LOWER RESPIRATORY TRACT

Question 1

what are the components of the LRT?

Answer 1

• larynx
• trachea
• bronchus
• bronchioles
• alveoli

Question 1

what are the functions of LRT?

Answer 1

• 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

Question 2

larynx is the passage of _____1_______.
it is located ____2_____ to ______3______ and starts from ___4_____ to _______5_______

Answer 2

1: air only
2: anterior
3: esophagus
4: hyoid bone
5: trachea

Question 3

what structure protects and maintain an open airway in larynx?

Answer 3

cartilage

Question 4

which structure assist the closing of the airway over swallowing?

Answer 4

epiglottis

Question 5

what are the 2 folds of the epiglottis?

Answer 5

vocal folds and vestibular folds

Question 6

function of vocal folds?

Answer 6

vocal cords, passing air cause vibrations = sound waves –> use for normal phonation

Question 7

why is male has deeper voice than female?

Answer 7

testosterone affects cartilage and muscle resulting in longer and thicker folds

Question 8

what is the function of the vestibular folds?

Answer 8

superior to vocal folds and used to prevent foreign object entry to glottiss

Question 9

how is the trachea situated?

Answer 9

anterior to esophagus, between the larynx and primary bronchi

Question 10

what lines the trachea?

Answer 10

respiratory epithelium

Question 11

what are the functions of the trachea?

Answer 11

maintain patent airway and ensure optimal air conditions

Question 12

how does trachea maintain patent airway?

Answer 12

• 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

Question 13

what is the purpose of the C-shaped rings? why is it C-shaped?

Answer 13

• reinforce anterior and lateral sides of trachea to maintain a patent airway
• C-shaped allows trachea to collapse slightly for food passing down esophagus

Question 14

what are the 2 mucus sources in trachea?

Answer 14

submucosa and goblet cells

Question 15

describe the mechanism of the mucociliary escalator:

Answer 15

• 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

Question 16

how many lobes are there in the left and right lungs?

Answer 16

• right lung: 3 lobes
• left lung: 2 lobes

Question 17

why is left lung 2 lobes, not 3?

Answer 17

leave a space for cardiac notch (where heart located)

Question 18

what is hilum of the lungs?

Answer 18

where bronchi and blood vessels enter

Question 19

where is the base and where is the apex of the lungs?

Answer 19

• apex = superior region
• base = inferior region, sits on diaphragm

Question 20

describe the bronchial tree from outer to lungs

Answer 20

trachea –> 1st (primary) bronchi –> 2nd and 3rd bronchi –> bronchioles –> terminal bronchioles

Question 21

what changes occur to the cartilage along the LRT?

Answer 21

• 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

Question 22

what changes occur to the epithelium along the LRT?

Answer 22

• 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

Question 23

what is pulmonary lobules made of?

Answer 23

alveoli arranged like bunch of grapes

Question 24

what is the purpose of having 150million alveoli per lung?

Answer 24

increase surface area to hold large capacity of air to breath in and out

Question 25

what is the wall of alveoli?

Answer 25

very thin wall: simple squamous epithelium on a thin basement membrane

Question 26

what covers the external surface of alveoli?

Answer 26

fine network of pulmonary capillaries to exchange gas with blood

Question 27

what is lung epithelial cells also called? how many types?

Answer 27

• pneumocyte
• 2 types

Question 28

describe type I and type II pneumocyte?

Answer 28

• 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

Question 29

what is the mechanism to keep the alveolus surface safe while there are no more goblet cells?

Answer 29

roaming macrophage - removes debris that made to the alveoli

Question 30

what structure form the respiratory membrane?

Answer 30

alveolus wall, fused basement membrane and capillary wall