Respiratory i Flashcards
Major function of respiratory system
Respiration: duh
- supply blood with O2 for cellular respiration and dispose of CO2 which is a waste of cellular respiration
- 4 processes involving respiratory and circulatory system
- also functions in olfaction and speech
4 processes of respiratory system function
Respiratory System
- Pulmonary ventilation = movement of air into and out of lungs
- External respiration = O2 and CO2 exchange between lungs and blood
Circulatory System:
- Transport = O2 and CO2 in blood
- Internal respiration = O2 and CO2 exchange between systemic blood vessels and tissues
Airways: structural and functional
Upper Respratory structures
-nose, nasal cavity, and pharynx (naso-, oro-, laryngo-)
Lower Respiratory structures
-larynx, trachea, bronchi, bronchioles, alveoli
Respiratory zone
-respiratory bronchile, alveolar duct, alveoli
Conduction zone
-everything else
Definition of the dif zones
Respiratory zone = site of gas exchange
Conducting zone = conduits to gas exchange sites –> cleanses, warms, humidifies air
Diaphragm and other respiratory muscles promote ventilation
Nose
Func:
- provides airway for respiration
- moistens and warms entering air
- filters and cleans inspired air
- serves as resonating chamber for speech
- houses olfactory receptors
Anatomy
-nasal cavity within and posterior to external nose –> divided by midline nasal septum –> posterior nasal aperatures (choanae) open into nasopharynx –> roof = ethmoid and sphenoid bones –> floor = hard and soft palates
Nasal vestibule and the rest of the nasal cavity
Nasal vestibule = nasal cavity superior to nostrils –> vibrissae (hairs) filter coarse particles from inspired air
Rest of nasal cavity lined with mucous membranes: olfactory and respiratory mucosa
Olfactory and Respiratory mucosa
Olfactory mucosa contains olfactory epithelium
Respiratory mucosa
- pseudostratified ciliated columnar epithelium
- mucous and serous secretions contain lysozyme and defensins
- cilia move contaminated mucus posteriorly to throat
- inspired air warmed by plexuses of capillaries and veins
- sensory nerve endings trigger sneezing
Nasal conchae and nasal meatus
Nasal conchae: superior, middle, and inferior
- protrude medially from lateral walls
- increase mucosal area
- enhance air turbulence
Nasal meatus = groove inferior to each concha
Function of structures within nose during breathing
During inhalation, conchae and nasal mucosa filter, heat , and moisten air
During exhalation these structures reclaim heat and moisture
Paranasal sinuses
In frontal, sphenoid, ethmoid, and maxillary bones
-lighten skull, secrete mucus, help to warm and moisten air
Pharynx
Muscular tube from base of skull to C6
- connects nasal cavity and mouth to larynx and esophagus
- composed of skeletal muscle
There regions: naso-, oro-, laryngo-
Larynx
Attaches to hyoid bone; opens into laryngopharyx; continuous with trachea
Func
- provides patent airway
- routes air and food into proper channels
- voice producetion: houses vocal folds
Nine cartilages of larynx
- All hyaline except epiglottis
- Thyroid cartilage with laryngeal prominence (adam’s apple)
- Ring-shaped cricoid cartilage
- paired arytenoid, cuneiform, and corniculate cartilages
- Epiglottis = elastic cartilage which covers the laryngeal inlet during swallowing –> covered in taste bud-containing mucosa
Vocal ligaments
In larynx –> deep to laryngeal mucosa
- attach arytenoid cartilages to thyroid cartilage
- contain elastic fibers
-form core of vocal folds (true vocal cords) –> glottis = opening between vocal folds –> folds vibrate to make sound as air rushed up from lungs
Vestibular folds (false vocal cords) -superior to vocal folds --> no part in sound production --> help to close glottis during swallowing
Epithelium of larynx
superior portion - stratified squamous epithelium
Inferior to vocal folds - pseudostratified ciliated columnar epithelium
Voice production
- speech = intermittent release of expired air while opening an dclosing glottis
- pitch determined by length and tension of vocal cords
- loudness depends upon force of air
- chambers of pharynx, oral, nasal, and sinus cavities amplify and enhance sound quality
- sound is “shaped” into language by muscle of pharynx, tongue, soft palate, and lips
Valsalva’s maneuver
glottis closes to prevent exhalation
- abdominal muscles contract
- intra-abdominal pressure rises
- helps to empty rectum or stabilizes trunk during heavy lifting
Trachea: definition and layers
Windpipe from larynx into mediastinum
3 layers
- mucosa = ciliated pseudostratified epithelium with goblet cells
- submucosa = CT with seromucous glands
- Adventitia = outermost layer made of CT tissue; encases C-shaped rings of hyaline cartilage
Tracheal cartilage and muscle
Trachealis
- connects posterior parts of cartilage rings
- contracts during coughing to expel mucus
Carina
- spur of cartilage on last, expanded tracheal cartilage
- point where trachea branches into two main bronchi
Trachealis muscle along posterior
Bronchi and subdivisions
Air passages undergo 23 orders of branching –> bronchial tree
