What are the functions of the respiratory system?
What are the contents of the upper and lower respiratory tract?
Gaseous exchange, acid-base equilibrium, phonation, warming/humidification/filtration of gas (concha bones make air spin), defence (airbourne pathogens)
URT: oropharynx and larynx (non-respiratory)
LRT: 1) conducting airways (trachea and bronchi, non-respiratory) 2) gas exchange tissue (alveoli and terminal bronchioles, respiratory)
How many times does the airway tree divide?
Which are the conducting airways, and the respiratory zone?
Roughly how many alveolar ducts are there per lung, and what do they divide to?
Where does gas exchange occur?
How many albeoli in the lungs?
CA: first 16, RZ: last 7
8 million, divide to terminal alveolar sacs
Alveolar sacs, ducts and bronchioles
What happens to the inward velocity of gas during inspiration as you go down the respiratory tree?
What is the volume of the conducting airways?
Define 'dead space gas'.
What type of epithelial cell is present in the conducting airways?
Becomes very small.
Exhale - have to breathe out volume of conducting airways first before you exhale alveolar gas - this gas = DSG.
Ciliated pseudostratified columnar epithelium
Label A-D in a conducting airway.
A: columnar cells
C: goblet cell
NB. in lower condicting airways (bronchioles), simple epithelium only. Epithelium EXCEPT ALVEOLAR is covered with mucus
Describe the 2 types of epithelial cells.
What types of mobile cells are also present in high proportions in the alveoli?
Type 1 pneumatocytes: 90%, simple squamous
Type 2 pneumatocytes: 10%, cuboidal cells, secrete surfactant
Macrophages ("dust cells")
Label A-C in the lungs
A: ciliated cell
B: goblet cell
C: connective tissue
What is surfactant?
Alveoli lined with water and dissolved surfactant = decreases surface tension and stops alveoli collapsing during exhalation (air pressure decreases)
Label A-C in the alveoli
A: Type 1 pneumatocyte
B: Type 2 pneumatocyte
C: Alveolar macrophage (b/c mucus would compromise gas exchange, so no mucus but macrophages instead)
What is the formular for partial pressure of gas A?
What is the pO2 in dry inspired air?
To calculate pO2 of alveolar gas, what do you need to allow for and why?
What are the rough values of pO2 and pCO2 in the alveoli?
pA = total pressure in gas mixture x fractional concentration of A
Total pressure is atm (760mmHg) and fractional conc is 21%, so pO2 = 760 x 0.21 = 160mmHg
Account for H2O vapour in inspiration (44mmHg) b/c it decreases partial pressures of other gases, making pO2 = 155mmHg
pO2: 100mmHg pCO2: 40mmHg
What are rough values for A and B?
A: pO2: 40 pCO2: 46
B: pO2: 95 pCO2: 40
What happens to pO2 at altitude and why?
respiratory rate/depth increases; O2 fraction stays the same but total pressure decreases
What are the 3 most common respiratory diseases?
List some others.
List some infectious respiratory diseases.
Bronchitis, emphysema, pneumonia (fluid build up in alveoli so O2 diffusion compromised)
Asthma, COPD (chronic bronchitis + emphysema), tumors, pulmonary fibrosis, occupational lung disease, disorders of chest wall, pleura and diaphragm e.g. pneumothorax etc.
Common cold (acute coryza), influenza, pneumonia, pulmonary TB
What percentage of all acute illnesses are acute viral respiratory illnesses?
What percentage of GP consultations are respiratory?
What 3 factors are interlinked and affect respiratory disease?
1/2 or more e.g. adenovirus, rhinovirus
social (housing, smoking, travel, drugs), environmental (pollution, dust mites), occupational (allergies, chemical exposure)