Lec 2 Flashcards
Explain the trachea
-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
trigger areas
Explain coughing
-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
Define glottis + epiglottis
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
Events of a cough
- 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)
- Inspiratory phase: brief + sudden inhalation = glottis opens, diaphragm contracts (down), and thoracic cage opens
- Compressive phase: glottis and larynx closes, muscles contract, pulmonary pressure increases
- Expulsion phase: pulmonary pressure increases enough that, glottis abrupt opens, causes high velocity + force + violent exhalation, removes irritant
Explain the carina, bronchi, bronchioles, terminal bronchioles
-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
Explain parasympathetic vs sympathetic stimulation
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
Explain the 2 types of alveoli cells
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
Explain the function of different collagen types in the alveoli
-1 + 3 = structural integrity of the alveolar walls
-4 = stability + tensile strength to very thin basement membrane (separates alveolar + capillary epithelium)
Explain collateral ventilation, the pores of kohn+ channels of lambert
- 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