From tips of bronchial tree –> conduction zone structures –> respiratory zone structures
Conducting zone structures of Bronchi
- Trache goes into right and left main (primary) bronchi
- Each main bronchus enters hilum of one lung (right is wider, shorter, and more vertical)
- Each main bronchus branches into lobar (secondary) bronchi –> 3 on right; 2 on left –> each supplies one lobe
- Each lobar bronchus branches into segmental (tertiary) bronchi –> divide repeatedly
- Branches get smaller and smaller –> bronchiles are less than 1 mm diameter and terminal bronchioles are less than 0.5 mm diameter
structural changes as bronchi branching occurs
- cartilage rings become irregular plates –> in bronchioles elastic fibers replace cartilage
- epithelium changes from pseudostratified columnar to cuboidal; cilia and goblet cells become sparse
- relative amount of smooth muscle increases –> allows constriction
Lungs
- Right lung = superior, middle, inferior lobes separated by oblique and horizontal fissures
- Left lung = superior and middle lobes separated by oblique fissure
-Bronchopulmonary segments (10 right, 8-10 left) separated by CT septa (if diseased, can be individually removed)
Lobules = smallest subdivisions visible to naked eye; served by bronchiles and their branches
Respiratory zone
-Begins as terminal bronchioles –> respiratory bronchioles –> alveolar ducts –> alveolar sacs
Alveolar sacs contain clusters of alveoli
- 300 mil alveoli make up most of lung volume
- sites of gas exchange
Respiratory membrane
Alveolar and capillary walls and their fused basement mambranes –> 0.5 um thick –> gas exchange across membrane by simple diffusion
Alveolar walls = simgle layers of squamous epithelium (type 1 alveolar cells)
Scattered cuboidal type II alveolar cells secrete surfactant and antimicrobial proteins
Alveoli
- Surrounded by fine elastic fibers and pulmonary capillaries
- Alveolar pores connect adjacent alveoli –> equalize air pressure throughout lung
- Alveolar macrophages keep alveolar surfaces sterile –> 2 million dead macrophages/hour carried by cilia –> throat –> swallowed
Progression of epithelium thinning in bronchi
Pseudostraified ciliated columnar epithelium up to and including lobar bronchi
Simple ciliated columnar epithelium in segmental bronchi and large bronchioles
Simple ciliated cuboidal epithelium in small, terminal, and respiratory bronchioles (progressive loss of cilia)
Simple squamous epithelium in alveolar ducts and forms alveoli
Pulmonary circulation
-low pressure; high volume
Pulmonary arteries deliver systemic venous blood to lungs for oxygenation
-branch profusely; feed into pulmonary capillary networks
Pulmonary veins carry oxygenated blood from respiratory zones to heart
Lug capillary endothelium has enzymes that act on substances in blood (e.g. angiotensin-converting enzyme activates blood pressure hormone)
Bronchial arteries
Provide oxygenated blood tp lung tissue
- arise from aorta and enter lungs at hilum
- part of systemic circulation (high pressure; low volume)
- supply all lung tissue except alveoli
- bronchial veins anastomose with pulmonary veins –> pulmonary veins carry most venous blood back heart
Pleurae
Thin, double-layered serosa; divides thoracic cavity into two pleural compartments and mediastinum
Parietal pleura on thoracic wall, superior face of diaphragm, around heart, between lungs
Visceral pleura on external lung surface
Pleural fluid fills slitlike pleural cavity –> provides lubrication and surface tension –> assists in expansion and recoil
Boyle’s Law
The pressure of a gas is inversely proportional to its volume at a given temp
Dalton’s law
The partial pressure of a gas in a mixture of gases is the percentage of the gas in the micture
Henry’s Law
The concentration of a gas dissolved in a liquid is equal to the partial pressure of the gas over the liquid times the solubility coefficient of the gas
Mechanisms of breathing
Pulmonary ventilation =
inspiration: gas flows into lungs +
expiration: gases exit lungs
Pressure relationships in thoracic cavity
Atmospheric pressure = pressure exerted by air surrounding body
-760 mm Hg at sea level = 1 atmosphere
Respiratory pressure is described relative to Patm
- negative respiratory pressure is less than Patm
- Positive respiratory pressure is greater than Patm
- Zero respiratoy pressure is equal to Patm
Intrapulmonary pressure
Also called intra-alveolar pressure –> Ppul
- pressure in alveoli
- fluctuates with breathing
- always eventually equalizes with Patm
Intrapleural pressure
Pip
- pressure in pleural cavity
- fluctuates with breathing
- always a negative pressure (less than Patm and Ppul)
- fluid level must be minimal (its pumped out by lymphatics, but if it accumulates –> positive Pip pressure –> lung collapse)
Negative Pip caused by opposing forces
- Two inward forces promote lung collapse: elastic recoil of lungs decreases lung size and surface tension of alveolar fluid reduces alveolar size)
- one outward force tends to enlarge lungs: elasticity of chest wall pulls thorax outward
