Respiratory phys part 1 Flashcards
Define pulmonary
anything to do with the lungs
define ventilation
movement of air going in and out
Define respiration
process of cellular metabolism
- cells need oxygen coupled with protein, glucose or fat to create ATP
- byproduct of this metabolism is CO2
What is the purpose of the respiratory system?
- to support cellular respiration by delivering O2 to the cells, removing CO2 because without O2 all tissues are affected.
How does respiration involve both tthe respiratory and circulatory systems? (4 processes)
- 4 processes that supply the body with O2 and dispose of CO2:
- pulmonary ventilation (air in and out)
- external respiration (exchange of gas at lungs)
- transport in the systemic circulation
- internal respiration (exchange of gas at the tissues)
What are the major organs of the respiratory system?
- nose, nasal cavity andparanasal sinuses
- pharynx
- larynx
- trachea
- bronchi and their branches
- lungs and alveoli
What are the 3 categories of the respiratory system?
- conducting zone: conduits to gas exchange sites, this includes all resp. structures that don’t participate in gas exchange (dead space)
- respiratory zone: site of gas exchange (micro structures: respiratory bronchioles, alveolar ducts and alveoli)
- Respiratory muscles: diaphragm and other muscles that promote ventilation
Relationship of trachea to the esophagus?
- trachea is anterior to the esophagus
Layers of tracheal wall?
- outermost: hyaline cartilage
- middle: submucosa
- innermost: ciliated mucosa
What are the conducting zone structures of the upper airway?
- nose and sinuses
- pharynx: nasopharynx which includes the adenoids, oropharynx which includes the palatine tonsils, and lingual tonsil and epiglottis, and laryngopharynx which houses the vocal cords
What is the fxn of the nose and sinuses?
- produce mucus, warm, humidify and filter the air
- nasal mucosa: continuous with mucosa of lower respiratory tract and extends into nasolacrimal ducts
Anatomy of the conducting zone structures?
- trachea: right and left main (primary) bronchi
- each main bronchus enter hilum of one lung (R bronchus is wider, shorter, and more vertical than left)
- each main bronchus branches into lobar (secondary) bronchi (three right and 2 left) - each lobar bronchus supplies one lobe
- each lobar bronchus branches into segmental (tertiary) bronchi: segmental bronchi divide repeatedly
- bronchioles are less than 1 mm in diameter
- terminal bronchioles are smallest, less than 0.5 mm diameter
How many orders of branching do the air passages undergo?
- 23 orders
- branching pattern called bronchial (respiratory) tree
What constricts the bronchioles?
- smooth muscle (bronchodilators work on smooth muscle during asthma attack)
What is the importance of elastic fibers that surround alveoli?
- impt for maintaining elasticity and compliance of the lungs
- pts with CT disorders - elastic fibers become very stiff and they develop restrictive disease
What kind of structural changes occur throughout the conducting zone?
- from bronchi through bronchioles - structural changes occur
- cartilage rings give way to plates, and cartilage is absent from bronchioles
- epithelium changes from pseudostratifiied columnar to cuboidal, cilia and goblet cells become sparse
- relative amount of smooth muscle increases
What makes up the respiratory zone?
- respiratory bronchioles, alveolar ducts, and alveolar sacs (clusters of alveoli)
- about 300 million alveoli account for most of lungs volume and are main site for gas exchange
What kind of cells make up the alveoli?
- walls: squamous epithelial cells that are only 1 cell layer thick (type 1 cells)
- scattered type II cuboidal cells that secrete surfactant and antimicrobial proteins (lysozymes)
- alveoloar and capillary walls and fused basement membranes, only 0.5 micrometer thick - air-blood barrier
- macrophages: clean out debris and infection (no cilia in alveoli) - keep alveolar surfaces sterile
What is purpose of open pores that alveoli contain?
- connect adjacent alveoli
- allow air pressure throughout lung to be equalized
What is the hilum?
- or root, site of vascular and bronchial attachments
structure of the lungs?
