Pulmonary Physiology (1) Flashcards
list the 6 major parts of the respiratory system from top to bottom
- nose
- pharynx
- larynx (voice box)
- trachea
- bronchi
- lungs
what are the 2 ways to classify the respiratory system?
- structure
- functions
list and describe the two structural divisions of the respiratory system
- upper resipiratory system: nose, nasal cavity, pharynx, associated structures
- lower respiratory system: larynx, trachea, bronchi, lungs
what are the 2 function divisions of the respiratory system?
- conducting zone
- respiratory zone
describe the conducting zone?
aeries of interconnecting cavities and tubes outside and within the lungs
what 8 structures are in the conducting zone?
- nose
- nasal cavity
- pharynx
- larynx
- trachea
- bronchi
- bronchioles
- terminal bronchioles
what is the function of the conducting zone?
filter, warm, and moisten air and conduct it to the lungs
what is the respiratory zone?
tubes and tissues within the lungs where gas exchange occurs
what 4 structures are in the respiratory zone?
- respiratory bronchioles
- alveolar ducts
- alveolar sacs
- alveoli
what is the function of the respiratory zone?
main site of gas exchange between air and blood
what is otorhinolaryngology?
branch of medicine that deals with diagnosis and treatent of diseases of ears, nose, and throat
what is a pulmonologist?
specialist in diagnosis and treatment of diseases of lungs
what do the R and L primary bronchi branch off from and where?
branch off from the trachea at the 5th thoracic vertebrae
compare the R primary bronchis to the L
R primary bronchus is more vertical, shorter, and wider than the L because the liver pushes it up
in which bronchus are aspirated objects more likely to get lodged?
the Right
what is the carina?
the point where the trachea divides into L and R primary bronchi
describe the structure of the carina
internal ridge formed by the last tracheal cartilage
describe the mucus membrane of the carina
very sensitive to the cough reflex
what happens to the primary bronchi once inside the lungs?
they branch and divide forming secondary (lobar), then tertiary (segmental) bronchi before branching into bronchioles
what does the left lung have that makes it 10% smaller than the right lung?
the cardiac notch
what is interspersed among the cells of the terminal bronchioles?
clara cells
what is the function of the clara cells in the terminal bronchioles? (3)
- may protect against harmful effects of inhaled toxins/carcinogens
- produce surfactant
- functions as stem cells for epithelium
what do the terminal bronchioles represent?
the end of the conducting zone
what does exercise do, related to the bronchi? (5 step process)
- stimulates sympathetic ANS
- causes adrenal medulla to release epi and norepi
- both hormones cause relaxation of smooth muscle in bronchioles
- this causes the airways to dilate
- this allows air to reach the alveoli quicker
what does an asthma attack do, related to the bronchioles?
- the release of histamine
- causes contraction of bronchiolar smooth muscle
- this causes constriction or distal bronchioles
what protects and encloses each lung?
a double-layered serous membrane
describe the 2 layers of the pleural membrane
- parietal layer: superficial
- visceral layer: deep
what is the space between the 2 layers of the pleural membrane called?
the pleural space
what does the pleural space contain? what is the function?
small amount of lubricating fluid from the membranes that reduces friction between the membranes, allowing them to slide easily over each other during breathing
what is pleurisy?
inflammation of the lungs; also called pleuritis
what can pleurisy cause and why?
may cause pain due to friction between layers of the pleural membrane
what is pleural effusion?
in inflammation from pleuritis persists, there may be excess fluid accumulating in the plueral space in a condition called pleural effusion
describe the lungs’ spatial relation to the thoracic cavity
take up MOST of the thoracic cavity
where are the lungs?
extend from the diaphragm to slightly superior to the clavicles (gigantor)
where do the anterior, lateral, and posterior surfaces of the lungs lie against?
the ribs
how far does the pleura extend? what does this mean?
the pleura extends about 5cm below the base of the lungs, meaning the lungs don’t completely fill the pleural cavity in that area
what does the excess room in the pleural cavity allow for?
excess fluid can be removed from that space without damaging the lungs
what is thoracentesis?
inserting a needle anteriorly through the 7th intercostal space, with that needle passing along the superior bornder ot the lower rib to avoid damage to intercostal nerves and blood vessels to remove fluid from the lungs
what are bronchopulmonary segments?
segments of lung tissue that each tertiary bronchus supplies
what does each bronchopulmonary segment have?
many lobules, or small compartments
describe each lobule of the bronchopulmonary segments
wrapped in elastic connective tissue
what does each lobule of the bornchopulmonary segments contain? (4)
- a lymphatic vessel
- an arteriole
- a venule
- and a branch from a terminal bronchiole
what do terminal bronchioles divide into? what do they have budding from their walls?
terminoal bronchioles divide into branches called respiratory bronchioles that have alveoli budding from their walls
what begins the respiratory zone?
respiratory bronchioles
what do respiratory bronchioles subdivide into?
severla alveolar ducts
approximately how many orders of branching are found in the respiratory passages from trachea into alveolar ducts?
approximately 25 orders of branching
what is the 1st order of branching?
branching from trachea into primary bronchi
what is an alveolus?
a cup shaped outpouching lined by simple squamous epithelium and supported by thin, elastic basement membrane
what is an alveolar sac?
