respiratory system Flashcards
mediastinum
The mediastinum is a central compartment within the thoracic cavity, situated between the left and right pleural cavities (which house the lungs). It acts as a divider and a container for various vital organs of the chest (heart, trachea, vessels and more).
define lungs.
what lung is bigger? (number of lobes of R/L lung)
The lungs are a pair of spongy, air-filled organs that reside within the chest cavity, also known as the thoracic cavity. They are the centerpiece of the respiratory system, responsible for the vital process of gas exchange.
- right lung → 3 lobes - upper, middle, and lower.
- left lung → 2 lobes - upper and lower ( smaller than right )
what’s the diaphragm? what does it do while breathing?
The diaphragm is a dome-shaped sheet of skeletal muscle that plays a critical role in breathing. It separates the chest cavity (thorax) from the abdominal cavity (abdomen).
During inhalation the diaphragm contracts and flattens downward. This increases the volume of the chest cavity, creating a lower pressure inside the lungs compared to the atmospheric pressure outside. Air rushes into the lungs to equalize the pressure differential.
(The diaphragm works in conjunction with the intercostal muscles between the ribs)
During exhalation (breathe out), the diaphragm relaxes and returns to its dome-shaped position.
The elastic recoil of the lungs and the downward movement of the rib cage due to relaxed intercostal muscles naturally push air out of the lungs.
The diaphragm doesn’t actively contract during exhalation in healthy individuals. However, forceful exhalation, such as coughing or singing, might involve some diaphragm activity.
define hilum of the lungs.
A part in each lung where the bronchus (airway), blood vessels, and nerves enter and leave the lung tissue.
what does the upper respiratory tract include?
what does the lower respiratory tract include?
upper- nasal cavity, Pharynx (throat) and larynx
lower - Trachea, Bronchi, Bronchioles, Alveoli and Lungs.
define pleural cavity. what are its 2 layers?
The pleural cavity, also known as the pleural space or intrapleural space, is the potential space that exists between the two layers of a membrane called the pleura, which surrounds each lung. It’s filled with a small amount of serous lubricating fluid called pleural fluid.
Visceral pleura: The inner layer that closely adheres to the surface of the lungs.
Parietal pleura: The outer layer that lines the inner wall of the chest cavity (thoracic cavity).
define nasal cavity
The nasal cavity, also sometimes called the nasal fossa, is the air-filled space inside your nose. It’s the very first chamber that inhaled air enters.
define larynx
and define epiglottis
The larynx, also commonly referred to as the voice box, is a hollow, tube-shaped organ located in the upper part of the throat. It plays a critical role in both breathing and communication.
The epiglottis is a small, leaf-shaped piece of elastic cartilage located in the throat, specifically at the upper opening of the larynx (voice box).
When swallowing, the epiglottis reflexively folds down over the opening of the larynx. This action briefly seals the airway, preventing food or liquids from entering the trachea (windpipe) and lungs. Once the swallow is complete, the epiglottis returns to its upright position, allowing air to pass through the larynx freely for breathing.
define nasopharynx
The nasopharynx, also sometimes referred to as the pharyngeal tonsil cavity is the uppermost section of the pharynx (throat) located behind the nasal cavity. It acts as a crossroads for air, food, and even sound, connecting several important structures.
define oropharynx
The oropharynx, also sometimes referred to as the mid-pharynx, is the middle section of the throat located behind the mouth. It serves as a common pathway for both air and food, connecting several important structures.
define trachea (layers and size)
The trachea, also widely known as the windpipe, is a tube-shaped organ in the respiratory system. It’s a vital conduit for air traveling between the larynx (voice box) and the lungs.
The trachea is a hollow, cylindrical tube measuring roughly 10-15 centimeters in length and about 2.5 centimeters in diameter.
-Mucosa: The innermost layer, also known as the mucous membrane. This layer is further divided into sub-layers:
Epithelium: This is the innermost surface lining, containing ciliated pseudostratified epithelium. These cells have tiny hair-like projections called cilia that move mucus upwards towards the pharynx.
Lamina propria: A connective tissue layer containing blood vessels, nerves, and glands. The glands within this layer produce mucus, which helps to trap dust, allergens, and other airborne particles.
-Submucosa: A layer of connective tissue containing blood vessels, nerves, and lymphatic vessels. It provides support and flexibility to the trachea.
-Hyaline cartilage: Crucially, the most distinctive feature of the trachea is a series of 16-20 incomplete C-shaped rings made of hyaline cartilage.
-Adventitia: The outermost layer, composed of loose connective tissue that anchors the trachea to surrounding structures in the chest. It also contains blood vessels and nerves.
define thyroid cartilage
The thyroid cartilage, often referred to as Adam’s apple, is the largest cartilage structure within the larynx (voice box) and a key component of the respiratory system in terms of Protection, Voice production and Maintaining airway patency.
what’s the pharynx?
