Lecture 7: The Respiratory System; Respiratory Physiology Flashcards
what is atmospheric pressure (Patm)
-pressure exerted by air surrounding the body
-760 mmHg at sea level = 1 atmosphere
-respiratory pressures are described relative to Patm
what does + - & 0 respiratory pressure mean in relation to Patm
-ve repiratory pressure: < Patm
+ve respiratory pressure: >Patm
0 respiratory pressure: = Patm
what is intrapulmonary pressure (Ppul) (intra-alveolar pressure)
-pressure in alveoli
-fluctuates with breathing
-always eventually equalizes with Patm
what is intrapleural pressure (Pip)
pressure in pleural cavity
-fluctuates with breathing
-always a negative pressure (<Patm and < Ppul)
-usually always 4mmHg<Ppul
-fluid level must be kept at a minimum
-excess fluid pumped out by lymphatic system
-if fluid accumulates, positive Pip pressure develops-> lung collapses
whathappens if fluid accumulates in the thoracic cavity
the lung will collapse
what two inward forces promoite lung collapse
- lungs’ natural tendency to recoil because of elasticity, lungs always try to assume smallest size
- surface tension of alveolar fluid, surface tension pulls on alveolu to try to reduce alveolar size
what is transpulmonary pressure = (Ppul - Pip)
-pressure that keeps lung spaces open (keeps them from collapsing)
-greater transpulmonary pressure the larger the lungs will be
lungs will collapse if Pip = ?
-Pip = Ppul
-Pip = Patm
-negative Pip must be maintained to keep lungs inflated
what is pulmonary ventilation
breathing
-consists of inspiration and expiration
-mechanical process that depends on volume changes in thoracic cavity
-volume changes lead to pressure changes
-pressure changes lead to flow of gases to equalize pressure
what is Boyle’s Law
-relationship between pressure and volume of a gas
-gases always fill the container they are in
-if the amount of gas is the same and container size is reduced, pressure will increase
-so pressure (P) varies inversely with volume (V)
-mathematically: P1V1= P2V2
what are the primary repsiratory muscles
external intercostal muscles & diaphragm
what are the accessory repsiratory muscles
sternocleidomastoid, scalenes, pectoralis minor, serratus anterior, internal intercostal muscles, transversus thoracis, external oblique, rectus abdominis, interal oblique
what does the body look like at resting state
-disphragm remained dome shapes
-pressure inside lungs (alveolar pressure) = Patm, 760 mmHg
-net effect- “no flow of air”
what are the events in inspiration
-diaphragm contracts and thoracic cavity floor becomes flattened
-thoracic cavity volume increases; pressure within lungs decreases. Patm is higher, air moves from outside to inside the lungs
-external intercostal muscles contract-> elevates the rib cage
-accessory muscles may contract to assist external intercostal muscles to elevate the ribs
what are the events in expiration
-diaphragm relaxes; rib cage returns to original position
-thoracic cavity volume decreases; pressure within the lungs increases-> outflow of air; pressure inside >Patm
-rib cage is lowered by internal intercostal muscles and transversus thoracis; thoracic cavity volume decreases
-external intercostal muscles can be aided by the abdominal muscles by condensing the abdomen, thereby pushing the diaphragm upwards
intrapulmonary pressure during inspiration and expiration
pressure inside the lunds decreases as lung volume increases during inspiration; pressure increases during expiration
intrapleural pressure during inspiration and expiration
pleural cavity pressure becomes more negative as chest wall expands during inspiration. returns to initial value as chest wall recoils
volume of breath during inspiration and expiration
during each breath the pressure gradients move 0.5 liters of air into and out of the lungs
what is non-repsiratory air movements
-many processes can move air into or out of lungs besides breathing
-may modify normal repsiratory rhythm
-most reslt from reflex action, although some are voluntary
what are some examples of non-respiratory air movements
coughing, sneezing, sighing, yawning, sobbing, crying, laughing, hiccupping, valsalva maneuver, pressurizing the middle ear
what is assessing ventilation
-several respiratory volumes (RVs) can be used to assess respiratory status
-combinations of RVs-> respiratory capacities, which can give information on a person’s respiratory status
-RVs and capacities are usually abnormal in people with pulmonary disorders
what is spirometry
-clinical tool used to measure respiratory volumes
what is tidal volume
amount of air moved into nad out of lung with each breath (normal quiet breathing)- avergaes ~500 ml
what is inspiratory reserve volume (IRV)
amount of air that can be inspired forcibly beyond the tidal volume (1000- 1200 ml)
what is expiratory reserve volume (ERV)
amount of air that can be forcibly expelled from lungs (1000-1200 ml)
what is residual volume
amount of air that always remains in the lungs, needed to keep alveoli open
-what are respiratory capacities
combinations of two or more respiratory volumes
