LOWER RESPIRATORY TRACT Flashcards
what are the components of the LRT?
- larynx
- trachea
- bronchus
- bronchioles
- alveoli
what are the functions of LRT?
- conducts air to/from site of gas exchange
- completes the process of cleaning, warming and humidifying air
- provides barrier between air and blood and a large surface area for gas exchange
larynx is the passage of _____1_______.
it is located ____2_____ to ______3______ and starts from ___4_____ to _______5_______
1: air only
2: anterior
3: esophagus
4: hyoid bone
5: trachea
what structure protects and maintain an open airway in larynx?
cartilage
which structure assist the closing of the airway over swallowing?
epiglottis
what are the 2 folds of the epiglottis?
vocal folds and vestibular folds
function of vocal folds?
vocal cords, passing air cause vibrations = sound waves –> use for normal phonation
why is male has deeper voice than female?
testosterone affects cartilage and muscle resulting in longer and thicker folds
what is the function of the vestibular folds?
superior to vocal folds and used to prevent foreign object entry to glottiss
how is the trachea situated?
anterior to esophagus, between the larynx and primary bronchi
what lines the trachea?
respiratory epithelium
what are the functions of the trachea?
maintain patent airway and ensure optimal air conditions
how does trachea maintain patent airway?
- C-shaped cartilage rings
- trachealis and the end, which is a band of muscle contracts for coughing
- many elastin fibres in lamina propria and submucosa
what is the purpose of the C-shaped rings? why is it C-shaped?
- reinforce anterior and lateral sides of trachea to maintain a patent airway
- C-shaped allows trachea to collapse slightly for food passing down esophagus
what are the 2 mucus sources in trachea?
submucosa and goblet cells
describe the mechanism of the mucociliary escalator:
- in context of URST, cilia wave backward to push mucus towards the throat, however for the respiratory tract below pharynx, mucus needs to be flown upward against gravity to pharynx
- mucociliary escalator removes debris by trapping them in the respiratory epithelium mucus and then push them torwards the pharynx to be digested
how many lobes are there in the left and right lungs?
- right lung: 3 lobes
- left lung: 2 lobes
why is left lung 2 lobes, not 3?
leave a space for cardiac notch (where heart located)
what is hilum of the lungs?
where bronchi and blood vessels enter
where is the base and where is the apex of the lungs?
- apex = superior region
- base = inferior region, sits on diaphragm
describe the bronchial tree from outer to lungs
trachea –> 1st (primary) bronchi –> 2nd and 3rd bronchi –> bronchioles –> terminal bronchioles
what changes occur to the cartilage along the LRT?
- larynx: complete rings (cricoid)
- trachea: C-shaped rings
- primary bronchi: complete rings
- 2nd and 3rd bronchi: cartilage plates
- bronchioles: no cartilage but thick smooth muscle for bronchoconstriction/dilation
what changes occur to the epithelium along the LRT?
- respiratory epithelium and then from 2nd and 3rd bronchi respiratory epithelium starts decrease in height with reduced number of goblet cells
- cuboidal epithelium in bronchioles whith no goblet cells
what is pulmonary lobules made of?
alveoli arranged like bunch of grapes
what is the purpose of having 150million alveoli per lung?
increase surface area to hold large capacity of air to breath in and out
what is the wall of alveoli?
very thin wall: simple squamous epithelium on a thin basement membrane
what covers the external surface of alveoli?
fine network of pulmonary capillaries to exchange gas with blood
what is lung epithelial cells also called? how many types?
- pneumocyte
- 2 types
describe type I and type II pneumocyte?
- type I pneumocyte = simple squamous - form respiratory membrance/blood-air barrie with capillary wall and shared basement membrane –> form wall of alveoli
- type II pneumocyte = cuboidal, scattered amongst type I - **secrete surfactant **(a complex lipoprotein/phospholipid) that reduces surface tension of alveolar fluid –> help with patent airway
what is the mechanism to keep the alveolus surface safe while there are no more goblet cells?
roaming macrophage - removes debris that made to the alveoli
what structure form the respiratory membrane?
alveolus wall, fused basement membrane and capillary wall