- left lung is smaller, separated into 2 lobes by oblique fissure
- R lung has 3 lobes separated by oblique and horizontal fissures
- bronchopulmonary segments ( 10 right, and 8-9 on left)
- lobules are smallest subdivisions, served by bronchioles and their branches
- each segment has own blood supply
Blood supply to the lungs? Pulmonary circulation
- pulmonary circulation (low pressure, and high volume)
- pulmonary arteries deliver systemic venous blood (branch profusely along with bronchi, and feed into the pulmonary capillary networks)
- pulmonary veins carry oxygenated blood from respiratory zones to the heart
Blood supply to the lungs? Systemic circulation?
- high pressure and low volume
- bronchial arteries provide oxygenated blood to lung tissue (arise from aorta and enter lungs at hilum, supply all lung tissue except alveoli)
- bronchial veins anastomose with pulmonary veins
- Bronchial veins anastomose with pulmonary veins
- pulm. veins carry most venous blood back to the heart
What is the pleurae?
- thin, double layered serosa
- parietal pleura on thoracic wall and superior face of diaphragm
- visceral pleura on external lung surface
- pleural fluid fills the slitlike pleural cavity: provides lubrication and surface tension
Describe the innervation of the lungs?
- parasympathetic stimulation = constriction of bronchioles
- sympathetic = dilation of the bronchioles
2 phases of the mechanics of breathing?
- ventilation consists of 2 phases:
1. inspiration: gas flows into lungs
2. expiration: gases exit the lungs
What principles do the mechanics of breathing rely on?
- pressure relationships in the thoracic cavity (intrapulmonary vs. intrapleural pressures)
- pulmonary ventilation: boyles law, airway resistance, alveoloar resistance, alveolar surface tension, and lung compliance
What is the pressure that keeps the lungs inflated?
transpulmonary pressure: this equals= Ppul (intrapulm)- Pip (intrapleural)
- Ppul and Pip can never be the same because then trans pressure would be 0 and the lungs would collapse (having a hole in the lungs) - need negative pressure to keep lungs inflated
Pressure relationships in the thoracic cavity?
- P atm is the pressure exerted by the air surrounding the body (760 mm Hg at sea level)
- neg resp pressure is less than P atm
- positive is greater than P atm
- 0 is = to P atm
What is intrapulmonary pressure?
- intraalveolar pressure (Ppul)
- pressure in alveoli, fluctuates with breathing but always equalized with P atm because not separated from atm Pressure (in the same compartment - open system)
What is intrapleural pressure?
- Pip: pressure in pleural cavity
- fluctuates with breathing
- always a negative pressure (less than Patm and Ppul)
- caused by opposing forces created by inward forces that promote lung collapse: elastic recoil of lungs decrease lung size, and surface tension of alveolar fluid reduces alveolar size
- one outward force that tend to enlarge the lungs: elasticity of chest wall pulls the thorax out
What is purpose of transpulmonary pressure?
- keep lungs open
- Ppul-Pip= transpulmonary pressure
- the greater the transpulm pressure the larger the lungs
- if Ppul= Pip then lungs would collapse
What occurs when pleura loses integrity?
- results in equalization of intrapleural pressure so lungs collapse, transpulm pressure would be 0
What is atelectasis (lung collapse) due to?
due to either:
- lack of air delivery: plugged bronchioles -leads to collapse of alveoli
- lack of integrity of pleura (wound that allows air entry into pleural cavity (pneumothorax)
What are 2 main categories of conditions that cause atelectasis?
- pleural problems (pneumothorax)
- ventilation problems
( infection: pneumonia)
How does pulmonary ventilation occur?
- through inspiration and expiration
- mechanical processes that depend on volume changes in the thoracic cavity: volume changes lead to pressure changes and pressure changes lead to gases flow to equalize the pressure
What is Boyle’s law?
