Introduction to the lungs (28) Flashcards
How does the structure of the left and right lung differ?
- right lung has 3 lobes: superior lobe, middle lobe and inferior lobe
- left lung has 2: superior lobe and inferior lobe
What is the name of the type of branching in the airways?
dichotomous
What is the carina?
the point at which the trachea splits into the 2 main bronchi (left- more vertical, and right)
When do the bronchioles occur?
after the first 3 generations of bronchi
- -> airways narrow
- -> no cartilage
- -> conducting bronchioles, terminal bronchioles, respiratory bronchioles (–> alveolar ducts)
What are the basic functions of the respiratory airways?
conduit/pipes to
- conduct oxygen to the alveoli
and - conduct CO2 out of the lung
^gas exchange
What is the structure of the alveolar wall?
- no cilia or smooth muscle
- pneumocytes: type 1 and type 2
What is the structure of the alveolar wall?
- no cilia or smooth muscle
- pneumocytes: type 1 (fewer, but cover most of wall) and type 2
- alveolar macrophages (can engulf pathogens and move up to mucociliary escalator)
What glues together the pneumocytes and capillaries at the alveoli?
basement membrane
What is the pharynx?
a common passageway for food, liquids, and air
What are the nasal conchae?
- highly vascular
- contribute to warming and humidification of intranasally inhaled air
What is the purpose of the nasal hairs?
to trap large particles of dust and pollen, as well as bacteria
What are the 3 regions of the pharynx?
- nasopharynx
- oropharynx
- laryngopharynx
What is the organisation inside the airway walls?
- layer of mucus
- cilia
- columnar ciliated epithelium w/ goblet cells (fewer)
- basement membrane
- submucosal gland
- smooth muscle (when it contracts, it squeezes mucosal glands)
What are the lining cells in the airways?
- ciliated
- intermediate
- brush
- basal
What are the contractile cells in the airways?
- smooth muscle (airway, vasculature)
What are the secretory cells in the airways?
- goblet (epithelium)
- mucous
- serous (glands)
What are the connective tissue cells in the airways?
- fibroblast
- interstitial cell (elastin, collagen, cartilage)
What are the neuroendocrine cells in the airways?
- nerves
- ganglia
- neuroendocrine cells
- neuroepithelial bodies
What are the vascular cells in the airways?
- endothelial
- pericyte
- plasma cell (+ smooth muscle)
What are the immune cells in the airways?
- mast cell
- dendritic cell
- lymphocyte
- eosinophil
- macrophage
- neutrophil
What is the arrangement of the submucosal glands in the airways?
- mucus cells (in the submucosal gland) secrete mucus
- serous cells in the gland secrete anti-bacterial enzymes
- water and salts also secreted
What are the functions of the airway epithelium?
- secretion of the components of mucus: mucins, water and electrolytes
- movement of mucus by cilia (mucociliary clearance)
- physical barrier
- production of regulatory and inflammatory mediators: NO, CO, arachidonic acid metabolites, chemokines and cytokines, proteases
What is the 9+2 relationship in individual cilia?
- 9 pairs of microtubules on outside, bound together
- 2 pairs of microtubules in middle, not bound together
How do cilia beat?
in a metachronal rhythm
- hydrolysis of ATP causes thin dynein arms to take steps towards the minus end of the neighbouring doublet, generating a sliding force that can slide doublets apart if crosslinks are removed
What are the 3 main functions of airway smooth muscle?
- structure: inflammation stimulates proliferation–> hypertrophy and hyperplasia
- tone: contraction/relaxation
- secretion: inflammatory mediators, cytokines, chemokines
What do smooth muscle cells secrete in response to cytokines?
- NOS–> produce NO
- COS–> produce prostaglandins
^^inflammatory mediators - immune cell recruiters: cytokines, chemokines, adhesion molecules
What blood vessels return to the heart from tracheal circulation?
systemic veins
What blood vessels return to the heart from bronchial circulation?
bronchial and pulmonary veins
What are the functions of the tracheo-bronchial circulation?
- good gas exchange between airway tissues and the blood (N.B. not pulmonary circulation )
- warming of inspired air
- humidification of inspired air
- clears inflammatory mediators
- clears inhaled drugs
- supplies airway tissue+ lumen w/ inflammatory cells and proteinaceous plasma
What is the effect of adrenaline on airways?
relaxation bc in response to stress, need to breathe more deeply
What is the effect of NO on airway smooth muscle?
relaxation
What is the effect of acetylcholine on the airway?
relaxation/dilation
What respiratory diseases are associated with loss of airway control?
asthma, COPD, CF
What is asthma?
a clinical syndrome characterised by increased airway ‘responsiveness’ to a variety of stimuli–> airway obstruction- varies over short periods of time, reversible spontaneously or w/ drugs
- dyspnoea (shortness of breath), wheezing and cough (mild to severe)
- airway inflammation–> airway remodelling
What is airway remodelling?
- structural changes due to/alongside chronic airway inflammation
- alterations in the airway epithelium, lamina propria, and submucosa–> leading to thickening of airway wall
How does an asthmatic bronchial layer differ from a normal one?
- inc. mucus and goblet cells
- inc. eosinophils in mucus and tissue
- thicker basement membrane
- inc. mast cells in lamina propria–> more histamine
- inc. neutrophils–> inflammation
- smooth muscle cell hypertrophy
What are the 3 main characteristics of asthma?
- airflow obstruction
- bronchohyperresponsiveness
- inflammation
What are symptoms of asthma?
- shortness of breath
- wheeze
- chest tightness
- dry, irritating cough
What is the role of T-helper 2 cells in asthma?
promote humoral immunity–> IgE antibody production–> inc. mast cell activity
