Chapter 16 - Respiratory System Flashcards
what is internal respiration
using O2 for oxidative phosphorylation inside mitochondria, releasing CO2 as waste
what is external respiration
pulmonary ventilation (moving air in/out of lungs), gas exchange between lungs and blood, transportation in blood, and gas exchange between blood and body tissues
what are the upper airways
air passages of the head and neck: nasal cavities, oral cavity, and pharynx
what is the respiratory tract
this term is used in the textbook and describes all airways from pharynx to lungs (lower respiratory tract): larynx, trachea, bronchi, and alveoli
what is the conducting zone
passages for air. passages in the conducting zone (with exception of bronchioles) have cartilage in their walls. remain open. trachea, bronchi and bronchioles have smooth muscles in their walls
what is the larynx
the voice box. consists of epiglottis - protects airways during swallowing, and glottis - opening between vocal folds. the walls are made of cartilage
describe trachea
the windpipe. 2.5 cm diameter, 10 cm long, wall contains 15-20 C shaped bands of cartilage, stays open
describe bronchi in conducting zone
primary (or main) bronchi right and left. secondary (or lobar) bronchi: 3 on right side to 3 lobes of right lung and 2 on left side to 2 lobes of left lung. in all there are 20-23 orders of branching in bronchial tree. terminal bronchioles are the smallest bronchioles and the end of conducting zone
what is the function of conducting zone
air passageway that conditions incoming air by humidifying, warming up, and removing dust and particles from air
describe mucosa of conducting zone
goblet cells and mucus glands secrete mucus that help to condition air. ciliated cells have cilia that move particles trapped in mucus toward mouth (mucus escalator)
what is the function of the respiratory zone
exchange of gases between air and blood. the mechanism of this action is diffusion
what are the structures of the respiratory zone
respiratory bronchioles (have alveoli in their walls). alveolar ducts, and alveolar sacs
what is epithelium like in respiratory zone
very thin
what is the arrangement of respiratory membrane
back to back arrangement: epithelial cell layer of alveoli along with endothelial cell layer of capillaries
describe alveoli
sites of gas exchange, 300 million alveoli in lungs (size of tennis court). rich blood supply because capillaries form dense network over alveoli. alveoli are connected through pores
name 3 cells of the alveoli
type 1 alveolar cells that form wall of alveoli (single layer of thin epithelial cells), type 2 alveolar cells secrete surfactant and alveolar macrophages
name bones of the thoracic cavity
sternum, thoracic vertebrae, and ribs
describe muscles of thoracic cavity
internal and external intercostal muscles in spaces between the ribs, and the diaphragm separates the thoracic and abdominal cavities
what is the pleura
the membrane lining of lungs and chest wall: a pleural sac surrounds each lung, intrapleural space is filled with intrapleural fluid (volume is 15 mL)
what is intrapleural space
a potential space between the visceral and parietal pleurae, that contains 15 mL of fluid
what is visceral pleura
part of the pleura that covers the surface of the lung
what is parietal pleura
part of pleura that attaches to rib cage, diaphragm, and pericardium
describe arrangement of visceral and parietal pleura
they are in contact with each other held together by surface tension of pleural fluid
what causes air to move in and out of lungs
bulk flow determines where air goes, so a pressure gradient drives the flow. air moves from high to low pressure. during inspiration the pressure in lungs is lower than atmospheric pressure, during expiration pressure in lungs is greater than atmospheric pressure
what is Patm, Palv, and Pip
atmospheric pressure, intra-alveolar pressure (pressure of air in alveoli), and intrapleural pressure (pressure inside pleural sac)
how do you calculate transpulmonary pressure and what is it
Palv-Pip = transpulmonary pressure. it is the distending pressure across the lung wall
what is atmospheric pressure
760mm Hg at sea level. other lung pressures are given relative to atmospheric pressure (set Patm = 0 mm Hg)
describe Palv
pressure of air in alveoli, given relative to atmospheric pressure, varies with phase of respiration. during inspiration it is negative (less than atmospheric), during expiration it is positive (more than atmospheric)
what drives ventilation
the difference between Palv and Patm
describe Pip
the pressure inside pleural sac is always negative under normal conditions and always less than Palv. it varies with phase of respiration but at rest it is -4 mm Hg.