2 or more alveoli that share a commonopening
what aare the 2 types of epithelial cells that the walls of alveoli contain?
Type I alveolar cells and Type II alveolar cells
describe Type I alveolar cells (2)
- more numerous than Type II
- simple squamous epithelial cells that form a nearly continuous lining of the alveolar wall
describe Type II alveolar cells (2)
- septal cells (more info later)
- found between Type I cells
describe the walls of Type I alveolar cells
thin
what is the function of Type I alveolar cells?
main site of gas exchange
describe the structure of Type II alveolar cells
cuboidal (rounded) epithelial cells that contain microvilli
what is the function of Type II alveolar cells?
secrete alveolar fluid
what does alveolar fluid do?
keeps surface netween cells and air moist
what does surfactant do?
reduces tendency of alveoli to collapse and maintains their patency (openness)
where is surfactant found?
in alveolar fluid
what is surfactant?
a complex mixture of phospholipids and lipoproteins
what is dipalmitoylphosphatidylcholine?
one of the phospholipids in surfactant; part of the molecule dissolves and the remainder spreads over the water surface
compare the surface tension of surfactant to pure water
surfactant has 1/12 to 1/2 the surface tension of water, much more slippery
where does exchange of O2 and CO2 between air spaces take place and how?
by diffusion across alveolar and capillary walls
where is the respiratory membrane?
extends from alveolar air space to blood plasma
what are the 4 layers in the respiratory membrane?
- alveolar wall
- epithelial basement membrane (for structure and stability)
- capillary basement membrane
- capillary endothelium
describe the thickness and function of the respiratory membrane
very thin to allow rapid diffusion of gases
approximately how many alveoli do the lungs contain?
approx 300 million
what is respiratory distress syndrome?
a breathing disorder of premature newborns where alveoli do not remain open due to lack of surfactant
what increases the chance of respiratory distress syndrome developing?
the more premature the newborn, the greater the chance that RDS will develop
what are 3 symptoms of respiratory distress syndrome?
- labored/irregular breathing
- flaring of nostrils during inhalation
- possibly blue skin color
what is done in mild cases of resipiratory distress syndrome?
supplemental O2
what is done in severe cases of resipiratory distress syndrome? (2)
- O2 delivered by continuous positive airway pressure, through tubes in nose or mask on face
- surfactant administered directly into lungs
what is a unique feature of pulmonary blood vessels?
constriction in response to localized hypoxia
why do pulmonary blood vessels constrict in response to localized hypoxia?
to divert pulmonary blood flow from poorly ventilated areas of lungs to well ventilated regions
what does diversion of pulmonary blood flow from poorly ventilated areas to well ventilated areas allow for? (2)
- more efficient gas exchange
- ventilation perfusion coupling
what is ventilation perfusion coupling?
perfusion to each area of lungs matches the extent of ventilation to alevoli in that area
what do bronchial arteries branch from and what do they do?
bronchial arteries branch from aorta and deliver oxygenated blood to lungs
what do bronchial arteries mainly perfuse?
bronchial arteries mainly perfuse walls of bronchi and bronchioles
what are the 3 steps to respiration?
1.pulmonary ventilation
2. external (pulmonary) respiration
3. internal (tissue) respiration
what happens in pulmonary ventilation? (1st step to respiration)
breathing; inhalation and exhalation of air
what happens in external (pulmonary) respiration? (2nd step to respiration)
exchange of gases between alveoli of lungs and blood in pulmonary capillaries
what happens in internal (tissue) respiration? (3rd step to respiration)
exchange of gases between blood in systemic capillaries and tissue cells
why does air flow between atmosphere and alveoli?
because of altering pressure differences
what causes the altering pressure differences that causes air to floow between atmosphere and alveoli?
contraction and relaxation of respiratory muscles
other than contraction and relaxation of muscles, what 3 things influence the rate of airflow and amount of effort needed for breathing?