The pharynx, also commonly referred to as the throat, is a muscular tube-shaped passageway that sits at the back of the nose and mouth and extends down the neck.
consists of: nasopharynx, oropharynx, laryngopharynx.
define esophagus (and size)
The esophagus, also sometimes referred to as the gullet or food pipe, is a hollow, muscular tube that forms part of the digestive system. It serves as the passageway for food and liquids traveling from the pharynx (throat) to the stomach.
The esophagus is a muscular tube measuring roughly 25-30 centimeters in length in adults.
define primary bronchi
The primary bronchi, also sometimes referred to as the main bronchi, are a pair of large tubes that branch off from the trachea (windpipe) at the carina (a ridge-like structure) in the lower part of the chest. They act as the initial pathways for air entering and exiting the lungs.
define secondary lobar bronchi and tertiary segmental bronchi.
The secondary lobar bronchi, also simply called lobar bronchi, are the first major branches arising from each primary bronchus.
The tertiary segmental bronchi, also known as segmental bronchi, are the next level of branching after the secondary lobar bronchi.
define bronchioles (and size)
Bronchioles are the finer airways within the lungs that form after the tertiary segmental bronchi.
diameter of about 1 millimeter or less.
define terminal bronchioles (and size)
are the last branching point before the alveoli. They are even smaller than the initial bronchioles and have minimal smooth muscle.
0.5 mm
define respiratory bronchioles
are even smaller airways that arise from terminal bronchioles and are directly connected to the alveoli. Their walls are lined with the specialized epithelium for gas exchange.
define goblet cells
Goblet cells, also sometimes referred to as mucous cells, are specialized epithelial cells found throughout the lining of your respiratory system and digestive tract. Their primary function is to produce and secrete mucus.
define alveoli (size, surface area)
are tiny, balloon-shaped air sacs located at the end of the bronchial tree in the lungs. They are the essential workhorses of the respiratory system, where the vital process of gas exchange takes place between inhaled air and your bloodstream.
- Air sacs - each with 200-300 alveoli
- surface area of ~ 100m^2
- Alveoli are microscopic, with a diameter of around 0.2-0.3 millimeters.
- extremely thin walls ( single layer of squamous epithelial cells ~ 0.5 micrometer thick )
define mucus escalator
The mucus escalator, also referred to as mucociliary clearance or mucociliary transport, is a self-cleaning mechanism within the respiratory system. It’s a remarkable system that constantly works to remove dust, debris, mucus, and even pathogens inhaled into the airways.
define alveolar duct
The alveolar duct is a tiny tube within the lungs that serves as a critical connection between the respiratory bronchioles and the alveolar sacs, the areas where gas exchange (oxygen and carbon dioxide) takes place.
Components:
Mucus: A sticky, wet secretion produced by goblet cells lining the airways. It traps dust, allergens, and pathogens inhaled with air.
Cilia: Tiny hair-like projections on the surface of cells lining the airways. They beat in a coordinated wave-like motion.
do alveoli have cilia?
no
what are alveolar macrophage cells?
Alveolar macrophages, also known as pulmonary macrophages or dust cells, are specialized immune cells residing within the alveoli of the lungs. They act as the first line of defense in the alveoli, safeguarding them from inhaled debris, pathogens, and harmful substances by phagocytosis.
What is pneumocytes?
(type 1 cells and type 2 cells)
Pneumocytes, also sometimes referred to as pneumonocytes, are the cells that make up the lining of the alveoli (the epithelial layer).
Type I Pneumocytes are the most abundant type of pneumocyte, covering around 95% of the alveolar surface area. They are extremely thin and flattened squamous epithelial cells, with a central nucleus and a cytoplasm that extends very thinly. The primary function of type I pneumocytes is gas exchange. Their thinness allows for the efficient diffusion of oxygen from inhaled air in the alveoli into the bloodstream, and carbon dioxide in the opposite direction.
Type II Pneumocytes are cuboidal-shaped cells, less numerous than type I cells, covering about 5% of the alveolar surface area. They are larger and contain numerous organelles, including lamellar bodies that store components for surfactant production. The primary function of type II pneumocytes is the production and secretion of pulmonary surfactant. This special fluid reduces surface tension within the alveoli, preventing them from collapsing during expiration (breathing out). Additionally, type II cells have the ability to differentiate into type I cells, which is crucial for repair and renewal of the alveolar lining.
how the elastic fibers in the alveolar walls help to breathe?
Expansion during inhalation: while inhaling, the diaphragm and chest muscles contract, creating a lower pressure inside the lungs compared to the outside. This pressure difference allows air to rush in. The elastic fibers in the alveoli readily stretch as they fill with air, allowing the lungs to expand efficiently.
Recoil during exhalation: Once inhaling stops and the muscles relax, the pressure inside the lungs starts to equalize with the outside pressure. the elastic fibers act like springs that naturally want to recoil. This recoil helps the alveoli shrink and passively push air out of the lungs, expelling carbon dioxide-rich air during exhalation.