what gives Pip its value
it is negative due to elasticity in lungs and chest wall. lungs have elastic recoil - tendency to collapse, chest also has elastic recoil - tendency to expand. between the lungs and chest wall is the sealed off intrapleural space. opposing forces pull on intrapleural space and so the pressure inside is less than atmospheric pressure. intrapleural fluid keeps visceral and parietal pleura in close contact and allows frictionless sliding against each other during breathing
what does an increase in transpulmonary pressure cause
lungs (alveoli) to expand, increasing the volume. increase in lung volume decreases lung pressure Palv below atmospheric pressure and air flows in down pressure gradient
describe a pneumothorax
the entry of air into intrapleural space. without negative intrapleural pressure, elastic recoil is unopposed and causes lung to collapse. to restore negative pressure and open the lung, the intrapleural space is sealed and air is sucked out of it
describe equation for air flow
Patm - Palv / R (R is resistance to air flow and is related to airway radius and mucus)
what is boyle’s law
pressure of gas is inversely proportional to its volume
do changes in alveolar pressure or atmospheric pressure affect the gradient for air flow
changes in alveolar pressure affect the gradient, atmospheric pressure is constant during breathing cycle
what is Palv at rest (between breathings)
0 (equal to atmospheric pressure) since there is no pressure gradient, no air flow in or out of lungs
what happens to Palv as lungs expand
alveolar volume increases so Palv decreases driving air into lungs
what happens to Palv as lungs recoil
alveolar volume decreases and so Palv increases pressure gradient drives air out of lungs
describe mechanisms of breathing in quiet respiration
contraction of inspiratory muscles increases volume of thoracic cavity while relaxation of inspiratory muscles decrease volume of thoracic cavity
describe diagphram and intercostals during quit respiration inspiration
diaphragm moves down, increasing superior-inferior dimension of thoracic cavity while intercostals move the ribs up and outward increasing lateral dimension of thoracic cavity
describe muscles involved in forceful inspiration
additional neck and shoulder muscle contract to increase force expanding the rib cage: sternocleidomastoid and scalenes pulls on the sternum and ribs as well as pectoralis major and minor pull on sternum and ribs
describe muscles involved in forceful expiration
muscles of abdominal wall increase intra-abdominal pressure and force the diaphragm up
compare external and internal intercostals
external intercostals are inspiratory muscles while internal intercostals muscles are expiratory muscles
describe inspiration sequence of events
neural stimulation of inspiratory muscles, diaphragm contraction causes it to flatten and move downward. contraction of external intercostals makes ribs pivot upward and outward, expanding the chest wall. collectively, thoracic cavity volume increases. outward pull on pleura decreases intrapleural pressure, which results in an increase in transpulmonary pressure. alveoli expand, decreasing alveolar pressure, and air flows into alveoli by bulk flow
what is lung compliance
the ease with which lungs can be stretched. the equation is: deltaV / delta(Palv-Pip)
what does a larger lung compliance mean
smaller change in trans-pulmonary pressure is needed to bring in a given volume of air, making it easier to inspire.
