respiratory Flashcards
functions
exchange of gas between atm and blood
- uptake of O2 + release of CO2
filtration, temperature regulation, + humidification of inspired air
olfaction = sense of smell
production of sound
respiratory area
~70 sq. m (750 sq. feet)
upper respiratory system
entry of air into body through mouth/nose to larynx
external nares → nasal vestibule → conchae → internal nares → nasopharynx → eustachian tube → oropharynx → laryngopharynx
external nares
nostrils
two holes leading into nasal cavity (one is larger)
nasal cavity = in visceral cranium
separated by septum (cartilage)
conchae
projections from lateral wall into nasal cavity
3 (top two = cartilage, lowest = bone)
turbinates when covered with mucous membrane
turbinates
turbulence of air
mucous membrane contains blood and moisture = warming + humidification of air
protects airway from cold air
internal nares
funnel air into pharynx
at the back of the nasal cavity
in line with end of hard palate (separation of oral + nasal cavities)
nasopharynx
nasal part of pharynx
contains eustachian tube
eustachian tube
connects nasopharynx to middle ear
air helps balance pressure of external forces squeezing eardrum (also movement from swallowing)
oropharynx
posterior to oral cavity
epiglottis
flap at posterior aspect of tongue
mobile structure = covers glottis leading to trachea when swallowing food
laryngopharynx
posterior to larynx
differentially direct air/food
protection of airway when swallowing
tongue pushes bolus into oropharynx
soft palate closes nasal cavity; laryngeal movement closes epiglottis to seal airway
pharygeal muscles push bolus into esophagus
lower respiratory system
below larynx
divided into conducting + respiratory portions
trachea branches into L + R primary bronchi
bronchi enter lungs at hilum → branch into secondary bronchi → tertiary bronchi → bronchioles → terminal bronchioles
hilum
root of lung
site where blood vessels, lymph vessels, nerves and airways enter and leave lungs
tail inferior to main entrance → often has vein (both lungs)
lungs
apex = top (above clavicle)
base = bottom (proximal to diaphragm)
oblique fissure separates inferior lobe from others
R lung
3 lobes = superior, middle, + inferior
horizontal fissure separates superior + middle lobes
L lung
2 lobes = superior + inferior
cardiac notch in medial surface = lung grows around heart
lingula: projection of superior lobe around heart (inferior to tissue of inferior lobe)
pleura
membrane surrounding lungs
outside layer = parietal pleura (inside of thoracic cage, on body wall)
inside layer = visceral pleura (covers outside of lungs)
forms pleural cavity in between two layers
pleural cavity
both layers of pleural membrane are serous = secrete fluid
fluid protects lungs from friction during expansion
primary bronchi
direct air into lungs
divide into secondary
have thinner cartilage rings, more spaced out
R side = shorter (before branching), straighter, wider
secondary bronchi
direct air into lobes
3 on R side; 2 on L side
divide into tertiary
tertiary bronchi
direct air into segments of lungs within lobe
bronchioles
airway projections
terminal bronchioles = smallest conducting passages
trachea
sits anterior to esophagus
anterior surface covered by C-shaped cartilage rings (posterior surface = smooth muscle, between esophagus)
smooth muscle
in all conducting branches of airway but predominates in smaller airways
(trachea → bronchioles)
controls diameter of airway: allows broncho-constriction/dilation = movement of air
constriction reduces airflow
conducting zone
trachea → terminal bronchioles
no alveoli
airways facilitate movement of air
respiratory zone
respiratory bronchioles → alveolar ducts (alveolar sacs)
have alveoli
airways conduct air and facilitate gas exchange
alveolar sacs
clustered alveoli
fed by capillary network
airway walls
cartilage (in larger airways; helps keep airways open)
smooth muscle
elastic fibres
elastic fibres
lots, around all airways
predominate in smaller airways and respiratory portion
elastic recoil provides force for expiration
asthma attack
smooth muscle in wall of bronchioles contracts = narrowing of airways
contraction caused by: parasympathetic stimulation
+ mediators of allergic reactions (histamine)
muscle contraction reduces airflow
bronchioles = most numerous airways → provide greatest resistance to airflow
emphysema
reduced ability to exhale air from lungs
due to breakdown of alveolar walls = produces abnormally large air spaces
lowered surface area for gas exchange → reduced respiratory efficiency
reduced elastic recoil due to loss of elastic fibers
causes: smoking, other irritants
respiratory epithelium
- pseudostratified epithelium line larger passages (nasal cavity, nasopharynx, large airways)
- stratified squamous (non-keratinized) in oropharynx
- gradually becomes simple in smaller tubes: simple columnar → cuboidal → squamous (in alveoli)
stem cells located at base
contains goblet cells = produce mucous
apical surface has lots of cilia
mucous layer floats on serous layer
alveolar wall
between alveolar air space and RBCs
alveolar epithelium (type I cells) → fused basement membrane → capillary endothelium → capillary lumen
how many plasma membranes does an oxygen molecule cross to pass from air space to bind a hemoglobin molecule in a RBC
5
across alveolar cell:
- luminal membrane
- basolateral membrane
across endothelial cell:
- basolateral membrane (facing basal lamina)
- luminal membrane (facing inside capillary)
into RBC
- rbc membrane
type I alveolar cells
simple squamous epithelium
line alveoli
type II alveolar cells
secrete surfactant
embedded in alveolar epithelium
surfactant
lowers surface tension of alveolar fluid
prevents alveolar walls from sticking together + collapsing (facilitates opening of alveoli)
respiratory distress syndrome
occurs in children born prematurely
under-developed type II alveolar cells
lack surfactant = alveoli cannot inflate properly
leads to insufficient oxygenation of blood
alveolar macrophages
“roomba”
ingest debris in alveoli to prevent interference with surface gas exchange
are expelled into airways → become trapped in mucous sheets → carried toward pharynx by ciliary action → expectorated or swallowed
pulmonary arteries
travel with airways → branch to reach alveoli
carry deoxygenated blood
pulmonary veins
travel in interlobular connective tissue
take direct path to return to L atrium
carry oxygenated blood
lymphatics
travel in interlobular connective tissue
alveolar capillaries
form network surrounding alveoli
muscles of quiet inhalation
diaphragm: contracts to flatten = ↑ vertical diameter of thoracic cavity
external intercostals: lift ribs superiorly + move sternum anteriorly
muscles of quiet exhalation
no muscles
relaxation of muscles contracted during insp
elastic recoil of lung tissue + thoracic wall
muscles of forced inhalation
accessory muscles
sternocleidomastoid = elevates sternum
scalenes = elevate ribs 1 + 2
pectoralis minor = elevates ribs 3-5
muscles of forced exhalation
internal intercostals (in between ribs)
abdominal muscles = move inferior ribs down + compress viscera to push diaphragm superiorly