- relationship b/t pressure and volume of gas
- pressure varies inversely with volume
- more volume leads to less pressure
Describe the process of inspiration
- active process
- inspiratory muscles contract
- thoracic volume increases
- lungs are stretched and intrapulm. volume increases
- intrapulm pressure drops (-1 mm Hg) and air flows into the lungs down its pressure gradient until Ppul=Patm
Is expiration passive or active?
- can be both
quiet expiration is passive process: - inspiratory muscles relax
- thoracic cavity volume decreases
- elastic recoil and intrapulm. volume decreases
- Ppul rises to +1 mm Hg (greater than Patm) so air flows out of lungs down its pressure gradient until Ppul= 0
- forced expiration: active process using abdominal and internal intercostal muscles
When does intrapulmonary pressure increase and decrease?
- increases during expiration and lung volume decreases
- decreases during inspiration as lung volume increases
When does intrapleural pressure become negative?
- when chest wall expands during inspiration, and it returns back to inital value as chest wall recoils
What are the physical factors that influence pulmonary ventilation? inspiratory muscles have to overcome what 3 factors that hinder air passage and pulmonary ventilation?
- airway resistance
- alveolar surface tension
- lung compliance
What is the major nonelastic source of resistance to gas flow?
- friction
What is relationship between flow, pressure, and resistance?
- flow = change in pressure/ resistance
- gas flow changes inversely with resistance (increase resistance you will decrease flow)
Why is resistance usually insignificant?
- because:
- large airway diameteres in the first part of the conducting zone
- progressive branching of airways as they get smaller, increasing the total cross-sectional area
- resistance disappears at the terminal bronchioles where diffusion drives gas movement
Where is the greatest resistance to flow seen?
- in medium sized bronchi because after that pt they branch a lot more and so the surface area is increased, that is why least amount of resistance is in terminal bronchioles
What occurs when airway resistance rises?
- breathing movements become more strenous
- severe constriction or obstruction of bronchioles can cause respiratory failure and can occur during acute asthma attacks and stop ventilation
What helps dilate the bronchioles and reduces air resistance? what kind of stimulation is this?
- epi which is released from sympathetic nervous system
- sympathetic response (relaxes smooth muscle)
What forces increases airway resistance?
- bronchospasm
- secretions
- mucosal edema
What are the 3 types of COPD, what happens in COPD?
- alveoli or bronchioles or both are destroyed
- lungs with COPD showed 72-89% reduction in number of terminal bronchioles/lung
3 types:
emphysema (destruction of alveoli), chronic bronchitis (destruction of bronchioles), and COPD (combo of two)
What conditions increase airway resistance?
COPD - emphysema and Chronic bronchitis asthma cystic fibrosis sleep apnea (Upper airway resistance)
What 3 factors that hinder air passage and pulmonary ventialtion do the inspiratory muscles have to overcome?
- inspiratory muscles overcome 3 factors that hinder air passage and pulmonary ventilation:
1. airway resistance
2. alveolar surface tension
3. lung compliance
What is alveolar surface tension?
- surface tension: attracts liquid molecules to one another at a gas liquid interface
- resists any force that tends to increase the surface area of the liquid
WHat is produced by the type II alveolar cells to reduce alveolar fluid surface tension?
- surfactant, a detergent like lipid and protein complex produced by type II alveolar cells
- discourages alveolar collapse
- insufficient quantity in premature infants cause infant respiratory distress syndrome (can give surfactant to babies)
What is lung compliance?
- a measure of the change in lung volume that occurs with a given change in transpulmonary pressure
low compliance: doesnt expand very easily
high compliance: very easy to expand lungs
Why is lung compliance normally high?
due to:
- distensibility of healthy lung tissue
- ability of the thoracic cage to expand during inspiration under normal circumstances
- reduction of alveolar surface tension secondary to surfactant
What kind of conditions decrease lung compliance?
- nonelastic scar tissue (restrictive lung disease)
- reduced production of surfactant
- decreased flexibility of thoracic cage
- deformities of thorax
- ossification of costal cartilage
- paralysis of intercostal muscles
