Ch. 15 - Respiratory System Flashcards
Ventilation
process of moving air from the atmosphere into the alveoli of the lungs and back out again. Two phases: inhalation/inspiration and exhalation/expiration
External respiration
the exchange of O2 and CO2 between the air in the alveoli and the blood supplying the alveoli
Transport
The transport of O2 and CO2 in the blood
Internal respiration
the exchange of O2 and CO2 between the blood and metabolically active cells of the tissues
What are the two divisions of the respiratory system?
conducting and respiratory
Conducting division
structures provide the passageway for air to move from atmosphere into areas where gas exchange occurs and then back out again; warms, humidifies, and cleans the air along its route
Respiratory Division
gas exchange between the lungs and blood occurs in these structures
Sinuses
air filled spaces within bone that contribute to voice, and decrease weight of the bones
Pulmonary capillaries
where gas exchange takes place
Alveoli
mainly contain space for air, but this space can be filled with infectious agents and immune cells if pneumonia sets in which prevents normal gas exchange from taking place.
Nose
entrance to respiratory tract and the primary organ of smell
Which lung has less lobes?
the left one to leave room for the heart.
Divisions of the respiratory system
upper and lower tracts
upper respiratory tract
structures above the vocal cords
lower respiratory tract
structures located below the vocal cords
Structures of upper respiratory tract
mouth, nose, pharynx, and the top end of the larynx
Structures of the lower respiratory tract
lower portion of larynx, trachea, bronchi, bronchioles, and alveoli.
Role of nasal cavities
increase surface area and are lined by mucous membranes; warm and humidify, and trap particles. If extensively vascularized, then the nose bleed happens.
Bones within nasal cavity
conchae; increase surface area, cause air moving past them to become turbulent/mixed which results in more contact between the air and the membrane.
What are the types of sinuses?
4 pairs: frontal, ethmoid, sphenoid, and maxillary; air-filled spaces that warm and humidify incoming air, connect nasal cavities; vocal resonance
Nasopharynx
- part of the conducting division
- conduit for air only
- adenoids lie in posterior wall
- closed off from oropharynx by uvula and soft palate
Oropharynx
- part of conduction division
- conduit for digestion and respiration
- palatine tonsils found at border
Laryngopharynx
- shortest of the three parts of pharynx
- part of conduction division
- conduit for both air and food
- opens into larynx and esophagus
Larynx
- directs air into trachea and food into esophagus
- contains vocal cords
- superior portion lined with stratified squamous epithelium
- inferior portion lined with mucous membranes that move trapped debris into pharynx for swallowing
Glottis and laryngeal cartilage
- cartilage in larynx prevents it from collapsing
- large cartilage: epiglottis, thyroid, cricoid
- small cartilage: arytenoid, corniculate, cuneiform
- glottis: vocal apparatus of the larynx (true vocal cords + rima glottidis)
Trachea
- extends from the larynx to its division into the left and right bronchi
- contains hyaline cartilage between fibrous tissue ligaments
- contains CARINA (ridge of cartilage that senses solid or liquids and triggers violent coughing to expel them)
- ciliated cells on the interior form the mucociliary escalator
- is ridged so it doesn’t collapse
Mucociliary escalator
traps particles and microorganisms and sweeps them into the pharynx to be swallowed
Order of bronchi through terminal bronchioles
- primary bronchi -> secondary bronchi -> tertiary bronchi -> primary bronchioles -> terminal bronchioles
Bronchi
supported by cartilage; interior contain ciliated mucous cells; little smooth muscle; mucociliary escalator
Bronchioles
- lack cartilage but have smooth muscle instead - lack mucous but still have ciliated cells
- no mucociliary escalator.
- have stem cells, and the ability to exchange gas
- have layer of smooth muscle that allows their diameter to change under the direction of the ANS/etc.
Features of Respiratory Bronchioles
- formed by division of terminal bronchioles
- inner lining of bronchioles lacks mucous glands, but does contain ciliated cells
- minimal smooth muscle in their walls
Features of alveolar ducts
- short conduits of mainly connective tissue; elastic
- smooth muscle cells scattered throughout
Features of Alveolar sacs
grape-like clusters of individual alveoli that opened from the alveolar ducts; elastic
Alveoli
- structures across which gas exchange occurs
- thin walled with large lumen
- provide intimate contact between inhaled air and blood in pulmonary capillaries that wrap the alveolar walls (ONLY ONE CELL THICKNESS)
- collectively, the alveoli have a surface area of 70 m^2 (size of singles tennis court)
- pores allow air to flow into neighboring alveoli to maintain the same pressure across the alveoli
Type 1 alveolar cell
- most common cell type
- connected to a thin, elastic basement membrane w/ a pulmonary endothelial cell on the other side (“respiratory membrane”)
- composes the respiratory membrane
Type 2 alveolar cells
- cuboidal cells
- make and secrete surfactant
Surfactant
- complex mixture of DPPC, other phospholipids, proteins, and cholesterol
- reduces surface tension between water molecules lining inner alveoli surfaces
- produced in last month of pregnancy
- w/o surfactant, water coating the alveoli surface would form droplets, causing the collapse of the alveoli and cessation of gas exchange.
- significantly increases the compliance of the lungs
Type 3 alveolar cells
- AKA alveolar macrophages
- resident alveolar immune cells
- phagocytic cells that scavenge microorganisms and other particles not captured prior
Features of the lungs
- occupy most of the thoracic cavity
- encased by pleural membrane (controls infection)
- costal surfaces of the lungs border the ribs and include anterior, lateral, and posterior sides.
- right lung has 3 lobes; left lung has 2
Lung lobes are further divided into:
broncho-pulmonary segments
Broncho-pulmonary segments are divided into:
pulmonary lobules
Lung Pleura
each lung is surrounded by a pleural membrane with 2 layers; fluid lubricates and provides a barrier to the movement of microorganisms between organs of thoracic cavity.
Layers of Lung Pleura:
- visceral pleura
- parietal pleura
Visceral Pleura
tightly covers each lung
Parietal Pleura
lines inner wall of thoracic cavity, mediastinum, and diaphragm
Pleural cavity
small space between the two layers containing pleural fluid (secreted by mesothelial cells)
Direction of deoxygenated blood flow:
- Pulmonary Trunk
- Pulmonary arteries
- Lobar arteries
- capillary beds surrounding alveoli