Lec 2

Question 1

Explain the trachea

Answer 1

-stacked, C shaped pieces of hyaline cartilage connected by dense connective tissue connected by fibre elastic membrane
-allows trachea to stretch + expand slightly during inhalation + exhalation
-has trachealis muscle (contracts, forcing air through when coughing/forced exhalation) + elastin rich connective tissue
-rings provide structural support + prevent the trachea from collapsing

Question 2

trigger areas

Explain coughing

Answer 2

-is forced exploratory manoeuvre against a closed glottis, followed by glottal opening + high velocity expiration
-important for clearing airway of secretions + preventing entry of foreign bodies/irritants
-reflex triggered when afferent nerve receptors stimulated in inhalation/aspiration/substances
-sensitive sites for the cough reflex initiation are larynx + carina

Question 3

Define glottis + epiglottis

Answer 3

Glottis: opening between vocal folds
Epiglottis: cartilaginous flap attached to the entrance of the larynx, open during breathing, allowing air into larynx then trachea, closed during swallowing + prevent aspiration (when food/something enters the airway/lungs accidentally), forcing liquids or foods in oesophagi

Question 4

Events of a cough

Answer 4

1. Irritation phase: stimuli detected by receptors, sent to control centre (medulla), send to expiratory muscles (trachealis muscles + trachea), (neuronal activity suppressed, but can still be consciously suppressed, to a degree)
2. Inspiratory phase: brief + sudden inhalation = glottis opens, diaphragm contracts (down), and thoracic cage opens
3. Compressive phase: glottis and larynx closes, muscles contract, pulmonary pressure increases
4. Expulsion phase: pulmonary pressure increases enough that, glottis abrupt opens, causes high velocity + force + violent exhalation, removes irritant

Question 5

Explain the carina, bronchi, bronchioles, terminal bronchioles

Answer 5

-contains specialised nervous tissue that induces violent coughing if a foreign body (e.f. Food) is present, separates left + right bronchi

• irregular plates of cartilage, passageway for air into lungs, form bronchioles (mucus producing cells go NO lower)

-1mm diameter, no cartilage, made of smooth muscle- so can contract/relax to change airway diameter

-last airway of conducting zone, and with cilia

Question 6

Explain parasympathetic vs sympathetic stimulation

Answer 6

Parasympathetic (anticholingeric) of airway smooth muscle = bronchoconstriction = narrowing = decreased radius

Indirect sympathetic (agonists) stimulation of airway smooth muscle = bronchodilator = widening = increased radius

• increase in radius = increase in airflow rate + decrease in resistance

Question 7

Explain the 2 types of alveoli cells

Answer 7

Type 1:
- simple squamous epithelium
-make up lining of alveoli wall, very thin
-responsible for gas exchange
-susceptible t a large no. Of toxic insults
-cannot replicate themselves

Type 2:
Round, cuboidal epithelium
-prices + secretes surfactants
-surfactant decreases surface tension of alveolar fluid + helps increase alveoli + lung stretch

Question 8

Explain the function of different collagen types in the alveoli

Answer 8

-1 + 3 = structural integrity of the alveolar walls
-4 = stability + tensile strength to very thin basement membrane (separates alveolar + capillary epithelium)

Question 9

Explain collateral ventilation, the pores of kohn+ channels of lambert

Answer 9

• back up system of alveolar ventilation
  -can by pass normal route of airflow, when airways are collapsed or blocked
• connect adjacent alveoli

-connect alveoli + bronchioles

-connect bronchioles

-these areas have high resistance, so low airflow rates during resting breathes
-high volumes breaths means low resistance, which means increase airflow rate