Respiratory Flashcards
What other body system does the respiratory system work closest with?
The cardiovascular system
What defines the lungs into lobes?
Fissures
How many lobes does the left lung have and what are they called?
Two
Superior and Inferior lobe (due to cardiac notch)
How many lobes does the right lung have and what are they called?
Three
- Superior
- Middle
- Inferior
Which primary bronchus is the largest?
The right
List the bronchial tree
Trachea > Primary Bronchi > Secondary > Tertiary > Bronchioles > Terminal Bronchioles
What epithelium is the trachea made up of?
pseudostratified columnar epithelium with goblet cells
What supports the trachea and what are the 2 main functions?
C rings of hyaline cartilage
- Prevents collapse
- Allows for expansion
What epithelium are the bronchial airways made up of?
Ciliated columnar epithelium with goblet cells
What do the bronchial airways do?
Conduct air deep into lungs
What do the terminal bronchioles branch/subdivide into?
Respiratory bronchioles
What two epithelium are the terminal bronchioles made of?
Simple cuboidal
Simple squamous
What are alveoli?
Microscopic air sacs where gas exchange occurs
What are the two types of cell in the alveoli?
Type I and Type II
What function do type I cells in the alveoli serve?
They form a continuous lining and are the main site of gas exchange
What function do type II cells in the alveoli serve?
These are septal cells that secrete alveolar fluid (including surfactant) which reduces surface tension preventing alveolar collapse
How thick is the respiratory membrane?
0.5 micrometres
What 3 things is the respiratory membrane made up of?
Alveolar cells Endothelium Connective Tissue (CT)
What happens at the respiratory membrane?
Gas exchange
What is ventilation?
The process of breathing
What are the two parts of ventilation?
- Inhalation (atmosphere to lungs)
- Exhalation (lungs to atmosphere)
How is ventilation achieved?
Due to pressure differences and the contraction and relaxation of respiratory muscles
How is inhalation achieved (rib cage and diaphragm)?
Rib cage up and out
Diaphragm down
To expand thoracic volume
How is exhalation achieved (rib cage and diaphragm)?
Rib cage down and in Diaphragm up (relaxes) To decrease thoracic volume
How does pressure change as volume increases?
Pressure decreases
What law governs pressure and volume?
Boyles law (pressure x volume = constant)
What is the equation for Boyles law?
P1V1 = P2V2 OR PV = K
What three factors affect ventilation?
- Alveolar surface tension
- Lung compliance
- Airway resistance
How does alveolar surface tension affect ventilation?
Fluid/surfactant reduces surface tension to allow for easier alveolar inflation
How does lung compliance affect ventilation?
High compliance is normal allowing for easy ventilation
Low compliance in disease states
How does airway resistance affect ventilation?
As diameter decreases, airflow resistance increases and leads to reduction in ventilation.
What conditions can cause increased airway resistance?
- Asthma (smooth muscle contraction)
- Bronchitis (inflammation and musuc)
- Emphysema (loss of elastic tissues)
What is a normal tidal volume Vt?
500ml
How much air is contained within ‘dead space’ each breath?
150ml
How do gases move from the air to blood and back?
Diffusion
What is partial pressure?
The pressure exerted by gases in air
~ how much of air is made up of oxygen?
21%
What does partial pressure difference determine?
The direction gases move in
What is the PO2 in venous blood compared to arterial blood?
Venous - 40mmHg
Arterial - 100mmHg
What is the PO2 in the atmosphere compared to the alveoli?
Atm - 159mmHg
Alveoli - 105mmHg
What is the PCO2 in the atmosphere compared to the alveoli?
atm - 0.3mmHg
Alveoli - 40mmHg
What is the PCO2 in venous blood compared to arterial blood?
Venous - 45mmHg
Arterial - 40mmHg
What two ways are oxygen carried around in the blood?
Dissolved in water (3ml/l)
Bound to haemoglobin (197ml/l)
What are the two components of haemoglobin?
Haem (pigment)
Globin (protein)
What is at the centre of each haem molecule?
Iron
How many oxygen molecules can potentially be carried by one Hb molecule
Four
What is the compound called when oxygen and haemoglobin are bound together?
Oxyhaemoglobin
What determines the level of oxygen saturation in the blood?
PO2 in the blood
What happens to O2 binding when pH becomes more acidic?
Less O2 binds to haemoglobin
What does the acidic environment at the tissues allow?
Delivery of O2 to the tissues
Where in the body is less acidic and what does it allow?
Lungs
Allows O2 to be picked up
What 3 ways are CO2 molecules transported in the blood?
- Dissolved in water (8%)
- Bound to Hb (carbaminohaemoglobin) (25%)
- Transported by HCO3 in plasma (67%)
What do central chemoreceptors respond to?
Changes in PCO2
What do peripheral chemoreceptors respond to?
Changes in PO2
Where is the respiratory control centre?
Brainstem
Where is the central chemoreceptor?
Medulla (brainstem)
Where are the peripheral chemoreceptors?
Aortic bodies (aortic arch) Carotid bodies
What does the respiratory centre end up doing?
Changing the activity of respiratory muscles