- alveolar surface tension
- compliance of lungs
- airway resistance
when does air move into the lungs?
when air pressure in lungs is less than air pressure in the atomosphere
when does air move out of the lungs?
when air pressure inside lings is greater than air pressure in the atmosphere
describe air pressure in the lungs and atmosphere just before inhalation
equal to each other, 760 mmHg
what must happen in order for air to flow into lungs? how is this achieved?
pressure in alveoli must become lower than atmosphere; achieved by expanding lungs (flattening diaphragm)
what does Boyle’s law state?
there is an inverse relationship between volume and pressure, so the pressure of gas in a closed container is inversely proportional to the volume of the container
according to Boyle’s law, what happens if the size of a closed container is increased?
the pressure of the gas inside the container will decrease
what do the differences in pressure caused by chnages in lung volume do to air during inhalation and exhalation?
force air into lungswith inhalation and force air out of lungs with exhalation
what must happen in order for inhalation to occur and why?
lungs must expand to increase lung volume to decrease pressure in lungs below atmospheric pressure
what is the first step in expanding the lungs?
contraction of the main muscles of inhalation
what are the 2 main muscles of inhalation and which is most important?
- diaphragm: most important!
- external intercostals
what is the diaphragm innervated by?
phrenic nerves
what does contraction do to the diaphragm? what is the result of this?
contraction cuases diaphragm to flatten, lowering its dome shape to increase the vertical diameter of the thoracic cavity
in quiet breathing, far does the diaphragm descend? what does this do to pressure and how much air is inhaled?
in quiet breathing, the diaphragm descends approx 1cm, causing a pressure difference of 1-3 mmHg and allowing for inhalation of approx 500 mL of air
in strenuous breathing, far does the diaphragm descend? what does this do to pressure and how much air is inhaled?
in strenuous breathing, diaphragm descends up to 10cm, producing a pressure difference of 100mmHg and allowing for inhalation of 2-3L of air
during quiet breathing, the diaphragm is responsible for what percent of air that enters the lungs?
approximately 75%
what are horse hiccups also called? in what horses are they common?
also called the thumps, common in endurance horses
why do endurances horses get the thumps?
they sweat a lot, so they lose a lot of electrolytes, which causes hyperexcitation of the phrenic nerve that sits on the right atrium; so when the heart contracts, the phrenic nerve reponds and the diaphragm bounces based on the heart beat
how do you treat the thumps in horses?
give electrolytes to end hyperexcitation of the phrenic nerve
describe what the ribs do during inhalation and exhalation by comparing them to the handles of a bucket
move up and out in inhalation
move down and in during exhalation
what 3 conditions can prevent complete descent of the diaphragm?
- pregnancy
- excessive obesity
- confining abdominal clothing
what happens when the external intercostals contract?
they elevate the ribs
what is the result of the elevation of the ribs caused by contraction of the external intercostals?
increase in anteroposterior (front to back) and lateral diameter of chest cavity
what percentage of air entering the lungs during quiet breathing are the external intercostals responsible for?
approx 25%
what is intrapleural pressure?
the pressure between the 2 pleural layers in the pleural cavity (parietal and visceral)
describe the relative level of intrapleural pressure during quiet inhalation
always subatmospheric during quiet inhalation
what is intrapleural just before inhalation?
approx 756mmHg, 4 less than atmospheric pressure
what happens to the overall size of the thoracic cavity as the diaphragm and external intercostals contract?
overall size of thoracic cavity increases
what happens to the pleural cavity as the overall size of the thoracic cavity increases? what is the result?
the volume of the pleural cavity increases, causing intrapleural pressure to drop to approx 754 mmHg
describe the parietal and visceral pleura during expansion of the thorax
normally adhere tightly because of subatmospheric pressure between them and because of surface tension created by moist adjoining surfaces
what happens to the parietal pleura lining the thoracic cavity as the thoracic cavity expands and what is the result?
parietal pleural cavity is pulled outward in all directions and pulls visceral pleura and lungs with it
what happens to alveolar pressure inside the lungs as the volume in the lungs increases? what does this establish and what is the result?
alveolar pressure inside lungs drops from 760 to 758 mmHg, establishing a pressure difference between the atmosphere and the alveoli, causing air to flow from the region of higher pressure (the atmosphere) to the region of lower pressure (the alveoli)
how long will air continue to flow into the lungs?
as long as a pressure difference exists
what is used during deep forceful inhalations? general and then give 3
accessory muscles such as
1. sternocleidomastoid
2. scalene
3. pectoralis minor
what does the sternocleidomastoid muscle do during deep forceful inhalation?
elevates the sternum
what does the scalene muscle do during deep forceful inhalation?
elevates the first two ribs
what does the pectoralis minor muscle do during deep forceful inhalation?
elevates the 3rd and 4th ribs
when does exhalation occur?
when pressure in lungs is greater than pressure in atmosphere
describe exhalation during quiet breathing (2)
- a passive process
- no muscular contractions involved
what causes exhalation?
elastic recoil of the chest wall and lungs, which both have a natural tendency to spring back after stretched
whar are the 2 inwardly directed forces that contribute to elastic recoil?
1, recoil of elastic fibers that were stretched during inspiration
2. inward pull of surface tension due to film of alveolar fluid
what is intrapulmonic pressure?
pressure inside the lungs themselves
