approximately 23 generations of airways
• Divides into secondary and tertiary bronchi, and then bronchioles.
• Bronchioles eventually lead to alveoli, the sites of gas exchange.

Respiratory Zone

• The region containing alveoli for gas exchange.
• Includes respiratory bronchioles, alveolar ducts, and alveoli.
• Alveoli are the primary structures where gas exchange takes place.

Respiratory Membrane

• Thin wall separating the alveolar surface and blood.
• Type 1 alveolar cells are most prominent, assisting gas exchange.
• Type 2 cells secrete surfactant, reducing surface tension to help alveoli inflate.

Alveolar Interdependence

• Alveoli are mechanically tethered, creating structural support.
• Important during the respiratory cycle for uniform ventilation and maximizing gas exchange.

Emphysema

• Characterized by the destruction of alveoli.
• Rupture of alveoli leads to larger air sacs.

COPD

• Chronic Obstructive Pulmonary Disease (COPD).
• Conditions like chronic bronchitis and emphysema.
• Inflammation and mucous buildup.
• Alveolar membrane breakdown.

Lung Volumes

• Tidal volume (VT): Air exchanged in a single breath.
• Inspiratory reserve volume (IRV): Extra air inhaled past a normal breath.
• Expiratory reserve volume (ERV): Extra air exhaled past a normal breath.
• Residual volume (RV): Air remaining in lungs after maximum exhalation.

Lung Volumes & Capacities

• Spirometry measures various lung volumes and stages of the respiratory cycle.
• Useful to assess airflow, indicating lung function or potential pulmonary disease.

Lung Capacities

• Vital capacity (VC): Maximum amount of air exhaled after a maximum inhale.
• Inspiratory capacity (IC): Maximum amount of air that can be inhaled after a normal exhale.
• Functional residual capacity (FRC): Amount of air left in lungs after a normal exhale.
• Total lung capacity (TLC): Total volume of air lungs can accommodate.

Ventilation

• Minute ventilation (VE): The total volume of air moved in and out of the lungs per minute.
• Alveolar ventilation (VA): The volume of fresh air reaching the alveoli per minute. This is calculated using the tidal volume and the anatomical dead space.
• Anatomical dead space volume: Air trapped in the conducting airways that doesn't reach the alveoli.

FEV1/FVC Ratio

• Measures the amount of air exhaled in the first second (FEV1) relative to the total amount exhaled (FVC).
• Important for diagnosing lung diseases like asthma and COPD where airflow is restricted.

Respiratory Control Center

• Located in the medulla oblongata and pons.
• Control the rate and depth of breathing to maintain adequate oxygen supply.
• Receives sensory information from peripheral and central areas.

Humoral Control

• Respiratory control center adjusts ventilation based on changes in chemical composition of the internal environment (for example, PCO2, PO2 and pH).
• Chemoreceptors, specialized cells, sense changes in blood gases (oxygen, carbon dioxide, and pH).

The Work of Breathing

• Oxygen cost of breathing varies at rest and during exercise, and is affected by pulmonary diseases.

Mechanics of Inspiration and Expiration

• Inspiration is driven by diaphragm contraction, decreasing intrapulmonic pressure and drawing air in.
• Expiration occurs when the diaphragm relaxes, increasing intrapulmonic pressure and forcing air out.

Muscles of Ventilation During Exercise

• Diaphragm, accessory muscles, scalenes, sternocleidomastoid, and abdominal wall muscles are involved in ventilation during exercise.

Gas Diffusion

• The process of gases moving from higher pressure to lower pressure across the respiratory membrane.
• Alveoli, capillaries and tissue are involved.

Factors Affecting Gas Diffusion

• Fick's Law for diffusion describes the gas diffusion rate relationship with gas solubility and surface area. The pressure gradient and surface area influences gas exchange rates.

Sites for Gas Diffusion

• External respiration occurs at the alveoli, with gas exchange happening between the alveoli and capillaries.
• Internal respiration occurs in the tissues, with gas exchange happening between capillary blood and tissue cells.

Oxygen Transport in the Blood

• Oxygen is transported in the blood dissolved in plasma and bound to hemoglobin.
• Hemoglobin is the primary oxygen-carrying protein in red blood cells.

Hemoglobin-Oxygen Saturation Curve

• Illustrates the relationship between hemoglobin saturation and the partial pressure of oxygen.
• The curve's shape shows how hemoglobin's oxygen binding affinity changes.
• Factors like blood pH, temperature and partial pressure of CO2 affect the curve.

Carbon Dioxide Transport in the Blood

• Dissolved in plasma, bound to hemoglobin (as carbaminohemoglobin), and transported as bicarbonate ions.
• Chemical reactions convert CO2 into bicarbonate to facilitate transport.