do lungs have a small or large compliance
they have a relatively large compliance
name two factors affecting lung compliance
elasticity and surface tension in alveoli
what does more elasticity mean for compliance
the more elastic the less compliant
describe surface tension in alveoli
surface tension: force alveoli to collapse or resist expansion. surface tension arises due to forces of attraction between water molecules at the air-water interface. thin layer of fluid lines alveolar surface and generates surface tension, greater tension leads to less compliance
how to alveoli overcome surface tension
surfactant secreted from type 2 cells is a detergent-like substance. it reduces forces of attraction between water molecules on surface of alveoli. this decreases surface tension therefore increasing lung compliance making it easier to inspire
what is LaPlace’s law equation
P = 2T / r
describe airway resistance
as in vascular resistance alveolar resistance is inversely proportional to 4th power of radius. as airways get smaller in diameter they increase in number keeping overall resistance low normally not impeding airflow. pressure difference of around 1 mm Hg is enough for normal breathing. asthma and chronic pulmonary diseases happen due to an increase in airway resistance
name passive forces affecting airway resistance
changes in transpulmonary pressure during respiratory cycle: inspiration - transpulmonary pressure increases causing smaller airways to expand. tractive forces: inspiration - as tissues move away from airways, they pull the airways open
name 2 non passive factors affecting airway resistance
contractile activity of smooth muscle and mucus secretion
describe role of bronchiolar smooth muscle in airway resistance
bronchoconstriction is where smooth muscle contracts reducing radius while bronchodilation is where smooth muscle relaxes leading to an increase in radius. these states are under the control of both extrinsic and intrinsic controls
describe sympathetic control of bronchiole radius
relaxation of smooth muscle and thus bronchodilation
describe parasympathetic control of bronchiole radius
contraction of smooth muscle leading to bronchoconstriction
describe hormonal control of bronchiole radius
epinephrine leads to relaxation of smooth muscle and thus bronchodilation
describe intrinsic control of bronchiole radius
histamine leads to bronchoconstriction, this is released during asthma and allergies. it also increases mucus secretion. CO2 leads to bronchodilation
name two pathological states that lead to increased airway resistance
asthma (which is caused by spastic contractions of bronchiolar smooth muscle), and chronic obstructive pulmonary diseases (COPD)
what is spirometry
a method of measuring volumes of air and rate of air flow, used as an assessment of lung function.
describe tidal volume
Vt is a single quiet (unforced) breath with normal volume of 500 mL
describe inspiratory reserve volume
IRV is after breathing in, the volume you can still inspire. normal volume is 3000 mL
describe expiratory reserve volume
after breathing out, volume you can still expire. normal volume is 1000 mL
describe residual volume
volume left inside lungs after ERV (cannot be measure by spirometry, measured by helium dilution method). but normal volume is 1200 mL
what is the equation for total lung capacity
TLC = Vt + ERV + IRV + RV = 5700 mL (normal)
what is forced vital capacity test
FVC is a maxiumum-volume inhalation followed by forced exhalation as fast as possible. a low FVC indicates restrictive pulmonary disease
what is forced expiratory volume
FEV1 is the volume that can be exhaled as fast as possible in the 1st second
what is Ratio FEV1/FVC
the percentage of FVC that can be exhaled within 1 second. 80% is normal and less than that indicates obstructive pulmonary disease
what is an obstructive pulmonary disease
associated with increased airway resistance. causes limitation in airflow. major obstructive pulmonary diseases are COPD diseases like chronic bronchities (long-standing inflammation of bronchioles/bronchi) and emphysema (destruction of alveolar walls, producing smaller numbers of larger alveoli). and then non COPD diseases like asthma (inflammation coupled with spasms of smooth muscle of bronchioles)
what is a restrictive pulmonary disease
any lung disorder that reduces FRC, VC or TLC. making lungs more difficult to expand. decreased compliance, increased stiffness in lung tissues - fibrosis (scarring), lack of surfactant. problems with pleura and chest wall. problems with nerves innervating muscles of chest wall. resistance to airflow is usually normal with these types of disorders
what is minute ventilation
total volume of air entering and leaving the respiratory system each minute. or minute ventilation = TV x respiration rate
what is a normal respiration rate
12 breaths/min
what is normal minute ventilation
500ml x 12 breaths/min = 6000 mL/min. not all of that air is available for gas exchange in alveoli. the reason is anatomical dead space
what is anatomical dead space
air that fills conducting zone does not participate in gas exchange. so conducting space is anatomical dead space. the volume of dead space is approximately 150 mL
what is alveolar ventilation
(tidal volume - dead space) x respiratory rate. this is more important for evaluating efficiency of ventilation that minute ventilation
what is normal alveolar ventilation value
(500ml/breath-150ml/breath) x 12 breaths / min = 4200 mL/min
which is more effective at increasing alveolar ventilation: increased depth of breathing or increased rate of breathing
increased depth leads to high alveolar ventilation
