Module 4 Flashcards
what are the 3 processes that make up respiration
- ventilation of the lungs
- exchange of rase between air and blood, and between blood and interstitial fluid
- the use of oxygen in cellular metabolism
what is the primary function of the respiratory system
supply the body with oxygen and dispose of carbon dioxide
how is the respiratory structures divided structurally
- upper respiratory system - filter, humidify and warm incoming air, reabsorb heat and water from outgoing heat
- lower respiratory system - conducts air to the gas exchanges
how is the respiratory structures divided functionally
- Conducting zone - passageways that conduct the air, cleanse, humidifying warm incoming air and reabsorb heat and water from outgoing air
- The respiratory zone - respiratory bronchioles, alveolar ducts and alveoli, where gas exchange occurs
function of hairs in nose
filters course particles
role of mucosal epithelium
produces mucus
role of mucus
- humidifies incoming air
- traps particulates
role of mucociliary escalator
- removes contaminated mucus
- moves mucus
- protects the respiratory zone from damage and infection
role of nasal conchae
increases mucosal surface area and enhance air turbulence
describe inhalation
- network of blood vessels underlying the epithelium warm and moisten air.
- Generates turbulence which warms and moistens air
describe exhalation
reclaims heat and moisture
functions of nasal cavity
- filters/cleanses the air (hair + turbulence)
- warms and humidifies the air (capillary plexuses and mucus)
- traps particulates (mucus)
- kills bacteria (defensins)
- removes contaminated mucus (escalator)
- sneezing dislodging irritants
- olfaction
- resonating chamber of speech
role of the pharynx
- passageway for air and food
- facilitates voice production
- includes escalator
describe the structure of the trachea
- windpipe
- extends from larynx to bronchi
- includes escalator
describe the structure of the bronchi
- trachea divides to form the right and left primary bronchi
describe the structures of the bronchioles
- no escalator
- no cartilage rings
- abundant elastic fibres
- circular smooth muscle to alter diameter
what makes up the respiratory membrane
- Alveolar epithelial cell (type 1)
- Basement Membrane
- Capillary enothelial cell
what is alveoli formed from
type 1 epithelial cells
what do type 2 epithelial cells secrete
surfactant which prevents alveolar collapse and antimicrobial proteins (e.g. defensins)
what is the site of gas exchange via simple diffusion
respiratory membrane
what are the 2 different types of circulations for the lungs
- Pulmonary circulation
2. Bronchial Circulation
Pulmonary circulation
- pulmonary arteries deliver blood requiring oxygen
- pulmonary veins return oxygenated blood to the heart
- provides nutrients for alveoli
Bronchial Circulation
- bronchial arteries provide oxygenated systemic blood to the lung tissue
- pulmonary veins return most systemic blood back to the heart
list the ways in which the lungs are innervated (3)
- Visceral sensory fibres
- Parasympathetic fibres - constrict the bronchioles
- Sympathetic fibres - dilate the bronchioles
describe the structure of the lungs and pleura
outside to inside
- thoracic wall
- parietal pleura
- pleural space
- visceral pleura
what does the parietal pleura cover
thoracic cavity wall
what does the visceral pleura cover
lungs
function of pleural fluid
facilitates adhesion of the visceral pleura covering the lungs to the parietal pleura lining the thoracic wall
inspiration
when air flows into the lungs
expiration
when air flows out of the lungs
what does pulmonary ventilation depend on
changes in the volume and pressure within the thoracic cavity and lungs
what type of gradient does air move
down a pressure gradient until equilibrium is reached
boyles law
decreased volume = increased pressure
mechanical events of inspiration
- thoracic cavity volume increases
- lungs stretch
- intrapulmonary volume increases
- air flows down the pressure gradient
- ribs elevates
- diaphragm moves up
- intercostal muscles contract
what are the inspiratory muscles
diaphragm and external intercostal muscles
mechanical events of expiration
- inspiratory muscles relax
- diaphragm descends
- rib cage descends
- thoracic cavity volume decreases
- intrapulmonary volume decreases
- intrapulmonary pressure rises
- air flows out of lungs down the pressure gradient to equal atmospheric pressure
describe passive expiration
- muscle relaxation
- depends on the elastic recoil of the lungs
describe forced expiration
- involves contraction of accessory muscles
- e.g. abdominal muscles
- increases intra abdominal and pushes diaphragm up
describe the 2 forces that act to collapse the lungs
- the lungs natural tendency to recoil
- surface tension of the alveolar fluid
what factors stop the lungs from collapsing
- surfactant: reduces surface tension of alveolar fluid
- adhesive forces of pleural fluid
- elasticity of the chest walls due to negative intrapleural pressure
what factors influence gas flow (ventilation) in the airways to the alveoli
- resistance
- compliance
- alveolar surface tension
describe resistance
- due to friction between the air and the airway walls
- dependant upon airway diameter
- altering bronchiole diameter regulates gas flow
sympathetic stimulation in context to resistance causes ….. ?
dilation = decreases resistance = increases gas flow
parasympathetic stimulation in context to resistance causes…. ?
constriction = increases resistance = decreases ventilation
describe pulmonary compliance
a measure of the ability of the lungs and/or thoracic cavity to expand/stretch and thus enable inhalation
what factors does compliance depend on
- lung elasticity
- alveolar surface tension (surfactant production)
- flexibility of muscles and joints of the thoracic wall
impact of alveolar surface tension
reduces alveoli to tallest possible size
makes alveolar expansion during inspiration difficult
describe infant respiratory distress syndrome
- premature infans
- do not produce adequate surfactant
- unable to keep alveoli inflated between breaths
- can result in alveolar rupture and haemorrhage
- treatment: spray airways with surfactant
how is pulmonary ventilation measured
- spirometre
tidal volume
amount of air inhaled or exhaled during quiet breathing
vital capacity
maximum amount of air that can be expired after maximal effort = total amount of exchangeable air in the lungs
describe obstructive pulmonary disorders
cause, effect on VC, e.g.
cause: reduced airway diameter and increased resistance and decreased air flow (dyspnea)
effect on VC: takes longer to achieve, more effort
e.g. emphysema
describe restrictive pulmonary disorders
cause, effect on VC, examples
cause: decreased compliance of lungs or thoracic wall = inability to change volume and thus draw in air
effect on VC: reduced
e.g. fibrosis
describe emphysema (obstructive)
alveolar destruction
bronchiole collapse during exhalation
describe bronchitis (obstructive)
inflammation and accumulation of mucus in lower airways
describe asthma (obstructive)
allergic inflammation leading bronchoconstriction
what can a decrease in compliance be a result of
- chronic inflammation and fibrosis
- lack of surfactant
what does the direction of gas movement depend on
the relative concentration of each gas in the alveoli compared with the blood
factors that influence the diffusion of O2 and Co2 across the respiratory membrane
- Partial pressure
- How soluble the gas is in the alveolar fluid and plasma
- Matching of alveolar ventilation and pulmonary blood flow
- Structural characteristics of the respiratory membrane
