a3: environmental exchange Flashcards
describe the functional division of the respiratory system?
conducting portion: nose, pharynx/larynx, trachea, bronchi, terminal bronchioles
exchange portion: respiratory bronchioles, alveoli, aveolar ducts & sacs
describe the structural division of the respiratory system?
UPPER: nose, nasal cavity, pharynx
LOWER: larynx, trachea, bronchi, bronchioles and alveolie
describe basic wall plan of tracheobronchial tree(inner most to outer most)
mucosa - epithelium, basment membrane, lamina propria plus smooth muscle and glands to secrete
submucosa - ring like hyaline cartilage
adventitia - connective tissue
what is mucosa?
epithelium with an underlying CT of a tube connecting to outside of the body
main, predominant tissue in alveoli?
elastic fibres/CT
general trend in respiratory wall structure?
general reduction in wall thickness and complexity with decreasing distance from gas exchange surfaces
what are some important trends in varying wall structure?
epithelial cells: pseudostratified -> simple
goblet cells: high -> low numbers..disappear @ tertiary bronchioles
cilia: reduction of surface covered..disappear @ respiratory bronchioles
cell height: columnar -> cuboidal -> squamous decrease in height
cartilage: ring shaped(trachea) -> plates & islands(bronchi)..disappear @ bronchioles downwards
glands: decrease in number..disappear @ bronchioles
if you inhale something where is it most likely to end up?
right primary bronchi to inferior lobe
difference between right and left lung?
right lung has 2 fissures(horizontal, oblique) and 3 lobes(inferior, middle, superior)
- liver extends extends upwards pushing dome of diaphragm on the right side slightly higher than left
left lung has one fissure(oblique) and 2 lobes(superior, inferior)
- has cardiac notch, where apex of heart extends into
what is the hilum?
point of attachment of vessels
relationship of lungs and pleura?
membrane lining the chest cavity and lungs.
cushion lungs
smooth movement of lungs within chest cavity: secrete fluid
allow alveoli to take in more air when breathing
what is the inter alveolar septum ?
wall between adjacent alveoli, contains extensive capillary network
what is COPD? and how does it compromise respiratory function?
chronic obstructive pulmonary disease “narrowing of the airways”
severely compromises air conduction to and from respiratory surfaces
whats the most common cause of COPD?
smokinggg
how do irritants/smoke/toxins cause in the lungs?
(1) Inflammation of walls of bronchi and bronchioles -> thickening of walls -> narrowing of lumen -> reduced air flow
(2) Increasing mucus clogs lumen -> narrowing air flow
(3) Destruction of elastic fibres in alveoli -> reduction of alveoli recoil -> reduced ability to expel air and reduce surface area for gas exchange
what are the requirements of ventilation?
patent air pathways(open and free from obstruction)
generation of a reversible flow
how is patency of airways achieved?
- rigid wall structure(bone in upper, cartilage in trachea and bronchi)
- hydrostatic pressure
- pulmonary surfactant
what is hydrostatic pressure?
outward pull on the walls of smaller air pathways(terminal/respiratory bronchioles alveolar ducts) holds them open
what is pulmonary surfactant?
decreases alveolar surface tension
-> less inward pull on alveoli during expiration -> less effort required to stretch alveoli and expand lungs
describe the relationship between lung volume and pressure:
increase in V -> decrease in P -> inflow of air
decrease in V -> increase in P -> outflow of air
atmospheric air pressure =
760mmHg
alveolar pressure =
758mmHg inhalation
762mmHg expiration
how do muscles contribute to volume of lungs?
contraction of muscle = EXPANSION in volume of thoracic cavity
- external intercostal muscles
- diaphragm
how does lung tissue contribute to volume of lungs?
elastic recoil of lungs and relaxation of previously contracted muscles reduced volume of thoracic cavity
role of pleura in ventilation?
surface tension of pleura fluid adheres pleural membranes ->
lungs pull outwards when thoracic volume increases pleural fluid produces bond between parietal and visceral pleura
preventing collapse of lungs
intrapulmonary pressure refers to pressure within _____?
alveoli of the lungs
is inspiration active or passive process?
active, due to contraction of diaphragm and external intercostal muscles
differences between normal and forced labour ventilation?
forced/labour ventilation uses an extra set of muscles during expiration
internal intercostal muscles depress ribs increase intra-thoracic pressure
abdominal muscles increase intra-abdominal pressure
what is the blood air barrier?
respiratory membrane of the interaveolar septum
state malfunctions of air modification:
environmental overload eg. smoking
cystic fibrosis
main changes to air before it reaches gas exchange site:
FILTERED: remove debris and/or pathogens
WARMED: to that similar of body temp
HUMIDIFIED: so gas exchange surfaces don’t dry out
where is air filtered?
vibrissae (nose hairs)
sticky mucus traps fine particles -> transferred to pharynx
dust cells(alveolar Macrophages) engulf any particles that reach alveoli
how is the removal of pathogens in air achieved?
defence cells in lumina propria
muco-ciliary escalator
where is air humidified?
seromucous glands(saturate air with water vapour)
where is inspired air warmed?
venous plexus in nasal mucosa
heat transferred from warm blood in superficial vessels to colder air in nostrils
breathing through the nose rather than the mouth is advantageous because?
air is warmed upon inhalation