formula for inspiratory capacity (IC)
TV + IRV
formula for functional residual capacity (FRC)
RV + ERV
formula for vital capacity (VC)
TV + IRV + ERV
formula for total lung capacity (TLC)
sum of all lung volumes (TV + IRV + ERV + RV)
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what are the three types of dead space
anatomical dead space, alveolar dead space, total dead space
what is anatomical dead space
does not contribute to gas exchange
-consists of air that remains in passageways
~150 ml out of 500 ml TV
what is alveolar dead space
space occupied by nonfunctional alveoli, can be due to collapse or obstruction
what is total dead space
summ of anatomical and alveolar dead space
what can spirometry distinguish between
- obstructive pulmonary disease
2.restrictive diseases
what are obstructive pulmonary diseases
increased airway resistace (ex. bronchitis)
TLC, FRC, RV may increase because of hyperinflation of lungs
what is restrictive diseases
reduced TLC due to disease (ex. tuberculosis) or exposure to enviromental agents (ex. fibrosis)
VC, TLC, FRC, RV decline because lung expansion is compromised
what can pulmonary function tests do
measure rate of gas movement
-forced vital capacity (FVC): amount of gas forcibly expelled after taking deep breath
-forced expriatory volume (FEV): amount of gas expelled during specific time interval of FVC
-FEV1: amount of air expelled in 1st second, healthy individuals can expel 80% of FVC in 1st second, patients with obstructive diseases expire <80% in 1st second whereas those with restrictive disease exhale 80% or more even with rediced FVC
what is forced vital capacity (FVC)
amount of gas forcibly expelled after taking deep breath
what is forced expiratory volume (FEV)
amount of gas expelled during specific time interval of FVC
what is FEV1
amount of air expelled in 1st second, healthy individuals can expel 80% of FVC in 1st second, patients with obstructive diseases expire <80% in 1st second whereas those with restrictive disease exhale 80% or more even with rediced FVC
what is minute ventilation
-total amount of gas that flows into or out of respiratory tract in 1 minute
-normal at rest= ~6L/min
-normal exercise = up to 200L/min
-only rough estimate of respiratory efficiency
what is alveolar ventilation rate (AVR)
-flow of gases into and out of alveoli during a particular time, better indicator of effective ventilation
-AVR takes into account amount of dead space, TV, and rate of breathing
-can be calculated by following equation: AVR= Frequency x (TV - anatomic dead space)
-because dead space in an individual is normally constant, AVR is affected by TV and frequency
what is gas exchange
gas exchange occurs between the lungs and blood as well as blood and tissues
external respiration in regards to gas exchange
diffusion of gases between blood and lungs
internal respiration in regards to gas exchange
diffusion of gases between blood and tissues
what are both internal and external respiration subject to (gas exchange)
- basic properties of gases
- composition of alveolar gas
what are basic properties of gases/ Dalton’s Law of Partial Pressures
Dalton’s Law: total pressure exerted by mixture of gases is equal to sum of pressures exerted by each gas
-Partial Pressure: pressure exerted by each gas in mixture, directly proportional to its percentage in mixture
total atmospheric pressure (Patm) = 760 mmHg
-N2= ~78.6% of air; therefore partial pressure of nitrogen Pn2, can be caculated: 0.786 x 760 mmHg= 597 mmHg due to 2
-O2= 20.9% of air so Po2 = 0.209 x 760 mmHg= 159 mmHg
-air also contains 0.04% CO2, 0.5% water vapour, and insignificant amounts of other gases
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whaat is composition of alveolar gases
-alveoli contain more CO2 and water vapour than atmospheric air because of:
-gas exchanges in lungs (O2 diffuses out of lung, and CO2 diffuses into lung)
-humidification of air by conducting passages
-mixing of alveolar gas with each breath
-newly inspired air mixes with air that was left in passageways between breaths
O2 & CO2 during interna; and externla respiration
also known as pulmonary gas exchange, involves the exchange of O2 and OC2 across respiratory membranes
-during external respiration, O2 diffuses from the alveoli into the pulmonary capillaries, CO2 moves in the opposite direction
-during internal respiration, O2 will diffuse from the systemic capillaries into the tissue, CO2 moves in the opposite direction
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list some disorders of the respiratory system
asthma, chronic obstructive pulmonary disorder (COPD), lung cancer, pneumonia, tuberculosis, common cold, pulmonary edema, cystic fibrosis, asbestos-related diseases, sudden infant death syndrome, acute respiraotry distress
what is asthma
what is COPD
what is lung cancer
what is pneumonia
what is tuberculosis
what is a common cold
what is pulmonary edema
what is cystic fibrosis
what is asbestos-related diseases
what is SIDS/ sudden infant death syndrome
what is actue respiratory distress
